Artificial intelligence to avoid space debris

On May 16, a very special accident almost happened. Almost 700 km above our heads, the Sentinel-1A satellite made an emergency maneuver to avoid approaching debris: a remnant of a Russian satellite deliberately destroyed by Moscow in November 2021. At the time, this anti-satellite missile test had caused a small shock wave at the risk of creating new debris dangerous for the machines in operation.

A prediction narrowly avoided this time. On Twitter, the European Space Agency (ESA) responsible for the satellite says: “The situation evolved quickly, the collision was difficult to avoid and we had less than 24 hours to act”. Despite these difficulties, the satellite managed to avoid the small debris of a few centimeters that could have been fatal.

Read too: Space debris management becomes one of ESA’s priorities

This misadventure, if it ends well, still raises some questions about the safety of satellites in orbit around the Earth. “These risks are more and more frequent”, guarantees Jean-Paul Kneib, director of the Space Center (eSpace) of the Federal Polytechnic School of Lausanne (EPFL). Once a month, the International Space Station must maneuver to avoid the worst. A complicated situation that is not about to improve as the number of satellites increases every day, as does the debris, and that no immediate solution seems possible to reduce that number.

AI to the rescue

For some, salvation may come from artificial intelligence. In late 2019, ESA announced the development of a system that allows satellites to detect collision risk on their own and act accordingly. Two years later, during the European conference on space debris, the agency guarantees that its results are positive and that in its tests, the satellites are able to make the right decision in the face of risk. COO Rolf Densing said: “Our results are not perfect, but in many cases artificial intelligence was able to correctly identify cases where action was needed.” For now, its role is limited to sending an alert for ground crews to practice the maneuver, but the idea is to make them 100% automatic.

“As far as computational calculations are concerned, it is something that is within our reach”, explains Jean-Paul Kneib. But the main hurdle is at the catalog level.” If the goal is to leave the cumbersome and expensive task of avoiding debris to the computers, they must, in fact, be given all the data they need. However, this data is only partial. There are many space debris catalogs, but they are not complete. Some debris too small to see is, however, dangerous. Military satellites are also invisible for security reasons.

Read too: The danger of space chaos

With these restrictions, going fully automatic becomes complicated according to Jean-Paul Kneib: “Without a complete catalogue, we cannot be sure that the maneuver will not lead to new risks. In addition, the catalog must be dynamic and account for changes in debris altitude, which is very difficult to configure.

space garbage truck

However, time is running out. Currently, each space mission dedicates 5 to 10% of its budget to avoiding debris, according to the OECD. And if the risks increase, the costs also increase. These maneuvers require fuel, and the later the risk is visible, the greater the change in trajectory must be. Not to mention the need to have teams dedicated to monitoring 24 hours a day. “Ideally, an artificial intelligence should inform us about the risk of a collision one to two weeks before impact, considers Jean-Paul Kneib. This leaves time to just change trajectory without using too much energy. You have to minimize the number of operations, but that requires great reliance on the computer.”

The other solution would be to reduce the amount of waste, and here too artificial intelligence seems to be a solution. Swiss start-up ClearSpace is currently preparing a “space junk truck” to tow debris into orbit to bring it back into Earth’s atmosphere, where it will burn when it lands. And it’s a computer that manages the approach! A tricky manoeuvre, as the wreckage in question rotates and moves. The project is promising, but it does not reduce risk in the short term. “If we want to explore Earth’s orbit, we must quickly find a solution,” argues Jean-Paul Kneib. Our satellites are not designed to constantly change course.”

Read too: Space junk hunt is underway

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