Walz Credit - www.spacefacts.de

Personal: Male, Married, Two children. Born in Cleveland, Ohio, USA. US Air Force US Air Force

Astronaut Career

Astronaut Group: NASA Group 13 - 1990. Active Entered space service: 17 January 1990. Number of Flights: 4.00. Total Time: 230.54 days. Number of EVAs: 3.00. Total EVA Time: 0.68 days.

NAME: Carl E. Walz (Lieutenant Colonel, USAF)

NASA Astronaut

PERSONAL DATA:

Born September 6, 1955, in Cleveland, Ohio. Married to the former Pamela J. Glady of Lyndhurst, Ohio. They have two children. He enjoys piano and vocal music, sports, and is lead singer for the Max Q rock-n-roll band.

EDUCATION:

Graduated from Charles F. Brush High School, Lyndhurst, Ohio, in 1973; received a bachelor of science degree in physics from Kent State University, Ohio, in 1977, and a master of science in solid state physics from John Carroll University, Ohio, in 1979.

ORGANIZATIONS:

American Legion.

SPECIAL HONORS:

Graduated Summa Cum Laude from Kent State University. Awarded the Defense Superior Service Medal, the USAF Meritorious Service Medal with one Oak Leaf Cluster, the Defense Meritorious Service Medal, the USAF Commendation Medal, and the USAF Achievement Medal with one Oak Leaf Cluster. Distinguished Graduate from the USAF Test Pilot School, Class 83A. Inducted into the Ohio Veterans Hall of Fame. Awarded three NASA Space Flight Medals and the NASA Exceptional Service Medal..

EXPERIENCE:

From 1979 to 1982, Walz was a Radiochemical Project Officer, responsible for analysis of radioactive samples from the Atomic Energy Detection System at the 1155th Technical Operations Squadron, McClellan Air Force Base, California. The subsequent year was spent in study as a Flight Test Engineer at the USAF Test Pilot School, Edwards Air Force Base, California. From January 1984 to June 1987, Walz was assigned as a Flight Test Engineer to the F-16 Combined Test Force at Edwards Air Force Base, where he worked on a variety of F-16C airframe avionics and armament development programs. He logged over 250 flight test hours in the F-16. In July 1987, he served as a Flight Test Manager at Detachment 3, Air Force Flight Test Center.

Selected by NASA in January 1990, Walz is a veteran of three space flights, and has logged over 833 hours (34.5 days) in space. He served as a mission specialist on STS-51 (September 12-22, 1993), was the Orbiter flight engineer (MS-2) on STS-65 (July 8-23, 1994), and was a mission specialist on STS-79 (September 16-26, 1996).

On STS-51, the crew of five aboard Space Shuttle Discovery deployed the U.S. Advanced Communications Technology Satellite (ACTS), and the Shuttle Pallet Satellite (SPAS) with NASA and German scientific experiments aboard. Walz also participated in a 7-hour space walk (EVA) to evaluate tools for the Hubble Space Telescope servicing mission. Following 158 orbits of the Earth, the mission concluded with the first night landing at the Kennedy Space Center. Mission duration was 9 days, 22 hours, and 12 minutes.

On STS-65, the crew of seven aboard Space Shuttle Columbia flew the second International Microgravity Laboratory (IML-2) spacelab module. During the 15-day flight the crew conducted more than 80 experiments focusing on materials and life sciences research in microgravity. The mission completed 236 orbits of the Earth, traveling 6.1 million miles, setting a new flight duration record for the Shuttle program.

Most recently, on STS-79, the six member crew aboard the Shuttle Atlantis docked with the Russian MIR station, delivered food, water, U.S. scientific experiments and Russian equipment, and exchanged NASA long duration crewmembers - bringing John Blaha to Mir and returning Shannon Lucid to Earth. During this mission, the Atlantis/Mir complex set a record for docked mass in space. STS-79 was the first flight of the double Spacehab module, and landed at KSC after a highly successful flight of 10 days 3 hours and 13 minutes.

• 12 September 1993 Flight: STS-51. Flight Up: STS-51. Flight Back: STS-51. Flight Time: 9.84 days.

• 8 July 1994 Flight: STS-65. Flight Up: STS-65. Flight Back: STS-65. Flight Time: 14.75 days.

• 16 September 1996 Flight: STS-79. Flight Up: STS-79. Flight Back: STS-79. Flight Time: 10.14 days.

• 5 December 2001 Flight: ISS EO-4. Flight Up: STS-108. Flight Back: STS-111. Flight Time: 195.82 days.

17 January 1990 - NASA Astronaut Training Group 13 selected.. The group was selected to provide pilot, engineer, and scientist astronauts for space shuttle flights.. Qualifications: Pilots: Bachelor's degree in engineering, biological science, physical science or mathematics. Advanced degree desirable. At least 1,000 flight-hours of pilot-in-command time. Flight test experience desirable. Excellent health. Vision minimum 20/50 uncorrected, correctable to 20/20 vision; maximum sitting blood pressure 140/90. Height between 163 and 193 cm.

Mission Specialists: Bachelor's degree in engineering, biological science, physical science or mathematics and minimum three years of related experience or an advanced degree. Vision minimum 20/150 uncorrected, correctable to 20/20. Maximum sitting blood pressure of 140/90. Height between 150 and 193 cm.. Reported to the Johnson Space Center in late July 1990 to begin their year long training. Chosen from 1945 qualified applicants, then 106 finalists screened between September and November 1989.

Engineers at the Mission Control Center outside of Moscow conducted a series of tests and verified that the exterior connections made by Commander Frank Culbertson and Pilot Vladimir Dezhurov during Monday's space walk had successfully brought the Pirs Docking Compartment's automated Kurs telemetry system to full functionality.

With the help of Flight Engineer Mikhail Tyurin, they spent Wednesday cleaning up, servicing and storing the Orlan spacesuits they had used on the 5-hour, 4-minute space walk. They also spent about 20 minutes answering questions posed by middle school students in Texas and Kansas as part of a regional education conference.

With those activities complete, the trio of space researchers began getting ready for a series of comings and goings, and packing for their impending return home. The Progress 5 resupply craft currently docked to the Zvezda service module is scheduled to undock Nov. 22; it later will be commanded to re-enter the Earth's atmosphere where it will burn up along with refuse being stored inside by the crew this week. Another supply vehicle, Progress 6, is scheduled to launch Nov. 26 from the Baikonur Cosmodrome in Kazakhstan and dock with the station Nov. 28.

All preparations for the launch of Space Shuttle Endeavour and the Expedition Four crew - Commander Yuri Onufrienko and Flight Engineers Dan Bursch and Carl Walz - are on schedule for launch at 6:42 p.m. CST Nov. 29. Mission managers will meet at Kennedy Space Center this Thursday to review all preparations for launch; an official launch target is expected at the conclusion of that meeting. The shuttle crew - Commander Dom Gorie, Pilot Mark Kelly and Mission Specialists Linda Godwin and Dan Tani - joined the new station crew in Florida for a final dress rehearsal of the launch last week.

While visiting the station, the shuttle crew will conduct a space walk to install insulation blankets on the beta gimbal assemblies for the station's large solar array wings. These large swivels, which allow the solar arrays to track the Sun's rays and provide maximum power generation, appear to be experiencing adverse effects related to the extreme temperature swings that occur as the station moves in and out of direct sunlight. These multi-layer insulation blankets are expected to reduce the temperature swings and allow normal operation of the solar arrays.

Meanwhile in Florida, the next major component to be launched to the space station has successfully completed acceptance testing and been moved to a work platform for final closeouts. One last software test remains, and that will be completed in January. The S-zero truss, which will serve as the base section of a framework connecting more large solar array wings, is scheduled for launch on STS-110 in March 2002.

With systems operating normally, the station is orbiting at an average altitude of 247 statute miles (397 km).

Science work aboard the station continues with emphasis on human physiology experiments as the crew nears the end of its time on orbit, and with autonomous microgravity materials research. Overall coordination of the research is the responsibility of the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, Ala. The Human Research Facility is managed by the Johnson Space Center.

The Progress, attached to the docking port at the rear of the Zvezda service module, is the fifth to visit the station. It will undock at 10:06 a.m. CST Thursday, to be deorbited and burn up in the atmosphere with its load of trash and unneeded equipment. Its undocking makes room for Progress 6, scheduled for launch from the Baikonur Cosmodrome in Kazakhstan at 12:24 p.m. CST Monday. The new Progress, filled with fresh supplies, is planned to dock to the station at 1:45 p.m. on Wednesday, Nov. 28.

The Expedition Three trio also began preparations for their return home after about four months in space. They began packing up gear and readying station equipment in anticipation of the arrival of the space shuttle Endeavour, targeted for a launch to the space station from Kennedy Space Center on Nov. 29 at 6:41 p.m. CST on the STS-108 mission. Endeavour is commanded by Dom Gorie. Pilot is Mark Kelly and Mission Specialists are Linda Godwin and Dan Tani.

The major purpose of the mission is bring the Expedition Four crew, cosmonaut and Commander Yury Onufrienko and Astronauts Dan Bursch and Carl Walz, to the station and bring home Expedition Three. Also during the flight, Godwin and Tani will do a spacewalk to install thermal blankets over the station's beta gimbal assemblies of the orbiting laboratory's solar wings, which stretch 240 feet from tip to tip. The assemblies let the wings track the sun to provide maximum power.

Flight controllers at Houston's Mission Control Center have seen in those mechanisms occasional unexpected surges in the power required to turn the wings. They believe the surges are related to extreme temperature swings that occur as the station moves in and out of direct sunlight. Installation of the blankets is expected to reduce the temperature fluctuations and eliminate the "power spikes" seen as the wings pivot.

The spacewalkers will go out of Endeavour's airlock, then get a 50-foot lift from the shuttle's robotic arm. They will have to climb with the blankets another 30 feet to the worksite, atop the P6 Truss and about 80 feet from Endeavour's cargo bay.

With systems operating normally, the station is orbiting at an average altitude of 247 statute miles (397 km).

Human physiology experiments continue to be a focus of crew science activities as the crew prepares for its return home. Autonomous microgravity materials research continued to accumulate scientific experiment run time hours in a variety of disciplines. Overall coordination of the research is the responsibility of the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, Ala. The Human Research Facility is managed by the Johnson Space Center.

At 12:24 p.m. CST (1824 GMT) today, the Progress 6 resupply craft, filled with fresh supplies for the station, launched from the Baikonur Cosmodrome in Kazakhstan and successfully reached orbit nine minutes later. Progress 6 is planned to dock to the station Wednesday at 1:40 p.m. CST (1940 GMT). The Progress 5 capsule that was attached to the docking port at the rear of the Zvezda service module undocked from the station last Thursday and reentered the atmosphere, where it was destroyed.

Today, the crew also tested a manual docking system, called the TORU, which can be used should the Progress 6 experience any problems with its automated docking system as it approaches the aft docking port of the Zvezda Service Module Wednesday. The crew also prepared some of the spacewalking equipment that will be used by STS-108 astronauts Linda Godwin and Dan Tani. Godwin and Tani will conduct a 4-hour spacewalk next week with Endeavour docked to the ISS to install thermal blankets over the station's mechanisms which enable the large U.S. solar wings to rotate to track the sun for the manufacture of electricity for station systems.

Flight controllers at Houston's Mission Control Center have seen those mechanisms experience occasional unexpected surges in the power required to turn the wings. They believe the surges are related to extreme temperature swings that occur as the station moves in and out of direct sunlight. Installation of the blankets is expected to reduce the temperature fluctuations and eliminate the "power spikes" seen as the wings pivot.

The major purpose of the 108 mission, however, is to bring the Expedition Four crew, Russian Commander Yury Onufrienko and U.S. Astronauts Dan Bursch and Carl Walz, to the station and bring home Expedition Three.

With systems operating normally, the station is orbiting at an average altitude of 247 statute miles (397 km).

Human physiology experiments continue to be a focus of crew science activities as the crew prepares for its return home. Autonomous microgravity materials research continued to accumulate scientific experiment run time hours in a variety of disciplines.

The Progress 6 craft, which launched from the Baikonur Cosmodrome in Kazakhstan Monday, gently docked to the aft port of the Zvezda Service Module over Central Asia at 1:43 p.m. CST, completing a two-day automated flight.

On board the station, Expedition Three Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin monitored the docking, and prepared for the opening of the hatch between Zvezda and Progress later today.

The Progress is carrying more than a ton of food, fuel and equipment for the Expedition Four crew, Russian Commander Yury Onufrienko and U.S. Astronauts Dan Bursch and Carl Walz, who are scheduled to be launched aboard the shuttle Endeavour tomorrow night on the STS-108 mission to relieve the Expedition Three crew, which has been in orbit since August. They will be ferried to the ISS by Endeavour Commander Dom Gorie, Pilot Mark Kelly and Mission Specialists Linda Godwin and Dan Tani. Launch from the Kennedy Space Center is scheduled for 6:41 p.m. CST.

With systems operating normally, the station is orbiting at an average altitude of 247 statute miles (397 km).

Human physiology experiments continue to be a focus of crew science activities as the crew prepares for its return home. Autonomous microgravity materials research continued to accumulate scientific experiment run time hours in a variety of disciplines. Overall coordination of the research is the responsibility of the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, Ala. The Human Research Facility is managed by the Johnson Space Center.

STS-108 cargo bay payload was dominated by the Raffaello (MPLM-2) logistics module with 4 RSP and 8 RSR resupply racks. Also in the cargo bay were the MACH-1 and LMC experiment trusses flown under the Goddard small payloads program. MACH-1 was an MPESS-type Hitchhiker bridge carrying the CAPL-3 capillary thermal control experiment on top. On its forward side was the Starshine-2 launch canister, the CAPL-3 avionics plate, the Hitchhiker avionics plate, and the SEM-15 canister. On the aft side was the G-761 canister containing experiments from Argentina, the PSRD synchrotron detector (a prototype for the AMS antimatter experiment which will fly on Station later), and the COLLIDE-2 and SEM-11 canisters. The SEM (Space Experiment Modules) are collections of high school experiments. LMC, the Lightweight MPESS Carrier carried four canisters with materials science and technology experiments: SEM-12, G-785, G-064 and G-730. In addition, an adapter beam on the starboard sidewall carried G-221 and G-775, with materials science and biology experiments.

Raffaello was transferred back to the Shuttle payload bay on December 14. Endeavour undocked from the Station at 17:28 UTC on December 15 and made a half loop around the station before making a small separation burn at 1822 UTC. The Starshine-2 reflector satellite was ejected from the MACH-1 bridge in Endeavour's payload bay at 1502 UTC on December 16. Endeavour landed on runway 15 at Kennedy Space Center at 1755 UTC on December 17. The Expedition 3 crew of Culbertson, Dezhurov and Tyurin returned to Earth aboard Endeavour, leaving the Expedition 4 crew of Onufrienko, Bursch and Walz in charge of the Station.

The station was about 250 statute miles above the central Indian Ocean as Endeavour rocketed away from Launch Pad 39-B at the Kennedy Space Center, FL, on time at 4:19 p.m. CST. Endeavour will close in on the station for the next two days and dock with the complex on Friday to begin a week-long stay.

Endeavour is commanded by Dom Gorie with Mark Kelly serving as pilot. Mission Specialists are Linda Godwin and Dan Tani. Also aboard Endeavour are station Expedition Four crew members Commander Yuri Onufrienko and Flight Engineers Carl Walz and Dan Bursch, who are beginning more than five months in orbit.

Endeavour will bring home the Expedition Three station crew, Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin, who have been aboard the station since mid-August. In addition to the new crew, Endeavour is carrying more than three tons of food, supplies and equipment in the Raffaello logistics module to the orbiting outpost.

Endeavour's crew will spend the next few hours unpacking equipment, setting up computers and conducting the first of periodic engine firings that will occur over the next two days to refine the shuttle's approach to the station. The shuttle crew will begin a sleep period at 11:19 p.m. CST and will be awakened at 7:19 a.m. CST Thursday. On Thursday, Endeavour's crew will check out the shuttle's equipment and systems that will be needed for Friday's final approach and docking to the International Space Station. Docking is planned for just after 2 p.m. CST Friday. On Saturday, the Raffaello module will be lifted from the shuttle payload bay using Endeavour's robotic arm and attached to a station berthing port to be unloaded. Godwin and Tani are planned to conduct a four-hour space walk on Monday to install insulation around two solar array rotation mechanisms. Raffaello will be returned to the shuttle payload bay later in the mission and brought back to Earth.

In addition to a new station crew and supplies, Endeavour is carrying a host of scientific investigations, including experiments from space agencies, schools and universities across the United States, Europe and South America as well as a small satellite that has involved more than 25,000 students in 26 countries.

The crew, Commander Dom Gorie, Pilot Mark Kelly, Mission Specialists Linda Godwin and Dan Tani, Expedition Four Commander Yury Onufrienko, Flight Engineer Carl Walz and Flight Engineer Dan Bursch, was awakened by the song "Soul Spirit" and "Put a Little Love in Your Life," sung by Bursch's daughter and her second-grade classmates.

The crew will spend the day preparing shuttle systems for docking with the International Space Station, which is scheduled for about 2 p.m. CST Friday. Preparations include powering up the shuttle's robotic arm and checking out the airlock and the space suits that will be used on Monday's planned four-hour spacewalk by Godwin and Tani to place thermal blankets on the motors that rotate the solar arrays atop the P6 truss.

In addition to performing the spacewalk, other activities during the mission include a crew exchange on board the space station Saturday and the transfer of more than three tons of cargo. The cargo, housed in the Raffaello logistics module that will be attached to the Unity module, includes food, supplies and equipment that the Expedition Four Crew will use during its stay on the station. The Expedition Three crew, Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin have been living aboard the space station since mid-August and will return home on Endeavour.

Also on board Endeavour is a host of scientific investigations, including experiments from other space agencies, schools and universities across the United States, Europe and South America. Two experiments located in the Multiple Application Customized Hitchhiker-1 (MACH-1) in the shuttle payload bay had already completed 15% and 10% of their mission objectives by the time the crew went to sleep last night. Those experiments are the Capillary Pumped Loop Experiment (CAPL) and the Prototype Synchrotron Radiation Detector (PSRD) respectively. The CAPL demonstrates a multiple evaporator capillary pumped loop system and the PSRD measures cosmic ray background data.

With the new Expedition Four station crew of Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch looking on from Endeavour's flight deck, shuttle Commander Dom Gorie brought Endeavour to a gentle linkup with the ISS at 2:03 p.m. CST as the two craft sailed over England. Within minutes, Pilot Mark Kelly and Mission Specialists Linda Godwin and Dan Tani began to conduct post-docking checks of the mechanical interface between Endeavour and the station's Destiny Laboratory prior to the opening of the hatches on the two vehicles. At first, the shuttle's docking ring and the docking mechanism on the ISS did not align properly, but after allowing the two craft to dampen their relative motion against one another, the vehicles were hard mated for a week of joint operations by the ten crewmembers.

On board the ISS in their 119th day in space and their 116th day aboard the station, Expedition Three Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin watched as their replacements arrived for the start of more than five months of orbital duty. The only other visitors for the Expedition Three crew during its increment arrived on the ISS in October to deliver a new Soyuz return vehicle.

The hatches were opened between Endeavour and the ISS' Destiny Laboratory at 4:42 p.m. CST, enabling the ten crewmembers to greet one another. Onufrienko, Walz and Bursch will officially take over command of the ISS Saturday afternoon from Culbertson, Dezhurov and Tyurin after transferring custom made Soyuz seatliners and conducting leak checks to their spacesuits.

The crews now begin a busy week of handing over station responsibilities and unloading tons of supplies brought to the complex by Endeavour. Saturday's activities will be highlighted by Kelly's use of the shuttle's robotic arm to hoist the Italian-built Raffaello logistics module from Endeavour's payload bay and attach it to a station berthing port. Raffaello will stay attached to the station for most of the week while it is unloaded. The crews will begin a sleep period at 10:19 p.m. CST today and awaken at 6:19 a.m. CST on Saturday.

Endeavour's crew - Commander Dom Gorie, Pilot Mark Kelly, Mission Specialists Linda Godwin and Dan Tani, Expedition Four Commander Yury Onufrienko, and Flight Engineers Carl Walz and Dan Bursch - will quickly move into their final rendezvous activities today, bringing the shuttle to a position about 9 ½ miles behind the International Space Station about 11:44 a.m. today.

From that position behind the station, Gorie and Kelly will command Endeavour 's jets in a final major rendezvous maneuver to begin the final phase of the approach for docking. Endeavour will close the final miles to the station during the next orbit of the Earth, about 90 minutes.

As Endeavour approaches the station, the on-board rendezvous radar system will begin tracking the station providing distance and closing rate information to the crew. During the approach, the shuttle can perform up to four, small mid-course corrections at regular intervals. Just after the fourth burn, Endeavour will be about one-half mile below the station. Gorie will take over manual control of the approach, slowing Endeavour's approach and maneuvering to a point about 600 feet directly beneath the station. There he will begin a quarter-circle of the station, slowly moving to a position in front of the complex, in line with its direction of travel.

Once Endeavour has firmly docked to the station, and required leak checks are complete, the hatches between the spacecraft will open around 4 p.m. allowing Expedition Three Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin to greet their newest guests.

Culbertson, Dezhurov and Tyurin began their formal residency on the station on August 13 as their custom-made Soyuz seat liners were installed on the Soyuz return vehicle. Their residency will officially end once those seat liners are transferred to Endeavour and the Expedition Four crew's seat liners are installed in the Soyuz on Saturday.

Pilot Mark Kelly and Mission Specialist Linda Godwin will work together to remove the Raffaello Multi-Purpose Logistics Module from Endeavour's payload bay and attach it to the Unity node of the International Space Station. Over the course of about three hours, Kelly will use the shuttle's robotic arm to gently lift Raffaello from the payload bay and maneuver it into place, securing it to the Earth-facing berthing port on the Unity module about 12:39 p.m. CST today.

As Kelly works to install the Raffaello module, the formal exchange of space station crews will occur as the Expedition Three crew - Commander Frank Culbertson, Pilot Vladimir Dezhurov, and Flight Engineer Mikhail Tyurin - and the Expedition Four crew - Commander Yury Onufrienko, and Flight Engineers Carl Walz and Dan Bursch, exchange their customized seat liners in the Russian Soyuz spacecraft. As each Expedition Four crew member's seatliner is installed in the Soyuz and checked out, he officially becomes a resident of the space station with the Expedition Three crew member moving over to become a member of the Endeavour crew. Handover briefings between the crews will continue throughout docked operations.

Mission Specialist Dan Tani will focus his attention on transferring equipment from Endeavour to the space station while Commander Dom Gorie tends to vehicle operations.

The three commanders onboard - Gorie, Culbertson and Onufrienko - along with Endeavour's Pilot Kelly will participate in media interviews at 3:44 p.m. CST. MSNBC, CBS News and WAGT-TV in Augusta, Georgia will have the opportunity to interview the crewmembers in the station's Destiny laboratory.

Two payload bay experiments located in the Multiple Application Customized Hitchhiker-1 (MACH-1) facility have already completed 50% and 76% of their mission objectives. Those experiments are the Capillary Pumped Loop Experiment (CAPL) and the Prototype Synchrotron Radiation Detector (PSRD) respectively. The CAPL demonstrates a multiple evaporator capillary pumped loop system and the PSRD measures cosmic ray background data.

The transfer of the Expedition Four seatliners to the Soyuz return vehicle attached to the station marked the official exchange of crews. Culbertson reported that his crew had completed the exchange and that Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch had become official station residents at 4:11 p.m. CST. Handover briefings between the two crews will continue for the duration of docked operations.

