Oh, space. You're so hard to explore. Sometimes you bombard spacecrafts with hurtling rocks and deadly cosmic rays, and other times you're so empty you don't give astronauts a darn thing to hold on to. But while scientists haven't quite figured out how to keep radiation at bay, the scientists at NASA's Jet Propulsion Laboratory---specifically, its Planetary Robotics Laboratory---are building machines that can get a grip on the most difficult surfaces astronauts will find out there.
Adhesion-wise, space presents a couple problems. First, robots typically struggle with uneven surfaces, let alone the kind of cliffs and crags you see on Mars. Second, space is kind of gravity challenged. "Out in zero gravity, even pushing tape against surfaces is difficult," say Jaakko Karras, a robotics electrical engineer at JPL. Without gravity to anchor your feet to the ground, it's easy to run afoul of Newton's third law. (For every action, there is an equal and opposite reaction. So you'll be pushed away from the wall with the same amount of force you applied to it. Physics!)
And that's not just a problem in microgravity. Low gravity environments, like asteroids or comets, can be uncooperative too. (Just ask the European Space Agency's Philae lander.) "If you got out there and wanted to do some sort of sampling and just started drilling, you’re more likely to spin about the drill bit than the drill bit into the surface," Karras says.
So what's a robot to do? "Nature solves the problems around us all the time," says Karras. "A fairly common path for us is the biomimicry approach." When Karras and his team would test climbing robots out on vertical rock walls, lizards would blaze right past them. But rather than getting annoyed at the speedy little reptiles, Karras decided to take his cues from evolution instead. His team's adhesive makes use of van der Waals forces, which geckos use to climb smooth surfaces. For bumpy ones, his team built claw-inspired microspine grippers that can bend and flex. (You can see them in action in the video up top.)
Both gecko adhesive and microspine grippers are well on their way to scoring a ticket to deep space. Gecko adhesive is already being tested on the International Space Station. Right now, astronauts are using it to anchor things to interior panels, but NASA is considering using it as a replacement for Velcro, which kicks off a lot of dust and bristles---particulates aren't all that welcome in the fragile environment of the ISS. And microspines are a crucial part of NASA's asteroid redirect mission: The little spikes will cover robotic arms used to snatch up an asteroid's boulder and deposit it in orbit around our moon.
Karras also hopes that future missions will use microspines' vertical climbing skills to explore Mars' caves and lava tubes. "They haven't been explored yet because they're difficult from a mobility standpoint," Karras says. "But they may once have been collection points for liquid water, and they're sheltered, low-radiation areas. They're of interest for investigating the possibility of past and present life." So if we find any Martians in the next couple of decades, you have lizards to thank.
