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AKA: Sigma 7. Launched: 1962-10-03. Returned: 1962-10-03. Number crew: 1 . Duration: 0.38 days. Location: Astronaut Hall of Fame, Titusville, FL.
The Sigma 7 spacecraft with Astronaut Walter M. Schirra, Jr., as pilot was launched into orbit by a Mercury-Atlas vehicle from Atlantic Missile Range. Schirra attempted and achieved a nearly perfect mission by sticking rigorously to mission plan.
Official NASA Account of the Mission from This New Ocean: A History of Project Mercury, by Loyd S. Swenson Jr., James M. Grimwood, and Charles C. Alexander, NASA Historical Series SP-4201, 1966.
On October 3, 1962, Schirra slipped into his capsule, buckled himself comfortably in the couch, and smiled when he saw an automobile ignition key hanging from the handcontroller safety latch. This represented a tension breaker provided by the ground crew. Then he began to inventory his gear inside the cabin - flight-plan bar charts neatly placed in a slot just below the instrument panel, star charts arranged in a rack to his side, cameras in place, and accessories stowed in his ditty bag. When he stuck his hand in the glove compartment, he found some crinkly plastic wrapped around a soft object that turned out to be a steak sandwich. Otherwise, everything was as it should be, and Schirra began his prelaunch checkout tests.
Outside the spacecraft, technicians busily bolted on the side hatch, and every bolt sank neatly in its threads. From there on, the countdown proceeded rapidly until about 6:15 (T minus 45 minutes), when the Canary Island station reported a malfunction in one of its radar sets. Since this equipment would be critical in ascertaining the orbital parameters, Williams quickly called a hold in the countdown. The Canary radar required only 15 minutes to be fixed and for the next 45 minutes the countdown ticked off with precision.
At 7:15 a.m., the engines of Atlas 113-D roared and the big booster rose from the pad to rocket Schirra and Sigma 7 on their journey through space. "I have the lift-off," Schirra shouted into his microphone to Slayton in the Mercury Control Center, "and she feels real nice." Ten seconds above the pad, however, No. 113-D telemetered signals showing an unexpected clockwise roll. Both primary and secondary sensors inside the launch vehicle, monitoring such movements to determine the seriousness of the situation, registered a rifling roll only 20 percent short of an abort condition. Then, to the relief of the capsule and booster monitors in the control center, the threatening twist suddenly smoothed out. Schirra began transmitting the status of his supplies and systems' operation. After a little more than a minute, he realized that he seemed to be talking to himself. Glancing around the cockpit, he noted that evidently the noise associated with max q had incorrectly operated the sound-activated radio microphone, and so he pushed the button to talk to Slayton. Surely something should be done to obviate this problem, he thought, because he needed to keep his hand on the abort handle, or "chicken switch," rather than having to press the "talk" button manually.
Schirra listened for booster engine cutoff; it came two seconds earlier than programmed. He saw a flash of light and smoke reflected from the booster engines at the time the aft section parted from the sustainer. Seconds later the escape tower jerked away from the top of Sigma 7, its rocket blast spreading a spotty film on the window. Sustainer engine acceleration seemed slow, Schirra mused, but since his escape tower had "really said 'sayonara,' " he could only wait and see if the sustainer would burn long enough to accelerate him into orbit. Acceleration seemed to drive on and on, the pilot said, and finally the sustainer engine cut off, about 10 seconds late. Data registered on the control panels at the Cape indicated a 15-foot-per-second overspeed that would send Schirra higher - 176 miles - and faster - 17,557 miles per hour - than any other astronaut had gone or would go during Project Mercury.
When Sigma 7 parted from its Atlas rocket, Schirra turned on the auxiliary damping controls to eliminate the spacecraft quivers produced by the blast of the posigrade rockets. Although he dearly wanted to look out the spacecraft window at the scene below, Schirra fixed his eyes on the instrument panel, flipped his attitude control to the fly-by-wire mode, and started a leisurely four-degree-per-second cartwheel movement to obtain his correct orbital attitude position. Turnaround, which was deliberately slow to conserve fuel, used only three-tenths of a pound from a total supply of almost 59 pounds of hydrogen peroxide. To Schirra the thruster jets operated as if they had been programmed by a computer, providing tiny single pulse spurts to obtain exactly the position he desired.