While the crew exchange was under way, aboard Endeavour Pilot Mark Kelly and Mission Specialist Linda Godwin used the shuttle's robotic arm to lift the Raffaello Multi-Purpose Logistics Module from the shuttle payload bay and attach it to a berth on the station's Unity node. Raffaello was removed from the payload bay at 11:01 a.m. CST and secured in place on the station at 11:55 a.m. CST. The hatch to Raffaello was opened and the crews began unloading the cargo module just before 7:30 p.m. CST. Over the course of the next several days, the crews will work together to transfer approximately three tons of food and supplies from Raffaello to the station.

The crews will begin a sleep period at 10:19 p.m. CST and awaken at 6:19 a.m. CST Sunday. Sunday's work will focus on unloading Raffaello, continuing an exchange of information between the two station crews and some preparatory work for a space walk planned to take place Monday by shuttle astronauts Godwin and Dan Tani. Endeavour and the International Space Station remain in excellent condition with no significant systems problems of concern to Mission Control.

Aboard Endeavour are 6,000 small United States flags that will be distributed to heroes and families of the victims of the attacks after the shuttle returns to Earth. Also aboard are a U.S. flag that was found at the World Trade Center site after the attacks, a U.S. flag that has flown above the Pennsylvania state capitol, a U.S. Marine Corps Colors flag from the Pentagon, a New York Fire Department flag, and a poster that includes photographs of firefighters lost in the attacks.

Shuttle Commander Dom Gorie said the flag carried aboard Endeavour which came from the World Trade Center elicited especially poignant thoughts among the crew.

"This was found among the rubble and it has a few tears in it. You can still smell the ashes. It is a tremendous symbol of our country," Gorie said. "Just like our country, it was a little battered and bruised and torn, but with a little bit of repair it is going to fly as high and as beautiful as it ever did. And that is just what our country is doing."

International Space Station Expedition 3 Commander Frank Culbertson and his crew -- cosmonauts Vladimir Dezhurov and Mikhail Tyurin -- were in orbit Sept. 11 and will be on their way home to Earth when Endeavour departs the station next week. The space station flew above New York the morning of Sept. 11, and the crew could see evidence of the attacks out the windows.

"That was quite a disturbing sight, as you might imagine, to see my country under attack," Culbertson said. "All of us were affected by that day greatly.

"To all of those who lost loved ones, to all of those who worked so hard to help people survive, and to the people who are trying so hard to stop this threat, we wish you the best. We have thought about you often over the last three months that we've been here ... and we will continue to keep you in our thoughts," Culbertson added. "We will continue, I hope, to set a good example of how people can accomplish incredible things when they have the right goals. We will continue to think of how we can improve peace around the world and how we can improve knowledge, and hopefully that will bring people together."

While the unloading of almost three tons of new food, supplies and experiments continued today, Culbertson's crew also conducted a handover of station work to the oncoming Expedition Four crew -- Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz. Also today, Endeavour fired its steering jets gradually over the course of an hour to increase the station's altitude by about two statute miles, the first of three similar reboost maneuvers planned for this week's mission.

The hatches were closed between the shuttle and the station, with only the Expedition Four crew remaining aboard the station, at about 6:43 p.m. CST today in preparation for a space walk planned from the shuttle on Monday. Closing the hatch allows the cabin pressure on the shuttle to be lowered slightly, part of a protocol that protects space walkers from decompression sickness when they go to the low pressure, pure oxygen space suits.

Astronauts Linda Godwin and Dan Tani are scheduled to exit the shuttle airlock at 11:24 a.m. CST Monday to begin four hours of work outside to add insulation to mechanisms that rotate the station's solar arrays. After the space walk is completed Monday afternoon, the hatches between Endeavour and the station will be reopened.

The crews begin a sleep period at 10:19 p.m. today and awaken at 6:19 a.m. on Monday.

A New York firefighter presented Pilot Mark Kelly with today's wake-up music when Kelly visited the World Trade Center site with former NASA Administrator Dan Goldin shortly after the September 11 attacks. All the astronauts and cosmonauts on board Endeavour and the International Space Station will take time today to remember the victims, their families and rescue workers in a special message from space, at 4:24 p.m. CST today.

Commander Dom Gorie, Kelly, Mission Specialists Linda Godwin and Dan Tani, Expedition Three Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin, Expedition Four Commander Yury Onufrienko, and Flight Engineers Carl Walz and Dan Bursch will all gather in the Destiny laboratory aboard the station to display a U.S. flag and take a moment to honor the victim's families and survivors of the attacks.

Coordinated through the "Flags for Heroes and Families" campaign, which was initiated by Former NASA Administrator Dan Goldin, several American flags are being flown aboard the space shuttle Endeavour. Those flags include 6,000 small U.S. flags, one U.S. flag that was recovered from the debris of the World Trade Center, a Marine Corps flag that was retrieved from the Pentagon, and an American flag from the State of Pennsylvania. Also onboard, is a large New York Fire Department flag, 23 replica New York Police Department shields, and 91 New York Police Department patches. Those items are stowed away in the shuttle and will be distributed upon Endeavour's return to Earth.

The crew's activities today will focus on continuing transfer of several hundred pounds of equipment and supplies from the Raffaello Multi-Purpose Logistics Module that was attached to the station yesterday. Transfer of equipment, supplies and experiments to and from the shuttle mid deck is already complete. Today, Godwin and Tani will also check out and prepare the tools they will use for Monday's scheduled spacewalk.

The space walk went smoothly as Godwin and Tani installed insulation around the two barrel-shaped devices atop the station's five-story tall truss structure. The space walkers also attempted to secure one of four legs that brace the starboard station array, but they were unable to close the latch, which has been open since the array was installed a year ago. The other legs have always been latched securely and are sufficient.

On their way down from the top of the station, the two space walkers stopped at a stowage bin to retrieve a cover which had been removed from a station antenna during an earlier flight. The cover will be brought back to Earth and may be reused. Godwin and Tani also performed a "get-ahead" task, positioning two switches on the station's exterior to be installed on an upcoming shuttle mission, STS-110, that will deliver a central, 40-foot long truss section this spring. Godwin and Tani left Endeavour's airlock at 11:52 a.m. CST as the shuttle and station flew above the Pacific Ocean off the coast of South America. They ended the space walk at 4:04 p.m. CST.

Meanwhile, aboard the station, the Expedition Four crew -- Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz -- continued moving supplies to and from the Raffaello logistics module, now more than 70 percent unloaded. So far, at least 3,500 pounds of food and supplies have been moved from Raffaello to the station and another 1,000 pounds of gear and experiments have been moved to the station from Endeavour's cabin. The hatches between Endeavour and the station, closed late yesterday to prepare for today's space walk, were reopened just before 6 p.m. CST.

Today's space walk completes a record year with 18 space walks conducted: 12 originating from the shuttle and six from the station. That number eclipses the previous records for most space walks performed in a single year, a tie between the years 1973, when nine space walks were conducted from the Skylab space station, and 1997, when nine space walks were conducted from the shuttle and from the Russian Mir space station combined. The space walking record set this year is expected to be broken again next year -- in 2002, 22 space walks are planned from the shuttle and station.

The crews will begin a sleep period at 10:19 p.m. CST and Endeavour's crew will awaken at 6:19 a.m. CST Tuesday with the station crew awakening a half-hour later.

The focus of activities aboard Endeavour today will be on the planned four-hour spacewalk to be conducted by Godwin and Dan Tani. Godwin and Tani will exit the shuttle's airlock about 11:24 a.m. and will be carried about half way up the truss of the space station by the shuttle's robotic arm, operated by Pilot Mark Kelly. Commander Dom Gorie will coordinate efforts as the two spacewalkers maneuver hand-over-hand to their worksite location at the top of the P6 truss, some 80 feet above Endeavour's cargo bay.

The prime objective of the spacewalk is to place insulating blankets on the two Beta Gimbal Assemblies (BGA) that control the rotation of the solar arrays as they track the sun. The thermal blankets will protect the BGAs from temperature variances experienced in space, which has been leading to current spikes from the motors inside the BGAs. Once that task is complete, the spacewalkers will perform some get-ahead-tasks including retrieving tools from an outside pouch and bringing them inside for use during a spacewalk on the next mission to the space station early next year.

With hatches between the two spacecraft closed for today's space walk, the Expedition Four Crew, Commander Yury Onufrienko, and Flight Engineers Dan Bursch and Carl Walz will continue transferring equipment and supplies from the Raffaello Multi-Purpose Logistics Module to the station. This is the crewmembers' first day alone on the space station after exchanging places with the Expedition Three Crew, Commander Frank Culberston, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin, on Saturday.

Shortly after the crews onboard Endeavour and the International Space Station were awakened, they prepared to take a moment to pay tribute to those who lost their lives in the attacks on America on September 11, as part of President Bush's "Anthems of Remembrance" event. The event will take place at 7:46 a.m. CST, the exact moment of the attack three months ago.

The United States and Russian national anthems will be played in the shuttle and station flight control rooms in Mission Control and aboard the shuttle and the space station. The three commanders aboard the two spacecraft - Shuttle Commander Dom Gorie, Expedition Three Commander Frank Culbertson, and Expedition Four Commander Yury Onufrienko, will share their personal thoughts as well as play a special pre-recorded message from the rest of the crew currently in orbit.

Onufrienko, along with Expedition Three crew members Vladimir Dezhurov and Mikhail Tyurin, will take time today to talk with Russian media located at the mission control center outside Moscow in an interview scheduled to begin at 9:24 a.m. Later in the day, the full crews - Gorie, Onufrienko, Culbertson, Pilot Mark Kelly, Mission Specialists Linda Godwin and Dan Tani, Expedition Four flight engineers Carl Walz and Dan Bursch, along with Dezhurov and Tyurin - will have an opportunity to talk with American news media during a crew news conference scheduled for 2:04 p.m.

A ceremony to mark the change of command from Culbertson to Onufrienko will take place at 2:48 p.m. today. Culbertson, in his 123rd day in space, will ceremoniously pass command of the space station on to Onufrienko, its newest commander. The official crew exchange occurred Saturday, December 8 with the transfer of Soyuz seatliners for each crew member. Today's event continues the tradition begun by Expedition One Commander Bill Shepherd in March of this year, when he relinquished command of the ISS to Expedition Two Commander Yury Usachev.

The crews will also continue transferring equipment and supplies from the Raffaello Multi-Purpose Logistics Module to the space station for later use by the Expedition Four Crew. About 4,000 pounds of cargo has already been transferred from Raffaello to the station.

When the day began, the crews had already completed unloading more than 4,600 pounds of food, clothes, supplies and equipment from Raffaello, about 95 percent of the module's total cargo. They also had completed moving the 1,000 pounds of station gear and experiments that were launched in Endeavour's cabin to the orbiting complex.

In repacking the cargo module and Endeavour with unneeded equipment bound for Earth, the crews have loaded more than 1,800 pounds of material into Raffaello, almost half the amount expected by the time the packing is completed. Packing of Raffaello and Endeavour will continue on Thursday. On Friday, Raffaello will be detached from the station and moved back into Endeavour's payload bay for the trip home.

In addition, Endeavour's crew - Commander Dom Gorie, Pilot Mark Kelly, Mission Specialists Linda Godwin and Dan Tani, and offgoing station crew members Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin - assisted the new station Expedition Four crew in replacing most components of a station treadmill today. Expedition Four - Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz - will use the new treadmill almost daily during their five and a half months aboard the station. The job went smoothly and the crews finished several hours ahead of schedule, loading the old treadmill parts into Raffaello to be refurbished on Earth and, eventually, reused. A third and final scheduled reboost of the station by Endeavour also was completed today. The three boosts performed during the mission, each accomplished by a gradual, hour-long periodic firing of the shuttle steering jets, have raised the station's altitude by a total of almost 9 statute miles. The station's average altitude is now about 241 statute miles.

On Thursday, the crews will continue maintenance work as well as packing, replacing a faulty compressor in a Russian air conditioner on the station. Although the new crew officially took over aboard the station on Saturday, a formal handover ceremony also is planned for the two station crews at 2:04 p.m. CST Thursday.

The crews begin a sleep period at 10:19 p.m. CST today and awaken at 6:19 a.m. CST Thursday.

Flight Day 8 for Endeavour's crew began with a wake-up call from Mission Control offering a rendition of "Fly me to the Moon", sung by Oliver "Ollie" O'Regin for Dan Tani.

The astronauts and cosmonauts have transferred more than 5,000 pounds of supplies and material from Endeavour's middeck, and the Raffaello Multi-Purpose Logistics Module to the station. Today, the crews will focus on packing up the Raffaello module with items bound for a return trip to Earth. Raffaello will be detached from the Unity module of the station onFriday and reberthed in Endeavour's cargo bay for its ride home.

With a one-day extension to the mission, Endeavour's crew - Commander Dom Gorie, Pilot Mark Kelly and Mission Specialists Linda Godwin and Tani - will spend today assisting the Expedition Four crew - Commander Yury Onufrienko and Flight Engineers Expedition Dan Bursch and Carl Walz - with maintenance tasks on board the station, including the replacement of some of the components of the on-board treadmill. Tomorrow, the crew will replace a failed compressor in one of the air conditioners in the Zvezda Service Module. As the Expedition Three crew - Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin - prepare for a return to Earth on Monday, they continue a series of handover briefings to acquaint the newest resident crew with their orbital home.

Endeavour is currently scheduled to undock from the ISS on Saturday morning, with landing planned for early Monday afternoon at the Kennedy Space Center.

Today's agenda for the shuttle crew - Commander Dom Gorie, Pilot Mark Kelly, and Mission Specialists Dan Tani and Linda Godwin - will focus on packing up the Raffaello Multi-Purpose Logistics module with unneeded equipment and supplies for the return flight home. Raffaello will be detached from the Unity module of the International Space Station tomorrow and reberthed in Endeavour's cargo bay for its ride back to Earth. Endeavour is currently scheduled to undock from the station on Saturday morning, with landing planned for early Monday afternoon at the Kennedy Space Center.

The Expedition Three crew will also continue handover activities with the Expedition Four crew - Commander Yury Onufrienko, and Flight Engineers Dan Bursch and Carl Walz.

A ceremony to mark the change of command from Culbertson to Onufrienko will take place at 3:09 p.m. CST. Culbertson, in his 125th day in space, will formally hand command of the space station on to Onufrienko, it's newest commander. The official crew exchange occurred Saturday, December 8 with the transfer of Soyuz seatliners for each crew member. Today's event continues the tradition begun by Expedition One Commander Bill Shepherd in March of this year, when he relinquished command of the ISS to Expedition Two Commander Yury Usachev.

With the crew completing the stowage of Raffaello for the trip home, work to replace a faulty compressor in an air conditioner unit in the Zvezda Service Module was deferred until tomorrow morning, concurrent with the closing of the hatch to the Raffaello module prior to its detachment from the ISS.

The crew has already unloaded almost three tons of station food, clothes, experiments and other gear that was launched aboard Endeavour and Raffaello. Early today, the crews had also completed more than 70 percent of the repacking of Raffaello for the trip home, loading the cargo module with trash and gear from the offgoing station crew's mission such as individualized Soyuz space suits and seat liners.

The 10 astronauts and cosmonauts aboard the shuttle-station complex gathered this afternoon in the station's Destiny Laboratory for a formal change of command ceremony as Expedition Three ends and Expedition Four begins. The new crew officially took over duties aboard the station on Saturday. Expedition Three -- Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin -- spent 117 days as the station crew. Expedition Four -- Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz -- will remain aboard the complex until May 2002.

On Friday, the crews will close the hatch on Raffaello and Endeavour Pilot Mark Kelly will use the shuttle's robotic arm to detach it from the station and lower it back into the shuttle's payload bay to be brought back to Earth. The crews also will continue maintenance work on the station, replacing a faulty air conditioner compressor. Endeavour will undock from the station on Saturday.

Endeavour and the International Space Station remain in good shape, orbiting at an average altitude of 241 statute miles. Last night, the crew and Mission Control noted a transient problem with one of the shuttle's three inertial measurement units (IMUs), the primary navigation units for the shuttle. Only two of the three IMUs were on line at the time, with the third unit off line to save electricity. The IMU that experienced a problem, designated IMU 2, was immediately taken off line and the third IMU brought on line. IMU 2 has operated well since then, but it has remained off line and is considered failed by flight controllers. The loss of one IMU has no impact on Endeavour's mission, and the other two units are operating in excellent condition. Endeavour could operate well on only one IMU if needed.

Endeavour's crew will begin a sleep period at 9:19 p.m. CST today and awaken at 5:19 a.m. CST on Friday.

Endeavour will leave the station with a new crew and almost three tons of new food, supplies, experiments and equipment. Endeavour will bring home the offgoing Expedition Three station crew -- Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin -- and more than two tons of unneeded station gear, food containers, clothes, and other cargo. The station's Expedition Four crew -- Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz -- will remain aboard the outpost until May 2002.

Endeavour Pilot Mark Kelly used the shuttle's robotic arm to detach the Raffaello logistics carrier from the station today and reberth it in Endeavour's payload bay. Raffaello was latched back into the shuttle bay at 4:44 p.m. CST. This morning, Dezhurov and Onufrienko worked together to replace a faulty air conditioner compressor in the station's Zvezda living quarters module as the crews completed cargo transfer activities.

Flight controllers are planning slight changes to Endeavour's departure from the station Saturday, allowing time for a small jet firing by the shuttle to boost the station's future path away from a piece of space debris that could pass near the complex on Sunday. Mission Control was notified early today that a spent Russian rocket upper stage launched in the 1970s could pass within three miles of the station if Endeavour did not perform the engine firing. With the shuttle reboost now planned on Friday, the station is predicted to instead pass more than 40 miles away from the debris on Sunday.

The new plan for Saturday's activities will have the station and shuttle crews bid farewell to one another and close hatches between the two spacecraft at about 7:30 a.m. CST. Endeavour will pulse its steering jets gradually for about 30 minutes beginning at about 8:55 a.m. CST to raise the station's altitude by almost three-quarters of a mile. Endeavour will then undock from the station at about 10:37 a.m. CST. Because of the changes, Endeavour will not perform a full-circle flyaround of the station after undocking. Instead, Endeavour will undock from the station and fly only a quarter circle of the complex, to a point about 400 feet directly above the station where it will fire its engines at about 11:20 a.m. CST to depart the vicinity of the oribting outpost.

Endeavour's crew will begin a sleep period today at 8:19 p.m. CST and awaken at 4:17 a.m. CST Saturday.

Raffaello has been loaded with unneeded equipment, as well as gear from the returning Expedition Three crewmembers, including their custom Soyuz spacesuits and seat liners. The hatch between Raffaello and the space station will be closed about 10 a.m. CST today once final transfers are complete. About 1:20 p.m., Pilot Mark Kelly and Mission Specialist Linda Godwin will begin the process of detaching Raffaello from the station using the shuttle's 50-foot long robotic arm. The process of removing Raffaello from the station and carefully placing it back in Endeavour's payload bay is expected to be complete shortly after 3:30 p.m.

The two station commanders - Frank Culbertson and Yury Onufrienko - will continue their handover briefings even as they prepare for Endeavour's scheduled departure Saturday morning. Expedition Three crew member Vladimir Dezhurov will join Onufrienko in some final maintenance work on the station this morning replacing a faulty compressor in an air conditioner unit in the Zvezda Service Module.

All of the crew members - Endeavour Commander Dom Gorie, Kelly, Godwin and Dan Tani, along with Expedition Three crew members Culbertson, Dezhurov and Mikhail Tyurin and the Expedition Four crew, Onufrienko, Dan Bursch and Carl Walz - will meet late in the day today for a final briefing in preparation for Endeavour's departure tomorrow. Following final farewells tomorrow morning, about 7:30 a.m., the hatches between Endeavour and the station will be closed for a final time during this mission. Endeavour will undock from the station at 10 a.m. Saturday, and after a brief fly-around of the station, a final engine burn will mark Endeavour's departure from the station, leaving the Expedition Four crew on board for a planned five-month stay.

Endeavour's crew was awakened at 5:12 a.m. today by a traditional Russian song, "My Sweetheart," played for Onufrienko, Dezhurov and Tyurin. The Expedition Four crew was awakened about a half-hour later with a wake-up tone on board the station.

Endeavour and the International Space Station remain in good shape, orbiting at an average altitude of 241 statute miles. Wednesday, the crew and flight control teams noted a transient problem with one of the shuttle's three inertial measurement units (IMUs), the primary navigation units for the shuttle. That IMU, designated IMU2, experienced about an hour-long "drift rate," subsequently returning to normal operation. Flight controllers have taken IMU2 off line and declared it "failed," though it has performed normally since the initial problem was observed. The remaining two IMUs on board are performing well and the loss of a single IMU has no impact on Endeavour's mission or planned landing. Endeavour could operate well on only one IMU if required.

Endeavour is bringing home the Expedition Three crew - Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin - who have been in space since they launched to the station on August 10. In addition to bringing home the Expedition Three crew, Endeavour carried to orbit both a new crew and almost three tons of supplies and experiments to the station. That new crew, Expedition Four Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz, will remain aboard the space station until May.

The Endeavour astronauts were awakened for their 11th day in space at 4:17 a.m. by the song "Where I Come From," by Alan Jackson, for Pilot Mark Kelly from his family.

Overnight, flight controllers decided to execute an additional reboost of the space station, designed to add about three-quarters of a mile to the station's altitude. On Friday, flight controllers received word from U.S. Space Command that a spent Russian rocket upper stage, launched in the 1970s, could pass within three miles of the station. With today's scheduled reboost, beginning at 8:55 a.m. and using Endeavour's small firing jets for about 20 minutes, the space debris is now expected to pass more than 40 miles away from the station.

With Kelly at the controls, Endeavour is scheduled to undock from the station about 10:37 a.m., concluding more than a week of docked operations. Because today's scheduled reboost will use additional propellant, Endeavour will not perform a full-circle flyaround of the station after undocking. Instead, the shuttle will undock from the station, performing a quarter circle flyaround of the complex to a point about 400 feet directly above the station where it will fire its engines in a final separation burn at 11:20 a.m. beginning its departure from the orbiting outpost.

On the station, all systems are functioning well, including a newly refurbished air conditioning unit in the Russian Zvezda Service Module which received a new compressor yesterday. The air conditioner was tested last night and is functioning normally.

The STS-108 and Expedition Three crewmembers will take time this afternoon to discuss the progress of their mission with KGO-TV in San Francisco, the Fox News

Network and Associated Press in an interview scheduled to begin at 3:09 p.m. today on NASA TV. The crew also will enjoy several hours of scheduled off duty time today prior to gearing up for Monday's scheduled landing.

Homecoming at the Kennedy Space Center is scheduled at 11:55 a.m. Central time Monday. The early weather forecast calls for possible scattered and broken clouds and thunderstorms within 30 nautical miles of the landing strip.

Endeavour undocked from the station at 11:28 a.m. CST as the spacecraft flew 240 statute miles above the Indian Ocean off the Australian coast. Pilot Mark Kelly flew Endeavour through a half-circle of the station before firing jets to leave the vicinity.

Before undocking, Endeavour's jets were fired in a series of small pulses beginning at 8:55 a.m. CST to raise the altitude of the station about three quarters of a mile. The maneuver ensures the station will fly well clear of an old Russian rocket body that had been predicted to potentially pass close to the complex later this weekend. The final small reboost by the shuttle, coupled with three larger reboosts done earlier in the week, means the station was raised a total of more than nine statute miles by Endeavour.

The new station crew, Expedition Four Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz, said goodbye to Endeavour's crew and the departing Expedition Three crew and closed hatches between the spacecraft at 7:16 a.m. CST. Now en route home, Expedition Three Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin completed 117 days as the primary station crew and spent 125 days aboard the station overall. When Endeavour lands on Monday, they will have spent a total of 129 days in space.

