Encyclopedia entry

Space Station Options 1993

Spacecraft · USA

Original archive entry. The text, images and links below are kept as they were written.

Space Station C4
Space Station Option C4.
Credit: NASA via Marcus Lindroos

American manned space station. Study 1993. Following the collapse of Space Station Fred, NASA quickly formed a Space Station redesign team which identified three major redesign options in April 1993....

These were:

Option B, the most expensive design, was very similar to the 1991 'Fred' design. Option B would have omitted one truss segment while simplifying some subsystems to save money. The Station assembly schedule would also have been delayed, and the project management structure would have been overhauled as well.. The total cost over five years could not be kept to under $9 billion, however, and this effectively killed the concept, although Space Station Freedom supporters in Congress preferred this option. Compared with Space Station Freedom, Option B would have saved some money by starting with half of the original design and grow to full size as the budget allowed. Like Option A, Option B would initially have relied on a docked Shuttle to provide housing for the crew. However, 'just going up for less than 20 days and coming back...is nothing but Shuttle plus. It wouldn't be worth the money to do that' according to the Advisory Panel's Daniel Hastings. The completed Option B station would have offered better on-board data storage and lab space than Option A, but would also have required an additional 10 assembly flights and 60 hours of external assembly and maintenance work by astronauts. The technical risk was regarded as lower than for the other two Options, but the design still wasn't detailed enough for an accurate assessment of its user capabilities to be made.

Option C was the most controversial alternative since it represented a radical departure from all previous Space Station plans. It featured a single large 28m long, 7m diameter pressurized 'can' that would be launched fully outfitted on a new Shuttle derived heavy-lift booster. The cost of the core module was estimated to be $3.19 billion; a total cost of $6.502 billion over five years excluding reserves, operations and the $1 billion Freedom termination cost. The Shuttle, ESA Columbus and Japanese Experiment Modules would all be docked to the Option C Space Station. This design would have given researchers more lab space and power than Freedom, and it could support a permanent crew from the start while requiring less external maintenance by astronauts.

It would have included no fewer than 136 experiment racks - nearly three time as many as 'Fred' and far more than the Option C solar arrays could support. But its microgravity environment was comparatively poor since the Station would have to rotate to keep its solar panels facing the Sun or else the power would vary. The design made adding more solar panels very difficult. The Europeans, Japanese and Canadians disliked this option since would have to change the electrical, thermal control and data management systems of their modules - if they could be accommodated at all. The international contributions would also be rendered largely useless (e.g. Canada's robotic arm would also be of little value since little on-orbit assembly would required).

The Option C Space Station would have been launched in one piece on a new unmanned Shuttle-derived heavy-lift rocket. The design was regarded as a very high-risk venture since the Station would have to be developed essentially from scratch and tested in a very short time, and it would rely on a new launch vehicle that would have to work on its maiden voyage (NASA was going to use cannibalized parts from the Shuttle Orbiter 'Columbia' to save money). Nonetheless, the 'blue ribbon' selection panel endorsed Option C along with Option A. NASA proposed to farm out the construction of the 'can' to Russia in order to save money. The Russians declined, however, since they felt the bid wasn't detailed enough.

Option A was the 'compromise option' eventually chosen by Clinton. Like Option B, this configuration was based on the abandoned Space Station Freedom design from 1991, so it was more acceptable to the international partners than Option C. Option A would start with a 'power station' to which an extended duration Shuttle could dock for initial research lasting 20 days at most. Lockheed's 'Bus-1' (a previously classified US Air Force spacecraft) would provide propulsion and attitude control. The US laboratory and node would also be integrated into a single module. Later, additional laboratories and a habitation module could be added to create the complete Option A Space Station shown here. A major drawback was the limited capability for scientific research, particularly for sensitive microgravity experiments since the Station periodically (every 2-3 months) would have to reorient itself 90 degrees to keep solar panels pointing toward the Sun. This would interrupt materials science regularly. Consequently, the Clinton Administration promised to use the same 'alpha' solar panel joints as Option B. The total estimated cost in 1994-98 was $13.3 billion, considerably higher than the $9-billion Space Station requested by the President in March 1993. NASA was asked to report back in September 1993 since the current Option A design was not detailed enough for an accurate assessment of its user capabilities to be made.