Now he could look out the window to track the sustainer tankage. Peering at a prescribed spot, Schirra saw the spent vehicle come into view in the upper left corner of his "picture" window, just as his predecessors had said it should. Glenn and Carpenter had mentioned that their tankage appeared to be silvery in color; to Schirra, his looked almost black, "with a white belly band of frost." The spent launch vehicle seemed to have completed the same turnaround maneuver as the spacecraft, because Schirra looked down its nozzle. The Sigma 7 pilot saw none of the ice crystals or contrails streaming from the tankage reported by Carpenter.
Schirra said that the fly-by-wire system that had been redesigned to use only the low thrusters, if desired, served well to adjust his attitude to track the spent sustainer. The thrusters responded crisply and cut off without residual reactions. Tracking the booster seemed even easier than following a target in an aircraft on an air-to-air gunnery problem. Schirra nevertheless knew that he had neither the attitude control and maneuvering thrust nor the computational ability to perform a rendezvous. There were simply too many conditions to be judged if he were to solve the orbital mechanics task so shortly after launching. Schirra later expressed the opinion that rendezvous with another vehicle in space appeared to be possible, but that he believed a pilot would have to have very precise attitude data to effect a coupling. He confirmed what students of celestial mechanics already knew, while providing them with a feel for the problems of perceiving relative motion. Differences in velocity of only 20 to 30 feet per second between two objects in space could be disastrous, he said.
As Schirra neared the Canary Islands, he turned aside from tracking the booster to check out the manual-proportional mode of spacecraft control. The pitching-up maneuver matched well with his experience on the procedures trainer. As Grissom had done before him in Mercury-Redstone 4, Schirra noted that he tended to overshoot his desired attitude position and that the manual mode of control seemed "sloppy" compared with the semi-automatic modes. Manual-proportional control clearly was not the best way to "park" the spacecraft in one attitude. A far better method, he learned, was to rely on fly-by-wire with low thrusters only.
Passing over Nigeria, Schirra transferred spacecraft control to the automatic stabilization and control system and busily monitored his panel dials. Minutes later he had traversed the African continent without yielding more than once to the temptation to watch the panorama passing beneath him. Moving toward Zanzibar, Schirra began to feel warm. He decided to devote full attention to this before somebody, as he said later in the postflight debriefing, started "jumping up and down in the control center" and yanked him out of orbit. Frank H. Samonski, the environmental control system monitor in the Mercury Control Center, had also watched the temperature rise. At Mercury Control the suit heat signal, creeping steadily upward, had indeed caused the ground controllers to think about terminating the mission after the first circuit. Samonski conferred with Charles A. Berry, who had relieved Stanley C. White as flight surgeon in the Control Center. Berry believed that the astronaut was in good condition. He advised trying a second orbit to see if the suit and its occupant could settle their temperature differences. Kraft, the flight director, listened to the two men and decided to give the go-ahead to Schirra for a second orbit. Wrestling with communications checks and with his suit temperature, he found himself halfway around the world before the Guaymas station relayed the official green light for his second orbit.
When the temperature problem first appeared, the control knob setting was at Position 4. Prior to the flight, Schirra had established a procedure for just this situation. Rather than rushing to a high setting, he slowly advanced the knob by half a mark at a time, then waited about 10 minutes to evaluate the change. Had the valve been advanced too quickly, the heat exchanger might have frozen and reduced its effectiveness even more. By the time Position 7 was reached, Schirra was much cooler and felt sure that his temperature problem was nearing resolution, but for good measure he turned to Position 8. Shortly he became a little cool, and Samonski recommended that he return to Position 3.5. Schirra, thinking that some kind of analysis had been performed in the Mercury Control Center, complied. Immediately noting that the temperature was rising again, he quickly returned the setting to 7.5 and left it alone for a while.
Rounding Muchea, Australia, on his first pass, Schirra had nosed the small end of Sigma 7 down to watch for the first ground flare launch. He said that he saw the flare before realizing the flash was only lightning. Shortly thereafter, Woomera reported flare ignition; the pilot still saw lightning - but only as a big blob of light, never like the jagged streaks seen nearer Earth. Again, as on past missions, the flare launching area was cloaked by clouds. Minutes later, however, he reported seeing the outline of a city, which he guessed to be Brisbane, Australia.