The crew members aboard Endeavour had several hours off duty after departing the station, a break from a very busy pace moving tons of supplies between the shuttle and station during the past week. Sunday's activities will focus on checking out systems used during descent and making preparations for a landing on Monday. Endeavour is set to land at the Kennedy Space Center, FL, about 11:55 a.m. CST Monday. The weather forecast predicts generally acceptable conditions except for a chance of rain showers in the vicinity of the landing site. Flight controllers determined today that all three Inertial Measurement Units on Endeavour, the primary navigation systems for the shuttle, would be usable for landing. One of the three units had been taken off line two days ago due to a brief fault. However, the unit has worked well since that time. Even if the problem were to recur, it would not affect Endeavour's entry and landing since the shuttle can operate with only one such unit if necessary. Endeavour's crew will begin a sleep period at 7:19 p.m. CST and awaken at 3:19 a.m. CST Sunday.

Concluding a successful mission to the International Space Station, today's landing brings to an end a voyage of more than 4.8 million miles for Endeavour and marks the 57th shuttle landing at the Florida spaceport.

On Endeavour's flight deck are Commander Dom Gorie, Pilot Mark Kelly and Mission Specialists Linda Godwin and Dan Tani. On the middeck, strapped into recumbent chairs to reduce the effects of reentry, is the Expedition Three crew, Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin.

Following routine medical examinations, the STS-108 and Expedition Three crewmembers will enjoy a reunion with their families. All seven crewmembers are expected to return to a public welcome home at Hangar 990 at Houston's Ellington Field about 1 p.m. Wednesday.

During their 12 days in orbit, the STS-108 crew worked with both the returning Expedition Three and newly-arrived Expedition Four crews to transfer more than three tons of material, hardware and supplies from Endeavour to the station. Godwin and Tani also conducted a spacewalk to install thermal protection on motor assemblies that control the motion of the station's large solar arrays.

On board the International Space Station, the Expedition Four crew - Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz - are settling in for a planned five-month stay on orbit, unloading the recently arrived Progress resupply vehicle.

Last Saturday, the three new station crewmembers bid farewell to their predecessors, the Expedition Three crew, and the crew of Endeavour as the shuttle undocked to begin its journey home. The Expedition Three crew of Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin returned to Earth on Monday and to Houston on Wednesday. The three have begun several weeks of physical rehabilitation to help their bodies readjust to the pull of Earth's gravity

Aboard the station, Onufrienko, Bursch and Walz spent the week activating science experiments, including a cell growth experiment used to study colon and ovarian cancer cells and human kidney cells. They also continued to familiarize themselves with their new home, unload the Progress 6 cargo ship, and unpack equipment and supplies brought aboard Endeavour.

The crew will continue experiment work next week, and they will have a day off on Christmas Day to observe the holiday. The station's food stores include turkey and some other traditional holiday foods. The crew also will observe a holiday on New Year's Day.

All International Space Station systems are currently operating well. However, on Tuesday flight controllers noted that the Beta Gimbal Assembly that rotates the port-side U.S. solar array experienced strain on its electric motor and briefly stalled. The mechanism was restarted quickly and has since been performing normally. The stall had no significant impact on station operations and is similar to events seen several times in the past. The Beta Gimbal Assemblies rotate the station's arrays, allowing them to precisely track the sun, generating the maximum possible power for the station.

During Endeavour's flight, thermal blankets were installed on both assemblies to better insulate them in hopes of alleviating such problems. Engineers have confidence the mechanisms will continue to operate, and they are continuing to gather data from both the port and starboard mechanisms to evaluate the effectiveness of the new insulation.

Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch observed a quiet New Year's holiday in orbit, spending time relaxing and communicating with family and friends. Later in the week, work resumed as the crew operated two experiments that study astronauts' reactions to weightlessness. Walz and Bursch both participated in the H-Reflex experiment, a study that gauges the effects of weightlessness on spinal cord excitability and reflexes, and the Pulmonary Function experiment, a study of the effects of space flight and space walks on lung function.

Bursch and Walz had an opportunity to train in the operation of the station's robotic arm, the Canadarm2, while maneuvering the arm on Thursday to latch on to fixtures on the exterior of the station. In addition to providing training for the crew, the arm operations tested a new technique being developed to alleviate tension that has been seen as the arm releases its latch on a fixture. The tests provided valuable data for engineers on the ground developing those techniques, and similar tests may be repeated later in the mission.

The crew members have virtually completed unpacking and stowing the more than three tons of supplies and equipment brought to the station with them aboard the space shuttle in early December. Their attention next week will turn to an upcoming milestone for their flight -- the first of two planned this month and as many as four spacewalks that are planned during their five-month stay aboard the station. Walz and Onufrienko are planned to conduct a spacewalk for up to six hours tentatively beginning at about 2:50 p.m. CST Jan. 14. This weekend, the crew will begin shifting their sleep period later to adjust for the timing of the upcoming spacewalk, and, next week, checkouts will begin of the spacesuits and spacewalking gear that will be used for the work outside.

The spacewalk will use Russian Orlan space suits and originate from the Russian Pirs docking compartment airlock. Onufrienko and Walz will reposition an exterior Russian strela cargo crane from the station's pressurized mating adapter 1 to the station's Zarya module, moving it within reach of a similar crane on the Pirs compartment. The move will allow the cranes to be used in tandem to maneuver equipment on the station's exterior during future space walks.

After exiting the station from the Russian Pirs docking compartment, Onufrienko and Walz will use a Russian cargo crane that is already installed on Pirs to relocate a similar crane from the station's Pressurized Mating Adapter 1 onto Pirs. On future spacewalks, the two cranes, called Strela (the Russian word for "arrow"), can be used to maneuver equipment and spacewalkers on the station's exterior. Onufrienko and Walz also will install an amateur radio antenna on a handrail at the end of the Zvezda service module.

Monday's spacewalk will be the thirty-second in support of the assembly of the International Space Station, the seventh such excursion conducted from the station itself, and the sixth based out of the station's Russian segment. A second spacewalk this month -- to be conducted by Onufrienko and Bursch -- is targeted for Jan. 25. The plan for this spacewalk currently includes the installation of thruster deflector shields on the end of Zvezda.

In addition to preparing for next week's spacewalk, the Expedition Four crew continued a series of upgrades to the station's computer hardware. The crew also completed the first session of a Human Life Sciences experiment called Renal, which is investigating ways to prevent the formation of renal stones during long-duration spaceflights.

The first space walk Expedition Four crew's five-month tour of duty began at 2:59 p.m. CST and ended at 9:02 p.m. CST, lasting a total of 6 hours, 3 minutes. Monday's spacewalk was the thirty-second in support of space station assembly, the seventh such excursion conducted from the station itself, and the sixth based out of the station's Russian segment. The total amount of time spent on space station-based spacewalks now stands at 29 hours, 04 minutes, and the total spacewalking time spent on station construction at 196 hours, 19 minutes.

After exiting the station from the Russian Pirs docking compartment, Onufrienko and Walz assembled an extension for a Russian cargo boom that had been previously installed on Pirs. They used the operational cargo crane, called Strela 1 (Strela is the Russian word for arrow), to get into position to detach and relocate a similar crane temporarily stored on the outside of the Unity-to-Zarya connecting tunnel. Known as Strela 2, this second crane was moved back alongside Pirs and attached to a base point on the opposite side of the docking compartment and airlock at 6:31 p.m. CST.

The first piece of Strela 2 had been delivered and installed in May 1999, and the second piece in May 2000. On future spacewalks, the two cranes may be used to maneuver equipment and spacewalkers.

Onufrienko and Walz also installed an amateur radio antenna on a handrail at the end of the Zvezda service module. The antenna is one of four that eventually will allow space station crew members to make "ham" radio contacts from the comfort of their living quarters inside Zvezda. Currently, the amateur radio station is inside the Zarya module.

The next spacewalk of the expedition - to be conducted by Onufrienko and Bursch - is targeted for Jan. 25. The plan for this spacewalk currently includes installation of the remaining three amateur radio antennae and thruster deflector shields on the end of Zvezda.

Flight Engineer Carl Walz worked with computer experts on the ground to install and activate a new solid state mass memory unit for one of the station's three main command and control computers, known by its acronym of "C&C1." It took Walz about two hours to remove the older mass memory unit, which used a spinning disk design, and another two hours for flight controllers on the ground to complete the reactivation of C&C1. Computer experts on the ground are continuing to evaluate data on the health of the computer, but expect to place it in the backup spot to the primary computer, C&C2, on Jan. 23. C&C2 had its mass memory unit upgraded earlier this month. The final new mass memory unit is to be installed in C&C3 on Feb. 1. In addition, flight controllers this week also installed new software in two guidance, navigation and control computers on the station.

Meanwhile, Commander Yury Onufrienko and Flight Engineer Dan Bursch continued preparations for the next spacewalk, scheduled for Jan. 25. This week, they replenished space suit consumables used by Onufrienko and Walz on Monday, dried out the suits and readied the hardware items they will install on the outer skin of the station. The spacewalk is expected to begin at 9:35 a.m. CST next Friday, and last about 5 1/2 hours. Onufrienko and Bursch will wear Russian Orlan spacesuits and exit the station through the Pirs module, which serves as a docking module and airlock. Walz will provide support inside, monitoring their progress and moving the robotic Canadarm 2 for television coverage of their activities. It will be the 33rd spacewalk in support of space station assembly, and the eighth conducted from the station itself.

The two space-age construction workers will install 11 different systems on the outside of the Zvezda Service Module, including six thruster plume deflectors, the second of four ham radio antennae, a replacement experiment for studying contaminating particles from control jets, and a physics experiment. The Efflux Protection Assembly deflectors are designed to redirect plumes from the jets that help control the station's orientation so that they do not leave potentially harmful residues on the outside of the station where spacewalkers must work. The suitcase-like Kromka 1 experiment will replace the existing Kromka 1-0 experiment package, placing new materials samples where they can collect contaminants from the thrusters for future analysis (the Kromka 1-0 samples will be bagged and returned to the station for delivery to Earth aboard a Soyuz return craft). The Platan-M package is a physics experiment designed to search for natural low-energy heavy nuclei of solar and galactic origin.

The amateur radio antenna is one of four that eventually will allow space station crew members to make "ham" radio contacts from the comfort of their living quarters inside Zvezda.

While crew members concentrated on construction and maintenance tasks, inside the Destiny Laboratory, a host of scientific experiments continued to collect information about the effects of long-term space flight on humans, biotechnology, medicine, agriculture, electronics and pharmaceutical compounds.

With Onufrienko and Bursch working outside, Astronaut Carl Walz served as intravehicular crewmember, helping to coordinate the spacewalk and maneuvering the station's robotic arm, Canadarm2, to allow its television cameras to view the spacewalk. This was the 33rd spacewalk for station assembly and outfitting and the eighth conducted from the station itself. Onufrienko and Bursch, wearing Russian Orlan spacesuits, installed six plume deflectors around attitude control thrusters at the rear of the Zvezda module. The deflectors are designed to limit deposits on the outside of the station that result from the firing of those thrusters.

The spacewalkers also removed an experiment called Kromka situated near one of the thruster groups. The experiment captured material that results from thruster firings. It will be returned to Earth in early May aboard a Soyuz spacecraft. By studying the captured materials, engineers will gain a better understanding of the nature of the deposits. Onufrienko and Bursch installed a virtually identical new Kromka experiment in the same place. Future analysis of the materials it captures will provide information on the effect of the plume deflectors. They also installed a ham radio antenna and associated cabling at the rear of Zvezda. The antenna is the second of four that eventually will be situated around the back of the module. Onufrienko and Walz had installed the first antenna during a Jan. 14 spacewalk.

Onufrienko and Bursch also attached a physics experiment called Platan to Zvezda. Platan is designed to capture low-energy heavy nuclei from the sun and from outside the solar system. In addition, they installed three materials experiments, called SKK for their Russian acronym, on Zvezda. The experiments examine effects of the harsh environment of space on a wide range of materials. The spacewalkers also installed fairleads on Zvezda handrails. The fairleads, called pigtails, keep spacewalkers' tethers from fouling equipment or experiments on the module's exterior. Throughout the spacewalk, they took photos to document their work.

The crewmembers took a few breaks from their schedule during the week to field questions from a Cleveland, Ohio, television station and a New York, N.Y., radio station during an event on Thursday and to address more than 650 educators from across the United States on Friday that were gathered in Houston for the Eighth Annual International Space Station Educators Conference.

Maintenance activities included some minor repairs on the Active Rack Isolation System (ARIS), replacing the hard drive of one of the command and control computers, troubleshooting the slight echo usually heard during space-to-ground communications, removing the automated docking system from the Russian Progress resupply vehicle and installing a laptop computer in the Quest airlock. The ARIS dampens the vibrations caused by movement by the crew in an effort to isolate the sensitive science experiments located in the Destiny Laboratory. A shock absorber pushrod was replaced after malfunctioning because of normal wear and tear on the system.

The crew replaced the hard drive on the third and final command and control computer with the new solid-state mass memory unit that is expected to operate better in the microgravity environment than the spinning disk type hard drive. The new unit is now activated and operating well.

Ground controllers in Mission Control Houston and Moscow are guiding the crew through several tests of the station's communications system. The crew is trying several configurations of the system to help find a solution to an echo. The echo does not impact flight operations, but slightly decreases the quality of the audio heard on the ground.

The crew -- Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz -- was never in any danger, but began quickly powering down backup equipment and several experiments in case the power generated by the station's solar arrays began to decrease. With the station's orientation not controlled, the solar arrays were not able to autonomously point directly at the sun to generate full power for the complex. The computer went off-line at about 7 a.m. CST.

Flight controllers in Houston and Moscow worked together to restore all operations of the station during the morning, and, at one point, the crew sent manual commands to ensure the solar arrays remained directed at the sun. Russian controllers have not yet determined the cause of the computer problem and are continuing to analyze it.

By 9:30 a.m., flight controllers at the control center in Korolev, Russia, had successfully restarted the computer, and, by 11:30 a.m., the station's orientation control system had begun to be restored to operation.

The crew began its sleep period as normal at around 3:30 p.m. CST. They will awaken at about midnight CST, and they will spend some time tomorrow continuing a recovery of the equipment that was powered down as a result of today's problem.

In addition, Walz and Bursh prepared a set of three dosimeters each that will be used to measure any radiation they might receive during their scheduled Feb. 20 spacewalk. The dosimeters are part of the EVARM experiment, which is studying the amount of radiation astronauts receive during spacewalks to better design future radiation shielding in spacesuits.

Today, the crew spent their 64th day in space doing an inventory of the supplies aboard the station. The inventory will help planners determine how much and what kind of supplies the next station crew will need. The crew began the inventory process today and will complete it as time permits.

On Monday, the crew's normal work was interrupted for a few hours when a main computer in the station's Zvezda module unexpectedly went off-line, disrupting the system that controls the spacecraft's orientation. The computer was quickly brought back on-line and all station systems have operated normally since then. Russian controllers are still working to determine the cause of the disruption.

On Wednesday, Onufrienko celebrated his 41st birthday. He and his crewmates have been in space since Dec. 5. The crew has a light weekend of planned activities ahead, but usually takes time to complete a variety of odd jobs on their task list, a list of work aboard the station that does not need to be done at any specific time.

Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch, beginning their 10th week on orbit, received volumes of information and training materials from the flight control team on the ground, participated in computer-based training sessions, and checked out the spacesuit, airlock and experiment systems that will be used Feb. 20. A full dry-run of the airlock depressurization is planned Friday.

The excursion will mark the first use of the station's airlock since July 2001 and will test equipment and techniques that will be used during the April STS-110 assembly mission, when four spacewalks out of the Quest airlock will install the first piece of the station's structural and electrical "backbone." Bursch and Walz will perform a checkout of the airlock's systems, connect and disconnect several electrical cables, remove insulation blankets from the Z-1 truss structure and bring inside several tools to expedite the work planned for STS-110.

They will use U.S. space suits, with Walz, wearing a suit with red stripes on the legs and Bursch wearing an all-white suit. The spacewalk is scheduled to begin at about 6 a.m. CST Wednesday. NASA Television coverage will begin at 5:30 a.m. CST Wednesday. Experiment work also continued aboard the station, as crew members set up and activated the second Advanced Astroculture experiment. The investigation will grow mustard plant seeds harvested on board the station by the Expedition Two crew and returned after analysis on Earth, making them a true second generation of space-grown plant life. The University of Wisconsin-sponsored experiment studies Arabidopsis thaliana, which is renowned in genetic research circles as a key to identifying genes and determining their functions for entire classes of similar organisms.

The crew disassembled the Active Rack Isolation System, which suffered a push-rod failure, and will soon conduct repairs that will enable the system to resume its work. The system protects sensitive microgravity experiments from the motions caused by everyday crew life aboard the station.

The crew also worked with flight controllers on the ground to complete some unplanned maintenance work after Sunday's failure in a Remote Power Conversion Module (RPCM) that distributes power to a variety of station systems. Full functionality was restored to the non-critical systems that were affected in the Destiny laboratory module after Bursch and Walz replaced the glorified breaker box with an onboard spare. To access the module, they removed Bursch's temporary sleep station and replaced it, installing additional high-density plastic radiation protection bricks while they had the opportunity.

A planned upgrade of the station's software was postponed until after the Feb. 20 spacewalk to allow software engineers on the ground to perform one last set of tests to verify all aspects of the software load. The new software will prepare the station's computer systems for the arrival of the truss structure and other components to be delivered on STS-110 and future flights.

It was the first spacewalk from Quest without the presence of a space shuttle at the station, earning it the designation of U.S. EVA 1. It also marked the first U.S. use of an Intravehicular (IV) officer, Astronaut Joe Tanner, working from Houston's Mission Control Center instead of from onboard the spacecraft, as has been the case up to this point. Also, new procedures were used to expedite airlock depressurization at the start of the spacewalk.

STS-110 will bring the S0 Truss to the station, the first segment of what will be the station's backbone. Four spacewalks will be conducted during that flight, all from the airlock and all using an oxygen/exercise protocol to purge nitrogen from the spacewalkers' bloodstreams. Walz and Bursch used that protocol today.

During the spacewalk today, Walz and Bursch deployed two electrical cables from their stowage area on the U.S. Laboratory Destiny and connected them to a cable tray near the base of the Z1 Truss. Plans to disconnect and restow the cables were put on hold while engineers evaluated unexpected readings from current conversion units in the circuit the cables completed. Walz removed four thermal blankets from the Z1 Truss and stowed them inside the truss, while Bursch retrieved tools to be used on STS-110 spacewalks and brought them to the airlock. The two also secured looser-than-expected latches on two oxygen tanks and two nitrogen tanks, on the airlock.

Walz and Bursch removed adaptors on which a Russian cargo crane had been mounted and attached one of them to the Zarya module's exterior. They brought the other, U.S.-made, adaptor into the airlock. They also inspected cable connectors outside the station and photographed the MISSE (Materials International Space Station Experiment). Some of the materials samples being exposed to the harsh conditions of space apparently were peeling back off their mountings.

Scientists used the spacewalk to gather additional data for an experiment looking at the effects of spacewalks and long-term exposure to microgravity on lung function. Also, Walz and Bursch will wear radiation sensors for the EVARM experiment, a study of radiation doses experienced by spacewalking astronauts.

Walz and Bursch each had made one previous spacewalk from the station last month, and Walz also made a spacewalk on STS-51 in September 1993. During today's spacewalk, Expedition 4 Commander Yury Onufrienko operated cameras on the station's Canadian provided robotic arm to document activities.

A planned upgrade of the station's software is scheduled for late this week to prepare station computers for arrival of the S0 Truss and other equipment to be delivered on subsequent flights.

Also today, Houston's Mission Control Center and the crew began a transition to new software for the station's computers, a process that is proceeding well and will continue with checkouts for several days.

Many of today's medical tests on crewmembers were done in the U.S. laboratory Destiny, in which the crew resumed work early this morning. As a precaution, they had spent much of the past 48 hours in the Russian segment while an air freshening system removed a musty odor that had spread through U.S. modules Wednesday. The odor originated from a Quest Airlock system that was being used to cleanse spacesuit air scrubbers Wednesday afternoon. The crew reported few remnants of the smell in the station this morning.

Russian flight controllers reboosted the station Thursday using the Progress vehicle docked at the rear of the Zvezda living quarters module. The reboost, performed in two segments, raised the altitude of the station by a little less than three statute miles to an average altitude of about 239 miles.

The crew began the week by bringing the Active Rack Isolation System back to life after installing a new shock absorber in the rack. One of the eight pushrods that was not operating correctly was replaced by the crew. The system works to dampen out the vibrations generated by crews' movement throughout the station. Those vibrations could affect the delicate science experiments located inside the rack. Air and water samples were taken from the Advanced Astroculture experiment inside the US Destiny laboratory. The samples will be brought back to Earth for scientists to study. Scientists hope to determine what nutrients and conditions are necessary for plants to grow in microgravity.

The Earthkam experiment was activated once again this week. The crew set up a digital camera in the window of Destiny, enabling middle school students on the ground to remotely take pictures of the Earth's geographical features from a vantage point 240 statue miles high.

To prepare for the Earthkam activation, the station's robotic arm was moved Tuesday so it would not block the view of Earth from the Destiny lab. The crew could not release the brakes to begin the move using the arm's primary avionics system. The secondary avionics system operated normally, however, and was used to perform the move. The specific cause of the problem with the primary avionics system is still being investigated.

Thursday, the crew put the arm through a practice run of the movements it will make during the next shuttle mission to the station, STS-110 in April. The arm will be used to attach the next major station component, the S0 truss. On Thursday, ground controllers also sent up tests for the primary and secondary computer workstations used to operate the arm. The secondary workstation was not able to boot up during the test, and engineers are evaluating it. When the workstation difficulties were encountered, the arm was left in a safe parked position while engineers study the problem.

The crewmembers onboard Columbia - Altman, Pilot Duane Carey and Mission Specialists John Grunsfeld, Nancy Currie, Rick Linnehan, Jim Newman and Mike Massimino - will have a rare opportunity to speak with another crew in orbit, the International Space Station Expedition Four crew.

At 2:15 a.m. Sunday the shuttle crew will talk with space station Commander Yury Onufrienko, and Flight Engineers Carl Walz and Dan Bursch. STS-109 is the first space shuttle mission not dedicated to assembly of the space station, since a crew has been living aboard the orbiting laboratory. The station has been continuously inhabited since the first expedition crew arrived in November 2000.

Columbia's crew also will participate in a live question and answer session with reporters at 6:47 a.m. WABC Radio in New York City; KARE-TV of Minneapolis, Minn., and the CBS Radio Network will discuss the Hubble servicing mission with the crew.

Flight Controllers at the Space Telescope Operations Center in Greenbelt, Md., report that all systems on Hubble are operating well after its release from Columbia. The new, more efficient solar arrays and Power Control Unit are performing excellently. The activation of the science instruments is scheduled to begin about 11 p.m. Sunday. Controllers will continue to monitor the newly installed components until everything is brought back on line.

Science observations are expected to resume in the next few weeks from the veteran Space Telescope Imaging Spectrograph and Wide Field Planetary Camera. Any possible moisture accumulated during the maintenance operations will be allowed to evaporate before some instruments will be activated. The newest science instrument, the Advanced Camera for Surveys, will begin peering more deeply into the cosmos in the next few months.

The crew will begin a sleep period at 11:22 a.m. Sunday.

Although it will be at least several weeks before all of the scientific equipment installed by Columbia's crew is tested, space telescope controllers report that all functional checks of Hubble continue to be fully successful.

The crew is now beginning to turn their attention to the trip home, with a landing by Columbia planned for 3:32 a.m. CST Tuesday at the Kennedy Space Center, Fla. The weather forecast for landing calls for generally acceptable conditions with only a slight chance of rain showers developing offshore.

Early this morning, the astronauts aboard Columbia made a long-distance call to their fellow space fliers, the Expedition Four crew of Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz, now in their fourth month in orbit aboard the International Space Station. With the aid of Mission Control, the two spacecraft crews conversed as Columbia flew 350 statute miles above the Atlantic Ocean and the station flew 240 miles above the South Pacific.

