Laser beams, wooden satellites or even space “tow trucks”: In Japan, scientists and start-ups are competing for projects to remedy the growing problem of space debris.
According to the latest estimates from the European Space Agency (ESA), one million pieces of debris over one centimeter – from used satellites or rocket bits – are already orbiting the Earth at very high speeds.
And that number is likely to grow disproportionately with the advent of “mega-constellations” of satellites aimed at providing fast and ubiquitous Internet access.
“We are entering an era where many satellites will be launched one after the other. Space will become more crowded”, recalls Miki Ito, leader of Astroscale, a young Japanese company working towards a “sustainable” space.
“Simulations indicate that if we continue like this the space will become unusable,” Ms Ito warned in an interview with AFP. “So we need to improve the sky environment before it’s too late.”
Incidents are already mounting: In January, a Chinese satellite was grazed by fragments of an old Soviet satellite. And last year, the thermal coating of a robotic arm on the International Space Station (ISS) was punctured by debris just a few millimeters across.
“Small debris is problematic because it’s not cataloged,” unlike larger objects, which have names and whose position and speed are “permanently identified,” explained Toru Yamamoto, a researcher at Japan’s space agency JAXA, to AFP.
Rules of good practice exist to limit space debris, such as moving end-of-life satellites into “graveyard orbits”. But this is not enough, especially since no legally binding international text currently exists.
“A geostationary satellite experiences about 100 + nearby debris + warnings every year,” Tadanori Fukushima, an engineer at Japanese satellite operator Sky Perfect JSAT, told AFP.
Mr. Fukushima founded a start-up to explore a still-experimental solution: a laser beam that would vaporize the surface of space junk, creating a pulse of energy to propel that object into a new orbit.
He hopes to launch the first experiment in space by spring 2025 in collaboration with various research institutes.
The AstroScale concept is more advanced: a kind of space “tow truck” works with a magnet that recovers satellites at the end of their lives.
The company passed a first test last year and plans a second by the end of 2024 in partnership with ESA and OneWeb, the British operator of a constellation of low-orbit satellites.
More unusual, another Japanese team envisions satellites made of wood, a material that would have the advantage of being completely consumed upon re-entry into Earth’s atmosphere.
The project by the University of Kyoto (western Japan) and the logging group Sumitomo Forestry is still in its infancy: in March, pieces of wood were sent to the ISS to test their response to cosmic rays.
Japan is one of the most dynamic space nations in developing space debris solutions, Fukushima said.
But according to this engineer, companies around the world are also racing to conquer this nascent market, which could really take off from 2030.
In late 2020, ESA signed a €100 million contract with ClearSpace, a Swiss start-up, to send the world’s first commercial mission to clean up space debris in orbit in 2025.
American companies such as Orbit Fab and SpaceLogistics (a subsidiary of aeronautics and defense group Northrop Grumman), or Australian Newman Space design various satellite repair services to prolong their use, for example by refueling them in space.
According to Jaxer Yamamoto, the space debris problem is sufficiently complex to allow a wide range of solutions to coexist. “There is no universal cure”.