With careful adjustments, Schirra peered into the periscope on his first night trip through space, endeavoring to prove its optical advantages. Very graphically, he finally reported, "I couldn't see schmatze through it. Schmatze translated means nothing." He, like Carpenter, found the periscope was excess baggage during the daytime and nearly useless at night. Reaching the morning side of Earth near Hawaii, he recoiled when the Sun, glaring through the scope, almost blinded him. Placing a chart over the scope, he commented that it "helps no end to cover up that blasted periscope."
Though he did not feel rushed in his few tasks, Schirra did notice a remarkable "speeding up of time" as distance flew by so rapidly. After crossing the Pacific, he reported to Scott Carpenter at Guaymas, Mexico, "I'm in chimp configuration," meaning that the capsule systems were all on automatic and working beautifully. Even the temperature range had now become more comfortable, and one more adjustment of the knob would end that problem. He then told Carpenter that he would soon start his first daytime yaw maneuver, using the window as a reference. Schirra said to Slayton, while sailing over the Cape, that the "reticle is working well for yaw, as well as for almost any other attitude." Any object that could be seen on Earth could be centered on the window reticle long enough to judge yaw misalignment. Always the most difficult of the three axes to judge precisely, as demonstrated during MA-7, yaw alignment with the flight path was a major control task to be tested by the MA-8 mission. Over areas of extreme cloudiness, there was no worry so long as rifts or thunderheads provided breaks in the blanket of cloud cover. By the end of his first circuit, Schirra felt he had become so adept in determining yaw attitude that he could estimate any yaw angle his ship happened to take away from the flight path.
The pilot for a second time carefully compared his visual ability, both with and without the periscope, to position the capsule's attitude correctly. He felt satisfied with the results. He conceded that by using the periscope on high magnification he could obtain the yaw attitude faster than with the window, but speed was unnecessary in most cases.
Schirra had to devote much of his time during the first orbit and a good portion of the second to correcting his suit temperature settings. Perspiration salted around his mouth as a result of suit inlet temperature reaching 82 degrees F; he became quite thirsty, but he resisted opening the visor so the suit could have every opportunity to settle in a more comfortable range. Despite the heat - which he described as comparable to what he had endured mowing his lawn in Texas on a summer's day - all other aspects of the flight were going well. Sigma 7 had consumed 1.4 pounds of fuel on the first orbit, Schirra noted as he reported the status of the spacecraft systems. He saw the exterior particles first reported by Glenn and tapped the cabin wall to obtain the same shower effect Carpenter reported. Much of his conversation with the tracking sites involved the status of his suit circuit. He seemed to enjoy talking with the communicators during his first orbit, but later he would complain that this became a chore, especially when he was trying to concentrate on his work.
On Earth's nightside, Schirra reported that the Moon made an excellent yaw reference; after completing and reporting on the yaw maneuver, Schirra told Slayton in the Mercury Control Center that he had shifted back to the automatic system. By now the temperature had subsided enough to permit a quick drink of water. He took the opportunity during this respite to report that all systems were performing very well. So far he had felt only one unwanted spurt from a 24-pound thruster when he returned to fly-by-wire for a yaw-maneuver exercise. Becoming a little bored with automatic flight halfway around the world, Schirra shifted to the manual- proportional system and produced a similar moment of double authority. About two percent of the manual supply spat out in a pitchdown motion of the spacecraft. "It was my boo-boo," he confessed.
Over Muchea, Australia, on his second pass, Schirra began a more serious and considerably more difficult night-yaw experiment. He was to test his ability to use celestial navigation to align the spacecraft properly. Using star-finder charts, Schirra was supposed to orient himself by positioning Sigma 7 in relation to known stars or planets and the Moon. Then he was to test his sense of facing to the right or left of his flight path by watching the apparent motions of heavenly bodies. The pilot found that the airglow layer was an excellent reference for pitch and roll. This belt, which appeared very thick above the horizon, could provide reference for these attitudes quite accurately. For experimentation with the airglow layer, he positioned Sigma 7 so that it appeared to aim at the upper layer of the belt. The panel indicators then showed a zero reference in pitch.
Schirra conceded that night-yaw reference could be a bit of a problem. The field of view from the window did not make it easy to identify the constellations and find a known star. Preferring to obtain the correct yaw reference on the daylight side, Schirra seemed to lack confidence in his ability to effect the night maneuver. To some degree his difficulty stemmed from his star-finder charts, which had been fixed in their relationship to Earth for a period up to about 7:16 a.m. on October 3. Schirra, now deep into the second orbit, knew that his launch time had been 7:15. The difference in time, plus his restricted field of view, reduced the value of this night-yaw exercise; but as it turned out, telemetry data received at the Muchea tracking station showed his error to be only four degrees.