Columbia's crew begins a sleep period at 11:22 a.m. CST and will awaken for what is planned to be their final full day in orbit at 7:22 p.m. CST. That day will be devoted to the standard shuttle checkouts conducted prior to landing, testing the flight controls and steering jets needed for the return to Earth.

Columbia remains in good condition, with no systems problems of concern to flight controllers. Tuesday's primary landing opportunity to Kennedy would begin with a deorbit engine firing by Columbia at 2:25 a.m. CST leading to the 3:32 a.m. CST touchdown. A second landing opportunity also is available for Kennedy on Tuesday, beginning with an engine firing at 4:07 a.m. CST leading to a touchdown at 5:13 a.m. CST.

Although opportunities do exist for landing at Edwards Air Force Base, Ca., shuttle managers plan to focus Tuesday only on a landing in Florida.

The first plant tissue samples were taken from the Advanced Astroculture experiment inside the U.S. laboratory Destiny. Air, water, soil and plant samples will be brought back to Earth for scientists to study and will be compared to crops grown on Earth. The EarthKAM experiment completed its observations for this expedition and was deactivated Saturday after the digital camera took 425 pictures last week. The experiment has allowed middle school students on the ground to remotely take about 2,271 pictures of the Earth's geographical features from a vantage point 240 statute miles high. The last reading for the Hoffmann Reflex experiment was taken this week. This experiment measures the ability of the spinal cord to respond to a stimulus after being exposed to microgravity and may provide input to improve exercise during long spaceflight missions. Eight crewmembers from expedition crews have participated in this experiment. Only post-flight observations remain for the current station crew.

The crew began packing used and unneeded equipment into the Progress resupply vehicle docked to the aft end of the Zvezda service module. The Progress spacecraft will be jettisoned from the station Tuesday and will burn up upon re-entry into the Earth's atmosphere. A new Progress resupply vehicle will launch from the Baikanour Cosmodrome in Kazahkstan March 21 and will arrive at the station three days later.

An audit is taking place on board the station in preparation for the next space shuttle visit in April. Using an electronic inventory management system, station crewmembers are organizing equipment to enhance efficiency. When the space shuttle Atlantis docks to the space station next month, there will be a total of 10 crewmembers working throughout the spacecraft, now the size of a three-bedroom house, for almost a week.

Walz and Bursch also operated the station's robotic arm, Canadarm2, to observe the exterior of the station via cameras located on the arm. The cameras focused on the claw-like latch cradle assembly mounted on the Destiny module. The crew also used the cameras to inspect the station's radiators and solar arrays. During STS-110 next month, Canadarm2 will be used to move the S-zero truss segment from the shuttle's payload bay to the latch assembly on Destiny to be installed during four planned spacewalks. Flight controllers on the ground continue to monitor the arm's operation after it experienced difficulties with the primary avionics system last week. The arm functioned successfully on the secondary system this week.

On command from Russian flight controllers, the Progress 6 vehicle undocked from the aft port of the Zvezda Service Module at 11:43 a.m. CST (1743 GMT). Expedition Four Commander Yury Onufrienko watched the undocking from the Pirs Docking Compartment and Flight Engineers Dan Bursch and Carl Walz monitored the departure from the Destiny Lab's robotics workstation.

The Progress' engines performed the first of two separation maneuvers within minutes of undocking. Flight controllers plan to deploy a small Russian student science satellite from the Progress later today before the resupply craft is commanded to deorbit and burn up in the atmosphere.

At the Baikonur Cosmodrome in Kazakhstan, preparations are complete for Thursday's launch of the new Progress 7 spacecraft, which will carry several tons of food, fuel and supplies to the ISS. The Progress 7 craft will link up to the ISS on Sunday afternoon.

The Progress 7 spacecraft lifted off on a Soyuz booster rocket at 2:13 p.m. CST (2013 GMT) and less than 10 minutes later safely settled into orbit. Automatic programmed commands enabled its solar arrays and navigational antennas to deploy. At the time of launch, the ISS and the Expedition Four crew, Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch, were traveling over Africa out of the line of sight of the launch itself.

A series of rendezvous burns from the new Progress' engines over the next three days will result in a docking by the craft to the aft port of the Zvezda Service Module on Sunday at 2:55 p.m. CST (2055 GMT) over Central Asia. That port was vacated on Tuesday when the previous Progress resupply vehicle undocked and was deorbited to a destructive re-entry back into Earth's atmosphere.

The Progress 7 spacecraft gently linked up to the aft docking port of the station's Zvezda Service Module at 2:58 p.m. CST (2058 GMT) as the two craft sailed over Central Asia at an altitude of 240 statute miles. Within minutes, hooks and latches engaged between the Progress's docking probe and Zvezda's capture mechanism to form a tight seal.

Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch, were scheduled to perform leak checks of the interface between the Progress and Zvezda later today before opening up the hatches to the newly arrived vehicle. The crew will begin to unload its cargo on Monday.

The successful docking sets the stage for the launch of Atlantis in less than two weeks on the next station assembly flight --- to deliver the S0 (S-zero) centerpiece truss structure for the station that will be mated and outfitted to the Destiny Laboratory during four spacewalks. Launch of the STS-110 mission is tentatively set for April 4. A firm launch date is expected to be set this week following the traditional Flight Readiness Review by NASA managers at the Kennedy Space Center.

While engineers on the ground will continue to study results of the exercise, it was a major step in proving redundancy in the arm, validating the backup operating string. The prime string was successfully tested on Thursday.

The tests were in preparation for STS-110, to be launched on April 4. The arm will be used to lift the S0 Truss from the shuttle's payload bay and install it on the station's U.S. laboratory Destiny. Atlantis crewmembers will do four spacewalks to complete installation.

Today's test of the arm completed a busy workweek for the crew, Commander Yury Onufrienko, Walz and Bursch. It began with the Sunday arrival of the unpiloted Russian Progress 7 resupply vehicle and concluded with the successful arm operations, completed ahead of schedule. Today's test was to have been done next Monday.

Science activities continued. Work today involved the ARIS-ICE vibration characterization experiment, the EVA Radiation Monitor and the Advanced Astroculture experiment.

Major systems aboard the ISS continue to function well as the station orbits at an average altitude of about 242 statute miles.

Commander Mike Bloomfield, Pilot Steve Frick, Flight Engineer Ellen Ochoa and spacewalkers Steve Smith, Rex Walheim, Jerry Ross and Lee Morin rocketed away from Launch Pad 39-B at the Kennedy Space Center at 3:44 p.m. Central time as the ISS orbited over the Atlantic Ocean due east of the northeastern United States at an altitude of 240 statute miles.

Launch occurred with only 12 seconds left in the 5-minute launch window due to a brief delay caused by a momentary ground launch system software glitch at the Launch Control Center at the Florida spaceport which paused the countdown at the T-minus 5-minute mark. Once the problem was solved, the countdown resumed.

Atlantis' launch marked a milestone as Ross became the first human to fly in space seven times, breaking a record of six flights previously held by Ross and fellow American astronauts John Young, Story Musgrave, Franklin Chang-Diaz and Curt Brown. No Russian cosmonaut has flown in space more than five times.

Now in their fifth month in orbit, Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch were able to watch Atlantis' launch through a video uplink from flight controllers in Houston. Atlantis' arrival will mark the first visitors for the Expedition Four crewmembers since their launch back in December.

Less than nine minutes later, Atlantis and its crewmembers settled into orbit as work began to prepare the shuttle for its planned 11-day mission and for a series of rendezvous maneuvers to reach the station on Wednesday morning. Atlantis will actually have to lap the ISS as a result of those maneuvers before its scheduled docking with the outpost Wednesday.

After Atlantis' payload bay doors are opened and approval is given for the start of orbital operations, the seven crewmembers will unstow computers and other gear required for the mission.

If all goes as planned, Atlantis will link up to the station Wednesday just after 11 a.m. Central time, setting the stage for the installation of the S0 (S-Zero) Truss on Thursday morning on the Destiny Laboratory and the first of four spacewalks to mate and activate the new component to Destiny. The S-Zero Truss will serve as a platform upon which other trusses will be attached and additional solar arrays will be mounted in future assembly flights to form a structure longer than the length of a football field. The new truss will also serve as a primary electrical switching station to route power from the stations' arrays to various modules and components.

The shuttle crew will begin its first sleep period at 8:44 p.m. Central time and will be awakened at 4:44 Tuesday morning to begin its first full day in orbit, designed to test the ship's robot arm, spacesuits and rendezvous equipment which will be used over the next few days.

With docking scheduled at 11:06 a.m. Central time (1606 GMT) tomorrow, Commander Mike Bloomfield, Pilot Steve Frick and Mission Specialists Rex Walheim, Ellen Ochoa, Lee Morin, Jerry Ross and Steve Smith verified all of Atlantis' equipment, setting the stage for the orbiter's linkup to a docking port at the forward end of the station's Destiny Laboratory.

Docking is planned over south central China, southwest of Shanghai. The crew will be up early Wednesday to complete preparations and to execute a number of engine firings to draw Atlantis close to the ISS for its eventual docking.

Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch tidied up their orbital home and completed routine maintenance on the eve of the arrival of their first visitors since they were launched to the ISS back in December. After docking and hatch opening tomorrow, the two crews will run through a dress rehearsal of procedures which will be used on Thursday to maneuver the large S0 (S-Zero) Truss structure from Atlantis' cargo bay for mating to a capture device at the top of Destiny.

Four spacewalks will be conducted by two teams of spacewalkers to electrically and structurally connect the new truss to the ISS. The 13 and a half-ton S-Zero is the mainframe for a series of trusses to follow which will expand the station to a length of a football field.

Late today, Bloomfield and Frick executed a rendezvous maneuver by firing Atlantis' reaction control system jets to refine the shuttle's path to the space station. Several larger engine firings will be conducted Wednesday morning to slow Atlantis' approach to the station, setting up its final path for linkup to the ISS.

With all of its systems functioning in excellent shape, Atlantis orbits the Earth at an altitude of around 220 statute miles. The crew began an eight-hour sleep period at 7:44 Central time this evening and will be awakened at 3:44 Wednesday morning.

Commander Mike Bloomfield guided Atlantis to a linkup with the forward docking port of the station's Destiny Laboratory at 11:05 a.m. Central time as the two vehicles sailed at an altitude of 240 statute miles. The docking culminated a textbook rendezvous executed by Bloomfield and Pilot Steve Frick. As Atlantis docked, Expedition Four Flight Engineer Dan Bursch, a Navy Captain, rang the ISS ship's bell to greet the arriving shuttle crew.

About two hours later, at 1:07 p.m. Central time as the two craft flew over New Zealand, hatches swung open between Atlantis and the station, and the ten crew members greeted one another inside Destiny, marking the arrival of the first visitors for Expedition Four Commander Yury Onufrienko, Flight Engineer Carl Walz and Bursch since they entered the ISS in December for the start of their six-month mission.

After a safety briefing for the shuttle astronauts by Onufrienko, the two crews began to transfer gear for the first spacewalk tomorrow by Steve Smith and Rex Walheim as well as experiments to be housed in Destiny.

Ellen Ochoa joined Bursch to brush up on procedures for the use of the station's Canadarm2 robotic arm tomorrow which will be employed to grapple and unberth the 13 1/2 ton S0 (S-Zero) Truss from Atlantis' cargo bay for mating to a capture device at the top of Destiny. Smith, Walheim, Jerry Ross and Lee Morin will conduct four spacewalks to electrically and structurally mate the S-Zero to Destiny over the next week. Ochoa maneuvered the arm and verified it is in good working order to support the S-Zero operations on Thursday.

Smith and Walheim set up all the equipment in the Quest Airlock on the ISS from which they will mount the first of the four spacewalks to deploy two of the four mounting struts to Destiny and to bring power to the new truss from the U.S. Laboratory. Ochoa is scheduled to grapple the S-Zero around 5 a.m. Central time with the first spacewalk set to get underway around 10 a.m.

Atlantis and the ISS are in excellent shape, orbiting the Earth every ninety minutes in an orbit inclined 51.6 degrees to either side of the Equator.

The two crews began an eight-hour sleep period at 7:44 Central time this evening and will be awakened at 3:44 Thursday morning for the fourth day of the mission.

On Friday, April 12, NASA Administrator Sean O'Keefe will deliver an address on future agency policy entitled, "Pioneering the Future", originating from Syracuse University. The address will be seen on NASA Television beginning at 1 p.m. Central time.

On board the station, the Expedition 4 crew, Commander Yury Onufrienko and flight engineers Carl Walz and Dan Bursch, also awoke at 3:44 a.m. to an alarm-clock-like tone. They have synchronized their sleep schedule to match that of the Atlantis crew to prepare for docked operations.

About two hours after Atlantis docks to the station, the hatches between the two spacecraft will open and Onufrienko, Bursch and Walz will greet their first visitors since beginning their stay aboard the orbiting laboratory last December. After a welcome and safety briefing, all 10 astronauts and cosmonauts will begin transferring equipment and supplies between the two vehicles.

Both crews will jointly review plans for installation of the S-Zero (S0) Truss, including procedures for Thursday's scheduled spacewalk, the first of four during this mission. Ochoa and Bursh will maneuver the station's robotic arm, Canadarm2, through a rehearsal of the motions it will use Thursday to pluck the 44-foot, 27,000 pound truss segment from the shuttle's cargo bay and install it atop the station's U.S. laboratory Destiny.

Major systems aboard Atlantis and the space station continue to function well.

During the S-Zero installation, Atlantis Commander Mike Bloomfield and Pilot Steve Frick operated the shuttle's robotic arm to provide additional camera views to Ochoa and Bursch, who were working in the Destiny Lab at one of the robotic workstations. The truss will serve as the backbone for future station expansion to the length of a football field. S-Zero contains navigational devices, computers, cooling and power systems necessary to attach additional laboratories to the complex.

Within minutes after the new truss was temporarily latched to the Destiny Lab, mission specialists Rex Walheim and Steve Smith left the station's Quest Airlock at 9:36 a.m. Central time to begin the first of four spacewalks of the mission to electrically and structurally mate S-Zero to the station.

Smith and Walheim first unfurled and firmly attached two of four mounting struts on the truss to Destiny before deploying trays of avionics equipment and cables on the truss which include power, data and fluid lines connecting Destiny to the S-Zero. They also attached an umbilical system from the truss to the Mobile Transporter housed on the forward face of the huge girder. The umbilical will enable the Transporter, which is the first railcar in space, to move up and down the length of the station to position the ISS robotic arm for future assembly work. Two other struts on the truss will be mated to Destiny Saturday during the second spacewalk, permanently bolting the truss to the Laboratory.

Working deliberately to connect all of the critical power connections, Walheim spent the day working at the end of the station's Canadarm2, the first time the large arm has been used as a form of cherry picker to maneuver astronauts during assembly work at the ISS. Smith operated as a so-called "free-floater", tethered to the station and to various work sites around the truss itself. Atlantis astronaut Jerry Ross and ISS Flight Engineer Carl Walz took turns choreographing the spacewalk from the aft flight deck of the shuttle.

With all but two tasks successfully completed, Smith and Walheim returned to Quest late this afternoon and ended their spacewalk at 5:24 p.m. Central time, completing a 7 hour, 48 minute excursion. It was the 35th spacewalk devoted to station assembly and the 10th staged from the station itself. As Smith and Walheim wrapped up their work, flight controllers reported that the activation of the S-Zero Truss had begun and that all of the initial systems appear to be in excellent shape.

Time ran out before Smith and Walheim could install two circuit breakers on the truss, but that task will be picked up on a subsequent spacewalk.

After a long and tedious day, the shuttle and station crew members were scheduled to begin an eight-hour sleep period at 7:44 p.m. Central time and will be awakened just before 4 a.m. Friday.

The Atlantis crew - Commander Mike Bloomfield, Pilot Steve Frick and mission specialists Rex Walheim, Ellen Ochoa, Lee Morin, Jerry Ross and Steve Smith - was awakened at 3:44 a.m. by the University of California-Berkeley fight song performed by the school band and "All Right Now," performed by the Stanford University band. Ochoa requested the songs be played for crewmates Walheim and Smith who attended the rival schools.

On board the station, the Expedition 4 crew, Commander Yury Onufrienko and flight engineers Carl Walz and Dan Bursch, also awoke at 3:44 a.m. to an alarm-clock-like tone. Both crews are ready to support the addition of the new segment to the station.

Ochoa, assisted by Bursch, will command the space station robotic arm, Canadarm2, to grapple S0 about 5 a.m. Canadarm2 will lift the truss segment out and away from Atlantis' cargo bay and temporarily install it on the U.S. laboratory Destiny. The Lab Cradle Assembly will provide a semi-rigid structural hold until the truss segment is permanently attached during four spacewalks this week.

The first spacewalk is set to begin about 10 a.m. today as Smith, wearing the suit with solid red stripes, and Walheim, in a solid white suit, float out of the station's Quest airlock. After initial setup procedures, their tasks during the 6½ hour venture include attaching two of four S0 mounting struts to Destiny, as well as an avionics tray that contains power, data and fluid cables and an umbilical system connected to the Mobile Transporter. If time permits, Smith will remove a launch support beam and also go inside the truss to install two circuit breakers.

Ochoa and Bursch will move Walheim on Canadarm2 to worksites throughout the spacewalk. Bloomfield and Frick will use the shuttle's robotic arm cameras to take video of the spacewalkers while Ross guides them through the outlined procedures.

Atlantis Commander Mike Bloomfield, Pilot Steve Frick, and Mission Specialists Ellen Ochoa, Rex Walheim, Lee Morin, Jerry Ross and Steve Smith - and the Expedition Four crew - Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch - spent their day transferring equipment and science experiments between the shuttle and the station. They also transferred oxygen from the shuttle to one of four high-pressure gas tanks on the Quest Airlock. The tanks are used to repressurize the airlock at the end of each spacewalk staged from the module.

Station flight controllers reported that four new computers on the S-Zero truss were tested successfully, as were new devices to determine the station's orientation relative to the Earth, Global Positioning System navigational antennas and the Thermal Control System for the 13 ½ ton girder, which will be the backbone for other trusses and solar array towers to be mounted on the station in the next year.

The two crews transferred a number of experiments from Atlantis to the station's Destiny Laboratory and reviewed plans for the second and third spacewalks of the mission Saturday and Sunday to continue the outfitting of the new truss.

Saturday's spacewalk by Ross and Morin is scheduled to begin around 9:30 a.m. Central time. The two spacewalkers will complete the bolting of two aft struts on the truss to Destiny, forming a secure structural mate between S-Zero and the Laboratory. Ross and Morin will also attach a second umbilical system to the truss' Mobile Transporter, a form of rail car that will eventually move the station's robotic arm some 350 feet up and down the entire length of the completed truss.

The two crews enjoyed some off duty time this afternoon and are scheduled to begin their sleep period at 7:44 p.m. Both crews will be awakened Saturday at 3:44 a.m.

The Atlantis crew - Commander Mike Bloomfield, Pilot Steve Frick, and mission specialists Ellen Ochoa, Rex Walheim, Lee Morin, Jerry Ross and Steve Smith - was awakened at 3:44 a.m. Central time by the song "Testify to Love," by Wynonna Judd played for Bloomfield from his family. On board the station, the Expedition 4 crew, Commander Yury Onufrienko and flight engineers Carl Walz and Dan Bursch, awoke about 30 minutes later.

Morin and Ross will move an experimental plant growth chamber to a rack inside the station's Destiny lab. This experiment will replace a protein crystal growth experiment that will return to Earth on board Atlantis. Walheim and Ochoa will install a freezer in the lab for future crystal samples.

Oxygen and nitrogen will be transferred from Atlantis to the station to refill the airlock high-pressure tanks with the gasses breathed by spacewalkers. The crew will also prepare for and review the procedures for the next two spacewalks, on Saturday and Sunday, to continue hookup of the S0 Truss.

Systems on the S0 Truss are functioning well after its installation Thursday. Friday, ground controllers will activate the Global Positioning System and the Rate Gyro Assembly located on S0 that will begin providing navigation and attitude data for the station.

Crewmembers will take a break to talk with reporters from MSNBC, CBS Radio Network and WWJ-TV in Detroit at 11:28 a.m. At 1 p.m. NASA television will switch to live coverage of NASA Administrator Sean O'Keefe's address on "Pioneering the Future." The address will be replayed on NASA TV at 3 p.m.

After two hours of time off during the afternoon, both crews are scheduled to begin their sleep period at 7:44 p.m.

Dubbed the "Silver Team" by their colleagues because of their age, 54-year old Jerry Ross and 49-year old Lee Morin of Atlantis' crew had little trouble extending and bolting the final two struts of the new S-Zero (S0) truss to the Destiny Laboratory, insuring that the centerpiece for the future expansion of the station would be permanently secured to accept additional trusses and solar array towers over the next year. The station will ultimately span some 350 feet from end to end, the length of a football field.

The first two struts of the truss were mated to Destiny on Thursday by the other Atlantis spacewalking team, Steve Smith and Rex Walheim, who will venture back outside Sunday to continue the outfitting of the truss and to reroute electrical power to the station's 58-foot long robotic arm.

Morin worked at the end of the ISS' Canadarm 2 throughout the day during his first spacewalk, while Ross, America's most experienced spacewalker and the most flown space traveler in history, remained tethered to the station to provide "free-floating" support during the eighth spacewalk of his career.

Smith, Walheim and Expedition Four Flight Engineer Dan Bursch helped choreograph the spacewalk from Atlantis' aft flight deck, while shuttle crew member Ellen Ochoa and station Flight Engineer Carl Walz took turns maneuvering Morin as they operated Canadarm2 from a robotic work station inside Destiny.

Shuttle and station Commanders Mike Bloomfield and Yury Onufrienko and shuttle Pilot Steve Frick provided photographic and television support for the spacewalk, the 36th devoted to ISS assembly over the past 3 ½ years.

After the truss struts were bolted in space, Ross and Morin removed a series of panels and clamps that provided structural support for the truss during its launch in Atlantis' cargo bay.

The spacewalkers then began work to install a backup device containing an umbilical reel for the Mobile Transporter railcar on the truss that will provide redundancy to a similar device mounted on the truss Thursday. The two sets of umbilicals for the Mobile Transporter, which is designed to move the robotic arm up and down the length of the completed station truss, provide power, data and video capability for the system, which will be tested for the first time in orbit Monday.

Ross tried to remove a restraining bolt on the mechanism which, if required, can cut the umbilical cable should it snag during its operation, but the bolt proved to be a bit balky and did not back out of its socket as planned. Flight controllers decided not to spend additional time troubleshooting the stubborn bolt today after engineers determined that the cable cutter cannot inadvertently fire in its current configuration. The backup umbilical system is operating normally and the stubborn bolt will be dealt with on one of the mission's two remaining spacewalks. The primary umbilical system installed Thursday is also operating normally.

The spacewalk, which was conducted out of the station's Quest Airlock, began at 9:09 a.m. Central time and concluded at 4:39 p.m. as Ross and Morin repressurized the outer compartment of the two-chamber module.

Late today, Frick fired Atlantis' steering jets in a one-hour procedure to slowly reboost the space station by about 2 statute miles. It was the first of three scheduled reboost maneuvers to eventually raise the orbit of the ISS by about 6 statute miles before Atlantis departs the station on Wednesday.

The ten shuttle and station crew members are scheduled to begin their eight-hour sleep period at 7:44 p.m. and will awaken Sunday just before 4 a.m. to begin preparations for the third spacewalk of the flight.

The Atlantis crew - Commander Mike Bloomfield, Pilot Steve Frick, and mission specialists Ellen Ochoa, Rex Walheim, Steve Smith, Morin and Ross - was awakened at 3:44 a.m. by the song "Voodoo Chile," by Jimi Hendrix. It was played for Morin, who will be making his first spacewalk, at the request of his wife. On board the station, the Expedition 4 crew, Commander Yury Onufrienko and flight engineers Carl Walz and Dan Bursch, also were awakened at 3:44 a.m.

