Robot grippers imitate gecko feet to help nab space junk

Get a grip. A new robotic gripping tool can grab floating objects in low gravity. The grippers could one day help robots clean up dangerous space junk or assist them in climbing around the outside of space stations. A new trick for doing this in the absence of gravity: mimicking gecko feet.

Ordinary glue and tape don’t work once you leave the planet. In fact, most adhesives don’t work in space. Glues can’t withstand the wide range of temperatures. And suction doesn’t work, since space is a vacuum.

But a different sticky trick might workt. Geckos are lizards that easily climb walls. Their feet don’t feel sticky. But they cling to surfaces using weak attractions between molecules known as van der Waals forces.

Mark Cutkosky has been working on stickers like this for more than a decade. He designs robots and other devices at Stanford University in California. Now his team has built robotic gripper “hands” inspired by geckos. These hands can grasp objects many times their size without pushing them away. The researchers described their results June 28 in Science Robotics.

The team first tested its grippers in the Robo-Dome. This is like a giant air hockey-table at NASA’s Jet Propulsion Laboratory in nearby Pasadena. One 370-kilogram (815-pound) robot gently pushed another around using a small square of gecko gripper.

Then, last summer, the gecko gripper took flight. Aaron Parness works at of the Jet Propulsion Lab. He and his colleagues tested the full gripper hand aboard NASA’s Weightless Wonder aircraft. This plane flies in steep up-and-down arcs, like a roller coaster. Each time it plunges, the people on board are briefly weightless.

The complete gripper hand has several patches of gripping material in an arrangement that lets them stick to smooth surfaces with just a light touch. Gripper hands could be used to repair or move dead satellites, Parness says. Or gripping parts could help miniature satellites called CubeSats hitch a ride on larger spacecraft.

The team used the hand to grab and release a cube, cylinder and beach ball. These represent some of the different types of junk that now litter outer space. Space junk includes all of the old rocket parts and other no-longer-useful stuff people have launched into space. In all, there may be hundreds of millions of bits — some tiny, others the size of refrigerators. If pieces of this junk collide, they could break into smaller pieces. And even tiny pieces can be dangerous to useful spacecraft or to astronauts on the space station.