During the night-yaw maneuver, Schirra happened to notice one excellent celestial pattern that he could use to align the spacecraft in the retrofire position when it was time to reenter the atmosphere. Checking the panel indicators against his own observations, he determined that the correct retrofire attitude would place the planet Jupiter in the upper right-hand corner of the window, the double-star constellation Grus tracking in from the left side of the window, and the star Fomalhaut at the top of the window, near the center.
Across the Pacific, Schirra again placed the controls in the automatic, or "chimp configuration," mode. He chatted with Grissom at the Hawaiian site about how well the spacecraft's systems were working. Grissom had made some rather strong points concerning the manual-proportional control operation during his suborbital flight, and the two astronauts, in a space-to-Earth conversation, compared notes. Just as Hawaii lost his signal and California picked it up, Schirra called that the "fireflies" were coming into view. "I have a delightful report for one John Glenn," he told the California communicator. "I do see fireflies." Impressed by the view out of the window, even though much of the California coast was covered with clouds, Schirra remarked to Glenn, "It's kind of hard to describe all this, isn't it, John?" Suddenly, through rifts in the clouds, he could see San Clemente Island, off the coastline. Then, looking northeastward, he saw more of the coastal area come into view, followed by the Salton Sea, an excellent view of lower California, the ridges of Mount Whitney, and several roads in the Mojave Desert area.
Although Schirra flew higher than either Glenn or Carpenter, he was rather unimpressed by the height of his voyage. Psychologically he had prepared himself for space flight, knowing that he would be flying 10 times higher than he had ever flown before. But once in space, the number, size, and detail of the objects he could see with the unaided eye, such as roads and terrain changes, made him actually feel no higher than he had climbed in an aircraft. "Same old deal, nothing new," he remarked in debriefing, "might as well be in an airplane at 40- to 50-thousand feet altitude."
According to his flight plan, if the yaw-reference checks had been satisfactory Sigma 7 would be phased into drifting flight during the third orbit. After giving Slayton a systems status report, Schirra proceeded to cage the spacecraft's gyros, cut off its electrical power, and allow Sigma 7 to drift through space. Schirra took this opportunity to make an old psychomotor experiment that Robert B. Voas a year earlier had asked to be performed. Choosing three dials on the control panel, he closed his eyes and attempted to touch the target points. In a total of nine trials, he made only three errors, the largest being a displacement of some two inches. The weightless state, he concluded, created no disorientation or new problems in blindly reaching for his controls.
After that test, Schirra drifted along, reporting his status again to the Canary station and enjoying a brief period of looking out the window. He mentioned that his outer pane was streaked with a pinkish-orange film and surmised that this had emanated from the exhaust gases of the launch escape rocket. According to his flight plan, he was supposed to eat and drink now; although he said, "I'm having a ball up here drifting," eat and drink he did - peaches and ground beef mush from squeeze tubes.
Out over the Indian Ocean, he informed the tracking ship in that vicinity that he had switched the electrical power back on and gone into fly-by-wire control to check systems operations after the "powered down," or free-flight, period. Excitedly, the Indian Ocean ship communicator told Schirra that some of the crew topside had actually caught sight of Sigma 7 for five minutes and through nine degrees of tracking. Schirra, quite pleased, said, "I'll have to go by and say hello." The pilot then reported that powering up again presented no difficulty; all systems worked beautifully, with absolutely no responses from the high thrusters. Smoothly transferring into the automatic stabilization and control system, he began to look toward the heavens for familiar stars. When the Moon failed to show, he went to the fly-by-wire, low-thruster control to bring it into sight. He identified Cassiopeia during the process, then said, "There's our friend the Moon." Over Muchea again by this time, he told the communicator that he had locked the automatic system onto the disk of the Moon. Mercury Control had alerted the ground stations to pay particular attention to fuel usage by the thrusters. Canton Island and Kauai, Hawaii, rolled by underneath with everything working so well that Grissom, at the Hawaiian station, gave Schirra the official good news that he had a "go" for the full six orbits.
