Mercury-Atlas 8 - Orbital Activities

Orbital Activities

After separating from the Atlas booster, Schirra stabilized the spacecraft and slowly cartwheeled into the correct attitude; he deliberately kept the motion slow to conserve fuel, and was able to position the capsule using half a percent of his fuel reserves. He briefly tracked the spent booster, which was rotating slowly past, but made no attempt to move towards it. As the spacecraft moved across the Atlantic, he turned his attention to testing manual control of the spacecraft, which he found sloppy compared to the fly-by-wire system.

Crossing over the eastern coast of Africa, he began to feel overheated; this problem was also apparent to the ground controllers, who were having a debate with the flight surgeon over whether it was safe to continue or if the mission should be ended after the first orbit. The flight director, Christopher Kraft, followed the surgeon's advice to see if the problem would settle, and gave the go for a second orbit. Schirra eventually stabilized the problem over time, slowly dialling the suit's control knob to a high cooling setting; he compared the heat to that of "mowing a lawn in Texas".

Over Australia, Schirra watched for a flare launched from the ground, but it was occluded by clouds; he, was however, able to see lightning and the lit outline of Brisbane. Through the night pass over the Pacific, he tested the capsule's on-board periscope, though he found it difficult to use and quickly covered it up as soon as the sun rose. Crossing over Mexico, he reported that he was in "chimp configuration", with the capsule running entirely on automatic without any input from the pilot, and as he began his second orbit began testing a yaw manoeuvre using the Earth through the main window as a reference, rather than via the much-maligned periscope.

On the second orbit, he confirmed the existence of Glenn's "fireflies", the shower of small bright particles first reported on MA-6, and during the night section practiced yaw manoeuvres using first the Moon and then known stars as reference points. The second proved difficult to work with, as the small windows of the Mercury capsule gave a very limited field of view, making it hard to identify constellations. Travelling across the Pacific, he again fell back into automatic flight, chatting with Gus Grissom at the Hawaiian tracking station about the qualities of the manual control system.

As he began the third orbit, Schirra disconnected the spacecraft's gyroscopes, turned off part of the electrical power system, and let the capsule drift. He took advantage of this quiet period to test his spatial awareness and motor control, which he found was broadly unaffected by weightlessness, and to eat a light meal. He powered the spacecraft back up over the Indian Ocean, and continued over the Pacific. At Hawaii, he was given clearance for a full six-orbit mission, and as he crossed over towards California shut down the electrical power for a second period of drifting flight, during which he occupied himself taking photographs with the onboard camera.

On the fourth orbit, drifting in an inverted spacecraft with the Earth 'above' him, Schirra continued his photography and attempted—unsuccessfully—to spot the Echo 1 satellite while passing over East Africa. As he approached California, he spoke briefly to John Glenn in a two-minute conversation broadcast live across the United States on radio and television. Problems began to recur with the pressure suit, with water condensing on the faceplate; Schirra, concerned about the internal temperature, avoided opening the visor to clean it for fear that the suit temperature would misbehave again.

By the fifth orbit, Schirra had begun to relax, commenting that it was the first rest he had had since December 1961. He used a small bungee cord exercise device for "a little bit of stretching", before dropping into manual attitude control, where he reported a sudden burst of oversteering and high fuel use. Over the Atlantic he returned to observation and photography; he failed to spot the planned high-power light near Durban, in South Africa, due to cloud cover, but did make out the brightly lit city of Port Elizabeth. Over the Philippines, he reported on his fuel status; after four and a half of the planned six orbits, he still had eighty percent remaining in both manual and automatic fuel tanks. Passing over Quito, Ecuador, towards the end of his fifth orbit, Schirra was asked by the tracking station if he had any message to pass on "in Spanish to the fellows down here", and he made some comments on how beautiful the country appeared from orbit, ending with a cheery "Buenos Dias, y'all!" Schirra later noted that he was "furious" at this point—he was preparing for re-entry and didn't want to be distracted with making public statements.

The sixth orbit was dominated by preparations for re-entry, though Schirra was able to take a last set of photographs of South America and try another set of spatial-orientation tests. He armed the retrorockets passing over the western Pacific, and fired the first one at 8:52 mission elapsed time. The automatic control system held the capsule "steady as a rock" during this period, though after the retrorockets had stopped firing Schirra noted that the system had burned almost a quarter of its fuel in the process.