Faced with the inevitable and disturbing increase of orbiting space debris, the international space community is redoubling its efforts and ingenuity to find solutions to reduce it and avoid any collision with these artificial objects by our satellites. Let’s take a look at the state of space pollution before looking at the solutions, from the most original to the most promising.
Ever smaller and more dangerous space debris
Among the 42,000 objects put into orbit in 60 years of space activity, only 1,200 are still operational. The rest are space debris which, before burning up as they re-enter the atmosphere, remain in orbit for a very long time, concentrated in a zone where satellites and the International Space Station (ISS) are also found. And this number is only going to increase with the OneWeb Project, which aims to launch into orbit close to 650 telecommunication satellites by 2022 to provide worldwide high-speed internet access. Concretely, the danger is from small debris (1 to 10 cm) which cannot be tracked by monitoring agencies and which releases such kinetic energy that satellites cannot protect themselves from that. As evidence, the impact from a piece of debris weighing just 10 gr with an average speed of 10 km/sec would be greater than a vehicle weighing 1,000 kg striking a wall at 100 km/h. The impact of a piece of space debris on a solar panel, an astronaut or on the ISS would be devastating financially, technically and in human terms, as well as creating a multitude of new pieces of debris that would collide with each other. In short, this snowball effect, called the Kessler syndrome in 1978 by this NASA consultant, would prematurely terminate space exploration and satellite launches.
Head-spinning solutions
Faced with this major problem, the Inter-Agency Space Debris Coordination Committee has imposed a rule stipulating that any object “must be de-orbited after 25 years of inactivity” either by atmospheric re-entry or by sending it higher to a “graveyard orbit“. As the owners have not conformed, the operators then resolved to limit the quantity of space debris and space agencies to find solutions to get rid of them. And ideas abound: an electrodynamic cable which, unrolled from the satellite, would allow it to descend and leave its orbit; a fishing net that would capture the satellite and pull it toward the atmosphere; a space chaser that would expel debris with its magnetic field; a space garbage truck equipped with a harpoon and a net; a multipurpose tow truck that, equipped with robotic pincers and sensors, would be controlled from Earth and could not only repair satellites but also de-orbit them, once the reach the end of their life. The most promising and hopeful idea comes from the Chinese Air Force Engineering university which advocates the use of a laser, from space, not Earth, which would bombard the debris with bursts of light for several minutes, in order to move it off about ten centimetres. The Chinese university is currently carrying out model simulations taking into account various factors such as the angle of attack, speed of objects or inclination of the station on which the laser would be manipulated.
If the international space agencies continue along the laser track, which seems promising to control orbiting space debris, then crucial questions would arise. Who would build these laser-equipped stations? Who would control these weapons that could be misused… to blind or even destroy a satellite?