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Space debrisRobotic gripper to help clean up space debris

Published 10 July 2017

Right now, about 500,000 pieces of human-made debris are whizzing around space, orbiting our planet at speeds up to 17,500 miles per hour. This debris poses a threat to satellites, space vehicles and astronauts aboard those vehicles. Researchers combined gecko-inspired adhesives and a custom robotic gripper to create a device for grabbing space debris. They tested their gripper in multiple zero gravity settings, including the International Space Station.

Right now, about 500,000 pieces of human-made debris are whizzing around space, orbiting our planet at speeds up to 17,500 miles per hour. This debris poses a threat to satellites, space vehicles and astronauts aboard those vehicles.

What makes tidying up especially challenging is that the debris exists in space. Suction cups don’t work in a vacuum. Traditional sticky substances, like tape, are largely useless because the chemicals they rely on can’t withstand the extreme temperature swings. Magnets only work on objects that are magnetic. Most proposed solutions, including debris harpoons, either require or cause forceful interaction with the debris, which could push those objects in unintended, unpredictable directions.

To tackle the mess, researchers from Stanford University and NASA’s Jet Propulsion Laboratory (JPL) have designed a new kind of robotic gripper to grab and dispose of the debris, featured in the June 27 issue of Science Robotics.

“What we’ve developed is a gripper that uses gecko-inspired adhesives,” said Mark Cutkosky, professor of mechanical engineering and senior author of the paper. “It’s an outgrowth of work we started about 10 years ago on climbing robots that used adhesives inspired by how geckos stick to walls.”

The group tested their gripper, and smaller versions, in their lab and in multiple zero gravity experimental spaces, including the International Space Station. Promising results from those early tests have led the researchers to wonder how their grippers would fare outside the station, a likely next step.

“There are many missions that would benefit from this, like rendezvous and docking and orbital debris mitigation,” said Aaron Parness, MS ’06, PhD ’10, group leader of the Extreme Environment Robotics Group at JPL. “We could also eventually develop a climbing robot assistant that could crawl around on the spacecraft, doing repairs, filming and checking for defects.”

Creating a gecko gripper
Stanford says that the adhesives developed by the Cutkosky lab have previously been used in climbing robots and even a system that allowed humans to climb up certain surfaces. They were inspired by geckos, which can climb walls because their feet have microscopic flaps that, when in full contact with a surface, create a Van der Waals force between the feet and the surface. These are weak intermolecular forces that result from subtle differences in the positions of electrons on the outsides of molecules.