On May 24, 1962, NASA narrowly escaped its first fatality in space. When Scott Carpenter reentered the atmosphere at the end of his Aurora 7 orbital flight, no one in mission control knew where he was going to land. They didn’t even know whether he’d be dead or alive when they found him.
Problems with Aurora 7’s internal guidance system dogged the flight. The gyroscopes couldn’t determine the capsule’s attitude and were sending the onboard computer false information. The automatic control system was stuck in a loop, trying to correct the error to no avail and burning through fuel in the process. But the guidance error was only part of the problem. Another was the man inside the capsule.
Flight director Chris Kraft considered Carpenter to be the least qualified of all Mercury astronauts; his performance in a training exercise the year before had revealed how little he understood of the business of spaceflight. Carpenter had been assigned the role of capcom to Alan Shepard on his Freedom 7 flight. Running though simulations before the mission, Carpenter had revealed his “shallow” understanding of the Mercury capsule and its procedures. In simulation after simulation, he sat at the console flipping switches seemingly at random, often time not realizing the simulated launch had been aborted. Kraft couldn’t in good conscience let the astronaut be Shepard’s link to the ground on such an important mission; the next day Deke Slayton was running through simulations with ease from the capcom console. But now, Kraft had Carpenter in orbit.
The last piece of the puzzle that condemned Aurora 7 was the Mercury control system. The Mercury capsule gave astronauts no control save attitudinal, which they achieved through two paths. The primary automatic control and stability system (ASCS) that had 12 thrusters feeding off of 32 pounds of fuel, and the secondary manual system that used 6 thrusters feeding off 23 pounds of fuel. The systems worked separately unless the astronaut forcibly overrode the ASCS, an incredibly fuel-intensive control method called fly-by-wire.
Aurora 7’s ASCS engaged once the capsule reached orbit. Almost immediately Carpenter switched fly-by wire and fell victim to the beauty of the Earth unfolding beneath him. He started twisting the capsule around for better views, calling down to mission control with descriptions of the beautiful whirls and vortices of clouds instead of his booster rocket’s position against the Earth. He used such significant amounts of fuel twisting around to get better views of the Earth that after one orbit he was down to 51 and 69 percent in his automatic and manual fuel stores respectively.
This was worrying so early in the mission. It raised a red flag to both Kraft and Aurora 7’s computer. Kraft told Carpenter to make an effort to conserve his fuel on the next orbit. The onboard computer illuminated a low fuel warning light that Carpenter covered over with a piece of tape.
During his second orbit, Carpenter made little effort to conserve fuel but kept up the poetic descriptions. At one point he released a balloon as part of an experiment to test drag and his own ability to judge distance in space. He told mission control that the balloon seemed to wander back and forth outside his window with abandon.
By the time he started his third and final orbit, the fuel situation had gotten much worse. Houston gave him a magic number: 40. As long as he had 40 percent of his fuel in both systems he would be fine for retrofire, reentry, and descent. Any less could make it impossible to correct his attitude and fire his retrorocket for reentry and leave him stuck in orbit or leave him to tumble through the atmosphere and burn up. Either scenario would be fatal. It would be a very bad day for NASA.
All the problems on the flight compounded in the final minutes before reentry. The faulty guidance system meant the computer couldn’t align Aurora 7 for retrofire forcing Carpenter to take over manually. But whether he could manage the task was anyone’s guess. Kraft was so worried he’d miss a step that he called he called Shepard, capcom at the California tracking station, and told him to talk Carpenter through manual realignment and retrofire. Kraft told Shepard he was the last hope to get Carpenter squared away.
Shepard did his job, but Carpenter’s reentry was far from optimal. He fired his retros late after letting his attitude slip. At the last second, his capsule twisted and entered the atmosphere at an angle. To make matters worse, he only had 20 and 5 percent in his automatic and manual fuel stores respectively. It wasn’t enough to keep him steady throughout his descent.
