Moon mission astronauts spent a lot of time on their butts. Those moon walks may have looked bouncy and peaceful, but cumbersome space suits had Apollo astronauts tripping and falling all over the place. And while it might seem silly—especially the aftermath, which looks like a kid trying to stand up in a bulky snowsuit—it's actually pretty dangerous for one of those suits to meet a shard of lunar regolith. That goes double for astronauts exploring Mars, where stronger gravity would mean falling twice as hard onto rocky ground far less forgiving than moon dust.

So to make sure that doesn't happen, Alison Gibson, graduate researcher at MIT's Man Vehicle Lab, is testing some newfangled space boots.

Since NASA isn't doing manned moon missions at the moment, astronauts wear soft boots that aren't made for walking at all—just floating around outside the International Space Station. Those ones are totally rigid below the knee. But even the relatively bendy moon boots won't cut it anymore. Spacesuit helmets cut astronauts' peripheral vision to basically nil, and pressurized boots are no good at feeling for obstacles. So to stay upright, astronauts spend a lot of time looking down at the ground, which isn't super conducive to science.

But how do you design a system that lets astronauts keep their heads up? "Having tactile cues on you feet is pretty intuitive," Gibson says. "On Earth that's what give us a clue to look down." That's why she designed each boot with two vibrating motors to buzz your big toe as you approach an obstacle. The vibrations ramp up as the boot gets closer and closer, and little orange dots on the boot's visual display become more opaque. And they're pretty maneuverable: Thanks to cheap 3-D printed bases, the boots weigh only a pound each.

Gibson collected motion capture data from 16 participants who strapped on the prototypes, and those tests suggest people spend significantly less time heads-down while wearing the boots. Oh, and they fall less, too. And while she emphasizes that these boots are still prototypes—to qualify for flight, they'd need souped-up sensors and materials that don't give off gases that could mess with the space suit—Gibson is optimistic. "NASA wants totally new EVA suits for Mars," she says, "and I think these could be incorporated into that space suit eventually."

That's a long way off—NASA doesn't expect to even put humans in orbit around Mars until the 2030s—but these boots are exactly the kind of Occam's Razor you need in space. "The astronaut teams on Mars are going to have to be relatively autonomous, since they're not going to have real-time communication with the ground," Gibson says. Whatever the obstacle avoidance tech ends up being, it needs to be simple, robust, and reliable. There's not much NASA can do if an astronaut sends an 'I've fallen and I can't get up' message.