As Sigma 7 came near the California tracking site on its third pass, Schirra told Glenn, "I'm going to shove off for a relaxation period," meaning he would cut his electrical power, cage his gyros, and start drifting again. Schirra's flight schedule now called for experimental observations and photography. He had to struggle getting the camera out of the ditty bag, but once out it was weightless, and Schirra easily snapped pictures from Baja, California to Cuba as Sigma 7 drifted along beautifully. Nearing the Cape, Slayton asked for a radiation reading from the hand-held dosimeter. Schirra replied that the value was so small that it was nearly unreadable. Then Kraft himself came on the air to compliment Schirra, to urge him to look for the giant Echo balloon-shaped satellite on his next pass over Zanzibar, and to notify him that his voice would be broadcast live for two minutes during his next flight across North America. The enthusiastic pilot then exclaimed that he had just drifted into an inverted position (head to Earth) and "for some reason or another, you can tell that the bowl (spacecraft) is upside down." He saw the whole eastern coastline of the United States, took a picture of that, and then another of an interesting cloud formation. Still complaining that the camera was difficult to extract, he decided not to stow it in the case for a while. As for Echo, he never saw that (or any other) man-made satellite while in orbit.
Floating through space around the world on his fourth orbit, Schirra took pictures that struck his fancy, watched the nightfall, recognized several stars as they appeared, and looked at lightning in the thunderstorms covering portions of the Australian continent. As he came over the Pacific command ship, he facetiously reported to Shepard that his hydrogen peroxide had not evaporated and suggested that they should make some plans, the next time around, about retrofire countdown. Schirra then tuned on the radar ships Huntsville and Watertown for a communications check. As Hawaii was sliding by, he told Grissom that he was in inverted flight and that the impression was similar to "looking out a railroad train window. You see the terrain going by you." The yaw attitude of the spacecraft was clearly discernible against this background.
As he approached, head down and looking toward California on his fourth pass, Schirra joked with Glenn about his "real weird attitude" and transmitted another short status report. Then at 6 hours, 8 minutes, and 4 seconds elapsed time from launch, Schirra and Glenn began a dialogue heard by much of the Western world via radio and television:
GLENN: Okay, Sigma 7. This is Cal Cap Com. You're at 6:08. Two minutes on live TV. Go ahead, Wally.
SCHIRRA: Roger, John. Just came out of a powered-down configuration where we had the ASCS inverter off. It came up in good shape and will stay on now for the rest of the flight. The amps and volts are reading properly.... I'm coming toward you inverted this time, which is an unusual way for any of us to approach California, I'll admit.
GLENN: Roger, Wally. You got anything to say to everyone watching you across the country on this thing? We're going out live on this.
SCHIRRA: That sounds like great sport. I can see why you and Scott like it. I'm having a trick now. I'm looking at the United States and starting to pitch up slightly with this drifting rate. And I see the moon, which I'm sure no one in the United States can see as well as I right now.
GLENN: I think you're probably right
SCHIRRA: Ha-ha, I suppose an old song, "Drifting and Dreaming," would be apropos at this point, but at this point I don't have a chance to dream. I'm enjoying it too much.
GLENN: Things are looking real good from here, Wally.
SCHIRRA: Thank you, John. I guess that what I'm doing right now is sort of a couple of Immelmanns across the United States.
And here ended Schirra's epistle from space. Glenn continued the conversation in relative privacy, asking whether Schirra had noticed anything surprising about the haze layer. Schirra replied with another understatement - "It's quite fascinating" - but later he recalled that this phenomenon had been his biggest spatial surprise. Both Glenn and Carpenter had briefed him on the night view of the horizon from the heavens, but "it just never did sink in to me that it was as large in magnitude as it really was." Schirra remarked that the airglow layer covered about a quarter of his view out the window. When first sighted, he said, "I thought it was clouds, until stars appeared below."
Halfway through the fourth orbit, liquid collected over the inner surface of his helmet faceplate, evidently from the water coolant circuit. Although Schirra was annoyed by this problem for the next two hours, he was thankful that the suit temperature remained reasonably comfortable. So long as his visor was sealed, he had to crane his head about inside the helmet to find a clear view out of the faceplate. He was still reluctant to disturb his suit temperature by opening his visor to wipe it clean.
Going into his fifth orbit, Schirra told Slayton by radio relay that the flight had been his first opportunity to relax since the previous December. His life had suddenly become so sedentary that he gladly used the bungee cord exerciser to tone up his muscles a bit. "Not exactly walking around," he said, "but a little bit of stretching." Because Sigma 7 was now over the Yucatan Peninsula, communications with the Cape were a little strained, causing Slayton to quiz Schirra, "Did you say you'd like to get up and walk around?" The ground controllers cleared the matter by switching circuits to a relay communications aircraft.
