There are no garbage trucks equipped to leave the atmosphere and pick up debris floating around the Earth. But what if we could send a robot to do the job?
Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, are working on adhesive gripping tools that could grapple objects such as orbital debris or defunct satellites that would otherwise be hard to handle.
The gecko gripper project was selected for a test flight through the Flight Opportunities Program of NASA’s Space Technology Mission Directorate. As a test, researchers used the grippers in brief periods of weightlessness aboard NASA’s C-9B parabolic flight aircraft in August.
“Orbital debris is a serious risk to spacecraft, including the International Space Station,” said Aaron Parness, a JPL robotics researcher who is the principal investigator for the grippers. “This is definitely a problem we’re going to have to deal with. Our system might one day contribute to a solution.”
The gripping system developed by Parness and colleagues was inspired by geckos, lizards that cling to walls with ease. Geckos’ feet have branching arrays of tiny hairs, the smallest of which are hundreds of times thinner than a human hair. This system of hairs can conform to a rough surface without a lot of force. Although researchers cannot make a perfect replica of the gecko foot, they have put “hair” structures on the adhesive pads of the grippers.
The synthetic hairs, also called stalks, are wedge-shaped and have a slanted, mushroom-shaped cap. When the gripping pad lightly touches part of an object, only the very tips of the hairs make contact with that surface.
“The stickiness of the grippers can be turned on and off, by changing the direction in which you pull the hairs,” Parness said.
To get the gripper to stick to a surface, force is applied to the adhesive pad material in a manner that makes the hairs bend. This increases the real area of contact between the hairs and the surface, which corresponds to greater adhesion. When the force is relaxed and the hairs go back to being upright, this process turns off the stickiness.
A phenomenon called van der Waals forces, named for Nobel Prize-winning physicist Johannes Diderik van der Waals, explains the non-permanent stickiness of the grippers, as well as gecko feet. These temporary adhesive forces happen because electrons orbiting the nuclei of atoms are not evenly spaced, creating a slight electrical charge. Such forces persist even in extreme temperature, pressure and radiation conditions.
“The reliability of van der Waals forces, even in severe environments, makes them particularly useful for space applications,” Parness said.
“The system could grapple objects in space that are spinning or tumbling, and would otherwise be hard to target,” he said.
The Latest on: Gecko Grippers
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The Latest on: Gecko Grippers
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- Gecko-inspired farmHand combines grasping strength with a light touchon December 16, 2021 at 3:59 pm
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- Engineers created a robotic hand with a gecko-like gripon December 16, 2021 at 1:44 pm
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- Stanford's gecko-inspired robot hand sets its sights on fruit pickingon December 15, 2021 at 12:47 pm
Stanford’s made a lot of progress over the years with its gecko-inspired robotic hand. In May, a version of the “gecko gripper” even found its way onto the International Space Station to test its ...
- Gecko-inspired adhesive combines strong bond with damage-free, clean removal propertieson November 29, 2021 at 3:59 pm
Shear Grip will also be available in the commercial print industry ... food packaging, and smart clothing. Gecko image courtesy mgkuijpers/Adobe Stock.
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