1993 SPACE STATION OPTIONS SUMMARY ------------------------------------------------------------------- COSTS ($ billions) Freedom A/Bus-1 Option-B Option-C R-Alpha ------------------------------------------------------------------- -FY 1994-98 $15.8 $13.3 $13.3 $11.9 $10.5 -FY'94 to assembly complete $22.1 $17.0 $19.3 $15.2 $19.4 -Ops. & payloads $25.0 $13.5 $15.1 $10.2 ? -Total lifetime cost incl.marginal STS $65 $47 $50 $41 flight cost -Total lifetime cost $101 $80 $87 $65 incl.average STS flight cost ------------------------------------------------------------------- MILESTONES Freedom A/Bus-1 Option-B Option-C R-Alpha ------------------------------------------------------------------- -1st element launch 3/96 10/97 10/97 9/99 6/97 -Man-tended capacity 6/97 4/98 12/98 - 8/97 -International modules 12/99 12/99 3/01 7/00 4/00 -Permanent crew 6/00 9/00 12/01 11/99 9/97 -Assembly complete 9/00 9/00 12/01 1/01 10/01 ------------------------------------------------------------------- PERFORMANCE Freedom A/Bus-1 Option-B Option-C R-Alpha ------------------------------------------------------------------- Orbit inclination 28.5 28.5 28.5 28.5 51.6 Crew research hr/yr 6866h 6724h 6566h 6866h Total power (kW) 68.3 57 68.3 61.5 105 User power (kW) 34.2 31 40.3 40.9 < 45 Habitable volume (m3) 878 760 878 1117 1200 Equipment racks system racks 65 59 65 50.5 51* user racks 45.5 39 45.5 72 33* user racks @ <1uG 29 8 29 40 ? Assembly EVA, h. 340h 224h 311h 24h 224h Annual maintenance EVA 240h 187h 253h 80h 197h Total assembly flights 20 16 20 10 14+12 Russian. Logistics flights/yr. 4 6 6 6 7 * = does not include Russian equipment racks.

Article by Marcus Lindroos

Family: Space station, USA - Space Stations
Country: USA
Launch Vehicles: Space Shuttle
Agency: NASA

Photo Gallery

Station Option A '93
Space Station Options 1993
Credit: NASA via Marcus Lindroos
Station Option A '93
Space Station Options 1993
Credit: NASA via Marcus Lindroos
Station Option A-Rus
Space Station Options 1993
Credit: NASA via Marcus Lindroos
Station Option A-Rus
Space Station Options 1993
Credit: NASA via Marcus Lindroos
Station Option B '93
Compared with Space Station Freedom, Option B would have saved some money by starting with half of the original design and grow to full size as the budget permits.
Credit: NASA via Marcus Lindroos
Space Station C3
Space Station Option C3. Option C was the most controversial alternative since it represented a radical departure from all previous Space Station plans. It featured a single large 28m long, 7m diameter pressurized "can" that would be launched fully outfitted on a new Shuttle derived heavy-lift booster.
Credit: NASA via Marcus Lindroos
Station Option C '93
The Option C Space Station would have been launched in one piece on a new unmanned Shuttle-derived heavy-lift rocket.
Credit: NASA via Marcus Lindroos
Station Option C '93
Space Station Options 1993
Credit: NASA via Marcus Lindroos
Station Option C '93
Space Station Options 1993
Credit: NASA via Marcus Lindroos
Space Station C5
Space Station Option C5
Credit: NASA via Marcus Lindroos
Space Station C6
Space Station Option C6. This illustration show the Shuttle, ESA Columbus and Japanese Experiment Modules docked to the Option C Space Station.
Credit: NASA via Marcus Lindroos
Space Station Fred
The most expensive "Option B" design was very similar to the 1991 "Fred" design shown here. Option B would have omitted one truss segment while simplifying some subsystems to save money.
Credit: NASA via Marcus Lindroos

Related

Photo Gallery