Saturday, July 1, 2017

Applications in Space for a Gecko-Inspired Gripper #Science #Space

Close up of the robotic gripper made by the Cutkosky lab at Stanford University. The gripper is designed to grab objects in zero gravity using their gecko-inspired adhesive.

Credit: Kurt Hickman/Stanford News Service

Here's the problem for the Gecko Gripper to solve:

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.

Science Daily:  Engineers design a robotic gripper for cleaning up space debris

The current science isn't about the device which will locate the space debris but rather the gripper which will be used to capture it when the debris is close-by.  The intelligence of that gripper was actually inspired by geckos, the tiny lizard-like creatures which can walk across your ceiling with no trouble.

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.

- SD

Apparently the gripper really does work in space when hardly anything else does so maybe it's not long before we hear one astronaut say to another, "Pass me a Gecko, if you would."

Most space tools don't have such cool names but this one could be novel.

We don't have a burning interesting any gecko's feet to any greater degree than most people but we do confess to some intrigue.

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.

The gripper is not as intricate as a gecko's foot -- the flaps of the adhesive are about 40 micrometers across while a gecko's are 200 about nanometers -- but the gecko-inspired adhesive works in much the same way. Like a gecko's foot, it is only sticky if the flaps are pushed in a specific direction but making it stick only requires a light push in the right direction. This is a helpful feature for the kinds of tasks a space gripper would perform.

- SD

It seems relatively simple but with devilishly-clever science behind it and there's a wealth of information for the interested student in the source article on how it works.  We will leave that for those who will be Engineers but in the Rockhouse we build cloud castles and more than one has said we don't have a grip on much of anything, Gecko Gripper or no.

There is a dream, however.

Next steps for the gripper involve readying it for testing outside the space station, including creating a version made of longer lasting materials able to hold up to high levels of radiation and extreme temperatures. The current prototype is made of laser-cut plywood and includes rubber bands, which would become brittle in space. The researchers will have to make something sturdier for testing outside the ISS, likely designed to attach to the end of a robot arm.

Back on Earth, Cutkosky also hopes that they can manufacture larger quantities of the adhesive at a lower cost. He imagines that someday gecko-inspired adhesive could be as common as Velcro.

- SD

Maybe that seems a silly dream but my parents didn't know anything about Velcro when they were growing.

This article won't continue into collecting space junk since the source article is focused entirely on grabbing the junk after it is found.  Likely you can envision some type of autonomous space robos which fly around finding the space junk and then the Gecko Gripper will be used to grab it.  That's for another installment but NASA is still writing that one.

Note:  that's the first Ithaka article out of over ten thousand which ever called for a sequel but I believe the application is valid.  There is tremendous glory in shooting things into space and it looks like we rapidly approach the point at which there will also be great glory in bringing things (i.e. space junk) out of space.

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