During their 6½-hour spacewalk Ross, wearing a spacesuit with broken red stripes, and Morin, wearing a spacesuit with diagonal broken stripes, will complete the structural attachment of S0's remaining two struts to the station's Destiny laboratory. With all four of the struts attached to Destiny, S0 will be able to support its design loads, including the solar arrays that will be on the ends of the truss at assembly complete.

After attaching the struts, Ross and Morin will remove the large metal rods used to support S0 during launch and store them on the truss. The pair will also attach a second cable system to the Mobile Transporter, which will eventually enable the space station's robotic arm, Canadarm2, to ride a railway along the truss structure.

For today's spacewalk Morin will be working from a platform at the end of the Canadarm2, operated by Ochoa. Using the shuttle robotic arm cameras, Bloomfield and Frick will take photographs and video of the spacewalkers. Walheim will coordinate the spacewalk from inside.

Both crews are scheduled to begin their eight-hour sleep period at 7:44 p.m.

The stage is now set for the inaugural run Monday of the so-called Mobile Transporter, a flatcar designed to transport the space station's robotic arm up and down an integrated truss system that will span the length of a football field.

Within minutes after starting their spacewalk at 8:48 a.m. Central time, Steve Smith and Rex Walheim released a claw-like device on the top of the Destiny Laboratory to which the new 13 ½ ton S-Zero (S0) truss was initially attached on Thursday. With the truss' four large struts now securely bolted to Destiny, the claw was no longer needed.

Smith and Walheim then reconfigured a number of connectors providing electricity to the 58-foot-long Canadarm2 robotic arm on the station so it can be powered from the S-Zero truss rather than Destiny. The arm has two sets, or "strings" of avionics equipment for its operation. As Smith and Walheim worked deliberately, one set of avionics was rewired and tested, followed by a separate set of redundant avionics.

Smith spent most of the day riding at the end of the shuttle's robotic arm, which was operated by Pilot Steve Frick during the rewiring of its companion station arm. Walheim was the so-called "free-floating" astronaut, tethered to the station to assist Smith. It was the seventh spacewalk of Smith's career. He is the second most experienced U.S. spacewalker behind crewmate Jerry Ross, who helped choreograph today's excursion from inside Atlantis with the help of Lee Morin. It was Walheim's second spacewalk.

With Canadarm2 successfully rewired and both of its electrical, data and video circuit sets checked out, Smith and Walheim pressed ahead to release clamps which secured the Mobile Transporter to the S-Zero truss during its launch last week. The railcar, which weighs about 1900 pounds, will be commanded Monday by ground controllers to move about 32 feet up and down the truss at a glacial speed of a little less than one inch per second in the first test of its computers, drive motors, suspension unit, video and data umbilicals and the first section of rails on the S-Zero.

The railcar, and an associated Mobile Base System device to be installed on the transporter in early June on the next shuttle assembly flight to the ISS, will ultimately enable the robotic arm to travel to various worksites on the expanding trusses of the station for future construction. The Mobile Base System will be the platform upon which the Canadarm2 will attach itself to be driven up and down the length of the ISS.

The only task not completed today was the attachment of a 14-foot ladder called the Airlock Spur from the S-Zero truss to the Quest Airlock designed to simplify the path for future spacewalkers moving back and forth from the truss to the airlock itself.

As the spacewalk neared its completion, final diagnostic tests of the newly wired station arm were taking longer than planned, and because the Canadarm2 is required for the airlock ladder to be pivoted away from the truss to Quest, flight controllers decided to defer its installation until the final spacewalk on Tuesday.

Smith and Walheim finally returned to Quest and completed their spacewalk at 3:15 p.m. Central time with the repressurization of the airlock.

Atlantis astronaut Ellen Ochoa and ISS Expedition Four crew member Dan Bursch backed up Frick in the operation of the shuttle's robot arm during today's spacewalk, the 37th devoted to space station assembly. Commander Mike Bloomfield documented the spacewalk from Atlantis' aft flight deck while Expedition Four Commander Yury Onufrienko and Flight Engineer Carl Walz continued to transfer supplies from the shuttle to the station for future use.

Late today, Frick conducted an hour-long reboost of the ISS, using Atlantis' steering jets to move the station higher by about two statute miles. It was the second of three planned maneuvers to raise the station's altitude and the second in as many days.

The ten crew members are scheduled to begin an eight-hour sleep period at 7:44 p.m. Central time tonight and will be awakened just before 4 a.m. to prepare for the testing of the new Mobile Transporter.

They are scheduled to step out of the station's Quest airlock at 9:34 a.m. Their first task is to release a claw atop the lab that temporarily secured the truss to it during the initial installation. Walheim, wearing a solid white spacesuit, will release the latch as Smith, wearing a spacesuit with red stripes, begins making connections to route power, data, and video through the truss for later operation of the space station robotic arm, Canadarm2. During the 6½-hour spacewalk, Smith will be working from a platform on the station arm, operated by Mission Specialist Ellen Ochoa and Flight Engineer Dan Bursch.

Walheim will install circuit breakers in the truss, a task left over from the first spacewalk, which lasted 7½ hours. Together they will then turn their attention to the Mobile Transporter, spending about 45 minutes releasing its many launch restraints and removing a small thermal cover from a radiator on the railcar. Then they return to work on the electrical connections for about another hour and a half.

After transferring tools and testing sensors on the side of S0, the last task will be to install the Airlock Spur. The 14-foot beam, fitted with handrails, will stretch from Quest to the forward side of S0, helping future spacewalkers work more efficiently.

Inside the shuttle/station complex, Mission Specialists Lee Morin and Jerry Ross will coach the spacewalkers through the outlined tasks. Shuttle Commander Mike Bloomfield and Pilot Steve Frick will provide photographic and video support during the spacewalk, using Atlantis' robotic arm.

Atlantis' crew was awakened about 3:52 a.m. by the song "All Star," performed by Smash Mouth from the Shrek movie soundtrack. The song was played for Walheim by his family.

Onboard the space station, Expedition Four Commander Yury Onufrienko, Flight Engineer Carl Walz and Bursch were awakened at 3:44 a.m. Both crews are scheduled to begin their sleep period at 7:44 p.m.

Expedition Four Flight Engineer Carl Walz sent commands from a laptop computer to the Mobile Transporter to move off of its launch position on the forward face of the new S-Zero (S0) truss, and at 7:22 a.m., the flatcar began its slow trek to an initial worksite 17 feet down a rail which spans the entire 44 feet of the girder.

It took only a half hour to traverse the distance, but sensitive software in the transporter prevented an automatic latching of the railcar to the worksite. Ground controllers accomplished the latching through a methodical series of commands.

Engineers believe that the subtle effects of weightlessness are causing the railcar to "lift" off its tracks by a microscopic distance, thus interfering with magnetic sensors that tell the transporter its position relative to each worksite. The effect is that the sensors are losing contact with magnetic positioning strips on the truss rail, preventing an automatic latching of the transporter. Manual commanding of the latching is working however, and the system is said to be in excellent working order.

The Mobile Transporter software controls about 20 motors, directing it to travel from one point to another, latch itself down to the truss, and plug itself into a power source. The transporter must latch with about three tons of force to insure a stable platform for the eventual mounting of the Canadarm2 robotic arm. On the next shuttle assembly flight to the ISS in June, a platform called the Mobile Base System will be mounted to the transporter upon which Canadarm 2 will eventually be attached so it can travel the length of a football field to support future assembly of station components.

Late today, the transporter traveled to a second worksite where manual latching commands were again required, then inched back to the first worksite, where the railcar was parked at 5:40 p.m. Central time and manually latched in place for a final time to await the arrival of the Mobile Base System component on the STS-111 mission. In all, the transporter traveled 72 feet from worksite to worksite at a glacial pace of about one inch per second.

Engineers believe a minor software modification may restore the transporter's ability to automatically latch itself to any worksite. All other transporter systems functioned perfectly throughout its initial test.

Atlantis Commander Mike Bloomfield, Pilot Steve Frick, Mission Specialists Ellen Ochoa, Rex Walheim, Lee Morin, Jerry Ross and Steve Smith, and Expedition Four Commander Yury Onufrienko and Flight Engineers Walz and Dan Bursch spent the day monitoring the transporter tests and continued the transfer of equipment and supplies from Atlantis to the station.

In addition, about 100 pounds of oxygen and 30 pounds of nitrogen have been transferred from Atlantis to the tanks on the Quest Airlock to support future spacewalk activity.

The fourth and final spacewalk of the flight will be conducted on Tuesday by Ross and Morin beginning around 9:30 a.m. Central time. At the start of the planned 6 ½ hour excursion, Ross and Morin will pivot a 14-foot ladder away from the S-Zero truss for attachment to Quest to act as a pathway for future spacewalkers. They will also install external lights on the Unity module, test microswitches on the sides of the S-Zero truss which will be used to confirm the attachment of future truss segments, troubleshoot a balky bolt on a cable cutting system on the Mobile Transporter and tie down a portion of insulation on one of four navigational antennas on the S-Zero.

The ten Shuttle and Station crew members are scheduled to begin an eight-hour sleep period at 7:44 p.m. Central time and will be awakened shortly before 4 a.m. Tuesday to prepare for the final spacewalk of the mission.

Ground controllers in mission control will command the Mobile Transporter to move up and down the truss three times, testing its computers, drive motors, suspension unit, video and data umbilicals, and the railway itself. The railcar will travel a total of about 71 feet at speeds of 1, 0.4 and 0.1 of an inch per second, stopping at future worksites to test its ability to latch and unlatch itself to the railway.

This is the first time that a software-controlled movable robot has been used on an orbiting vehicle. The Mobile Transporter software controls about 20 motors, directing it to travel from one point to another, latch itself down to the truss, and plug itself into a power source. The Mobile Transporter ultimately will move the station's robotic arm, Canadarm2, along the orbiting laboratory's 356-foot Integrated Truss.

The Atlantis crew - Commander Mike Bloomfield, Pilot Steve Frick, Mission Specialists Ellen Ochoa, Rex Walheim, Lee Morin, Jerry Ross and Steve Smith - was awakened at 3:48 a.m. to "Magic Carpet Ride" by Steppenwolf, dedicated to Smith. The station crew - Commander Yury Onufrienko, Flight Engineers Carl Walz and Dan Bursch - was awakened at 4:14 a.m.

The crews will continue to transfer equipment between the two spacecraft and will review procedures for the fourth and final spacewalk of the mission, scheduled for Tuesday.

The 10 crewmembers will participate in a news conference with media representatives at NASA centers in Florida and Houston and at Mission Control- Moscow. The event will be carried live on NASA television beginning at 11:47 a.m. CDT. Afterwards, the crews will have a few hours off. Both crews are scheduled to begin their eight-hour sleep period at 7:44 p.m.

Work during the 6½-hour spacewalk includes installation a 14-foot beam extending from Quest to the newly installed S-Zero (S0) Truss to help spacewalkers maneuver around the station more efficiently. They will install halogen work lights on the Unity module and the U.S. laboratory, Destiny -- the 40-watt lamps are five times more powerful than standard 40-watt lamps and will shine a 9- by 7-foot elliptical beam of light 20 feet away. The spacewalkers will setup and partially assemble a work platform.

Ross, working from the station's robotic arm, also will install shock absorbers to either side of the Mobile Transporter to provide a barrier and attach point between the railcar and future hand-propelled carts that will be used by spacewalkers.

Morin will deploy an instrument to measure and characterize the radiation environment outside the station. He also will troubleshoot a balky bolt on a redundant cable cutting system on the Mobile Transporter. A successful test run of that railcar concluded late Monday when ground controllers commanded it to latch onto the railway and plug into a power source. The railcar is ready to receive the Mobile Base System during the next shuttle mission, STS-111, giving the station's Canadarm2 points of attachment on the rail-car base capable of moving along the station's Integrated Truss.

Additional tasks include installing handrails on S0, relocating tools for STS-111 spacewalks, adjusting a thermal blanket partly obstructing a GPS antenna on S0, performing photo and video documentation of station components and checking out a gauge that is designed to detect minute amounts of gas in the environment of space.

The Atlantis crew - Commander Mike Bloomfield, Pilot Steve Frick, Mission Specialists Ellen Ochoa, Rex Walheim, Steve Smith, Morin, and Ross- was awakened at 3:44 a.m. to "I Am an American," performed by the Purdue University Marching band. It was dedicated to Purdue graduate Ross. The station crew - Commander Yury Onufrienko, Flight Engineers Carl Walz and Dan Bursch - was also awakened at 3:44 a.m.

Ross and Morin began the fourth and final spacewalk of the STS-110 mission and the 38th devoted to space station construction at 9:29 a.m. Central time, first pivoting a 14-foot beam called the Airlock Spur from the S-Zero truss to the Quest Airlock to provide a quick pathway for future spacewalkers working on truss assembly.

Ross then conducted tests of switches on both sides of the 44-foot long truss to insure they will work properly later this year in confirming the attachment of additional truss segments to the S-Zero. The main truss of the ISS will eventually stretch more than 350 feet, longer than a football field.

The two spacewalking grandfathers pressed ahead to install floodlights on the station's Unity connecting module and the Destiny Laboratory which will provide illumination for future spacewalkers as they move around the expanding outpost.

Ross and Morin then affixed a work platform on the station for future construction work, installed electrical converters and circuit breakers, dressed up a piece of insulation around one of the four navigational antennas on the truss and attached shock absorbers to the new Mobile Transporter railcar. The shock absorbers will prevent vibrations to the station's robotic arm from the future use of carts on the truss which will be used to move spacewalkers from one end of the station to another.

The only tasks not accomplished were the removal of a balky bolt from a backup cable cutting device on one of two umbilical systems for the Mobile Transporter, which was successfully tested on Monday and the installation of a gas analyzer on the truss which proved to be faulty.

The bolt will have no impact on the operation of the flatcar, upon which a Mobile Base System platform will be mounted in June as the ultimate base for the transport of the station's robotic arm up and down the length of the ISS. The gas analyzer was considered the lowest priority of the flight.

With all of their major work completed, Ross and Morin returned to the Quest Airlock and concluded the spacewalk at 4:06 p.m. Central time.

Atlantis Mission Specialist Ellen Ochoa and Expedition Four Flight Engineer Dan Bursch operated the station's Canadarm2 robotic arm to move Ross around the ISS during the spacewalk while Morin operated as the "free-floating" spacewalker, tethered to the station to assist Ross in the final tasks of the mission. For Ross, America's most experienced spacewalker, it was his ninth excursion to conduct work in the void of space during his career, totaling 58 hours and 18 minutes of spacewalking time. Only Russian cosmonaut Anatoly Solovyev has performed more spacewalks in human spaceflight history. Today's spacewalk was the second for Morin. Rex Walheim and Expedition Four crew members Carl Walz helped choreograph the spacewalk from Atlantis' aft flight deck.

While the spacewalkers went about their work, Shuttle and Station Commanders Mike Bloomfield and Yury Onufrienko, Pilot Steve Frick, and Steve Smith continued their transfer of equipment to and from both Atlantis and the ISS and provided photographic and television support to Ross and Morin.

With all of the objectives having been successfully accomplished for the mating and outfitting of the S-Zero truss to the ISS, the stage is set for Wednesday's final farewells between the two crews and undocking of Atlantis from the station at 1:31 p.m. Central time as the two craft sail some 244 statute miles above the north Atlantic due west of Ireland. Atlantis is scheduled to land at the Kennedy Space Center early Friday afternoon.

The shuttle crewmembers will begin an eight-hour sleep period tonight at 7:14 p.m. Central time followed thirty minutes later by the station crew. Atlantis' crew will be awakened at 3:14 a.m. Wednesday to prepare for undocking. The station crew will be awakened an hour later.

Farewells and closing of the hatches between the spacecraft is set to begin about 10:30 a.m. About 1:30 p.m., Atlantis astronaut Jerry Ross will send commands to release the docking mechanism. The initial separation will be provided by springs that will gently push the shuttle away from the station. When Atlantis is about two feet away from the station and the docking devices are clear of one another, Pilot Steve Frick will fire Atlantis' steering jets to begin slowly moving away.

About 45 minutes after undocking, when Atlantis is 450 feet away, Frick will fly the shuttle around the station 1¼ times. The flyaround is set to begin at 2:16 p.m. and will last about an hour. Atlantis will move directly over the station, then behind it, underneath it, and back in front, where the flyaround began. The last quarter-circle brings the shuttle directly above the station. Finally, Frick will fire Atlantis' jets to move away from the station about 3:15 p.m. Atlantis is scheduled to land at the Kennedy Space Center at 11:26 a.m. CDT Friday.

Atlantis leaves behind the newly installed S-Zero (S0) Truss, the first part of the main truss that will support cooling and power systems essential for the addition of future international laboratories to the station. All of the S0 systems have been operating well since its attachment to the station's U.S. laboratory Destiny on Thursday.

The shuttle also delivered additional supplies and science experiments for the station crew to work with during its final weeks on the station. The Expedition Four crew - Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch - is scheduled to return to Earth aboard the space shuttle Endeavour in June.

The Atlantis crew - Commander Mike Bloomfield, Frick, Mission Specialists Ellen Ochoa, Rex Walheim, Steve Smith, Lee Morin, and Ross- was awakened at 3:44 a.m. to "Noah," performed by Frick when he was a teen-ager. The station crew was awakened at 4:14 a.m.

After more than a week of joint operations between the shuttle and station crews, Pilot Steve Frick backed Atlantis away to a distance of about 400 feet in front of the outpost, where he began a 1 1/4 lap flyaround of the ISS, newly equipped with the 27,000 pound S-Zero truss, the first segment of a truss structure which will ultimately expand the station to the length of a football field. Aboard the station, Flight Engineer Dan Bursch rang a ship's bell in the Unity module to mark Atlantis' departure in what has become a tradition.

Finally, at 3:15 p.m., as Atlantis flew directly above the station, Frick fired the shuttle's jets one more time in a separation maneuver to depart the station for good.

Left behind on the ISS are Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Bursch, now in their 133rd day in space and their 131st day on board the outpost.

Also left behind on the station were more than a ton of supplies, almost 200 pounds of oxygen and nitrogen for the station's Quest Airlock, 1,463 pounds of water and the new truss, which will serve as a backbone for future station construction and a power switching station for new solar arrays to be delivered to the ISS next year. Atlantis's week-long visit to the ISS was the 13th shuttle mission devoted to station assembly and resupply.

Earlier today, Commander Mike Bloomfield, Frick and Mission Specialists Rex Walheim, Ellen Ochoa, Steve Smith, Lee Morin and Jerry Ross completed final transfers of logistical supplies to the station and bid farewell to their station counterparts in the Destiny Laboratory. Hatches between the station and the shuttle swung shut at 11:04 a.m. Central time and leak checks were performed to insure that all was in order for the undocking.

As Atlantis' crew turns its attention to preparations for landing at the Kennedy Space Center Friday afternoon, the Expedition Four crew will prepare to button up the ISS temporarily and enter its Soyuz return craft early Saturday for a brief flyover from one docking port to another.

With Onufrienko at the controls, the Soyuz will undock from the station's Zarya nadir docking port at around 4 a.m. Central time Saturday, back out to a distance of about 250 feet and redock to the Pirs Docking Compartment 35 minutes later. That will clear the Zarya docking port for the arrival of a new Soyuz return vehicle and a three-man taxi crew on April 27 for a week-long visit.

Both Atlantis and the International Space Station are in excellent shape following their joint mission. Atlantis' astronauts are scheduled to begin an eight-hour sleep period at 6:44 p.m. Central time and will be awakened just before 3 a.m. Thursday for what is expected to be their final full day in orbit.

The crew - Commander Mike Bloomfield, Pilot Steve Frick, Mission Specialists Ellen Ochoa, Rex Walheim, Lee Morin, Jerry Ross and Steve Smith - was awakened at 2:44 a.m. to "Somewhere Over the Rainbow," performed by Bloomfield's daughter.

Bloomfield, Frick and Ochoa will test fire the reaction control system jets and flight control surfaces that will be used to guide Atlantis through the atmosphere on Friday morning. Atlantis is scheduled to return to the Kennedy Space Center in Florida at 11:26 a.m. CDT Friday where preliminary weather forecasts for landing are favorable.

Crewmembers will take a break from their on orbit work today to talk with media representatives from CNN, WDIV-TV in Detroit and the Fox News Network this morning in an interview beginning at 9:14

Atlantis' orbital maneuvering jets will be fired twice today. Once will be for scientists to look at the exhaust's effects on radar echoes and effects of orbital kinetic energy on the ionosphere. The other firing will reduce the cross range for Friday's backup landing opportunity in Florida. Walheim, Morin, Ross and Smith will continue to pack away equipment and supplies onboard the shuttle and prepare the cabin for landing.

On board the International Space Station the Expedition 4 crew - Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz - was awakened at 3 a.m. They are preparing for their next visitors, a Soyuz taxi crew slated to arrive April 27. Onufrienko, Walz and Bursch, will board the current Soyuz spacecraft and move it from its location on the Zarya docking port to the Pirs docking compartment on Saturday to make room for the replacement Soyuz.

The crew of Atlantis will begin a scheduled eight-hour sleep period at 6:14 p.m. today, waking just after 2 a.m. Friday to prepare for reentry and landing of Atlantis concluding a successful mission to the station.

Commander Mike Bloomfield, Pilot Steve Frick and Flight Engineer Ellen Ochoa activated one of three hydraulic power units on Atlantis and tested all of the shuttle's aerosurfaces to ensure that Atlantis will have full controllability during its high-speed return to Earth Friday. Bloomfield and Frick then test-fired Atlantis' steering jets, which were declared ready to support entry and landing.

Bloomfield, Frick and Ochoa joined crewmates Rex Walheim, Lee Morin, Jerry Ross and Steve Smith to stow all of the equipment they have used over the past 10 days and parked the shuttle's KU-band dish antenna in preparation for the closing of Atlantis' cargo bay doors early Friday morning.

Atlantis has two landing opportunities at the Kennedy Space Center on Friday. The first begins with the firing of Atlantis' braking rockets at 10:20 a.m. Central time, enabling the shuttle to drop out of orbit for its hour-long descent back to Earth and a touchdown on the 3-mile long Shuttle Landing Facility at KSC at 11:26 a.m. Central time. In the unlikely event weather prevents a landing on the first opportunity, a second opportunity is available for a Florida landing, beginning with the deorbit burn of the orbital maneuvering system engines on Atlantis at 11:59 a.m. Central time, resulting in a landing at KSC at 1:03 p.m. Central time.

The weather forecast calls for very favorable conditions for landing at the Florida spaceport Friday, with only scattered clouds and light winds expected. As a result, the backup landing site at California's Edwards Air Force Base was not called up for support Friday. Atlantis has enough consumables to stay in orbit, if necessary, until Monday.

Meanwhile, on board the ISS, Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch spent a relatively quiet day in the wake of a week of joint operations with Atlantis' crew to install and activate the S-Zero (S0) truss and the Mobile Transporter railcar on the complex. Both of the new components continue to be checked out and are said to be in excellent shape.

Onufrienko, Walz and Bursch will spend part of the day Friday deactivating some of the ISS systems as they prepare to board their Soyuz return vehicle early Saturday for a brief flyover from its current docking location at the nadir port of the Zarya module to the Pirs Docking compartment. The relocation of the Soyuz, which is expected to take about 35 minutes, will begin with undocking Saturday at 4:02 a.m. Central time (902 GMT). Coverage of the operation on NASA Television begins at 3 a.m. Central time (800 GMT).

The movement of the Soyuz 3 vehicle from Zarya to Pirs opens the Zarya port for the arrival of a new Soyuz 4 craft on April 27 by a three-man "taxi" crew comprised of Commander Yuri Gidzenko, formerly of the Expedition One crew, Flight Engineer Roberto Vittori of the European Space Agency and South African spaceflight participant Mark Shuttleworth. They will be launched from the Baikonur Cosmodrome in Kazakhstan on April 25 and will spend about a week in joint operations with the Expedition Four crew before departing from Pirs in the Soyuz 3 craft on the night of May 4.