Schirra now began another check of the manual-proportional attitude controls, recording a third brief instance of double authority control. Regarding this latest spew of fuel, he complained that he "really flotched it. It's much too easy to get into double authority, even with the tremendous logic you have working on all these systems." His check of all the axes of movement proved that the manual-proportional system was still in good working order. After this trial he returned to observing and photographing targets of opportunity.
As he prepared to look for the 140-million candlepower light near Durban, South Africa, Schirra reported "getting some lighted areas over the southern tip of Africa. . . . I definitely have a city in sight." Betting that this was Port Elizabeth, a city a little more than 300 miles to the southwest of Durban, Schirra did not seem surprised that Durban was being drenched with rain and its brilliant light was not visible on this pass.
Passing into its fifth revolution of Earth, Sigma 7 still performed beautifully in all respects. Astronaut Schirra had little to tell the ground tracking station except to repeat how well the systems were working and how gorgeous were the sights. With each orbit, he was now moving farther from the beaten track nominal to a three-pass flight, and the periods of silence were longer. A lighted area appearing much like an airport showed up in what he surmised were the Philippine Islands. "Possibly it's at Zamboanga," he guessed, a city on the southwest coast of Mindanao. Minutes later he talked with Alan B. Shepard aboard the Pacific command ship, reporting with pleasure that his fuel supply stood at 81 and 80 percent in the automatic and manual tanks, respectively. His oxygen supply was properly pressurized, and his suit temperature was at a comfortable 62 degrees. Shepard replied, "Well, I could say that you were definitely go." Quickly he checked in with the Huntsville and Watertown, presenting, as he put it, a "hunky dory" report. As the pilot came over the Kauai station, Grissom fed him the correct retrosequence time that he should use on his next, and final, pass. Checks with Glenn at Point Arguello and with Carpenter at Guaymas showed that communications should be good for checkoff and reentry during the sixth orbit. Schirra then bade farewell to South America with a "Buenos dias, you-all," to the Quito, Ecuador, communications relay station.
Going into the sixth orbit, Schirra almost regretfully began his preparations to return to Earth. On his last pass over South America, heavy cloud coverage obscured most of the hemisphere but he did catch sight of a large winding river. He reached for the slow-scan camera and pointed it downward at the surface of the window to capture the view, making a panoramic shot of the continent that he thought would aid the Weather Bureau in continental cloud analyses. Then he stowed the camera, rearranged the contents of the ditty bag and glove compartment, and began going down the checklist of actions to be accomplished before retrofire and reentry.
He shifted the control mode from the automatic system to the fly- by-wire, low-thrusters, and found his command of the system still worked well. He looked briefly out the window for the lights of Durban, but clouds still hid the glow of that huge lamp from sight. He closed the faceplate, found it fogging again, and opened it briefly to wipe the visor clean. The instrument panel showed that the inverter temperatures were in a good range, that the battery voltage checked out high, and that the oxygen pressure was holding its mark. Although quite comfortable, he decided to advance the suit-circuit knob "just a tad to increase the cooling for reentry," to Position 8. The checkoff proceeded so methodically that he had time to try another eyes-closed orientation test. He reached for the manual handle and felt it in his grasp. Then he reached for the emergency handle but brushed an adjacent radio box before touching it.
Down below, the Indian Ocean ship communicator asked if he needed any help in completing the pre-retrosequence checklist. "Negative," he replied. All was in readiness for the last-minute arming of the retrorocket squibs. He waited and watched until he came in range of Shepard aboard the Pacific command ship. In the darkness, he viewed a moonset, saw the proper star and planet pattern for his correctly aligned attitude swing into view, and noticed that one of his fingertip lights had burned out. Musing out loud for whoever could listen, he likened his situation once again to riding a train on celestial tracks leading back toward Earth. Listening to the humming of the systems, he was reminded also of a ship underway at sea. As a pilot, Schirra curiously refused to compare his limited control of the spacecraft with his freedom of maneuver in aircraft.
