More than half a century ago, on 20 February 1962, America’s first citizen to orbit the Earth thundered into space atop an Atlas rocket. Inside a cone-shaped Mercury capsule—which his children had nicknamed “Friendship 7″—astronaut John Glenn felt the peculiar sensation that the first few seconds of ascent from Cape Canaveral were incredibly slow. “The Atlas’ thrust was barely enough to overcome its weight,” he wrote in John Glenn: A Memoir. “I wasn’t really off until the umbilical cord that took electrical communications to the base of the rocket pulled loose. That was my last connection with Earth. It took the two boosters and the sustainer engine three seconds of fire and thunder to lift the thing that far. From where I sat, the rise seemed ponderous and stately, as if the rocket were an elephant trying to become a ballerina.” For the first few seconds, the Atlas climbed straight up, before its automatic guidance system placed it carefully onto a north-easterly heading; a transition which Glenn found noticeably “bumpy.” The bumpiness of the flight would be unrestricted to the ascent phase, for in orbit and during re-entry Glenn’s mission would be full of drama.
By 9:52 a.m., according to the operations team in their flight logs, the mission was “through the gates” and Glenn was in orbit. It was barely five minutes since liftoff.
Although he was able to describe the magnificent views he was seeing, it was on this mission that the rest of the world was also able to capture something of the grandeur of Earth—thanks to a camera. Glenn had considered this idea some months earlier and started searching for an appropriate device: small enough to operate with one hand, yet adaptable, so that he could advance the film with his thumb and snap the shutter with his forefinger whilst encased in a pressure suit. The search achieved little success. Then, one day, whilst getting a haircut in Cocoa Beach, Glenn saw a little Minolta camera in a display case. The camera, he noted, had automatic exposure; he would have no need to fiddle with light meters and f-stops. He bought it for $45. NASA technicians adapted it for the spacecraft and Glenn found that it was the easiest camera to use, even wearing his pressure suit gloves. It would yield some of the most amazing images of the entire mission.
Five minutes after launch, as planned, Glenn achieved orbital speed of 28,200 km/h and an altitude of some 160 km, and—for the first time—he experienced the strange state of weightlessness. “Zero-G and I feel fine,” he exulted. “Capsule is turning around,” he added as Friendship 7 slowly swung around into the re-entry attitude. “Oh, that view is tremendous!” he exclaimed as the horizon appeared in the window and he caught his first sight of the curvature of the Earth and the fragile atmosphere.
At length, Friendship 7 oriented itself into its “normal” operating position, with its blunt end facing into the direction of travel, flying eastwards. Looking back, Glenn could clearly see the spent Atlas making slow pirouettes as it tumbled away. At first, the parameters of his trajectory were so good that he was given a go-ahead by Capcom Al Shepard for “at least seven orbits.” With all systems running as expected, Friendship 7 crossed the Atlantic and passed over the Canary Islands.
Glenn’s first tasks involved checking the spacecraft’s roll, pitch, and yaw attitude controls in case an emergency re-entry became necessary. At 9:59 a.m., he crossed the coast of western Africa—“a fast transatlantic flight,” he later wrote—and felt one of his earliest sensations of weightlessness: a grey-felt toy mouse, pink-eared, with a long tail, drifted from an equipment pouch. After quickly checking his blood pressure for the Canaries ground station, Glenn turned his attention to photographing selected spots on Earth’s surface. One of the first was a patch of cloud covering the Canaries, followed by shots of enormous dust storms brewing over the Sahara Desert. Next came further checks of his attitude controls, which were “well within limits,” followed by exertion tests with a bungee cord attached beneath the instrument panel and then reading the vision chart at eye-level. Glenn’s vision, it seemed, was not changing. Head movements, too, did not cause him any disorientation, “indicating,” he wrote later, “that zero-G didn’t attack the balance mechanism of the inner ear.”
