Inspired by geckos, researchers at NASA’s Jet Propulsion Lab in Pasadena in California have created a material that will allow robot gecko grippers to cling to spacecraft and perform maintenance in the vacuum of deep space.
The newest generation of grippers can support more than 150 Newtons of force, the equivalent of 35 pounds (16 kilograms).
Thanks to tiny hairs on the bottom of geckos’ feet, these lizards can cling to walls with ease, and their stickiness doesn’t wear off with repeated use.
NASA scientists have mimicked this to create a material with synthetic hairs that are much thinner than a human hair. When a force is applied to make the tiny hairs bend, that makes the material stick to a desired surface.
“This is how the gecko does it, by weighting its feet,” JPL engineer Aaron Parness said.
Using a concept called van der Waals forces, a slight electrical field is created because electrons orbiting the nuclei of atoms are not evenly spaced, so there are positive and negative sides to a neutral molecule.
Space lizards help NASA get a grip
The positively-charged part of a molecule attracts the negatively-charged part of its neighbour, resulting in “stickiness”. Even in extreme temperature, pressure and radiation conditions, these forces persist.
In a microgravity flight test last year through NASA’s Space Technology Mission Directorate’s Flight Opportunities Programme, the gecko-gripping technology was used to grapple a 20-pound (10 kilogram) cube and a 250-pound (100 kilogram) person.
The gecko material was separately tested in more than 30,000 cycles of turning the stickiness “on” and “off” when Parness was in graduate school at Stanford University in Palo Alto, California. Despite the extreme conditions, the adhesive stayed strong.
‘We might eventually grab satellites to repair them, service them, and we also could grab space garbage and try to clear it out of the way’
– AARON PARNESS
Researchers have more recently made three sizes of hand-operated “astronaut anchors”, which could one day be given to astronauts inside the International Space Station.
The anchors are made currently in footprints of 1x4in, 2x6in and 3x8in. They would serve as an experiment to test the gecko adhesives in microgravity for long periods of time and as a practical way for astronauts to attach clipboards, pictures and other handheld items to the interior walls of the station.
Parness and his team are also testing the Lemur 3 climbing robot, which has gecko-gripper feet, in simulated microgravity environments.
The team thinks possible applications could be to have robots like this on the space station conducting inspections and making repairs on the exterior. For testing, the robot manoeuvres across mock-up solar and radiator panels to emulate that environment.
“We might eventually grab satellites to repair them, service them, and we also could grab space garbage and try to clear it out of the way,” Parness said.