When he came into range of the Pacific command ship, he glanced at the fuel levels: 78 percent in both the automatic and manual tanks, the meters read. Shepard asked him how he stood on the checklist. Completed, with the exception of arming the rocket squibs, Schirra replied. He told Shepard that his ship was holding well in the retroattitude mode on the automatic system, that the high thrusters were in good working order, and that he had the manual-proportional system in a standby position. With everything set, Shepard gave the countdown to arm the squibs on the "Mark!" Next came the retrosequence countdown. Eight hours and 52 minutes after Sigma 7 lifted off from the Cape, the first retrorocket fired. When Schirra punched the button for this action, the tiny instant of time before the firing "seemed agonizingly long." As each retrorocket fired crisply at five-second intervals, Schirra was pleasantly amazed that the spacecraft appeared to hold as steady as a rock. Quickly he checked this impression with a glance out of the window; the star pattern he could see did not even appear to quiver. After retrofire he checked the automatic fuel gauge and found the needle hovering between 52 and 53 percent.
Then Schirra shifted gears to his favorite fly-by-wire, low-thruster mode of control. He armed the retropack jettison switch and the spent unit spun away. Shortly after retrofire his attitude control felt "a little bit sloppy," and he felt himself wobble toward reentry. Although this could have been corrected by using the low thrusters, he intentionally cut in the high thrusters to get into position quickly. Schirra pitched Sigma 7 up to the 14-degree reentry attitude with no difficulty and cut in the automatic control mode to damp away undesirable motions. Then, as the engineers had asked him to do, he turned on the fuel-gulping rate stabilization control system (RSCS). His return to the atmosphere was "thrilling" to the astronaut. He said the sky and Earth's surface really began to brighten, but, most surprisingly, the "bear" he rode felt "as stable as an airplane."
Schirra realized that he had heard none of the hissing noises reported by Glenn and Carpenter. Possibly, he thought, his concentration on the rate control system caused him to miss the sounds. Having conserved his hydrogen peroxide so well thus far, Schirra was quite perturbed with the rate system because he could see the fuel supply being dumped like water being flushed. Resisting the temptation to switch to a more economical mode of control because the engineers wanted to evaluate this system once and for all, he pulled his eyes away from the gauge and looked out the window. He could see the green glow from air friction that Carpenter had reported. To him it looked limeade in color, almost chartreuse. Suddenly, as a three-foot strap flopped past the window, he exclaimed, "My gosh !" Then he remembered, "That's the same thing John saw."
Soon the barometric altimeter dial came into operation, and Schirra calmly waited for the needle to edge toward the 40,000-foot reading. He punched the drogue button, heard a "strong thrumming," and then felt the drogue parachute pop open. What had felt like a smooth highway now seemed like turning off on "a bumpy road." As long as he could, the astronaut strained to watch "the drogue up there pounding away," but the window became virtually occluded by smoky deposits from reentry. Schirra then turned back and flipped on the fuel jettison switch.
At the 15,000-foot mark he ejected the main parachute and saw it stream and blossom at 10,500 feet. This event, as Schirra quipped, "sort of put the cap on the whole thing." As he started his descent to Earth, Schirra remarked to Shepard, "I think they're gonna put me on the number 3 elevator" of the carrier Kearsarge. Sigma 7 missed this mark by a scant 4.5 miles downrange from the planned landing point, but the recovery force had the spacecraft well within its sights electronically and visually. The carrier made radar contact with Sigma 7 at a slant-range of 202 miles; 90 miles uprange from the carrier, sailors of the destroyer Renshaw reported hearing a sonic boom. Men on the deck of the Kearsarge then saw a contrail, while a few of its crew claimed to see the drogue and others heard two successive sonic booms and saw the main chute unfurl. After nine hours and 13 minutes in flight, Sigma 7 settled on the water, in full view of the ship's crew and the cameras of newsmen.
Sigma 7 hit the surface with a "plop," as Schirra described it, and "went way down" before it surfaced and floated. He waited patiently for 45 seconds and then broke off the main parachute and switched on the recovery aids. Inside, the spacecraft remained dry and the temperature range was very comfortable as Sigma 7 rode the lazy ocean swells. This condition prompted the pilot to exaggerate in debriefing that he "could stay in there forever, if necessary." Through the window he could see the green dye permeating the water in a widening perimeter, and he knew that the whip antenna had telescoped out fully. Seeing the antenna pole deploy while Sigma 7 was still submerged, Schirra later joked that he thought he might spear another bluefish. All was well, and so far as this test pilot could judge, the Mercury spacecraft "had gone to the top of the list," even over the F8F aircraft he liked so well.