The crew of Atlantis was scheduled to begin a scheduled eight-hour sleep period at 6:14 p.m. today, and will be awakened just after 2 a.m. Friday to prepare for entry and landing. All shuttle and ISS systems are operating normally.

If Atlantis lands on Friday, the STS-110 astronauts will return home to Ellington Field in Houston near the Johnson Space Center at around 1 p.m. Central time Saturday.

Atlantis has two landing opportunities at KSC today. The first begins with the firing of Atlantis' braking rockets at 10:20 a.m. and a landing at 11:26 a.m. CDT. A second opportunity for a Florida landing would see the deorbit burn at 11:59 a.m. and a landing at KSC at 1:03 p.m. CDT. Forecasts call for favorable weather for landing in Florida Friday, with only scattered clouds expected. The backup-landing site at California's Edwards Air Force Base was not called up today. Atlantis has enough consumables to stay in orbit until Monday.

The crew of Atlantis - Commander Mike Bloomfield, Pilot Steve Frick, and Mission Specialists Ellen Ochoa, Rex Walheim, Lee Morin, Jerry Ross and Steve Smith - was awakened at 2:21 a.m. by the song "Message in a Bottle," performed by The Police.

Meanwhile, aboard the ISS, Expedition 4 Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch monitored station systems this morning during another reboost of the orbiting laboratory. The Progress cargo ship's jets were fired to raise the station's altitude a little more than half a mile. During the STS-110 mission, Atlantis did three station reboosts, totaling about six miles.

The station crew also will deactivate some ISS systems today to prepare to board the Soyuz return vehicle early Saturday for its 35-minute move from the nadir port of the Zarya module to the Pirs Docking compartment. The relocation of the Soyuz will begin with undocking Saturday at 4:02 a.m. Coverage on NASA Television begins at 3 a.m.

The move frees the Zarya port for the arrival of a new Soyuz 4 craft on April 27 with a three-man "taxi" crew comprised of Commander Yuri Gidzenko, Flight Engineer Roberto Vittori of the European Space Agency and South African spaceflight participant Mark Shuttleworth. They will be launched from the Baikonur Cosmodrome in Kazakhstan on April 25 and will spend about a week aboard the station before departing in the Soyuz 3 craft May 4.

Commander Mike Bloomfield eased Atlantis to a textbook landing on runway 3-3 at the Florida spaceport at 11:27 a.m. Central time under clear skies and light winds. Bloomfield, Pilot Steve Frick and Mission Specialists Rex Walheim, Ellen Ochoa, Lee Morin, Jerry Ross and Steve Smith completed an 11-day flight in which four spacewalks were conducted to deliver and activate the new S-Zero (S0) girder to the ISS, which will serve as the centerpiece for a truss that will eventually span the length of a football field. Solar arrays will be mounted on the truss as well as new station modules. The S-Zero component will also serve as a switching station for electricity from the station's solar arrays to ISS elements. In addition, the truss is a base for the first rail system in space through the use of its Mobile Transporter and the upcoming Mobile Base System to be delivered to the ISS in June on which the station's robotic arm will be affixed to move up and down the length of the outpost.

The shuttle crewmembers were scheduled to depart Atlantis about an hour after landing to be driven back to the crew quarters at KSC for medical tests and reunions with their families.

The STS-110 astronauts will return home to Hangar 990 at Ellington Field in Houston near the Johnson Space Center at around 1 p.m. Central time Saturday for a welcome home ceremony. The public is invited to attend.

Meanwhile, aboard the ISS, Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch spent the day configuring station systems for the temporary closure of the complex early Saturday in advance of a short departure in their Soyuz return vehicle and a relocation of the craft to another docking port.

Onufrienko, Walz and Bursch will board their Soyuz return vehicle early Saturday for a brief flyover from its current docking location at the nadir port of the Zarya module to the Pirs Docking compartment. The relocation of the Soyuz, which is expected to take about 35 minutes, will begin with undocking Saturday at 4:02 a.m. Central time (902 GMT). Coverage of the operation on NASA Television begins at 3 a.m. Central time (800 GMT).

The movement of the Soyuz 3 vehicle from Zarya to Pirs opens the Zarya port for the arrival of a new Soyuz 4 craft on April 27 by a three-man "taxi" crew comprised of Commander Yuri Gidzenko, who served on the first resident crew of the ISS, Flight Engineer Roberto Vittori of the European Space Agency and South African spaceflight participant Mark Shuttleworth. They will be launched from the Baikonur Cosmodrome in Kazakhstan on April 25 and will spend about a week in joint operations with the Expedition Four crew before departing from Pirs in the Soyuz 3 craft on the night of May 4.

Major systems aboard the ISS continue to function well as the station orbits at an average altitude of about 247 statute miles.

Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch undocked the Soyuz 3 capsule from the nadir docking port of the Zarya module of the ISS at 4:16 a.m. Central time (916 GMT) and flew a short distance down the station for a redocking to the Pirs Docking Compartment at 4:37 a.m. Central time (937 GMT) over Central Asia. The station's key systems had been deactivated for the brief flight in the unlikely event Onufrienko could not redock the vehicle.

The Zarya docking port is now free for the arrival of the new Soyuz 4 capsule next Saturday, and a three-man "taxi" crew, Commander Yuri Gidzenko, who was a member of the first resident crew of the ISS, Flight Engineer Roberto Vittori of the European Space Agency and South African space flight participant Mark Shuttleworth. They are scheduled to be launched Thursday from the Baikonur Cosmodrome in Kazakhstan at 1:26 a.m. Central time (626 GMT) and will link up to the ISS on April 27 at around 3 a.m. Central time (800 GMT).

The "taxi" crew will spend almost eight days aboard the ISS conducting experiments. A fresh Soyuz is delivered to the station every six months as an assured means of bringing the resident crewmembers home if an emergency forces them to leave the complex.

The Soyuz relocation comes one day after the shuttle Atlantis landed at the Kennedy Space Center to wrap up an 11-day flight which featured four spacewalks to install and activate the 13-ton S-Zero (S0) truss to the ISS. The truss, which is the major backbone for future station construction, is functioning perfectly.

Atlantis' seven astronauts will return from the Kennedy Space Center to Hangar 990 at Ellington Field in Houston near the Johnson Space Center this afternoon for a welcome home ceremony at around 1 p.m. Central time. The public is invited to attend.

All systems aboard the ISS continue to function well as the station orbits at an average altitude of about 245 statute miles.

Russian Commander Yuri Gidzenko, Flight Engineer Roberto Vittori of the European Space Agency and South African businessman Mark Shuttleworth rocketed away from the Central Asian launch site at 1:26:38 a.m. Central time (626:38 GMT) in their Soyuz TM-34 craft. Less than nine minutes later, with the Soyuz solar arrays and navigational antennas successfully deployed, they had reached orbit to begin a two-day chase to reach the ISS early Saturday. At the time of launch, the ISS was flying over Iraq at an altitude of 244 statute miles. The Expedition Four crew on board the station had just awakened at the time the Soyuz began its journey.

Gidzenko, who is making his third flight into space, is the first former resident of the ISS to return to the complex, having been a member of the Expedition One crew, the first crew to live aboard the station. Gidzenko first arrived at the ISS in November 2000. Vittori, who is a professional astronaut, is making his first spaceflight, traveling to the ISS under a contract between the Italian Space Agency and the Russian Aviation and Space Agency. Shuttleworth is a South African Internet entrepreneur flying under contract with the Russian Aviation and Space Agency as well on his first mission.

The three crewmembers will dock to the Zarya module of the ISS on Saturday at 2:57 a.m. Central time (757 GMT). That docking port was freed up last Saturday when Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch relocated the Soyuz vehicle currently at the ISS from Zarya to the Pirs Docking Compartment.

Gidzenko, Vittori and Shuttleworth will spend almost eight days on the station, conducting experiments and educational activities. They will depart the ISS on the evening of May 4, U.S. time, in the Soyuz currently docked to the station, and will land a few hours later on the Kazakh steppes.

All systems aboard the ISS continue to function well as the station orbits at an average altitude of about 245 statute miles.

Two days after their launch from the Baikonur Cosmodrome in Kazakhstan, Russian Commander Yuri Gidzenko, Flight Engineer Roberto Vittori of the European Space Agency and South African businessman Mark Shuttleworth docked their Soyuz TM-34 craft to the nadir docking port of the Zarya module of the ISS at 2:56 a.m. Central time (756 GMT) as the two vehicles flew over Central Asia.

On board the ISS, Expedition Four Flight Engineer Dan Bursch, a Navy Captain, maintained a tradition by ringing the ship's bell in the Unity module to mark the arrival of new visitors. ISS Commander Yury Onufrienko and Flight Engineer Carl Walz monitored the docking along side Bursch.

Parked nearby at the Pirs Docking Compartment was the Soyuz TM-33 craft, which was brought to the ISS by another crew last fall. Gidzenko, Vittori and Shuttleworth will ride home to a landing on the Kazakh steppes in that older Soyuz capsule on May 4, U.S. time (early May 5, Kazakhstan time).

Gidzenko, who is making his third flight into space, is the first former resident of the ISS to return to the complex, having been a member of the Expedition One crew, the first crew to live aboard the station. Gidzenko first arrived at the ISS in November 2000. Vittori, who is a professional astronaut, is making his first spaceflight, traveling to the ISS under a contract between the Italian Space Agency and the Russian Aviation and Space Agency. Shuttleworth is a South African Internet entrepreneur flying under contract with the Russian Aviation and Space Agency as well on his first mission.

Gidzenko, Vittori and Shuttleworth will spend their visit on the station conducting experiments and educational activities

About an hour and a half after docking, and after leak checks were performed to insure a tight seal between the Soyuz and the ISS, hatches swung open at 4:25 a.m. Central time (925 GMT) and the six crewmembers greeted one another. Congratulations were offered to the two crews from Russian, Italian, European Space Agency and South African officials who watched the linkup from the Russian Mission Control Center outside Moscow.

All systems aboard the ISS continue to function well as the station orbits at an average altitude of about 245 statute miles.

Russian Commander Yuri Gidzenko, Flight Engineer Roberto Vittori of the European Space Agency and South African businessman Mark Shuttleworth undocked their Soyuz TM-33 craft from the Pirs Docking Compartment of the ISS at 7:31 p.m. Central time (00:31 GMT May 5) over China after eight days of joint activities with Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch.

Left behind on the nadir docking port of the Zarya module of the ISS is a new Soyuz TM-34 return craft, in which Gidzenko, Vittori and Shuttleworth were launched on April 25 and which they guided to a docking to the ISS last Saturday. The older Soyuz arrived at the station last October. Fresh Soyuz spacecraft are brought to the station every six months to serve as an emergency return vehicle in the event a problem forces station residents to leave the complex prematurely.

After backing the older Soyuz away from the Pirs docking port, Gidzenko fired the Soyuz' thrusters to begin a separation maneuver away from the station. Later this evening, Gidzenko will conduct a four-minute deorbit burn of the Soyuz engines to begin the capsule's descent back to Earth.

Gidzenko, Vittori and Shuttleworth are scheduled to land on the steppes of Kazakhstan at 10:52 p.m. Central time (352 GMT May 5) to wrap up their mission.

Gidzenko, who is completing his third flight into space, was the first former resident of the ISS to return to the complex, having been a member of the Expedition One crew, the first crew to live aboard the station.

Gidzenko, Vittori and Shuttleworth spent most of their time on the station conducting experiments and educational activities.

All systems aboard the ISS continue to function well as the station orbits at an average altitude of about 245 statute miles.

The Expedition 4 crew began their week by having Sunday, Monday and half of Tuesday off after playing host to three visitors for more than eight days. The multinational Soyuz Taxi crew left the International Space Station Saturday, May 4, having delivered a fresh Soyuz crew return vehicle to the outpost.

Onufrienko, Walz and Bursch also worked with the Zeolite Crystal Growth experiment and the Biomass Production System, a plant growth experiment that is the second such experiment for the Expedition 4 crew.

Russian ground controllers continue to work with Onufrienko to troubleshoot the Elektron oxygen generating system in the Zvezda Service Module, which has been working off and on for most of the last week. The Elektron, which breaks down water into hydrogen and breathable oxygen, is off. When necessary, the crew has been burning chemical candles that release oxygen and have resupplied the ISS with oxygen from the Progress supply tanks. Although they do not plan to use it, the crew has an additional supply of oxygen in the high-pressure gas tanks attached to the station's Quest airlock. The Elektron problem has had no impact on station operations.

Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch continued packing experiments and other gear in anticipation of the arrival of the Space Shuttle Endeavour, their ride home, early next month. Shuttle managers Thursday cleared Endeavour for launch on mission STS-111 May 30, which would lead to a docking with the station on June 1.

With Onufrienko's assistance, Russian flight controllers repaired the Elektron system on the station, one of several methods available to replenish oxygen aboard the spacecraft. The Elektron splits water into hydrogen, which is disposed of, and oxygen, which is released into the cabin, as part of onboard recycling. The unit had been functioning only intermittently for the past two weeks and Russian flight controllers and the crew made several troubleshooting attempts. The problem eventually was traced to an errant sensor which was bypassed with a software adjustment provided by the Russian Mission Control Center.

There was no shortage of oxygen in the cabin air aboard the station throughout the Elektron troubleshooting procedures. While the Elektron was not operating properly, the crew supplemented the cabin air's oxygen by using several Solid Fuel Oxygen Generator cartridges, chemical canisters that release oxygen when heated. Even without the Elektron in operation, the station has oxygen supplies aboard -- in the solid fuel canisters and in U.S. oxygen tanks -- to last in excess of three months. Oxygen reserves also are replenished each time a shuttle or Progress supply craft visits the station.

In the Destiny laboratory, the crew wrapped up work this week with an experiment that grew the first zeolite crystals, a key element of refining processes used in the petrochemical industry on Earth, in a Destiny Laboratory furnace. The experiment had been delivered last month aboard the shuttle Atlantis and the completed crystals will be returned to scientists on the ground by Endeavour. In addition, work continued on the Biomass Production System, a plant growth experiment, with the crew regularly preserving Brassica plant samples and checking the growth chambers' status.

The crew spent several hours this week reviewing the plans for joint work with the astronauts that will arrive aboard Endeavour during STS-111 and the handover of station responsibilities to the upcoming Expedition 5 crew. In addition to exchanging station crews, STS-111 will deliver a Canadian-contributed Mobile Base System that will enable the station's Canadarm2 to move up and down the station's truss railway, delivered on a shuttle flight last month. Endeavour's crew also will replace a faulty wrist roll joint on the Canadarm2, preparing the arm and railway for use in missions later this year and in 2003 that will add more segments of truss to the station.

Meanwhile, station managers are investigating the need to add a safeguard mechanism to some of the fluid umbilical connections that will be used as the truss is assembled during missions later this year and early in 2003. The mechanism is designed to prevent a slight possibility of the umbilical connections, called quick disconnects, jamming over time. The mechanisms will ensure that the umbilicals may always be disconnected as needed for future assembly or maintenance operations. The new mechanisms will be installed during upcoming shuttle missions and station increments. Over this period, the installation may add one spacewalk above what is currently planned.

Expedition 4 Commander Yury Onufrienko and astronauts Carl Walz and Dan Bursch were launched last Dec. 5 aboard Endeavour's STS-108 mission, and have been on the ISS since Dec. 7.

Endeavour is scheduled for launch on May 30. That would result in a docking with the station on June 1. Endeavour Commander Ken Cockrell, Pilot Paul Lockhart, and mission specialists Chang-Diaz and Perrin are bringing the Expedition 5 crew to the station. That crew is commanded by Valery Korzun and includes astronaut Peggy Whitson and cosmonaut Sergei Treschev.

The first two of the three spacewalks by Chang-Diaz and Perrin will focus on installation of a new Mobile Base System for the station's robotic arm, Canadarm2. It will allow the arm to move along the railroad-like tracks of station's main truss, eventually to reach a length of more than 350 feet. The third spacewalk is to change out the wrist roll joint of Canadarm2.

On Friday, Dan Bursch worked with the Biomass Production System, a plant growth experiment using wheat and a plant related to cabbage and radishes. Each crewmember was scheduled for an hour to pack personal possessions, as they have been for much of this week. On Thursday Walz and Bursch completed their final session with the PuFF (pulmonary function in flight) experiment, which looks at effects of microgravity on lung function.

Several experiments have been deactivated, including the Physics of Colloids in Space, which was shut down Tuesday and which will be returned to Earth on Endeavour. It is a study of fine particles suspended in a fluid. An example of such fluids is paint.

Major systems aboard the station continue to function well as the ISS orbits at an average altitude of about 243 statute miles.

Aboard Endeavour are Commander Ken Cockrell, Pilot Paul Lockhart, Mission Specialists Franklin Chang-Díaz and Philippe Perrin of the French Space Agency, CNES, along with Expedition 5 Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev. As Endeavour launched from Florida, the space station orbited 240 statute miles over the southern Indian Ocean west of Perth, Australia.

Aboard the ISS, Expedition 4 Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch are wrapping up their 182nd day in space, their 180th day on the station. Walz and Bursch will break the U.S. record for the longest single space flight - 188 days - set by astronaut Shannon Lucid in 1996. Another record was equaled today as Chang-Díaz became only the second human to fly in space seven times, tying a mark set in April by Jerry Ross on the STS-110 mission.

Less than nine minutes after launch, Endeavour and its crewmembers settled into orbit and work began to prepare the shuttle for its planned 12-day mission.

Endeavour is scheduled to dock to the station Friday afternoon, setting the stage for the handover between the Expedition 4 and Expedition 5 station crews. Three spacewalks are scheduled during the mission by Chang-Díaz and Perrin. The first two will help install and activate the Mobile Base System, a platform that will be mated to the Mobile Transporter on the S-Zero (S0) Truss. The new platform will allow the station's Canadarm2 robotic arm to "walk off" the Destiny Laboratory onto the Mobile Base System so it can be transported up and down the length of the ISS for future assembly tasks. On the third spacewalk, Chang-Díaz and Perrin will replace a faulty wrist roll joint on the station's robotic arm that has experienced an electrical problem in one of its two data and power channels.

The shuttle crew will go to sleep at 10:23 p.m., and will be awakened at 6:23 a.m. Thursday to begin its first full day in orbit.

Aboard Endeavour, Commander Ken Cockrell, Pilot Paul Lockhart, Mission Specialists Philippe Perrin and Franklin Chang-Díaz and Expedition Five Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev, were awakened at 6:23 a.m. Central time by the song "Gettin' Jiggy Wit It," by Will Smith. The song was played for Korzun, who will soon take command of the space station.

The Expedition Four crewmembers - Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch - are in their 183rd day in space, their 181st day aboard the ISS. They will return to Earth aboard Endeavour after six months in orbit on June 17.

In preparation for docking Friday, Perrin and Chang-Díaz will set up a centerline camera to help Cockrell with views of the station's docking mechanism during Endeavour's final approach tomorrow and will test the orbiter docking system ring. Cockrell and Lockhart will fire the shuttle's jets to raise the altitude of Endeavour and draw it closer to the station. The maneuvers will bring the shuttle about 46 statute miles behind the station by Friday morning.

Cockrell and Perrin will also activate the shuttle's robotic arm and use its cameras to survey the contents of the payload bay, including the Leonardo Multi-Purpose Logistics cargo module, the Mobile Base System and the replacement wrist roll joint for the station's robotic arm, Canadarm2, as well as debris shields for the Zvezda Service Module. Chang-Díaz and Perrin will install these components during three spacewalks scheduled for the mission. Today, they will prepare their spacesuits for use out of the Quest Airlock on the station next week.

Later this morning, Cockrell and Chang-Díaz will participate in a live conversation with Costa Rican President Abel Pacheco and reporters from two Hispanic television networks. Costa Rican-born Chang-Díaz tied the human spaceflight record yesterday when he launched on his seventh mission. Astronaut Jerry Ross set the record in April during the STS-110 mission.

With docking scheduled at 11:17 a.m. CDT tomorrow, STS-111 Commander Ken Cockrell, Pilot Paul Lockhart and Mission Specialists Philippe Perrin and Franklin Chang-Díaz today verified all of Endeavour's equipment is ready. Perrin and Chang-Díaz set up a centerline camera Cockrell will use during Friday's final approach to align Endeavour with the station's docking port. They also successfully tested the shuttle docking system and extended it to a position ready for contact with the station.

Cockrell and Perrin activated the shuttle robotic arm and used its cameras to survey the contents of the payload bay. Perrin and Chang-Díaz, who will conduct the three spacewalks scheduled for the mission, successfully checked out the spacesuits they will use during their scheduled spacewalks. During the first two spacewalks, the duo will help install a new aluminum platform, the Mobile Remote Servicer Base System or MBS, atop the station's railcar, the Mobile Transporter. Once installed, the MBS will allow the station's robotic arm, Canadarm2, to travel along the station railway, moving up and down an eventual 300-foot truss for maintenance and assembly work.

Cockrell and Lockhart fired Endeavour's jets three times today to adjust the speed at which the shuttle is closing in on the station. A final Terminal Phase Initiation burn will be conducted Friday morning to begin the final phase of the rendezvous.

The Expedition Four crewmembers - Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch - tidied up their orbital home and completed routine maintenance on the eve of the arrival of the STS-111 crew.

Cockrell and Chang-Díaz took time out today to participate in a live conversation with Costa Rican President Abel Pacheco, U.S. Ambassador to Costa Rica John Danilovich and reporters from Univision and Telemundo. Costa Rican-born Chang-Díaz tied the human spaceflight record yesterday when he launched on his seventh mission.

At 2:08 p.m. central time, hatches between Endeavour and the station swung open, and the station's Expedition Four crewmembers-Commander Yury Onufrienko and Flight Engineers Dan Bursch and Carl Walz-greeted their visitors-Cockrell, Lockhart, Mission Specialists Franklin Chang-Díaz and Philippe Perrin and oncoming Expedition Five Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev.

The 10 astronauts and cosmonauts immediately set to work transferring priority equipment, supplies and experiments between the two vehicles. Items moving to the station included two Extravehicular Activity spacesuits and EVA tools to be used during the mission's three scheduled spacewalks. The Expedition Five crewmembers' custom-made Soyuz return craft seat liners and their Russian entry suits were transferred from Endeavour to the station at 5:55 p.m. central time, marking the official start of the Expedition Five Increment. With that transfer complete, Onufrienko, Bursch and Walz formally concluded their 182-day stay as space station residents. Korzun, Whitson and Treschev now begin their tenure as the fifth resident crew to live and work on board the International Space Station.

Communications checks between the station's Quest Airlock and the EVA suits Perrin and Chang-Díaz will use also were completed today. The spacewalks will see installation of a new platform, the Mobile Remote Servicer Base System, on the station's railcar, the Mobile Transporter, and replacement of the wrist roll joint on the station's arm.

Late in the day, the Flash Evaporator System Primary B controller failed for an as-yet unknown reason. The system has three redundant controllers, Primary A, Primary B and Secondary, and the failure of one controller will have no effect on mission operations.

The Flash Evaporator System sprays excess supply water into the inside of a trash-can shaped vessel that is wrapped by Freon coils. The heat being carried in these coils causes the water to flash into vapor and be vented overboard, disposing of excess heat and excess supply water.

Commander Ken Cockrell, Pilot Paul Lockhart and Mission Specialists Philippe Perrin and Franklin Chang-Díaz, and Expedition Five Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev, were awakened just after 4:30 Central time this morning by "American Woman," by Lenny Kravitz, a song selected for Whitson.

