 You know that scene at the end of the Martian where Matt Damon pokes a hole in his glove and uses the force of the escaping gas to rendezvous with his crew like his Iron Man? NASA considered something similar, but properly, i.e. not with a hole in a suit, but using jet shoes. Jet shoes were almost a thing we saw during the early space age. Two, one, we have a lift of 32 minutes. Hi everyone, I'm Amy, welcome to The Vintage Space, my little corner of the internet where we talk about all things old and tech that fascinate me, many of which happened to be in space. And this unrealized concept for jet shoes definitely fits that bill. In the early years of human space exploration, there were a lot of unknowns, and the list of questions got longer as mission goals got more sophisticated. Getting a human into orbit was one thing, but when NASA started figuring out how to have him step outside, for a working spacewalk, there were new challenges that needed solutions. Namely, how would he maneuver around in a vacuum? Actually getting an astronaut outside was one thing, the spacesuit would be a wearable spacecraft of sorts with all the life support he needed. But to work, he'd need to be able to move around the spacecraft and perform complex tasks. Contrary to cartoons of the era, you can't actually make swimming motions and move in a vacuum. There's no air to push against, so you can't paddle like you're in water. You need a source of propulsion. A group of engineers at NASA's Langley Research Center, led by John D. Bird, came up with a simple, propulsive solution, jet shoes. Bird took inspiration from another early mobility concept, the flying platform, developed by his colleagues Charles Zimmerman and Paul Hill. This proof-of-concept device was designed to take advantage of our natural, upright posture. Humans are really good at standing up and making micro-adjustments while walking or running to maintain that upright posture. Zimmerman and Hill figure that an astronaut standing on a propulsive board would be able to stay upright. It was never developed, but early studies proved humans can maneuver with foot-based propulsion. The added benefit was that with the propulsion being at the feet, the astronaut's hands could be free for work. Bird's system worked on the same basic principle as the flying platform. His was a pneumatic design, with the bulk of the system being external. 15 pounds of gas's oxygen pressurized at 6,000 pounds per square inch was stored in a backpack worn by the astronaut. That gas fed into the jet-powered boots worn over the space suit that delivered two pounds of thrust from each thrust valve nozzle, with a pressure of about 165 pounds per square inch. The nozzle came from a toe-activated switch inside the boot against the bare skin. The device sat under the ball of the foot. The astronaut would turn on a specific jet under a boot by pressing the switch with his big toe, and turn off the switch by lifting his toe up. Controlling his movement was as simple as controlling his body. If you imagine an astronaut standing upright in space, even though there isn't really an up and down in space, the thrust from the shoes going straight down would send him straight up. To move at an angle or sideways, the astronaut just had to move his legs to redirect that thrust. The jet shoes went through a series of tests at Langley. One test had a subject suspended from a pendulum-type system from the ceiling. Another used a whippletree suspension setup to practice translational and rotation movements. Still another test used the overhead dolly from Langley's rendezvous and docking simulator to create a translating suspension system. The final test setup used an air-bearing facility that had the test subject effectively moving like a puck on an air hockey table. All in all, testing proved the jet shoes were viable for EVA mobility. But the tests were limited. Each setup had the subject lying on his side and only gave him three degrees of freedom in a horizontal plane, pitching for an aft and head-to-foot movement. No test was able to truly simulate the six degrees of freedom an astronaut would have in space. Initially the system was interesting because it promised to be lighter, cheaper, and more reliable than other options of similar systems. But further research raised practical questions like whether the toe switch would work in a pressurized spacesuit. If the suit expanded during an EVA and the astronaut couldn't put pressure on the switch, he'd be stuck and in real trouble. There was also an issue of weight. The whole system ended up being pretty heavy for how minimal it was. And the backpack could be cumbersome. NASA worried that the ease of the system might be offset by these challenges. The idea lived on. NASA tested the foot-controlled maneuvering unit during the second and third Skylab missions in the early 1970s. These Skylab experiments saw the mission commanders Al Bean and Jerry Carr, as well as backup commander Vance Brand, trained to use the system on Earth before testing it out in Skylab's orbital workshop. Though only being in car flu, so only they have the chance to actually test it in space. The unit for these tests was a post that fit between the astronauts' legs that held the foot-mounted