More efforts are needed to make valuable orbits sustainable, according to a new report from the European Space Agency (ESA).
Space activity, both by national governments and private companies, is growing substantially. More than 2,400 new tracked payloads were launched Earth orbit last year, more than ever, according to ESA’s Space Environment Report 2023, which was published in August.
These active satellites, however, must perform an increasing number of collision avoidance maneuvers to escape other satellites and spatial waste.
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Although the space above Earth is vast, much of the activity is concentrated around particularly useful orbital paths and altitudes, particularly in low earth orbit (LEO). Keeping them useful and safe is vital to protecting astronauts and spacecraft, which provide a wide range of commercial, economic and scientific uses.
“Long term, increasing space the activity could lead to ‘Kessler syndrome‘ — the situation in which the density of orbiting objects is high enough that collisions between objects and debris create a cascading effect, where each crash generates debris which then increases the likelihood of further collisions. At this point, some low Earth orbits will become completely inhospitable,” the report warns.
We are not there yet, but the situation is not good. Decades of space activity have already led to the formation of clouds of space debris orbiting the Earth.
Junk satellites, inactive spacecraft, debris from rocket launches, satellite fragmentation and collision results mean that, according to ESA models, there are likely over a million objects in Earth’s orbit larger than 0.4 inches (1 centimeter), whizzing around at orbital velocity.
While measures to mitigate the effects of associated space debris are increasingly being adopted by space actors, such as assurance satellites exiting orbit within a defined period of time after the end of their missions, this is not enough, according to the report.
“The adoption of space debris mitigation measures is improving, but, given the huge number of new satellites and the amount of existing debris, the rate is still not sufficient and our behavior in space appears to be unsustainable in the long term” , says the 123. -page says the ESA report.
Space debris mitigation guidelines state that satellites should vacate protected orbits within 25 years of ending their use.
The good news is that satellites launched in the last decade largely follow international guidelines for deorbiting, both passively and actively.
“Satellites from the first constellations, for example, had very low compliance, while the compliance of those launched in this decade is almost 100%,” the report states.
Active satellites, with their sophisticated tracking and warning systems, are also capable of avoiding each other using propulsion systems.
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However, satellites that are no longer active and are not removed from their operational orbits at the end of their mission may collide with other satellites. Such collisions can create dangerous clouds of debris, further cluttering orbits with high-velocity shrapnel for years to come.
“Even if we didn’t launch anything from now on, collisions between space debris already in orbit would make the problem worse,” the report’s authors write. “Efficient satellite disposal is one of the most important things to keep low Earth orbits safe.”
The report highlights ESA efforts such as ClearSpace-1 spatial waste collection mission – which was itself, touchingly, hit by debris – and the recent Eolo managed to return as a demonstration of a more sustainable approach.
The take-home message: As more and more things are going into space, it’s important to bring them back down safely.