Former NASA astronaut John Glenn, the first American to orbit the Earth, died on Thursday at the age of 95. A pioneer of humanity’s first foray into space, Glenn helped to usher a new vision for the United States as a leader in the world beyond this planet.

Glenn’s legacy extends beyond his monumental 1962 orbit around Earth. In addition to serving as a U.S. Senator from Ohio for 24 years, and later becoming the oldest person to fly into space (at age 77, in 1998), Glenn was a lifelong advocate of NASA and the push to open spaceflight to far bigger ambitions.

Glenn, the last surviving member of the Mercury Program, was something of a guinea pig when it came to human spaceflight. The United States, already lagging behind the Soviet Union when it came to the space race, was still figuring out exactly how to train its astronauts and prepare them for the rigors of a rocket launch and life in microgravity.

One of those new training apparatuses infamously stuck with Glenn — the Gimbal Rig.

“I guess you could call it the weirdest training we ever did,” Glenn said in a NASA Glenn Research Center video posted to YouTube in February.

There’s no air flowing around in space. It’s an endless vacuum. Controlling a vehicle in space requires a finessed control that is unlike anything experienced on Earth. Instruments onboard the early Mercury spacecraft helped measure the roll, pitch, and yaw. But any good pilot knows a thousand things can go wrong in the air — and any good astronaut knows a million things can go wrong in space.

story continues below

“There was a big question about what if you had a runaway control system say ‘in yaw’, or ‘in pitch?’” Glenn explained. If your spacecraft was tumbling in a single way uncontrollably, what then? “Would you be able to control it?”

That gave rise to the Gimbal Rig — a multiple-axis structure meant to simulate tumbling maneuvers that could be experienced in spaceflight. The Gimbal Rig could spin indefinitely in any or all of the three axes you would have to control if you were in a spacecraft. The astronaut-in-training sitting in a cockpit-like chair in the middle would be subjected to a wild combination of spins in a variety of speeds — and be tasked with wrestling control over those axes and forcing the roll, pitch, and yaw to revert back to zero.

“If you can imagine,” said Glenn, “you’re doing 30 rpm in pitch and in roll and in yaw — all at the same time — and then there you sit, watching your instruments, and you bring this rate back to zero. And we could do that.”

story continues below

“That Gimbal Ring,” Glenn reminisces, “that was one of the more demanding tests or training exercises we went through anywhere in the whole training floor for spaceflight. We really hated that Gimbal Rig!”

Photos via NASA/YouTube