While it’s now commonplace for astronauts to prepare for the weightlessness of space by training underwater, in the earliest days of Project Gemini, the norm was aircraft simulations: Trainees would be taken up in a KC-135 Strato-tanker, which would fly a ballistic trajectory, giving the passengers a brief period of freefall.
Of course, no one knew what to expect in real micro-G. When cosmonaut Alexei Leonov —armed with a suicide pill in case things went horribly wrong —first stepped into space from the Voskhod 2 spacecraft on March 18, 1965, he was sweating so profusely that his spacesuit sloshed when he moved.
The first American to perform an extravehicular activity (EVA) was Gemini 4’s Edward White, who on June 3, 1965, made a 36-minute excursion to evaluate the feasibility of spacewalking. Except for wrestling with a jammed spacecraft hatch, things went as planned. No one made another EVA until Gemini 9, when, on June 5, 1966, Gene Cernan exited the spacecraft, using handrails, Velcro pads, and foot restraints to help keep him in place. Even with these devices, Cernan was unable to control his movements, eventually running into an antenna and tearing the outer layers of his spacesuit.
During his second EVA on Gemini 10, Michael Collins let go of the handrail for an instant, causing his body to smack the spaceship’s side so hard that the attitude control system’s thrusters fired in compensation.
It was clear to NASA that EVA training needed to be modified.
The Gemini astronauts had a swimming pool at their disposal — courtesy of the McDonough School of Boys in Baltimore, Maryland — and even though underwater simulations weren’t mandatory, Aldrin made extensive use of the pool.
“I was an experienced scuba diver before beginning astronaut training,” he wrote in 1989, “and it seemed to me that practicing underwater was better preparation for an astronaut’s EVA than with the wire-and-pulley training gadgets that came and went in Houston, but never really worked.”
The underwater training paid off: during Gemini 12 in November 1966, Aldrin made three successful spacewalks. From then on, underwater training was mandatory. And it’s still used today, with astronauts spending hundreds of hours underwater before setting foot in space. “Your first underwater training includes a rite of passage,” says Greg-ory Harbaugh, a former NASA astronaut, veteran spacewalker, and now president and CEO of the Sigma Chi Foundation, which provides scholarships to fraternity members. “It’s called ‘doors and latches training,’ and people don’t do well the first time out. You’re holding a very heavy tool that wants to drop to the bottom of the pool. You’re upside down. It can be very humbling. And I think that’s the goal of EVA training. You can’t be arrogant; you have to know what your capabilities are and what the overall team’s capabilities are.”
Since 1996, astronauts have trained in the Neutral Buoyancy Laboratory at Houston’s Johnson Space Center, which boasts a mammoth tank (202 feet long, 102 feet wide, and 40 feet deep) that took nearly a month to fill. “In the old tank you couldn’t do a whole heck of a lot,” says Harbaugh. “Now you can put an entire spacecraft in there. It’s a quantum leap forward.”