The European Space Agency (ESA) warned in its annual report that near-Earth space is increasingly filling up with destructive, fast-moving pieces of defunct satellites and rockets that threaten the future of operating beyond our planet’s gravity.
The number and scale of commercial-satellite constellations in certain economically valuable low-Earth orbits continues to increase while not enough remnants of old satellites leave these heavily congested areas at the end of their lives, the ESA stated.
Spacecraft that remain in their operational orbits at the end of their missions are at risk of fragmenting into dangerous “clouds” of debris that linger in orbit for many years.
Active satellites must now perform an increasing number of collision-avoidance manoeuvres to dodge other satellites and fragments of space debris.
“Ever since the start of the Space Age [in 1957], there has been more space debris in orbit than operational satellites,” the ESA said. “As space debris poses a problem for the near-Earth environment on a global scale, only a globally supported solution can be the answer.”
According to the ESA, “Under the current extrapolation conditions, the amount of catastrophic collisions could rise quickly.”
Of the more than 30,000 individual pieces of space debris larger than 10cm in diameter currently identified, more than half of them litter the low-Earth orbit area, that which is less than 2,000km from the planet’s surface.
This does not include objects that are yet to be tracked and those currently too small to identify. Based on ESA models, the total number of objects in Earth orbit larger than 1cm across is probably above one million.
More satellites were launched in 2022 than ever in a single year and the number and scale of commercial satellite constellations in certain economically viable low-Earth orbits continues to increase. A significant number of defunct satellites do not leave these heavily congested orbits at the end of their lives.
A record number of human-made objects fell from space in 2022, driven by descending “payload fragments”, mostly resulting from an anti-satellite test (AST) performed in orbit. Last year, a record number of satellites re-entered Earth’s atmosphere, according to the ESA.
In October 2022, the UN General Assembly’s First Committee adopted a resolution calling on all States to pledge not to conduct destructive direct-ascent anti-satellite missile tests (DA-ASAT). The resolution was co-sponsored by France and adopted by a large majority of UN member states. French authorities described the move as “a milestone in protecting a safe, stable space environment”.
More than 80 per cent of constellation satellites launched in 2022 were placed into orbits that will cause them to gradually descend towards Earth within a timespan of less than two years once they are no longer operational or if they experience catastrophic mechanical failure, experts say.
Consequently, the upward trend in the number of satellites re-entering Earth’s atmosphere is projected to persist in the years ahead.
The significance of space is growing steadily, serving as a valuable and even indispensable resource for modern society, the ESA said, adding: “But we must ensure that it is not just the benefits that we extract from orbit, but also the waste.”
Significant fragments of space debris give rise to two distinct types of risk: the immediate threat of direct collision with operational satellites; and the longer-term danger of disintegration into an array of smaller fragments, each capable of causing severe damage to spacecraft.
The ESA warned that, in the long run, the escalating level of activity in space could trigger the “Kessler Syndrome”.
That scenario entails a situation where the density of objects in orbit reaches a point where collisions between them and space debris trigger a cascading effect, with each collision generating more debris that subsequently elevates the probability of additional collisions. At this juncture, specific low-Earth orbits will become practically untenable.
When it comes to older bits of space rubbish, the sole recourse is “active debris removal,” according to the ESA.
For that reason it is undertaking the ClearSpace-1 mission as a service from the Swiss start-up Clearspace SA, with the objective of showcasing the essential technologies required for active orbital debris removal.
This mission is intended to serve as the first step towards establishing a novel and enduring commercial sector specifically focused on eliminating high-risk “entities” in orbit.