A new net-membrane could clean up some tricky space debris

We’ve reported on all kinds of wacky ideas for capturing and deorbiting space debris safely. From electric tethers to lasers, engineers and scientists have been trying everything they can think of to deal with the ever-increasing orbital debris problem. But one simple design keeps popping up over and over again—a net. A new paper from researchers at the Chinese Academy of Sciences and the University of Electronic Science and Technology of China details one of the most advanced net concepts yet—but whether we can actually build one remains to be seen.

A net has obvious advantages. Alternative solutions, such as robotic arms, require a “cooperative” satellite that is able to be easily interfaced with. Others, such as grappling hooks, don’t have the same requirements but could result in even more debris by breaking up the satellites in situ. Still others, such as the aforementioned lasers, require significant amounts of power and a complex understanding of the dynamics of the target to be effective.

Nets, on the other hand, are much simpler. But they do have disadvantages as well. Once they are deployed, they are essentially uncontrollable. And perhaps more importantly, they are notoriously difficult to reuse. So if a net were to be used to deorbit debris, we would have to send a specific mission up to deorbit each piece—a potentially prohibitively expensive proposition.

Enter the new net from the paper, which was published in the journal Space: Science & Technology. It could actually be thought of as more of a hybrid “net-membrane” system. It incorporates a multilayered flexible membrane with electronics, battery layers and shape-memory alloys (SMAs), which are becoming ubiquitous on some types of spacecraft.

Deploying the net is simple enough. A “chaser” satellite approaches a target piece of debris and fires four bullets, each attached to a corner of the net, at a 30-degree angle (which is the optimal angle according to the paper). The pull from the bullets unfurls the membrane, which then wraps around the debris, effectively capturing it.

Using the SMAs embedded in it, the membrane can maintain its shape and hold onto the debris tightly while deorbiting it to a point where it will safely drop into the atmosphere. And, crucially, the membrane then folds itself back up and retracts back into the chaser satellite, which is then ready for another run.

There are lots of “firsts” in the description of how that works. But according to the paper, it works in theory, at least. The researchers decided to model that process using a technique called the Multiparticle Method (MPM), rather than the traditional finite element analysis (FEA) techniques, due to the latter’s computational complexity. MPM allowed them to break the membrane itself down into a grid of masses that are connected via spring-dampers to simulate bending, stretching and shearing.

A few key features came through in the simulations. One was the deployment angle mentioned above. But another was the fact that the distance to target makes a huge difference in the forces the membrane is subjected to. At a 2-meter (6.6-foot) distance, it will undergo a massive 3,374N force, but moving the deployment distance back to 3 meters (9.8 feet) drops that number in half.

While simulations are great, withstanding that amount of force is a lot to ask of a 10-micron-thick piece of material. Even more so when it has so many interwoven layers that aren’t necessarily designed for their mechanical properties. The simulations themselves also represented simplified versions of the operational environment the membrane would be working in—they ignored solar radiation pressure as well as atmospheric resistance, both of which play a huge role in orbital debris capture.

But when it comes to tackling the problem of orbital debris, we need all the help we can get. Proving an idea is theoretically possible is the first step to actually doing it, though it will probably be years, if not decades, before we would see such a hybrid membrane actually deployed in a debris removal mission. In the meantime, other technologies, such as robotic arms and magnetic plates, are making progress in testing. Though, in this writer’s opinion, the more options we have for solving this potentially devastating problem, the better.

Who’s behind this story?

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021.

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Andrew Zinin

Master’s in physics with research experience. Long-time science news enthusiast. Plays key role in Science X’s editorial success.

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