Wall-crawling Gecko Robots can Stick in Space too Using Dry Adhesive, Discover ESA Researchers

Climbing robots that mimic the stickiness of gecko lizard feet could work in space as well as on Earth, ESA has shown, raising the prospect of hull-crawling automatons tending future spacecraft. Robots crawling across spacecraft surfaces are a common sight in science fiction films from Silent Running to Wall-E. But, in reality, how might they stick in place while still remaining mobile?

Researchers from ESA and Simon Fraser University in Canada subjected gecko-inspired dry adhesive materials to space vacuum and temperatures, finding the stickiness is retained throughout. Engineers from the Universitys School of Engineering Science have demonstrated such adhesives with a family of Abigaille crawling robots.

"This approach is an example of biomimicry, taking engineering solutions from the natural world," explained Michael Henrey of Simon Fraser University. A geckos feet are sticky due to a bunch of little hairs with ends just 100?200 nanometres across - around the scale of individual bacteria. This is sufficiently tiny that atomic interactions between the ends of the hairs and the surface come into play.

"Weve borrowed techniques from the microelectronics industry to make our own footpad terminators," he said. "Technical limitations mean these are around 100 times larger than a geckos hairs, but they are sufficient to support our robots weight."

Interested in assessing the adhesives suitability for space, Michael tested it in ESAs Electrical Materials and Process Labs, based in the Agencys ESTEC technical centre in Noordwijk, the Netherlands, with additional support from ESAs Automation and Robotics Lab.

"The reason were interested in dry adhesives is that other adhesive methods wouldnt suit the space environment," Michael notes. "Scotch, duct or pressure-sensitive tape would collect dust, reducing their stickiness over time. They would also give off fumes in vacuum conditions, which is a big no-no because it might affect delicate spacecraft systems.

"Velcro requires a mating surface, and broken hooks could contaminate the robots working environment. Magnets cant stick to composites, for example, and magnetic fields might affect sensitive instruments."

"A depth-sensing indentation instrument was used inside a vacuum chamber to precisely assess the dry adhesives sticking performance," said ESAs Laurent Pambaguian. "Experimental success means deployment in space might one day be possible." "Its very expensive to upgrade hardware once it is up in space so the idea would be to fly a more genera