Aurora 7 started oscillating, then tumbling, as it reentered the atmosphere. Once Carpenter deployed his parachute, it acting like an anchor point underneath which the capsule’s tumbling turned into a wide swing. Inside the capsule he could feel the rhythmic increase and decrease in g forces. At one point, the telemetry later revealed, the capsule swung higher than the chutes.
Meanwhile mission control was in chaos as controllers tried desperately to regain contact with Carpenter. Retrofire engineer John Llewellyn couldn’t do his job of tracking the capsule’s trajectory to splashdown. He effectively lost Aurora 7 after its last minute twist before reentry. He knew Carpenter was going to land long, but didn’t know how long. Without some idea, he couldn’t send recovery forces out to meet the astronaut. The thought of Carpenter landing in some remote location completely cut off from NASA was making him sweat so much his headset slipped off every time he turned his head. Surveying the room from his vantage point in the back, Kraft was silently furious.
Carpenter had landed safely 250 miles downrange from his intended impact point. There were no recovery forces where he landed; none even close to him. Gus Grissom serving as capcom in mission control radioed to Carpenter that he had at least an hour’s wait in front of him and urged his colleague to sit tight. But he didn’t. The cabin was cramped and hot after reentry and Carpenter decided to wait outside. He pushed the parachute pack out of the neck of the capsule and squirmed his way out, emergency life raft in hand. He plunked down into the Atlantic, untroubled at being alone and exposed, and waited. It was a calm day, perfect for quiet reflection.
It was three hours before recovery crews arrived to pull Carpenter from the ocean. First planes arrived and circled the small raft like hawks, then divers joined him in the water. When a pair swam up to the astronaut, he offered them some food from his survival pack but they declined.
Carpenter’s good mood ebbed on his trip back to NASA as he realized he was responsible for the mission’s nearly fatal end. Back on land, he came face to face with Administrator James Webb. Carpenter admitted his fault and promised to take full responsibility at the press conference; Webb told him he would do no such thing. America needed a hero and they were getting one. Carpenter was ordered to blame faulty machinery for the problems during his missions.
Carpenter’s reprieve was limited to his public appearance; the mission debriefing was far less kind. Carpenter was heavily criticized for making unnecessary attitude adjustments for the sake of a good view, an action that led the Mercury capsule’s designer Max Faget to call him more of a poet than a good test pilot. Llewellyn was horrified at how close he’d come to losing an astronaut during reentry and vowed to never let it happen again. Within months he had developed an auxiliary computer unit that allowed him to override all retrofire functions in the spacecraft from his own console.
Kraft was livid, not only with Carpenter’s poor performance but that he had ignored instructions to conserve fuel and check his guidance instrumentation throughout the mission. He vowed that as long as he held any sway with the agency Carpenter would never fly again. He didn’t. Carpenter took a leave of absence from the astronaut corps in 1963 before finally retiring in 1967.
Whether Carpenter was truly at fault for the nearly fatal end to his mission has been debated, though it’s not hard to see how he was at the very least a contributing factor. The mission certainly did little to soothe the tension between the engineers and astronauts that dominated the Mercury program, not to mention did nothing to advance the astronauts’ case in their fight to gain control in space. The other Mercury astronauts, with the exception of John Glenn, nicknamed Carpenter’s flight “Stigma 7″ for the shadow they felt it cast on their collective reputations within mission control. They agreed to support one another in erasing this stigma on the remaining two Mercury flight, proving they deserved a more central role in the upcoming Gemini and Apollo programs.
Wally Schirra’s Sigma 7 flight did just that in October 1962. He flew a perfect mission, landing on point with more than half his fuel on board. The flight marked the beginning of the thaw between astronauts and engineers.
Scott Carpenter and Kris Stover. For Spacious Skies: The Uncommon Journey of a Mercury Astronaut. Harcourt: Orlando. 2002.
Scott Carpenter et al. We Seven: by the Astronauts themselves. Simon and Shuster: New York. 1962.
Chris Kraft. Flight: My Life in Mission Control. Plume: New York. 2001.
Gene Kranz. Failure is Not an Option: Mission Control for Mercury to Apollo 13 and Beyond. Berkley Books: New York. 2000.