At the time of the crew's wakeup call, Endeavour had closed to within 900 statute miles of the ISS, aiming for a linkup to the docking port at the forward end of the Destiny Laboratory at 11:17 a.m. Central time as the two vehicles fly off the northeast coast of Australia, south of New Guinea. On board the station, the Expedition Four crew, Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch, are spending the morning preparing for the arrival of Endeavour's astronauts and their Expedition Five replacements. Onufrienko, Walz and Bursch are in their 184th day in space, their 182nd day aboard the ISS.

A little less than two hours after Endeavour docks to the station, the hatches between the two spacecraft will open and Onufrienko, Bursch and Walz will greet their counterparts and conduct a safety briefing. Then, the ten astronauts and cosmonauts will begin transferring equipment, supplies and experiments between the two vehicles. The two Expedition crews will exchange their custom-made Soyuz return craft seat liners for the rescue vehicle currently docked to the station. Once the new Expedition Five crew conducts checks of their Russian entry suits, they will officially take over command of station operations, and Onufrienko, Walz and Bursch will become shuttle crewmembers.

All systems aboard Endeavour and the ISS continue to function in excellent shape.

The Leonardo Multi-Purpose Logistics Module (MPLM) was unberthed from the payload bay early this morning by Commander Ken Cockrell operating the shuttle's robotic arm to move the module to the station's Unity module. Leonardo's installation proceeded perfectly with completion at 9:28 a.m. Central time. About 4:30 p.m. Central time, the MPLM's hatch was opened. Dan Bursch of Expedition Four called down at 4:52 pm that all crew members had entered the logistics module and were working to get the transfers rolling. The crew got a good start on the movement of more than 5,600 pounds of cargo to the station.

Early today, one of four control moment gyroscopes used in the station's attitude control system experienced a mechanical failure. Flight controllers turned it off and began using the remaining three gyros to maintain the station's attitude. It is believed that one of its spin bearings failed, causing it to seize. Flight Engineer Carl Walz reported that the crew could feel and hear "growling" vibrations as it failed. While the failure is a serious complication for the long-term space station operations, there are multiple backup systems for control of the station's attitude so it poses no threat to the safety of the shuttle or expedition crews. The situation is expected to require only minor changes to the STS-111 flight activities.

Franklin Chang-Díaz, and Perrin, with help from Paul Lockhart, readied their extravehicular mobility unit space suits and tools, and reviewed procedures for Sunday's spacewalk. The two first-time spacewalkers will install a Power and Data Grapple Fixture (PDGF) to the station's P6 solar array truss and temporarily store some Russian meteoroid/debris shields. They'll also remove thermal blankets from the Mobile Base System (MBS) in Endeavour's cargo bay, and support its unberthing. The MBS will be parked on the shuttle's arm near its installation point so that hardware temperatures can equalize before it is attached to the existing Mobile Transporter platform. At the end of the day, flight controllers will activate the MBS from the ground in preparation for the next day's operations. Chang-Díaz also will inspect and photograph the exterior condition of station's failed control moment gryoscope at the end of his spacewalk.

The combined STS-111 crew of Cockrell, Lockhart, Chang-Díaz, Perrin, Yury Onufrienko, Dan Bursch and Carl Walz will wake up at 4:23 am CDT Sunday, while new station Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev will arise at 4:53 am.

Commander Ken Cockrell, Pilot Paul Lockhart and Mission Specialists Philippe Perrin and Franklin Chang-Díaz, and the newest shuttle crewmembers - former Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch, were awakened at 4:23 Central time this morning by "I Have a Dream," by ABBA, a song selected for Treschev.

Using the shuttle's robotic arm, Cockrell and Perrin will reach into Endeavour's payload bay and latch onto Leonardo at mid-morning. The pressurized cargo module will be attached to the nadir berthing port on Unity. After Walz and Whitson perform pressure checks, the hatch to the cargo carrier will be opened. Leonardo contains equipment, supplies and experiments necessary for the fifth resident crew's 4 ½-month stay in orbit.

The six Expedition crewmembers will continue their handover conferences and the 10 cosmonauts and astronauts will review procedures for the first spacewalk of the flight tomorrow. Perrin and Chang-Díaz will step out of the Quest Airlock Sunday to begin installing the Mobile Base System, a new platform which will enable the station's robotic arm, Canadarm2, to ride a railway the length of the station for future assembly tasks. Two more spacewalks are scheduled for Tuesday and Thursday to complete the Mobile Base system installation and to replace an ailing wrist roll joint on the station's robotic arm.

The Expedition Five crew officially assumed command of station operations last night just before 6 p.m. Central time, marking the end of the Expedition Four increment at 182 days. Onufrienko, Walz and Bursch are now considered part of Endeavour's crew, aiming for a homecoming on June 17.

Systems on Endeavour and the ISS are functioning normally as the two vehicles orbit the Earth every 90 minutes at an altitude of 240 statute miles.

The newly arrived crewmembers of Expedition Five aboard the International Space Station - Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev - will continue settling into their new home today as they work with Endeavour's astronauts to move the Leonardo Multi-Purpose Logistics Module from the shuttle's cargo bay to the Unity module of the complex in advance of the start of the transfer of almost 3 tons of equipment and supplies.

Commander Ken Cockrell, Pilot Paul Lockhart and Mission Specialists Philippe Perrin and Franklin Chang-Díaz, and the newest shuttle crewmembers - former Expedition Four Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch, were awakened at 4:23 Central time this morning by "I Have a Dream," by ABBA, a song selected for Treschev.

Using the shuttle's robotic arm, Cockrell and Perrin will reach into Endeavour's payload bay and latch onto Leonardo at mid-morning. The pressurized cargo module will be attached to the nadir berthing port on Unity. After Walz and Whitson perform pressure checks, the hatch to the cargo carrier will be opened. Leonardo contains equipment, supplies and experiments necessary for the fifth resident crew's 4 ½-month stay in orbit.

The six Expedition crewmembers will continue their handover conferences and the 10 cosmonauts and astronauts will review procedures for the first spacewalk of the flight tomorrow. Perrin and Chang-Díaz will step out of the Quest Airlock Sunday to begin installing the Mobile Base System, a new platform which will enable the station's robotic arm, Canadarm2, to ride a railway the length of the station for future assembly tasks. Two more spacewalks are scheduled for Tuesday and Thursday to complete the Mobile Base system installation and to replace an ailing wrist roll joint on the station's robotic arm.

The Expedition Five crew officially assumed command of station operations yesterday at 5:55 p.m. Central time, marking the end of the Expedition Four increment at 181 days. Onufrienko, Walz and Bursch are now considered part of Endeavour's crew, aiming for a homecoming on June 17.

Systems on Endeavour and the ISS are functioning normally as the two vehicles orbit the Earth every 90 minutes at an altitude of 240 statute miles.

With the help of Endeavour Pilot Paul Lockhart, who will help coordinate the spacewalk from inside Endeavour, Chang-Díaz and Perrin will leave the Quest Airlock this morning for a planned six-hour spacewalk to first install a Power and Data Grapple Fixture to the station's P6 truss for its future relocation. The two first-time space walkers will then temporarily park micrometeoroid debris shields on the Russian segment of the station. Expedition Five Flight Engineer Peggy Whitson and ISS Commander Valery Korzun will install the shields on the Zvezda Service Module during a spacewalk set for late July.

The final task of the spacewalk will involve the removal of thermal blankets from the Mobile Base System. That component will be mated tomorrow to the Mobile Transporter on the S0 (S-Zero) Truss of the ISS to enable the Canadarm2 robotic arm to "walk off" the Destiny Laboratory onto the station's railcar system for transport up and down the length of the complex. Chang-Díaz will be identifiable by solid red stripes on the legs of his spacesuit. Perrin will wear the pure white suit with no stripes.

Commander Ken Cockrell will use the shuttle robotic arm's cameras to monitor the activities outside. Whitson and Endeavour Astronaut Carl Walz will transport Chang-Díaz on the end of Canadarm2 during the spacewalk.

During the spacewalk, Chang-Díaz will conduct a visual and photographic inspection of one of the station's four control moment gyroscopes (CMGs) on the station's Z1 Truss. The gyroscope experienced a mechanical failure of its spin bearing yesterday and will no longer be able to be used to assist in station attitude control.

Three other CMGs are operating normally to provide full attitude control for the ISS. If necessary, station control can be maintained with only two functioning CMGs, with other backup attitude control systems also available. The CMG failure will have no impact on ISS operations. A substitute CMG is available on the ground and program managers are evaluating future replacement options. To accommodate the use of three CMGs and varying thermal conditions, the orientation of the shuttle and station will be altered slightly for today's spacewalk.

Once the protective blankets are removed from the Mobile Base System, Whitson and Walz will latch onto the platform in Endeavour's cargo bay with Canadarm2, remove it from its carrier, and maneuver it to a position just above the Mobile Transporter, which was installed on the S-Zero Truss in April. Canadarm2 will be left in a parked position overnight to thermally condition the Mobile Base System before it is mated to the Transporter railcar Monday.

At the start of their fifth day in space, Endeavour's crew was awakened at 4:23 a.m. Central time to the sound of "Drops of Jupiter" by Train, a tune selected for Cockrell.

Chang-Díaz and Perrin ventured outside the station's Quest airlock at 10:27 a.m. Central time. With the help of Endeavour Pilot Paul Lockhart, who guided the spacewalk from inside the shuttle, Chang-Díaz and Perrin first installed a Power and Data Grapple Fixture to the station's P6 truss. The fixture will be used to relocate the P6 truss structure to its final location on the station.

Attached to a foot restraint at the end of the station's robotic arm, Canadarm2, operated by Expedition Five Flight Engineer Peggy Whitson and ISS Commander Valery Korzun, Chang-Díaz gathered six micrometeoroid debris shields from the shuttle cargo bay and, with help from Perrin, temporarily stored them on Pressurized Mating Adapter-1 which links Unity to Zarya. Whitson and Korzun will install the shields on the Zvezda Service Module during a spacewalk set for late July.

Chang-Díaz then conducted a visual and photographic inspection of one of the station's four control moment gyroscopes on the station's Z1 truss, a task that was added to today's spacewalk after the gyroscope experienced a mechanical failure yesterday. The photos may help ground controllers better understand why the gyroscope failed.

Removal of thermal blankets from the Mobile Remote Servicer Base System or MBS was the final task of the spacewalk. At 5:21 p.m. Endeavour Commander Ken Cockrell commanded the release of latches that had secured the MBS to its carrier in the payload bay. Whitson and Carl Walz then latched onto the MBS with Canadarm2, removed it from its carrier, and maneuvered it to a position about three feet above the station's railcar, the Mobile Transporter. Canadarm2 will be left in a parked position overnight to thermally condition the MBS before it is mated to the railcar Monday.

Later, the Canadarm2 robotic arm will be commanded to "walk off" its position attached to the Destiny Laboratory onto a Power and Data Grapple Fixture atop the MBS. The arm will then be able to move up and down along the station truss for use in future assembly operations.

Following an inventory of the tools they used during the spacewalk, Perrin and Chang-Díaz re-entered Quest. Airlock repressurization began at 5:41 p.m. Central time, signaling the end of the spacewalk.

The MBS was attached to the Mobile Transporter on the Destiny Lab at 8:03 a.m. Central by Expedition Five Flight Engineer Peggy Whitson and Endeavour Astronaut Carl Walz. The two used the station's robotic arm, Canadarm2, to maneuver the MBS into position. Controllers on the ground then commanded latches on the transporter to close, securing the MBS in place. Eventually, Canadarm2 will "walk off" its current base location on the Destiny Lab onto the MBS. The MBS is an important part of the station's future Mobile Servicing System, which will allow the station's arm to travel the length of the station to perform future construction tasks.

The astronauts and cosmonauts on the Shuttle/Station complex, including STS-111 Commander Ken Cockrell, Pilot Paul Lockhart, Mission Specialists Philippe Perrin and Franklin Chang-Díaz, as well Expedition Four crew Yury Onufrienko, Dan Bursch and Walz, and Expedition Five crewmembers Whitson, Commander Valery Korzun and Flight Engineer Sergei Treschev, continued their transfer of equipment and supplies to the station from the Leonardo Multi-Purpose Logistics Module. As they began their Monday morning in space, the crewmembers already had transferred 73 percent of the equipment and supplies.

Though the Expedition Five crew has been in charge of station operations since Friday afternoon, an official change of command ceremony between the two Expedition crews took place this afternoon. The crew also reviewed procedures for tomorrow's second spacewalk of the mission by Chang-Díaz and Perrin in which the two astronauts will hook up cables between the Mobile Base System and the Mobile Transporter and firmly bolt the two components together.

At 4:53 p.m. today, Endeavour completed a one-hour reboost maneuver to increase the station's altitude by a little over a mile. This is the first of three such maneuvers that eventually will raise the station's altitude by six miles. Systems on both Endeavour and the station continue to function normally as they orbit the Earth every 90 minutes at an altitude of about 240 statute miles.

The Mobile Base System (MBS), parked overnight on the station's robotic arm about three feet from installation, has had a chance to receive the proper thermal conditioning to match the temperatures on the Mobile Transporter, the actual railcar on the truss itself. Operated by Expedition Five Flight Engineer Peggy Whitson and Endeavour Astronaut Carl Walz, the space station robotic arm will mate the MBS platform to the railcar and flight controllers on the ground will command latches to close to secure the platform in place. Eventually, the station arm will "walk off" its current base location on the Destiny Laboratory to the MBS and ride the railway to move up and down the entire length of the station.

The 10 astronauts and cosmonauts on the Shuttle/Station complex will also continue their transfer of equipment and supplies to the station from the Leonardo Multi-Purpose Logistics Module.

Endeavour's crew - Commander Ken Cockrell, Pilot Paul Lockhart, Mission Specialists Philippe Perrin and Franklin Chang-Díaz, and former station residents Yury Onufrienko, Walz and Dan Bursch - were awakened at 4:23 a.m. Central time to "I Only Have Eyes for You" by the Flamingoes, from the American Graffiti soundtrack which was selected for Lockhart.

Although Expedition Five crewmembers Whitson, Commander Valery Korzun and Flight Engineer Sergei Treschev have been in charge of ISS operations since Friday afternoon, an official change of command ceremony between Expedition crews will occur early this afternoon.

The crews will also participate late today in a review of procedures for tomorrow's second spacewalk by Chang-Díaz and Perrin to hook up cables between the Mobile Base System and the Mobile Transporter and to bolt the two components together. Systems on both Endeavour and the ISS continue to function normally as the two craft orbit the Earth every 90 minutes at an altitude of about 240 statute miles.

The first contribution to the station by Canada was the space station's robotic arm, Canadarm2, which was delivered to the ISS last year. Today, in a planned 6 1/2 hour spacewalk, Chang-Díaz and Perrin will connect power and data cables to the newly installed Mobile Base System and permanently bolt it to the Mobile Transporter railcar which was affixed to the S0 (S-Zero) Truss on the ISS in April. The new platform will enable Canadarm2 to "walk off" the Destiny Laboratory and mate itself to any one of four grapple fixtures so it can be driven up and down the length of the station's trusses for future construction tasks.

Canadarm2 has provided power to the Mobile Base System since its unberthing from Endeavour's payload bay Sunday near the end of the first spacewalk. The platform was attached to the Mobile Transporter on Monday. Chang-Díaz and Perrin will connect primary and backup cables for video and data and primary cables for power between the MBS and the Mobile Transporter. Once the cable connections are completed, ground controllers will send commands for the MT to remotely plug in its umbilical attachments to receptacles on the truss railway. Flight controllers will then begin a checkout of the MBS systems to ensure all connections are established.

With that completed, Chang-Díaz and Perrin will deploy an auxiliary grapple fixture on the MBS called the Payload Orbital Replacement Unit Accommodation, or POA. The fixture will be used to transport additional cargo elements on the MBS as it is moved along the truss railway.

After the ground-controlled checkout complete, the two spacewalkers will connect redundant power cables to the MT.

The final task for the spacewalkers will be to relocate a television camera on the MBS and add an extra extension cable for the platform.

Handover conferences between the two Expedition crews and the transfer of equipment and supplies to the Leonardo Multi-Purpose Logistics Module will also continue today. The crew has emptied Leonardo's cargo into the station and is now refilling the module with unneeded supplies to be returned to Earth.

Endeavour's crew - Chang-Díaz, Perrin, Commander Ken Cockrell, Pilot Paul Lockhart, Yury Onufrienko, Carl Walz and Dan Bursch - was awakened at 4:23 a.m. Central this morning to the sound of "Mi PC" by Juan Luis Guerra, selected for Chang-Díaz by his family.

All systems on both Endeavour and the International Space Station continue to function normally as the two craft orbit the Earth every 90 minutes at an altitude of 240 statute miles.

Chang-Díaz and Perrin ventured outside the station's Quest airlock at 10:20 a.m. Central time. With the help of Pilot Paul Lockhart, who guided the spacewalk from inside the shuttle, Chang-Díaz and Perrin first connected primary and backup cables for video and data, and primary power cables between the Mobile Transporter railcar and the MBS. Once the connections were made, ground controllers sent commands for the MT to remotely plug in its umbilical attachments to receptacles on the S0 (S-Zero) truss railway.

With that complete, Chang-Díaz and Perrin then deployed an auxiliary grapple fixture on the MBS called the Payload Orbital Replacement Unit Accommodation, or POA, and placed it in its final configuration. Identical to the end effectors on Canadarm2, the fixture can grapple payloads and hold them as they are moved along the station's truss atop the MBS.

Continuing to run ahead of schedule, the two spacewalkers then secured four bolts between the MBS and the railcar, completing installation of the new MBS platform. Later this month or next, Canadarm2 will "walk off" the Destiny Laboratory and mate its free hand to any one of four power and data fixtures on the new platform so it can be driven up and down the length of the station's truss for use in future station assembly and maintenance operations.

The spacewalkers then relocated a television camera to its final position on top of a mast atop the MBS. The camera will provide views of station assembly and maintenance operations to ground controllers. Final tasks included adding an extra extension cable for the platform, a wire tie to one of the cables installed earlier during the spacewalk and to photograph connectors near the lower portion of the MBS that tie into the MT.

Following an inventory of the tools they used during the spacewalk, Perrin and Chang-Díaz re-entered Quest. Airlock repressurization began at 3:20 p.m. Central time, signaling the end of the spacewalk. It was the 40th spacewalk in support of ISS assembly and maintenance and the second of the mission, bringing the total spacewalking time for STS-111 to 12 hours and 14 minutes.

After flight controllers verified that all connections on the Mobile Remote Servicer Base System were working properly, the capture latch on Canadarm2 was released. The arm, which had been supplying power to the MBS, was then repositioned for Thursday's third and final spacewalk of the mission, which will see replacement of its wrist roll joint.

Handover conferences between the two Expedition crews and the transfer of equipment and supplies to the Leonardo Multi-Purpose Logistics Module also continued today. Working ahead of schedule, the crew continued to refill the module with unneeded supplies to be returned to Earth.

At 9:19 Central time tonight, Endeavour crewmembers and former Expedition Four Flight Engineers Carl Walz and Dan Bursch will set a new U.S. space endurance record, exceeding Shannon Lucid's record of 188 consecutive days spent in space. Walz will set another record in the process, exceeding Lucid's U.S. record for cumulative days spent in space as he reaches 223 days accrued over the course of five flights. Expedition 4 Commander Yury Onufrienko has spent a total 381 days in space, but remains far behind the world record for time in space of 747 days, held by Sergei Avdeyev.

At 1:55 a.m. Central time, Walz set a new U.S. record for most aggregate days spent in orbit, exceeding Shannon Lucid's record as he reached the 223 day mark accrued over five flights. Last night, Walz and Bursch also surpassed Lucid's U.S. single spaceflight endurance record of 188 days at 9:19 p.m. Central time.

Today, along with Expedition Five Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev, the 10 astronauts and cosmonauts will continue to transfer unneeded station equipment and supplies to the Leonardo Multi-Purpose Logistics Module to be returned to earth. Handover conferences will also continue between the two Expedition crews.

The crewmembers will also review the plans for the third and final spacewalk of the mission on Thursday. Chang-Díaz and Perrin will replace a faulty wrist roll joint on the space station's robotic arm, the Canadarm2.

Reporters in the U.S., France and Canada will also have a chance to question the two crews on the progress of the flight during a Joint Crew News Conference this afternoon.

The second of three reboosts of the station's altitude will be performed later today, using the shuttle jets to counter the natural effects of atmospheric drag on the station's orbit.

All systems on both Endeavour and the International Space Station continue to function normally as the two craft orbit the Earth every 90 minutes at an altitude of 240 statute miles.

Working side by side, the Endeavour crew - Ken Cockrell, Paul Lockhart, Franklin Chang-Díaz, Philippe Perrin, Yury Onufrienko, Carl Walz and Dan Bursch - and the Expedition Five crew of Valery Korzun, Peggy Whitson and Sergei Treschev have transferred approximately 4,500 of the expected 4,665 pounds of material that will return to Earth inside the MPLM. All of the items slated to be moved from Endeavour's middeck to the station have been transferred and the astronauts are now restowing return items.

Also today, Endeavour's small steering jets were fired in a series of pulses to gently raise the station's orbit by another mile. This was the second of three scheduled reboost maneuvers designed to raise the station's altitude by a total of six miles.

The crewmembers also reviewed the plans for the third and final scheduled spacewalk of the mission. Thursday morning, at 9:43 a.m. Central, Chang-Díaz and Perrin will float out of the Quest airlock and begin work to replace a faulty wrist-roll joint on the space station's robotic arm, Canadarm2. The spacewalk is slated to last about seven hours.

This afternoon, the crews took a break from the stowage activities to discuss the progress of their mission with reporters in the U.S., France and Canada during a joint crew news conference.

Endeavour's payload bay cameras captured views of wildfires burning in Colorado about 4:40 p.m Central today. Smoke rising from the wildfires was clearly visible as the shuttle/station complex orbited 240 miles over the surface of the Earth.

The two crews are scheduled to go to sleep just before 8 p.m. today and will awaken just before 4 a.m. Thursday. All systems on both Endeavour and the International Space Station continue to function normally as the two craft orbit the Earth every 90 minutes at an altitude of 240 statute miles.

Canadarm2 experienced an electrical problem in March in one of two redundant power and data channels which command the operation of the seven-jointed apparatus. It was determined that a short created inadvertent commanding in the arm's primary channel which resulted in the unexpected activation of the arm's brakes. The backup commanding channel has functioned perfectly. Even though the arm has continued to operate flawlessly through a software modification, the replacement of the problematic wrist joint was added to the STS-111 mission.

Inside the shuttle, Pilot Paul Lockhart will choreograph the planned seven-hour spacewalk while Commander Ken Cockrell will use the shuttle's robotic arm to provide television views of the spacewalk activity. Inside the station, Endeavour Astronaut Dan Bursch and Expedition Five Commander Valery Korzun will conduct a checkout of the health of the arm once the new joint is installed. Expedition Five Flight Engineers Peggy Whitson and Sergei Treschev will continue cargo transfer activities throughout the day.

Each joint of Canadarm2 is attached to the next joint by six bolts and an additional bolt that disconnects power, data and video connections. The first task for the spacewalkers is to remove the latching end effector (LEE), essentially the hand of Canadarm2, leaving the faulty wrist roll joint exposed. Next they will disconnect the wrist roll joint and Perrin will carry the failed unit to Endeavour's payload bay to temporarily store it next to the new joint. Chang-Díaz will assist in removing the new joint from its launch carrier and Perrin will bring it up to Canadarm2. The spacewalkers will align the new component with the wrist yaw joint at the end of the arm, tighten the six bolts and turn the final bolt to connect power, data and video lines. They will reinstall the LEE and power will be turned back onto Canadarm2.

Endeavour's astronauts - Cockrell, Lockhart, Chang-Díaz, Perrin, Bursch, Yury Onufrienko and Carl Walz - were awakened just before 4 a.m. Central time this morning to the song, "On the Road Again," by Willie Nelson, selected for Walz by his family. Walz is returning to Earth after a six-month stay in orbit.

