How can AI contribute to space debris management?

Sputnik, in 1957, paved the way for the conquest of space. Since then, many satellites have been launched, whether for scientific research like the ISS or for commercial purposes like Quantum. Some exploded, collided with others: objects from the last stages of launchers to simple screws are currently in orbit. The European Space Agency (ESA) Space Debris Office at ESOC in Darmstadt, Germany, estimated that in a million of those measuring at least 1 cm, a collision with active satellites could cause great damage to the latter, but also their destruction. ESA relies in particular on AI to avoid these risks.

The number of debris in low Earth orbit, whether the result of collisions, explosions or simply end-of-mission abandonments, is growing and poses a significant risk to active satellites.

The ISS, the international space station, travels at an altitude of 400 km and at 28,800 km/h and circles the Earth in 92 minutes. The risk of collision with debris in this low orbit is significant and, since its launch in 1998, it has also had to perform about thirty diversion maneuvers, more frequent in recent years.

In particular, it had to modify its trajectory in November 2021 to avoid collision with debris generated by a test shot of a Russian anti-satellite missile, which allowed the destruction of Kosmos-1408, launched in 1982, which became useless, and remade a similar maneuver, for the same reason, on 16 June.

The destruction of Kosmos-1408 also gave rise to approximately 1,500 pieces of debris. On May 16, the Sentinel-1A satellite, developed by ESA as part of the European Copernicus program, had to deviate its trajectory to avoid one of them.

NASA had said in November 2021:

“All countries have a responsibility to prevent the deliberate creation of space debris by ASATs and to promote a safe and sustainable space environment. »

For ESA, progress has been made in recent years towards a sustainable space environment. So most satellite launchers in low earth orbit are disposed of responsibly as more and more satellites at the end of the mission, the problem is getting rid of all the others, especially those that are already there.

ESOC Debris Office

ESA’s European Space Operations Center (ESOC) is located in Darmstadt, Germany. In particular, it includes the Debris Office, responsible for providing operational services to missions underway or planned within the ESA and to third parties.

These services include:

  • avoid collisions in orbit (forecasts, forecast refinements and recommendations on avoidance maneuvers),
  • re-entry forecasting and risk assessment (forecasting time and location of re-entry, forecasting decay and disappearance of spacecraft, and ground risk assessment),
  • maintenance of spatial situational awareness information on all traceable objects in the DISCOS (Database and Information System Characterizing Objects in Space) database.

In its April 2022 report, it recalls that the most effective way to prevent the increase in the number of debris is to strictly follow the IADC space debris mitigation guidelines (Inter-Agency Coordinating Committee space debris): avoid collisions in orbit, with Safely dispose of spaceships at the end of your mission and above all avoid the risk of explosions.

Holger Krag, head of the Debris Bureau, says:

“In-orbit explosions are the biggest current contributor to the space debris problem; they are caused by leftover energy – fuel and batteries – on board satellites or launchers. Despite measures that have been in place for years to prevent these explosions, we are not seeing any slowdown in the frequency of these events. The tendency to act to deorbit the spacecraft at the end of a mission is improving, but slowly. »

Securing space with AI

ESA invited the global AI community to participate in the development of a system capable of autonomously avoiding space debris or at least reducing the burden on experts. Since 2021, AI algorithms have alerted teams when one of their satellites could collide with another object in orbit.

Holger Krag then said:

“Any maneuver to avoid collisions is a nuisance. Not only because of fuel consumption, but also because of the preparation associated with it. We have to book passes for ground stations, which costs money, sometimes we even have to turn off scientific data acquisition. We must have a specialist on staff available 24 hours a day. »

He added:

“Until now, we’ve automated everything that would require an expert brain to be awake 24/7 to respond to and track collision alerts. Making the final decision on whether or not to perform the evasive maneuver is the most complex part of automating and we hope to find a solution to this problem in the coming years. »

However, space debris catalogs are not complete enough to train AI algorithms: small pieces of debris are not listed there, as are military satellites…

Clean Earth Orbit: ClearSpace-1

Eliminating debris can be a more effective solution than trying to avoid it. In 2013, the Espaço Limpo office was created, with the mission of “ secure the future of space activities by protecting the environment on Earth and in space”. The team aims to clean Earth’s orbit of its debris and in 2020, ESA signed a €86 million contract with Swiss start-up ClearSpace, created in 2018 and based in Innovation. Park from EPFL, for the acquisition of a unique service: the first removal of space debris in orbit.

ClearSpace-1’s mission is to retrieve the upper stage of an ESA Vega rocket launched in 2013. It will enter orbit 500 km above Earth, just below the wreckage, to test its proper functioning. It will then approach it, grab it with its four robotic arms, and disintegrate with it as it descends back into Earth’s atmosphere. The mission is scheduled for 2025-2026.

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