La Croix: The International Space Station had to maneuver for the third time this year to avoid collision with a piece of an old rocket. Is space increasingly polluted by space debris?
Pierre Yesterday: Yes. Already because there are more and more objects in space overall. Projects with constellations of satellites, like Starlink for example, send several dozen satellites at each launch. But also because, over the years, the items sent in space age and wear out, creating about ten explosions per year. With each explosion, several hundred pieces of debris are scattered.
→ READ. ISS veers off course again to avoid rocket debris
We only follow debris longer than a dozen centimeters, as the rest are too small to be seen. But in reality, a piece constitutes a danger starting from ten millimeters.
Isn’t there a law to manage the end of life of satellites and reduce waste?
P. O. : Yes. In France, we have the law on space operations which dates from 2008. Concretely, satellites are obliged to keep a reserve of fuel to change orbit and, after 25 years maximum, fall back into the Earth’s atmosphere. which disintegrates them. But this law did not exist at the start of the conquest of space, and even if other space agencies have a similar policy, not all countries turn out to be so virtuous.
Above all, at the time, small satellites without propulsion, such as CubeSat, did not exist (1). From ten to several hundred sent into space each year. However, without propulsion, these satellites represent “debris” as soon as they are put into orbit. Imagine a highway where go-karts without pedals or steering wheels would be placed in the middle of the tracks; it’s up to other motorists to maneuver to avoid them.
It is not only necessary to update French law, but above all to establish international regulations concerning these objects without propulsion. France only sends 3 to 4% of objects in space; we have to mobilize other countries. The solution could be to restrict these satellites to an altitude of up to 600 kilometers, the height at which they remain attracted to the Earth and descend inexorably to be finally destroyed in the atmosphere.
Are other solutions being studied to “clean” the space of this debris?
P. O. : In any case, rockets should not be sent to destroy them! I remind you, each explosion in space scatters hundreds of pieces, so that would only add to the problem. In Europe, researchers are studying the possibility of capturing space debris, but such missions would be very expensive. Who will foot the bill for the space garbage collection?
→ INVESTIGATION. Has space become a trash can?
At Cnes, we mainly work on not adding new debris. The ISO 24113 standard, for example, guarantees manufacturers that the satellites and launchers that send them do not generate debris.