Long before Schirra's splashdown, the Kearsarge had launched helicopters with swimmer teams, and soon three swimmers jumped into the dye beside the floating capsule. During the 30 seconds while he was keeled over in the water, Schirra had had some trepidation about his watertight integrity. He momentarily wished for the pressure regulator handle that had been deleted from Sigma 7 to save another pound of weight. As the capsule righted itself and remained shipshape, he noticed that communications had been better with Hawaii than they were with the Kearsarge. The pararescue men then cut the whip antenna and attached the flotation collar around the heatshield. Since he was comfortable, he radioed a request to the helicopter pilot that he "would prefer to stay in and have a small boat come alongside" and tow him to the carrier's cranes. Five men piled into a motor whaleboat and within minutes had covered the half-mile to the bobbing Sigma 7 and attached a tow line to it.
Some nine hours and 54 minutes after launch, the small space ship was hoisted aboard the huge carrier. Five minutes later Schirra whacked the plunger to blow the explosive hatch, incurring the same kind of superficial hand injury as Glenn before him. He stepped out onto the deck of the Kearsarge and paused to acknowledge the jubilant shouts and applause of the ship's crew. As he walked down to the ship's sick bay, Schirra looked tired and hot but happy. When reporters called out, "How do you feel, Wally?" he replied, "Fine," with a flip of the hand.
For the next three days, the Kearsarge was to be his home during the medical examinations and technical debriefings. While still in his space suit and sitting on a cot in the officers‘ sickroom, he received successive congratulatory telephone calls from President Kennedy, his wife Josephine Schirra, and Vice President Johnson.
Richard A. Pollard of MSC, Commander Max Trummer of the Navy, and several other physicians began to check Schirra in every medical way possible. When his phone calls were completed, about 45 minutes after he came on board, the systematic examinations began. At first appearance, the spaceman showed no evidence that he was dizzy or required walking assistance. He told the physicians, "I feel fine. It was a textbook flight. The flight went just the way I wanted it to." Contrary to the impression of some newsmen, the physicians did not find Schirra overly fatigued. He talked easily and actively assisted in his postflight physical. Only after he had been strapped on a tilt table did several unusual symptoms begin to appear. For example, when lying supine his heartbeat averaged 70 a minute; standing, it rose to 100. Blood pressure readings, although not so pronounced in range, registered differently in standing, sitting, and prone positions. His legs and feet assumed a dusky, reddish-purple color when Schirra stood up, connoting that his veins were engorged. This condition persisted for about six hours, and then the astronaut was permitted to retire for the night. The next morning Schirra's heart and blood pressure readings were near normal, and there was no evidence of pooling of blood in his legs when he stood.
Other than this minor anomaly, and the small lesion on his hand, Schirra seemed none the worse for his lengthy weightless sojourn in space. Life-systems specialists in NASA, at McDonnell, and at AiResearch, however, had another question: What caused the elevated suit temperatures during the first two orbits? Postflight inspectors dug into the matter promptly. The technical ills of the spacecraft's systems were more easily determined than the subtleties of man's physiological system; as it turned out, the flow in the suit coolant circuit had been impeded by the silicone lubricant on a needle valve's having dried out and flaked.
Postflight inspection of Sigma 7 found little else that seemed out of the ordinary. Circular cracks on the ablation shield were moderately larger than on Glenn's and Carpenter's spacecraft; also it appeared that the shield had banged into the fiber-glass protective bulkhead upon impact, causing several small holes. Once again the heatshield showed some delamination from the center, but it still appeared, as in past flights, that this occurred after reentry. Char depth on the shield, about a third of an inch, was quite nominal. The shield's center plug, which had been loose or missing after previous missions, stayed tightly in place. All in all, the inspectors found very few problems to analyze or to correct. The quality of the mission, of the hardware, of the software, of procedures, and of the pilot were all superb. In terminology the engineers agreed with Schirra that MA—8 was a "text book flight" - the best so far.
Walter Williams was especially jubilant over the MA-8 success; now he could confidently turn his operations team to the task of the day-long mission. Schirra's conservation of fuel and the excellent manner in which the spacecraft had performed, he said, made planning for MA-9, if not routine, at least considerably easier.
More at: Mercury MA-8.
Family: Manned spaceflight. People: Schirra. Country: USA. Spacecraft: Mercury. Launch Sites: Cape Canaveral. Agency: NASA.
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