All systems on both Endeavour and the International Space Station continue to function normally as the two craft orbit the Earth every 90 minutes at an altitude of 240 statute miles.

Endeavour astronaut Philippe Perrin completed the last major task of the STS-111 mission today when he successfully returned the Leonardo Multi-Purpose Logistics Module to the shuttle's payload bay at 3:11 p.m. Central.

Leonardo brought a total of 8,062 pounds of supplies and equipment to the space station, including a new science rack to house microgravity experiments and a glovebox that will allow station crews to conduct experiments that require isolation. More than 1,000 pounds of equipment was also brought to the station on Endeavour's middeck.

In addition to carrying home the results of several science experiments, Leonardo is returning to Earth with 4,667 pounds of equipment and supplies that are no longer needed aboard the station. More than 1,000 pounds of equipment also will be returned to Earth in Endeavour's middeck.

Endeavour's steering jets were used today to raise the station's altitude by an additional four miles, the third and final reboost of the mission. Together, the three reboosts raised the altitude of the station by approximately six miles.

Early Saturday morning, about 6:30 central time, following final goodbyes, the hatches between the two spacecraft will swing shut. About three hours later, the crew of Endeavour - Ken Cockrell, Paul Lockhart, Franklin Chang-Díaz, Perrin, Dan Bursch, Yury Onufrienko and Carl Walz - will depart the space station, leaving the Expedition Five crew - Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev - to begin their 4½ -month mission of continued station growth and scientific research.

All systems on both Endeavour and the International Space Station continue to function normally as the two craft orbit the Earth every 90 minutes at an altitude of 240 statute miles.

Working with the International Space Station's Expedition Five crew, Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev, Endeavour's astronauts will deactivate the Leonardo Multi-Purpose Logistics Module and will remove it from its location on the Unity node of the International Space Station. Using the shuttle's robotic arm, Cockrell will place the module back into Endeavour's cargo bay for its return to Earth.

About 5,600 pounds of equipment and supplies are being left behind on the ISS, including a new phone booth-sized rack to house delicate microgravity experiments and a glovebox to provide the Expedition Five crew future hands-on interaction with contained experiments. The cargo module is returning with 4,665 pounds of discarded equipment and supplies to Earth.

Last night, an initial attempt to provide power from the newly installed Mobile Base System platform to the space station robotic arm, Canadarm2, was not successful. Engineers believe that a minor software glitch is preventing commanding from the platform to reach the newly refurbished robotic arm so that the new platform, rather than the Destiny Laboratory, can provide power for the arm. This is not believed to be a serious problem, and should be corrected well before the arm "walks off" its base location on the Destiny to use the Mobile Base System as its formal platform for a ride down the length of the station's truss structure. Canadarm2 received a new wrist roll joint yesterday during the final spacewalk of the flight by Chang-Díaz and Perrin, and the arm itself has full functionality and redundancy.

Endeavour's steering jets are being used to raise the station's altitude a third and final time today prior to tomorrow's scheduled undocking. The three maneuvers are expected to raise the altitude of the ISS by around six statute miles.

Endeavour is scheduled to undock from the ISS Saturday morning at 9:32 a.m. Central time while the two spacecraft fly over western Kazakhstan, not far from Russia's primary launch site at the Baikonur Cosmodrome. Once Endeavour departs, ISS residents Korzun, Whitson and Treschev will begin their 4 ½ month mission in earnest, unpacking gear and settling in to their new home in orbit.

All systems on both Endeavour and the International Space Station continue to function normally as the two craft orbit the Earth every 90 minutes at an altitude of 240 statute miles. Endeavour is scheduled to undock from the space station Saturday morning.

After final farewells and the closing of the hatches between the two vehicles, Endeavour will undock from the ISS at 9:32 a.m. Central time as the two craft fly over western Kazakhstan, not far from Russia's primary launch site at the Baikonur Cosmodrome.

The initial separation will be provided by springs that will gently push the shuttle away from the station. When Endeavour is about two feet away from the station and the docking devices are clear of one another, Pilot Paul Lockhart will fire Endeavour's steering jets to begin slowly moving away.

About 45 minutes after undocking, when Endeavour is 450 feet in front of the ISS, Lockhart will begin a one-hour flyaround of the station. After 1 1/4 laps of the complex, Lockhart will fire Endeavour's jets to move away from the station about 11:16 a.m. Once Endeavour departs the outpost for the final time, the new ISS crew will begin to unpack gear and prepare for its long duration stay on orbit.

Endeavour's astronauts - Lockhart, Chang-Diaz, Commander Ken Cockrell, Philippe Perrin, Dan Bursch, Yury Onufrienko and Carl Walz - were awakened just before 3:30 Central time this morning to the song, "Hello to All the Children of the World", prepared for Bursch by his son's classmates.

Endeavour is scheduled to land at the Kennedy Space Center just before noon Central time Monday, bringing Onufrienko, Bursch and Walz home after 194 days in space, which for Walz and Bursch will set a new U.S. single spaceflight endurance mark. Landing Monday will result in one more day in space for Onufrienko than he logged in 1996 as Commander of the former Russian Mir Space Station.

Endeavour and the ISS to continue to function normally as they orbit at an altitude of around 240 statute miles.

After final farewells among the STS-111 and Expedition Four and Five crews, the hatches between the spacecraft were closed at 7:23 a.m. Central today. Following a series of pressure and leak checks, Endeavour gently undocked from the Station at 9:32 a.m. as the two spacecraft flew over western Kazakhstan.

As Endeavour departed the station, Whitson rang the ship's bell on board, announcing "Expedition Four departing, Endeavour departing." Dan Bursch, who along with Yury Onufrienko and Carl Walz, spent 181 days aboard the station, responded with "smooth sailing, Peggy." After a 1 ¼ lap flyaround of the station, Pilot Paul Lockhart fired a final separation burn of Endeavour's engines at 11:15 a.m. and began its final departure from the station. The two spacecraft are now about 315 miles apart, with the gap widening by 40 miles every orbit.

Both crews will enjoy some well-deserved time off today to relax following a busy week of joint operations. Endeavour's crew will go to sleep at 7:23 p.m. today, waking at 3:23 a.m. Sunday. The Expedition Five crew began an extended sleep period about 3 p.m., shifting over to its standard daily wakeup time of 1 a.m. on Sunday.

The focus of activities aboard Endeavour on Sunday will include a checkout of the systems that will be used during Monday's planned landing at the Kennedy Space Center. Endeavour is scheduled to land at the Kennedy Space Center just before noon Central time Monday, bringing Onufrienko, Bursch and Walz home after 194 days in space.

Aboard the station, Korzun, Whitson and Treschev will begin unpacking some of the supplies and equipment transferred from Endeavour and set up house for their planned 4 ½ month stay on the station. They are scheduled for about four hours of off-duty time Sunday.

Commander Ken Cockrell, Pilot Paul Lockhart, Mission Specialists Franklin Chang-Diaz and Philippe Perrin, and returning Expedition 4 crewmembers Yury Onufrienko, Carl Walz and Dan Bursch were awakened at 3:23 a.m. to "Where My Heart Will Take Me," the theme song from Star Trek: Enterprise, performed by Russell Watson.

Today, Cockrell, Lockhart and Chang-Diaz will test the reaction control system jets and flight control surfaces that will be used to guide Endeavour through the atmosphere Monday morning. Onufrienko, Walz, Bursch and Perrin will install their seats for re-entry on Endeavour's middeck. Perrin will help the Expedition 4 crewmembers into their seats Monday. Endeavour is scheduled to land at Kennedy Space Center in Florida Monday at 11:59 a.m. CDT.

Onufrienko, Walz and Bursch are coming back to Earth after 181 days aboard the International Space Station. If Endeavour lands on time, Walz and Bursch will set a new record of U.S. spaceflight endurance with 194 days in orbit. Astronaut Shannon Lucid held the previous record of 188 days, set on her mission to Mir in 1996.

The Expedition 4 crew will talk with media representatives from the Fox News Network and TV stations in Ohio and New York in a news conference beginning at 12:38 p.m.

Cockrell and Lockhart will fire Endeavour's orbital maneuvering system engines for 10 seconds today to allow sensors to observe the plume created by the burn to help improve models on the ground.

On board the space station, the Expedition 5 crew - Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev - was awakened at 1 a.m. The crew is unpacking and settling into its new home, preparing for a 41/2-month stay in orbit.

The crew of Endeavour will begin a scheduled eight-hour sleep period at 7:23 p.m. today. They are to be awakened just before 3:30 a.m. Monday to prepare for re-entry and landing of Endeavour, concluding a successful mission to the station.

Today, Commander Ken Cockrell, Pilot Paul Lockhart and Flight Engineer Franklin Chang-Diaz activated one of three hydraulic power units on Endeavour, tested all of its aerosurfaces, and then test-fired Endeavour's steering jets. The remaining crew members - Philippe Perrin of CNES, and former Expedition Four crewmembers Yury Onufrienko, Carl Walz and Dan Bursch - continued packing up gear and hardware in anticipation of tomorrow's landing.

Endeavour has two opportunities to land at the Kennedy Space Center on Monday. The first begins with a deorbit burn of the Orbital Maneuvering System engines at 10:51 a.m., followed by a landing at 11:59 a.m. Central time (12:59 p.m. Eastern.) In the event weather prevents a landing on that first opportunity, there is a second opportunity, beginning with a deorbit burn at 12:30 p.m. and resulting in a 1:36 p.m. Central (2:36 p.m. Eastern) landing in Florida. Preliminary weather forecasts call for the possibility of clouds and rain showers within the vicinity of the three-mile long landing strip on Monday. The backup landing site at California's Edwards Air Force Base was not called up for support Monday. Endeavour has sufficient consumables to remain in orbit, if necessary, until Thursday.

Onufrienko, Bursch and Walz took a few minutes this afternoon to talk with Fox News, WOIO-TV of Cleveland - Walz' hometown, and WICZ-TV of Vestal, NY - Bursch's hometown. The crew extended their best wishes on this Father's Day and discussed their 193-day stay in space. With an on-time landing Monday, Onufrienko, Bursch and Walz will have spent 194 days in space.

Meanwhile, aboard the space station, the Expedition Five crew - Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev - spent today settling into their new home, unpacking some of the equipment and hardware carried to the station by Endeavour. They also enjoyed a few hours of off-duty time today.

Endeavour's crew will begin a scheduled eight-hour sleep period at 7:23 p.m. today, waking just before 3:30 a.m. Monday to prepare for a homecoming to the Kennedy Space Center.

Endeavour crewmembers, Commander Ken Cockrell, Pilot Paul Lockhart, and Mission Specialists Philippe Perrin and Franklin Chang-Diaz, and Expedition 4's Yury Onufrienko, Carl Walz and Dan Bursch, were given the word to back out of deorbit preparations about 10:30 a.m. today.

Endeavour has two landing opportunities at KSC Tuesday. The first begins with the firing of Endeavour's braking rockets at 9:47 a.m. and a landing at 10:55 a.m. CDT. A second opportunity for a Florida landing would see the deorbit burn at 11:24 a.m. and a landing at KSC at 12:31 p.m. CDT. Preliminary weather forecasts call for the possibility of clouds and rain showers in the area of the three-mile landing strip on Tuesday.

The Edwards Air Force Base landing site will be activated Tuesday, though KSC remains the preferred landing location. Forecasts for both KSC and Edwards called for questionable weather that could prevent a Tuesday landing. Endeavour has enough consumables on board to remain in orbit until Thursday.

The first of two Tuesday opportunities to land at Edwards would see a deorbit burn at 12:54 p.m. and a landing at 2 p.m. CDT. For the second opportunity, the deorbit burn would begin at 2:32 p.m. with a landing at 3:36 p.m. CDT.

Endeavour completed all major objectives of its STS-111 flight. It rotated station crews, brought more than 9,000 pounds of equipment and supplies to the station, and in three successful spacewalks gave the station's robotic arm, Canadarm2, a mobile base for future station assembly and maintenance work, and replaced its wrist-roll joint.

Crewmembers aboard Endeavour were scheduled to begin a sleep period at 6:23 p.m. and be awakened at 2:23 a.m. Tuesday.

Meanwhile, the ISS Expedition 5 crew - Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev - is still unpacking the supplies and equipment delivered by Endeavour to the station.

Endeavour completed all major objectives of its STS-111 flight. Expedition 5 crewmembers were taken to the station while Expedition 4 crewmembers are coming home. Tons of equipment and supplies were transferred between the two spacecraft and three spacewalks replaced the wrist roll joint of the station's robotic arm, Canadarm2, and gave the arm a mobile base for future station assembly and maintenance work.

Endeavour has two landing opportunities at KSC today. The first begins with the firing of Endeavour's braking rockets at 10:51 a.m. and a landing at 11:59 a.m. CDT. A second opportunity for a Florida landing would see the deorbit burn at 12:30 p.m. and a landing at KSC at 1:36 p.m. CDT. Preliminary weather forecasts call for the possibility of clouds and rain showers in the area of the three-mile-long landing strip on Monday. The backup landing site at California's Edwards Air Force Base was not activated today. Endeavour has enough consumables to stay in orbit until Thursday.

Endeavour Commander Ken Cockrell, Pilot Paul Lockhart, and Mission Specialists Philippe Perrin and Franklin Chang-Diaz, and Expedition 4 crewmembers Yury Onufrienko, Carl Walz and Dan Bursch were awakened at 3:23 a.m. by the "The Eyes of Texas," performed by the University of Texas Marching Band. Cockrell and Lockhart hold degrees from that university.

Meanwhile, aboard the ISS, the Expedition 5 crew - Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev - is still settling into its new home, unpacking the supplies and equipment delivered by Endeavour to the station.

Rain and thundershowers in the area of the Kennedy Space Center landing site in Florida caused flight controllers to wave off both of Monday's opportunities to bring Endeavour home.

Endeavour crewmembers, Commander Ken Cockrell, Pilot Paul Lockhart, and Mission Specialists Philippe Perrin and Franklin Chang-Diaz, and Expedition 4's Yury Onufrienko, Carl Walz and Dan Bursch, have two landing opportunities at KSC today. The first begins with the firing of Endeavour's braking rockets at 9:47 a.m. and a landing at 10:55 a.m. CDT. A second opportunity for a Florida landing would see the deorbit burn at 11:24 a.m. and a landing at KSC at 12:31 p.m. CDT.

The Edwards Air Force Base landing site in California will be activated today, though KSC remains the preferred landing location. The first of two opportunities to land at Edwards would see a deorbit burn at 12:54 p.m. and a landing at 2:02 p.m. CDT. For the second opportunity, the deorbit burn would begin at 2:32 p.m. with a landing at 3:38 p.m. CDT.

Preliminary forecasts for both KSC and Edwards call for a chance of showers and thunderstorms in Florida and gusty winds in California that could prevent a Tuesday landing. Endeavour has enough consumables on board to remain in orbit until Thursday.

Endeavour's crew completed all major objectives of its STS-111 flight. It rotated station crews, brought more than 9,000 pounds of equipment and supplies to the station, and in three successful spacewalks gave the station's robotic arm, Canadarm2, a mobile base for future station assembly and maintenance work, and replaced its wrist-roll joint.

Meanwhile, the ISS Expedition 5 crew - Commander Valery Korzun and Flight Engineers Peggy Whitson and Sergei Treschev - is still unpacking the supplies and equipment delivered by Endeavour to the station and familiarizing themselves with their new home.

Houston's Mission Control Center told Endeavour crewmembers, Commander Ken Cockrell, Pilot Paul Lockhart, and Mission Specialists Philippe Perrin and Franklin Chang-Diaz, and Expedition 4's Yury Onufrienko, Carl Walz and Dan Bursch, of the second of two wave offs about 9:35 a.m.

Similar inclement weather on Monday resulted in a wave-off of those landing opportunities. Wednesday offers two landing opportunities at KSC and three at Edwards Air Force Base in California. Forecasters are predicting improving weather at both sites. Endeavour has enough consumables on board to remain in orbit until Thursday, if necessary.

The first of the KSC landing attempts would begin with a deorbit burn at 8:44 a.m. and a landing at 9:53 a.m. CDT (10:53 a.m. eastern.) A second opportunity for a Florida landing would see the deorbit burn at 10:19 a.m. and a landing at KSC at 11:27 a.m. CDT (12:27 p.m. eastern.)

The first of the three subsequent opportunities at Edwards would begin with a deorbit burn at 11:50 a.m. and a landing at 12:58 p.m. CDT. The deorbit burn for the second attempt would be at 1:27 p.m. and a landing at 2:33 p.m. CDT. The third opportunity would see a deorbit burn at 3:06 p.m. and a landing at 4:11 p.m. CDT.

Crewmembers aboard Endeavour are scheduled to begin a sleep period at 5:23 p.m. and be awakened at 1:23 a.m. Wednesday.

All continues to go smoothly aboard the International Space Station in the early days of Expedition 5's residency. Commander Valery Korzun, and Flight Engineers Peggy Whitson and Sergei Treschev, are still unpacking the supplies and equipment delivered by Endeavour.

Endeavour touched down on Edwards' concrete runway at 12:58 p.m. CDT (10:58 a.m. PDT), concluding a record 196-day stay in space for Expedition 4 crewmembers Yury Onufrienko, Carl Walz and Dan Bursch. The STS-111 flight of Endeavour delivered the Expedition 5 crew - Commander Valery Korzun, Astronaut Peggy Whitson and Cosmonaut Sergei Treschev - to the International Space Station. In addition, the shuttle carried more than 9,000 pounds of equipment and supplies to the station and the crew conducted three spacewalks to expand the station's capabilities.

Endeavour traveled 5,781,115 statute miles since its June 5 launch from KSC's Pad 39A. Today's landing followed weather-related wave-offs on Monday, Tuesday and today because of rain showers, thunderstorms and cloud cover in the area of the Kennedy Space Center, the primary shuttle landing site.

The STS-111 and Expedition 4 astronauts will return to a welcoming ceremony at Ellington Field's Hangar 990 in Houston near the Johnson Space Center around 3 p.m. Central time Friday, June 21. The public is invited.

Meanwhile aboard the International Space Station, the Expedition 5 crew continues to settle into its new home with Whitson beginning investigations with a cell culture experiment today.

For a second day, rain, thundershowers and clouds around the Kennedy Space Center in Florida caused flight controllers to wave off Tuesday's opportunities to bring Endeavour and its crew home.

Similar weather Monday resulted in a wave-off of those landing opportunities. Wednesday offers two landing opportunities at KSC and three at Edwards Air Force Base in California. Forecasters are predicting improving weather at both sites. Endeavour has enough consumables on board to remain in orbit until Thursday.

The first of the KSC landing attempts would begin with a deorbit burn at 8:44 a.m. and a landing at 9:53 a.m. CDT (10:53 a.m. EDT.) A second opportunity for a Florida landing would see the deorbit burn at 10:19 a.m. and a landing at 11:27 a.m. CDT (12:27 p.m. EDT.)

The first of the three subsequent opportunities at Edwards would begin with a deorbit burn at 11:50 a.m. and a landing at 12:58 p.m. CDT (10:58 a.m. PDT). The deorbit burn for the second attempt would be at 1:27 p.m. and a landing at 2:33 p.m. CDT (12:33 p.m. PDT). The third opportunity would see a deorbit burn at 3:06 p.m. and a landing at 4:11 p.m. CDT (2:11 p.m. PDT).

All continues to go smoothly aboard the International Space Station in the early days of Expedition 5's residency. Commander Valery Korzun, and Flight Engineers Peggy Whitson and Sergei Treschev are activating equipment, initiating scientific experiments and getting used to the space station environment and routines.

Expedition 5 Commander Valery Korzun, astronaut Peggy Whitson and cosmonaut Sergei Treschev began their 4½-month tour of duty on June 5 when they launched on board space shuttle Endeavour, They arrived on the ISS June 7. Since the shuttle undocked from ISS on Saturday, the new crewmembers have spent time familiarizing themselves with the station and its systems while unpacking the gear that arrived on board with them.

This week the crewmembers started loading unneeded equipment and other trash into the Progress 7 supply ship docked to the aft port of the Zvezda Service Module. That cargo ship is slated to undock from ISS at 3:23 a.m. CDT Tuesday and will be destroyed during entry into Earth's atmosphere. A new unpiloted capsule, Progress 8, loaded with food, fuel, clothing and other supplies for the station crewmembers, is targeted to launch from the Baikonur Cosmodrome in Kazahkstan at 12:36 a.m. CDT Wednesday, and will dock automatically to ISS early June 29. Korzun and Treschev are scheduled to spend time this weekend refreshing their knowledge of the station's backup approach and docking system in preparation for Progress operations next week.

This week Whitson completed operations with the StelSys experiment in the Biotechnology Specimen Temperature Controller (BSTC), which supports investigations in cell biology and tissue engineering in a weightless environment. The BSTC houses stationary bioreactors that maintain samples at a specified temperature in a controlled environment. The StelSys Liver Cell Research experiment, a Space Product Development investigation done under a licensing agreement with StelSys, Inc. of Baltimore, Md., seeks to compare the function of liver cells in microgravity with that of duplicate cells on Earth as a means of learning more about how to maintain the health of humans living and working in space. Whitson's tasks included analyzing the growth media in those bioreactors, replacing the media, preserving and photographing sample cultures, and purging the growth chamber with carbon dioxide to prepare it for its next use. The StelSys samples are stowed in a refrigerator/freezer in the Lab for return to Earth on the next space shuttle assembly mission, STS-112/9A, targeted for launch in August.

Each day station crewmembers are assigned time for physical exercise, using the station's treadmill, bicycle ergometer, or resistive exercise devices, to strengthen the muscles and cardiovascular systems which don't get the workout in weightlessness that they do on Earth. Along with their routine exercise this week, Korzun and Treschev completed two sessions of a Russian-Japanese experiment in which they shot close-up high-definition video of themselves while running on the treadmill. Researchers study the crewmembers' facial features as part of the medical evaluation of a crewmember on orbit.

The ISS Expedition 4 crewmembers --Commander Yury Onufrienko and astronauts Carl Walz and Dan Bursch--completed a 196-day mission when they and their STS-111 crewmates touched down at Edwards Air Force Base in California at 10:58 a.m. PDT Wednesday. Walz and Bursch are now the co-holders of the record for the longest single spaceflight in U.S spaceflight history, 196 days,and Walz' total of 231 days on orbit during his five missions makes him the American astronaut with the most cumulative time in space.

The workweek began with a U.S. milestone being recognized when Commander Mike Foale surpassed the astronaut cumulative time in space record of 231 days. During a special phone call Monday, Carl Walz, the previous record holder, called Foale to congratulate him on the milestone and discussed life on the Station and future endeavors in space.

Tuesday and Wednesday Foale - joined by Flight Engineer Cosmonaut Alexander Kaleri - dismantled the high-tech exercise treadmill and identified the cause of a problem preventing its use in the motorized mode. A bad bearing associated with its gyroscope assembly was determined to be the culprit and a replacement will be shipped to the Station on the next Progress resupply vehicle in late January. Until that time, the treadmill is usable for exercise without the stabilization system active.

Thursday Foale, also the onboard NASA ISS Science Officer, "flew" the Station's robotic arm for the first time through a survey of various modules and components of the complex. The survey had two-purposes: To continue investigating the source of an unusual noise heard by the crew a couple of weeks ago while in the Zvezda Service Module and to check for any other changes outside the station, a check normally handled by a Space Shuttle upon undocking and flyaround. This survey detected no abnormalities.

Foale and Kaleri discussed their mission with news organizations from ABC and the website SpaceflightNow.com. The crew also enjoyed a lengthy question-and-answer period with schoolchildren at the Wright Brothers National Memorial in North Carolina, as celebrations are ongoing in advance of the 100th anniversary Dec. 17 of powered flight.