According to the 1950s, we should have jet packs and flying cars by now. Another lost transportation method from yesteryear: jet shoes. In the 1960s, NASA engineers built jet shoes for astronauts, which, in the revised history of everyone’s dreams, could have eventually trickled down to a consumer version.
Jet shoes emerged because engineers and mission planners really didn’t know what kinds of challenges astronauts would be facing in on spacewalks. They just knew astronauts would need a way to maneuver in a vacuum. In 1965, NASA Langley engineer John D. Bird came up with the simple solution of putting jets on their shoes.
Bird drew inspiration from two colleagues, Charles Zimmerman and Paul Hill, whose “Flying Platform” was a proof-of-concept technology that demonstrated humans were pretty good at controlling their direction fo travel with a foot-based propulsion system. It made sense: humans spend a lot of time upright so why not harness this natural orientation for maneuverability in space? As a bonus, a foot-based system would free up the astronauts’ hands for working.
Bird’s jet shoes system was pneumatic and fairly simple. The bulk of the system was external — a backpack served as the storage assembly for the 15 pounds of oxygen pressurized at 6,000 pounds per square inch that would power the jets. The gas would travel through a solenoid valve to the supply line that would bring it to the jet. Each jet would deliver a burst of the compressed gas at two pounds of thrust from each thrust valve nozzle with a pressure of about 165 pounds per square inch. The shoes themselves were to be worn over the astronaut’s boots.
Control came from the internal part of the shoe. Operating switches would be under the ball of the foot with a toe switch that, when depressed, sent a burst of compressed gas to a thruster. It was a far simpler system than the eventually-abandoned mouth-controlled bite bars and sip switches. For directional control, the astronaut would only have to point his feet in the opposite direction that he wanted to travel. It was all pretty intuitive.
Engineers tested the shoes at NASA’s Langley laboratory (some of that footage is in my video) and proved that the concept did help with EVA mobility. But some issues were insurmountable. There was concern that the toe switches wouldn’t be easy to operate in a pressurized space suit, and the externally-mounted system could be unwieldy in practice.
Nevertheless, the jet shoes did return some valuable data that helped engineers design the Manned Manoeuvering Unit shuttle astronauts tested in the 1980s before deciding that they, too, weren’t ideal systems. Sadly not jet packs of any kind have become staples of space flight — at least not yet.
A longer version of this article appears on my former blog at PopSci; I wanted to revisit it for the sake of a video because how neat is this story!