Forty minutes into the mission, Friendship 7 drifted into darkness as Glenn approached his 240 km apogee. A sunset from space was one of the features of the flight about which he was most excited. “Above” him, the sky was absolutely black, although he could see stars, successfully identifying the Pleiades cluster. Then, as Friendship 7 passed directly over Perth and Rockingham, in Australia, Capcom Gordo Cooper asked him if he could see lights. “I can see the outline of a town,” he replied, “and a very bright light just to the south of it.” Glenn thanked the residents of Perth for turning on their lights to greet him.
Travelling over the South Pacific, close to the tiny coral atoll of Canton Island, midway between Fiji and Hawaii, the astronaut lifted his visor and ate: squeezing some apple sauce from a toothpaste-like tube into his mouth and gobbling some malt tablets. As he approached orbital sunrise, Glenn was surprised to see around the capsule a huge field of particles, like thousands of swirling fireflies. “They were greenish-yellow in colour,” he said later, “and they appeared to be about six to ten feet apart. I seemed to be passing through them at a speed of three to five miles an hour. They were all around me and those nearest the capsule would occasionally move across the window, as if I had slightly interrupted their flow.” The particles diminished in number as he flew eastwards into brighter sunlight. Scott Carpenter, who flew in May 1962, would also see them and they would be attributed to more than ice crystals venting from Friendship 7’s heat exchanger.
Meanwhile, Glenn continued putting his capsule through its paces. It was shortly after passing the two-hour mark of the mission, however, that he received an unusual request from Mission Control: to keep the switch for Friendship 7’s landing bag in the Off position. He confirmed that the switch was indeed off and pressed on with his work. Later, Gordo Cooper asked him to confirm it again. Then, during another pass over Canton Island, Glenn overheard an indication from a flight controller that his landing bag—located between the base of the spacecraft and the heat shield—might have accidentally deployed. He queried Mercury Control and was assured that the ground was monitoring the situation. Glenn began to suspect that the fireflies might be related to some shifting of his heat shield.
As early as the second orbit, telemetry engineer William Saunders noted that “Segment 51″—an instrument providing data on the landing system—was generating unusual readings, and Mercury Control instructed all tracking sites to monitor it carefully. A little over four hours into the flight, however, it became clear that the landing bag might be deployed or, at least, not securely locked into position. Whilst over Hawaii, the capcom informed Glenn that the signal was probably erroneous, but, to be sure, asked him to set the landing bag switch in its “auto” position. “Now, for the first time, I knew why they had been asking about the landing bag,” Glenn wrote in his memoir. “They did think it might have been activated, meaning that the heat shield was unlatched. Nothing was flapping around. The package of retrorockets that would slow the capsule for re-entry was strapped over the heat shield. But it would jettison and what then? If the heat shield dropped out of place, I could be incinerated on re-entry.”
If the green landing bag light came on, Glenn wrote, it would clarify that it had indeed accidentally deployed. However, “if it hadn’t, and there was something wrong with the circuits, flipping the switch to automatic might create the disaster we had feared.” He flipped the switch.
No light came on.
This suggested that the landing bag was secure. As retrofire approached, Capcom Wally Schirra, based at Point Arguello in California, told Glenn not to jettison his retrorocket package at least throughout his passage across Texas. It marked the first of several efforts to ensure that, if the heat shield had been loosened, the retrorocket package might hold it in place just long enough to survive the hottest part of re-entry.
Six minutes before retrofire, Glenn duly manoeuvred Friendship 7 into a 14-degree, nose-up attitude. At 2:20 p.m. EST, the first retrorocket fired, causing a dramatic braking effect on the capsule and making him feel momentarily as if he was flying backwards, towards Hawaii. The second and third retrorocket firings came at five-second intervals, slowing the capsule sufficiently to drop it out of orbit. Once again, Schirra repeated, “Keep your retro pack on until you pass Texas.” The tension at Mission Control was palpable. “I looked around the room,” wrote Procedures Officer Gene Kranz in his autobiography, Failure is Not an Option, “and saw faces drained of blood. John Glenn’s life was in peril.”
The concluding part of this article will appear next weekend.