thrusters worn over the feet. The thrusters were operated by a mechanical link to foot pedals the astronaut could step on to activate. And the gas that fed the thrusters came from a separate tank that was part of a backpack assembly, which also held the battery. The idea was that wearing this heaviest part of the system would have the least effect on the astronauts' balance while using the system. And like Bird's earlier design, the whole setup was meant to keep the astronauts hands free for work. The system didn't include any kind of gyro or power subsystem for attitude stabilization and control. Again, the idea was to use the human ability to adjust their own body for stability. The thruster setup was comprised of two sets of four small thrusters. Two were mounted in opposite directions aligned with the four aft or x-axis of the body. When firing, these generated 0.3 pounds of thrust by the ankle moving in a toe-up or toe-down direction for pitch and yaw control. The other thrusters were set in the opposite direction, aligned with the up and down or z-axis of the body. They were a little more powerful, producing one pound of thrust. The test had the subject do a series of pre-planned, then freestyle maneuvers in the center of the workshop. He was meant to start about six feet above the base of the lab and seven and a half feet from the center line of the spacecraft. A second astronaut would be on hand for assistance, positioning the test subject at the start and retrieving him at the end of the run. It was clear the system, at least for the moment, needed a bit of a helping hand. These in-orbit tests were the same as those done pre-launch in simulators, though, of course, the air-bearing simulators and visual task simulators couldn't completely mimic the true six degrees of freedom an astronaut has in orbit. The first three moves were basic attitude, control, and pitch, yaw, and roll to test the astronaut's ability to change his orientation relative to a given reference axis while maintaining that orientation against the other axes. Then there was a translational Z-reference-axis test. The last two maneuvers were a double-axis and dog leg moves that had him change attitude and direction while translating from one location to another. A separate test had him a recover from a spin wherein he was tumbling around all three axes. Then came the freestyle maneuvers, a test of how easily he could move from one spot to another, however he felt most comfortable. The test didn't go as planned for a myriad of reasons. In the end, there were only five sessions, three by being and two by car. Both were meant to do tests in a shirt sleeve setup and then a suited setup, but only being ended up doing the tests in a suit. The test sessions lasted between four and five hours each but only 20 or 30 minutes was actually spent maneuvering. In total, both missions did just 140 minutes of actual foot-controlled testing, only 22 of which were done in a suit, as would be the case on an EVA. And the results were mixed. Albion had a lot of problems with the harness that kept the backpack and the whole system in place. The straps were too loose, allowing the assembly to wobble. Tightening them helped, but was extremely uncomfortable and pulled him into a backwards leaning position that restricted his view down his own body. During the suited tests, Bean found the suit legs moved forward, giving the booths a tendency to disengage from the pedals because of a quick release feature built into the system. All in all, he performed 16 maneuvers. Car wasn't as well prepared for his tests. He'd had less time to go through familiarization with the system. He had some problems coordinating his foot and ankle movements while performing a total of 12 maneuvers. But by and large, the tests were successful, though both Bean and Car wobbled around a lot and had their share of problems. Bean had initially thought the foot-controlled system would be great, but found that it wasn't precise and ultimately didn't think it was worth pursuing. He thought it was less useful and usable than an equivalent manual system. Car disagreed. He thought the foot controls were a very useful feature. It was clear personal preference was a big deciding factor. Nevertheless, both astronauts agreed the logic of inputs was fine, but it would need some kind of attitude stabilization system if it were to go through further testing. Though in-flight testing proved the foot-based system could be viable, we know NASA went in another direction, briefly pursuing the MMU or Manned Maneuvering Unit Jetpack that gave us this amazing shot of Bruce McCandless taking himself far away from the orbiter. I've always thought this was a super fun tech that never really went anywhere, so I hope you guys enjoyed this little look into jet shoes as well. That is going to do it for me for today. I wanna remind you guys that both of my books, Fighting for Space and Breaking the Chains of Gravity, are available however you like to consume books. I've got links for both in the description below. And I also want to give a very, very special thank you to all my Patreon supporters and YouTube members. You guys truly make these videos possible. 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