On the final day of America’s last Mercury mission, the spacecraft’s brain went dark. One by one, the systems that were supposed to steer Faith 7 home failed. Gordon Cooper, alone in a capsule barely bigger than a telephone box, lined it up by eye, timed the most important burn of the flight on his wristwatch and landed closer to his recovery ship than any American astronaut before him.

A post doing the rounds on Instagram tells the story well. The main points are right. A few details deserve a closer look, starting with which light came on and what it actually meant.

One More Mercury Flight

Faith 7 almost did not fly. Wally Schirra’s Mercury-Atlas 8 flight in October 1962 had gone so well that some at NASA wanted to stop there and move on to Gemini. The Manned Spacecraft Center argued for one more mission to keep an American in orbit for a full day. Every Soviet Vostok flight after Gagarin’s had already lasted longer than that.

McDonnell modified the capsule for the long flight, removing the periscope and a redundant set of thrusters and adding batteries and oxygen. At over 3,000 lb it was the heaviest Mercury spacecraft. Cooper, an Air Force test pilot and the youngest of the Mercury Seven, named it Faith 7 for the faith he had in the Atlas rocket and the capsule. Not everyone at NASA liked the name.

After a scrub on 14 May, Faith 7 lifted off at 8:04 a.m. on 15 May 1963. The Atlas put it into a good orbit, and for the next 30 hours the flight went almost to plan. Cooper ran experiments, photographed the Himalayas and Tibet, slept in short stretches, sent back the first television pictures from an American spacecraft, and on his seventh orbit passed Schirra’s record for the longest American spaceflight.

Things Start to Stack Up

The trouble began on the 19th orbit. A light on the instrument panel marked 0.05 g came on. It was meant to tell the astronaut that the capsule had started to slow down in the atmosphere at the start of reentry, which was plainly not happening. The Instagram caption describes this as a warning about the automatic control system. It was not quite that: the light itself was a faulty indication. But it was the first sign that the spacecraft’s electrics were going wrong.

On the 20th orbit Cooper lost all his attitude readings. On the 21st a short circuit in the bus bar serving the main 250 VA inverter cut power to the automatic stabilisation and control system, the equipment that would normally have held the capsule at the right angle for retrofire and reentry. At the same time the carbon dioxide level was rising in the cabin and in his suit. Passing over Zanzibar, he summed it up for fellow astronaut Scott Carpenter.

Lines on the Window, a Watch on the Wrist

The retrofire had to be right. Fire the three retrorockets too early or too late and the capsule would come down far from the recovery force; fire them with the capsule pointing the wrong way and it could miss the narrow corridor through the atmosphere altogether. Without the automatic system, Cooper would have to hold the attitude himself with the hand controller and fire the rockets on cue.

He was not working entirely alone. John Glenn, the first American to orbit the Earth, was the capsule communicator on the tracking ship Coastal Sentry Quebec near Japan. On the 21st orbit Glenn helped Cooper work through a revised retrofire checklist, with many of the steps now done by hand. At the end of the 21st orbit Cooper reported that Faith 7 was in retro attitude and holding manually. Glenn counted down from ten.

Cooper had drawn lines on his window to keep the capsule lined up against the stars and the horizon. He held it at a 34-degree nose-down pitch and fired the retrorockets on Glenn’s “Mark!”. He later said he used his wristwatch to time the burn and his eyes to hold the attitude. He then flew the capsule through reentry himself.

Four Miles From the Carrier

Fifteen minutes after retrofire, Faith 7 splashed down about 70 nautical miles south-east of Midway Island, roughly four miles from the prime recovery ship, the aircraft carrier USS Kearsarge. It was the most accurate landing of the Mercury programme, made without the automatic system that was supposed to do the job. The capsule briefly tipped over in the water, then righted itself. Cooper asked, as an Air Force officer, for permission to be hoisted aboard the Navy carrier, and about forty minutes later blew the hatch on Kearsarge’s deck.

Doctors found him slightly dehydrated and a little light-headed after more than a day sitting in the capsule, but otherwise fine. President Kennedy presented him with the NASA Distinguished Service Medal at the White House on 21 May, and New York gave him a ticker-tape parade the next day. A proposed three-day Mercury-Atlas 10 flight was dropped, and NASA moved on to Gemini. Cooper flew again in 1965 as commander of Gemini 5.

What the Viral Post Gets Right and Wrong

The caption gets the essentials right. The launch date, the 22 orbits, the duration of more than 34 hours, the electrical failures, the manual alignment using the window and the stars, the wristwatch, the help from the ground and the splashdown about four miles from Kearsarge all check out. So does the claim that this was the longest American spaceflight at the time.

Two points need care. The warning light that started it all was the 0.05 g indicator, and it was a false reading rather than a warning about the control system; the real failures came over the next two orbits. And “the last time a NASA astronaut flew alone” is right in the sense that matters: Faith 7 was the last time an American was launched alone on an entirely solo orbital mission. Apollo command module pilots later spent long stretches alone in lunar orbit, but never on a solo flight.

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Sources: NASA History Office, Project Mercury records and Mercury-Atlas 9 air-to-ground voice transcription; NASA SP-4201, This New Ocean; Wikipedia, Mercury-Atlas 9; Smithsonian National Air and Space Museum; Space Center Houston.