Animal IQ

This Gecko-Inspired Robot Gripper Could Someday Clean Up Space Junk

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Earth has a space junk problem. More than half a million pieces of debris float in orbit around our planet, any of which could collide with a satellite or spacecraft and cause real damage. Unfortunately, we don't have a reliable way to capture the junk and move it to a more distant orbit where it won't cause harm. Now, Stanford and NASA researchers have developed a robotic device to do just that, inspired by the sticky feet of the gecko.

Close up of the robotic gripper made by the Cutkosky lab at Stanford University. The gripper is designed to grab objects in zero gravity using their gecko-inspired adhesive.

Get A Grip

Pop quiz: there's a piece of glass floating through space, and you want to catch it so it doesn't run into any expensive equipment. What do you use? Sending an astronaut out to capture it doesn't make a lot of sense, since debris moves ridiculously fast and anyway, human arms aren't that long. You could use a robot arm, but clumsy robot pinchers are likely to slip and lose their grip. It's glass, so you can't use magnets. Glue, tape, and other adhesives don't work in the punishing cold of space. Neither do suction cups, which don't work in a vacuum. See the problem?

That's what led the researchers toward the gecko. Geckos can scale vertical surfaces and even travel upside down, thanks to the hundreds of nanoscale hairs that line each of their toes. The hairs are so tiny that they actually interact with the atoms on a surface, creating molecular attractions known as van der Waals forces. You guessed it: those forces work in space.

This image shows the underside of the gripper. The squares of the gecko-inspired adhesive are glowing as they grip a piece of glass that is lit purple.

Gecko Robots In Space!

In a study published in Science Robotics, the researchers lay out exactly how their robotic device works. The gripper uses pads lined with silicone rubber hairs only 20 microns in diameter, which is thicker than those on gecko feet but still a fifth the diameter of a human hair. When the gripper approaches an object it wants to snag, motors inside pull "tendons" that point the pads in the direction required to grip the surface. When the gripper needs to let go, the motors loosen those tendons and move the pads in the opposite direction — the same way a gecko loosens its grip.

The device has already been tested in conditions similar to those of outer space: the hairs themselves demonstrated that they worked in microgravity aboard the ISS in 2016, and the robot itself worked brilliantly aboard a zero-gravity simulation flight. Now the researchers just need to prove that their device works in the frigid temperatures of space. Or we need to make tiny space suits for an army of astro-geckos. One or the other.

Crazy Engineering: Gecko Gripper

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