Agir pour réduire le nombre de débris spatiaux en orbite autour de la terre | Techniques de l’Ingénieur
At the moment, the Parliamentary Office for the Evaluation of Scientific and Technological Choices (OPECST) has made several recommendations to reduce the number of space debris. In addition to monitoring these objects and suspending satellite destruction tests, it advocates finding solutions to manage their end of life and remove the most dangerous debris from space.
One million. That’s the number of human-made objects larger than one centimeter orbiting the Earth as estimated by the European Space Agency (ESA). These debris mainly come from the fragmentation of obsolete satellites disintegrating in space. Their number is expected to increase in the coming years, given the proliferation of launches, especially in low Earth orbit. While 540 satellites were active in outer space in 2003, their number now stands at 8,700. Whether intact or reduced to debris, these objects pollute space and can collide with still operational satellites. The OPECST has published a note in which it makes several recommendations to address this situation.
The authors recommend “deepening surveillance efforts and exploiting and processing tracking data.” This monitoring will, among other things, further avoid collisions by identifying proximity risks and making a maneuver decision if a risk is confirmed. On average, for each satellite in low Earth orbit, one maneuver is performed each year, and in 2023, the International Space Station had to perform 6 maneuvers. The European Union already implements a monitoring program using 3 lasers, 9 radars, and 28 telescopes, but the largest debris catalog is held by the US military, which lists more than 28,000 objects larger than 10 cm in low Earth orbit or larger than 1 meter in geostationary orbit.
Another recommendation is to “suspend all satellite destruction tests.” Only four countries have done so to date: the United States, Russia, China, and India. For the latter, it is usually a show of strength, as destroying a satellite by firing a missile from Earth is a feat, as it not only takes into account the long distance but also the target’s trajectory and speed. The most recent example is with Russia, which destroyed its satellite Cosmos 1408 in 2021, which was orbiting the Earth. It scattered into a cloud of about 1,500 orbital debris of at least 10 centimeters in diameter.
The issuance of launch authorizations subject to sustainable end-of-mission solutions is another recommendation of the OPECST. “For the future, regulations should encourage operators to provide sufficient fuel (propellants) to propel the end-of-life satellite into a graveyard orbit,” write the authors. They add that cost issues come into play. According to their estimates, “between 85% and 100% of space objects that reached the end of their life in the last decade in geostationary orbit have already attempted to comply with the current standards for limiting debris. Between 60% and 90% of them have succeeded, which means that more than half of the total workforce has succeeded in any case.”
Finally, it becomes necessary to start quickly removing the most dangerous debris in low Earth orbit in the face of their proliferation. This work must be carried out at the rate of “about 10 large debris each year, starting naturally with the 50 most dangerous,” according to an expert from CNES interviewed. In 2026, ESA will launch the ClearSpace-1 mission whose objective is to safely return an adapter Vespa from the VEGA rocket, in orbit since 2013 and weighing 112 kg. This mission is carried out with a robotic arm and is prepared in partnership with the Swiss start-up ClearSpace SA. In 2018, ESA launched a first active debris removal mission as part of the RemoveDebris project and demonstrated the viability of technologies such as net capture or harpooning. Currently, the operator Eutelsat equips its satellites in low Earth orbit with a gripping surface opening the possibility that they may eventually be recovered by a grappling system.
At the beginning of the year, the Japanese company Astroscale conducted a first debris removal experiment in orbit using a magnetic capture and deorbit system, called ELSA-d. A second experiment, called ADRAS-J19, involved an approach to facilitate the recovery of inert waste. The ADRAS-J satellite moved synchronously with an upper stage of the Japanese H2A rocket, measuring about 11 meters long, 4 meters in diameter, and weighing about 3 tons. It was able to characterize the state and trajectory of this waste, as well as the risks posed by it. This is a preliminary step to a removal operation.
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