A giant inflatable bag could catch asteroids and space junk

Asteroids contain large quantities of both precious and common metals, and despite the obvious challenges in reaching them, a few startups say these celestial bodies could offer a sustainable alternative to Earth-based mineral extraction, which is plagued by issues like diminishing supply and environmental damage.

The race is on to access this wealth of resources. Among the companies working on the problem is California-based TransAstra, which has developed and tested a device called Capture Bag, an inflatable bag that comes in different sizes, intended to catch anything from small rocks to house-sized boulders. The company says the bag could also be used for cleaning up human-made space junk, a problem that is increasingly a source of worry for governments and scientists.

“Asteroid mining is a very risky, challenging thing to do,” said Joel Sercel, an aerospace engineer who taught at Caltech, and founder of TransAstra. “To solve the asteroid mining problem, you actually have to solve four other problems that we call detect, capture, move and process.” In other words, an asteroid mining system must be able to detect the space rock to be mined, capture it, successfully move it to a safe location in space and then process it to extract the minerals.

“We have tech in all those areas,” Sercel added. “At last count, we have about 21 patents, and we get a new patent issued about every month.”

TransAstra completed a preliminary test of the Capture Bag, without any actual capture, aboard the International Space Station in early October, and through private and NASA funding it is now preparing to create a much larger, more functional version of the device.

Sercel knows where to look to find asteroids worth mining, aiming to focus his search on a special population of bodies in highly Earth-like orbits around the sun: “They drift very slowly by the Earth, at a distance of just a few billion kilometers,” he said.

“We already know where hundreds of these objects are, and we’re planning on going and getting the first one in 2028 — that, we think, will foment a true industrial revolution in space.”

Space gold rush

To date, TransAstra has raised about $12 million from private sector venture capital and about $15 million from contracts and grants, including with NASA and the US Space Force.

Collecting samples from asteroids is difficult and costly. Two startups working in the filed — Planetary Resources and Deep Space industries — folded before achieving any significant results. To date, only three missions have brought back asteroid samples captured in space, performed by government agencies from the US and Japan, and costing hundreds of millions of dollars.

TransAstra has already deployed about a dozen telescopes in three locations — Arizona, California and Australia — part of a network tasked with looking for asteroids suitable for mining. A fourth location is already planned, in Spain.

The company calls these telescopes Sutter, after Sutter’s Mill in California: “That’s where they discovered gold in California that led to the gold rush,” Sercel explained. “And we think that the prospecting of asteroids with telescopes will lead to the gold rush to space.”

Once an asteroid has been profiled as suitable, TransAstra plans to use its Capture Bag to grab it. The bag, which is made of materials typically used in aerospace applications, such as kevlar and aluminum, is leak-proof and can be mounted on a carrier vehicle that will release it near a target, at which point the bag will inflate to make room for the object.

Capture Bags come in six sizes, from micro to super jumbo: “The micro ones could fit in a coffee cup,” said Sercel. “They can capture a small piece of debris, the size of a watermelon.”

TransAstra tested the next size up — about a meter in diameter — on the ISS: “We went from a sketch on a whiteboard to delivered hardware for the flight demonstration in seven months — in the space business, that’s unheard of,” said Sercel. “It launched on a Falcon Nine rocket, was brought into the space station by astronauts, and put on what I would consider the outside of the space station, which is the inside of the airlock. Then … it was tested in microgravity and vacuum, and it worked.”

The largest proposed Capture Bag would be large enough to fit a 10,000-ton asteroid, as big as a small building.

TransAstra is now developing a 10-meter version of the bag — the “large” size — with $5 million in funding, half of which is from NASA. Sercel said that the engineering will be completed in just over a year, after which it will be ready for a space flight. But before going for the valuable space rocks, the bag will be tested with less glamorous space debris, which Sercel calls “a risk mitigator for the full asteroid mining mission.”

“That 10-meter capture bag will be big enough to find satellites that are in graveyard orbits but might be causing navigational issues. It will capture them and move them to a safer place. That’s an important mission,” Sercel said. “But it’s also big enough to go out and get asteroids, so we are currently working with industrial partners on a plan to get an asteroid that might be 100 tons.”

Sercel says it doesn’t make economic sense to bring mined material back to Earth. He is convinced that mining asteroids will enable humanity to process material needed for space hardware, and produce the hardware, directly in space.

Searching for solutions

Both space junk removal and asteroid capture are attracting significant interest and investment. Earlier this year, US-based startup Astroforge launched Odin, a probe that was designed to assess an asteroid for mining purposes. It was the first ever private mission to an asteroid and it was launched as part of the IM-2 lunar mission, but Astroforge lost contact with Odin after launch.

Space junk capture tests have been successfully conducted for years, but while no full-scale solution has yet been deployed, the risks associated with orbital debris keep growing. Many different technological solutions have been proposed, from complex robotic arms to magnets and even harpoons.

One advantage of the capture bag over more complex and sophisticated methods to grapple objects in space, Sercel said, is that it’s inexpensive and robust: “The same capture bag can be used to capture objects of different shapes, as long as the bag is big enough,” he said, adding that initially each bag will cost millions of dollars, but that cost is going to drop at scale, becoming much more competitive than robotic systems.

According to Eleonora Botta, an associate professor at the Department of Mechanical and Aerospace Engineering of the University at Buffalo, who’s not involved with TransAstra, the capture bag’s key feature is that it can secure objects of varying shapes, sizes, and rotational dynamics. “This versatility is valuable for asteroid capture and even more so for managing space debris,” she added. “One of the major engineering challenges lies in deploying large, highly flexible structures in the vacuum and microgravity conditions of space; this aspect will be critical as the system is scaled up from its ISS-based experimental version. Encouragingly, TransAstra has recently secured funding to advance this scaling effort in partnership with NASA.”

John Crassidis — a professor of mechanical engineering also at the University at Buffalo, who works with NASA, the US Air Force and other agencies to monitor space debris, and is not involved with TransAstra — said the company has a very innovative approach for asteroid mining, starting with the Sutter telescope used to find and track small asteroids in space. “If it works, then it’ll really open the doors for asteroid mining, because there are many small ones out there that we can’t see right now,” Crassidis said. “The big question is: can they find enough asteroids to make it cost feasible? We’ll find out — 2028 is pretty ambitious in my opinion, but I hope they make it.”

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