A Sticky Solution for Grabbing Objects in Space
A new robotic arm uses electroadhesion to clamp onto virtually anything it finds.
One of the most challenging tasks in space is for one spacecraft to grab onto another spacecraft. Although the robotic arms on the space shuttles and International Space Station (ISS) have made it look easy over the years, the process requires complex manipulator arms and special fixtures on the objects the arms are grasping, limiting the technology’s use. A small startup company is testing a new approach, though, that could greatly expand the applications of robotic arm technology to include, for example, cleaning up orbital debris and servicing the ISS.
Colorado-based Altius Space Machines is developing a robotic arm system it calls the “sticky boom,” which can extend up to 100 meters. At the end of the boom is a pad that uses a technology called electroadhesion to induce electrostatic charges onto any material—metal, plastics, glass, even asteroids—it comes into contact with, allowing it to clamp onto the object because of the difference in charges between the boom and object.
The key advantage of the sticky boom is that it can attach to any spacecraft or object, whether or not it was designed to be grappled by a robotic arm. “You don’t even have to know what the thing is made of or what it’s shaped like before you go stick to it,” says Altius president Jonathan Goff.
SRI International of Menlo Park, California, developed the electroadhesion technology for wall-climbing robots and other robotic applications. SRI International is collaborating with Altius to make the technology work on the new boom, but Altius says it is also examining alternative solutions.
The company has successfully tested a small-scale prototype of the sticky boom in weightlessness—on a parabolic aircraft flight—and in a thermal vacuum chamber that simulates space conditions.
While the sticky boom could have a wide range of uses, Altius is focusing on a concept that would allow just-in-time deliveries of supplies to the ISS. In this “direct to station” approach, small resupply spacecraft would be launched toward the ISS, but instead of having their own docking systems, the small spacecraft would be reeled in by the ISS with a sticky boom.
The direct to station approach has several advantages. More frequent access to the ISS could be a boon to scientists, allowing them to accelerate the pace of their research on the station. It could also create a market for small launch vehicles, especially proposed “nanosatellite” launchers designed to put satellites weighing only a few tens of kilograms into orbit. “It’s a hard problem, but if we pull it off, it will make a big difference,” says Goff, adding that initial conversations with NASA about the concept have been encouraging.
Some of the initial work on the sticky boom has been supported by NASA Small Business Innovation Research contracts. Altius also won the $25,000 first prize in the NewSpace Business Plan competition for entrepreneurial space companies, organized by the Space Frontier Foundation and held in July at NASA’s Ames Research Center in California.
Altius is also looking at other uses of the sticky boom. It could make it much easier to repair satellites, since most are not equipped with fixtures designed for conventional robotic arms. The boom could also grapple orbital debris as part of proposed efforts to clean up the growing population of space junk in Earth orbit.