Инженеры NASA и Стэнфордского университета успешно испытали «геко-клешни» для захвата космического мусора и работы в невесомости

Grabbing something in orbit is harder than it sounds. There is no friction to lean on, no solid ground to brace against, and most spacecraft surfaces are not magnetic, so a standard magnetic claw is useless. Tape and other conventional adhesives fail too, since they lose their stick after a handful of uses and cannot survive the temperature swings or vacuum conditions found in space. A dead satellite spinning end over end, or a stray bolt travelling at thousands of miles an hour, gives a robotic arm nothing dependable to grip onto, and that gap has left a growing amount of debris essentially untouchable once it reaches orbit. Engineers at NASA's Jet Propulsion Laboratory looked at that problem and borrowed a solution that nature had already worked out. Geckos climb glass, ceilings, and smooth bark without any sticky residue, without slowing down, and without ever needing to reapply anything. For years, the JPL team tried to recreate that same mechanism in synthetic material. In 2014, they took it far enough and tested it in the one environment for which it was built: weightlessness. The C-9B Flight tested a 20-pound cube and a 250-pound person In August 2014, engineers at JPL tested a gecko‑inspired gripping system aboard NASA’s C‑9B parabolic aircraft, the plane used to create brief stretches of weightlessness for research purposes. The test was carried out through the Flight Opportunities Program under NASA’s Space Technology Mission Directorate. On the flight, researchers grappled a 20‑pound floating cube and, on another pass, clamped onto a fellow scientist wearing a vest made of Spacecraft Material Panels, in essence a 250‑pound person serving as a tumbling piece of equipment. The paper says the C‑9B tests were meant to probe how the grippers behave in brief weightlessness before any spaceflight use and notes that the team was already aiming them at operations like grappling spinning debris or defunct satellites. Parness said the system could one day help address orbital debris, which he called a serious risk to spacecraft and the International Space Station. The most notable aspect of the demonstration was what the grip did not require. It required neither glue nor suction and no residue remained when the pads relinquished grip and the very same part of the substance might be used up once again for the next capture. Wedge-shaped synthetic hairs replicate Gecko foot structure Gecko feet have arrays of microscopic hairs that can branch and their smallest strands are hundreds of times thinner than a human hair. The gecko's toe can conform to the contours of even a rough surface without exerting pressure thanks to the branching structure. That structure cannot be copied exactly in synthetic materials, so engineers at NASA's Jet Propulsion Laboratory manufactured plastic microscopic stalks that are angled and end in miniature mushroom-shaped caps, which achieve a similar gripping effect. Dragging the foot pad in one direction makes the hairs flop over to increase contact and drag it the other way and the hairs snap back to a nearly non-sticky state. The adhesive held up through 30,000 on-off cycles and minus 76°F But JPL didn’t test the gripping pads a few times and then tossed them in a closet. The hardware was tested against more than 30 spacecraft surfaces and then blasted in a thermal vacuum chamber at minus 76°F (-60°C), approximating conditions in orbit. The adhesive was cycled on and off more than 30,000 times. The motivation behind this level of testing shows up clearly in Gecko-like Adhesives for Orbital Debris Applications , JPL's own research task summary led by Parness. The task page says the adhesive was designed to work on more than 30 spacecraft surface types and that the zero-gravity airplane trials let the team grapple floating targets, manipulate them and release them with near-zero force. It also notes larger system-level tests on an airbearing floor, using a 350 kg floating robotic spacecraft in JPL’s Formation Control Testbed. It puts a number on the scale of the problem: more than 20,000 pieces of orbital debris circle the Earth at speeds exceeding 22,000 mph. The 2009 crash of a working U.S. communications satellite with an out-of-commission Russian satellite is given in the same brief as another type of event that keeps creating more bits and pieces. The project says its hairy gripping surface uses van der Waals forces to cling to glass and bark and that engineers have since been testing a 350 kg (770-pound) free-floating robotic space vehicle on the JPL airbearing floor. Stanford test: a 70‑kilogram climber scaled 3.7 metres of vertical glass The 250‑pound grapple test raised an obvious follow‑up question: could the same family of adhesives support a person's full body weight against gravity, not just in a brief weightless window? Researchers at Stanford, working in the same lab tradition that trained Parness, answered that in Human climbing with efficiently scaled gecko‑inspired dry adhesives , published in the Journal of the Royal Society Interface i n January 2015. Elliot Hawkes, the research lead, designed handheld plates studded with gecko‑friendly adhesive tiles, each connected to the edge of the plate via a nitinol, or nickel-titanium alloy, spring. The springs help distribute the climber's weight across the tiles rather than concentrating the load at the top or bottom edges of the plate, which had caused earlier gecko-adhesive attempts such as the team's robot Stickybot to fail. In their demonstration, 140 sq cm (0.02 sq m, less than the area of a large piece of printer paper) was used on either hand by an individual weighing 70 kg to scale the 3.7m high vertical glass surface without ropes and without suction. In the study, the team built hand‑sized adhesive pads with controllable load sharing and showed that a 70 kg climber could ascend a 7.7 m vertical glass wall using gecko‑inspired dry adhesion. The authors say the work demonstrates that synthetic adhesives can scale to human climbing with little loss of performance, provided the load is distributed efficiently across the pads. The paper noted that, at the time of publication, approximately 384 papers on gecko-based adhesives had been published, although only a small number addressed load-sharing at the human scale. The paper also noted a similar but unpublicized success earlier that summer by DARPA, known as the Z-Man project. DARPA had also released video footage showing a climber partway up a vertical wall but had never described the mechanics behind its sticky pads. As such, the Stanford paper was one of the first to openly describe a working, human‑scale mechanism for gecko‑inspired climbing with quantified load sharing. Microgravity grappling versus human‑scale climbing When the JPL flight test and the Stanford climbing study are viewed together, they describe essentially the same material behaving in different ways depending on loading and gravitational conditions. In zero gravity, the challenge is gripping a tumbling object; in Earth gravity, it is distributing the load across the material without tearing the adhesive, all thanks to the same hairs and van der Waals forces. JPL has since refined the device into a range of handheld “astronaut anchors” in three sizes, allowing crew members to attach tools or themselves to a wall without leaving holes or sticky tape behind. More than a decade later, NASA is revisiting the same basic material technology on the space station with Astrobee, a 54.7-pound free-flying robot that performs adhesive demonstrations while astronaut Victor Glover operates the tool from inside the spacecraft. What began as a demonstration with a NASA JPL researcher and a vest full of pads in an airplane has since progressed to a mission aboard the space station.