Space junk collisions: The 'huge risk' circling Earth

More than 60 satellites visible in the night sky. Photo / Getty Images

The launch of thousands of new satellites in "mega-constellations" to improve global internet access will exacerbate the growing problem of space debris, experts at a European Space Agency conference warned on Tuesday.

"We face entirely new challenges as hundreds of satellites are launched every month now — more than we used to launch in a year," said Thomas Schildknecht of the International Astronomical Union. "The mega-constellations are producing huge risks of collisions. We need more stringent rules for traffic management in space and international mechanisms to ensure enforcement of the rules."

Addressing the threat that space junk, defunct satellites and fragments from their disintegration, poses to active spacecraft has become one of ESA's top priorities, said Josef Aschbacher, the agency's director-general.

"These particles are causing enormous danger to the spacecraft on which our services down on Earth depend — communications, weather forecasting and a lot of infrastructure," he said.

An estimated 900,000 objects larger than 1cm in diameter, and 128m fragments larger than 1mm, are already in Earth's orbit. They move so fast that even a centimetre-sized fragment can disable or destroy an operational spacecraft, as has already happened more than once, generating more junk.

Constellations are a dramatic change in the way space is being used

Manuel Metz, Inter-Agency Space Debris Co-ordination Committee representativeHundreds of collision avoidance alerts are issued every week to satellite operators. Their spacecraft then have to carry out costly collision avoidance manoeuvres, about once every two weeks in the case of ESA's 20 satellites, said Holger Krag, head of the agency's space safety office.

"This is nothing compared to what is coming," he warned, as companies begin to launch mega-constellations into low-Earth orbit, an altitude of up to 2,000km, to boost global internet access.

Starlink, part of Elon Musk's SpaceX company, is leading the rush to grab space in low Earth orbit, followed by competitors including OneWeb, Amazon, Telesat and others.

Schildknecht, an astronomy professor at the University of Bern, said that as well as increasing the risk of collisions, mega-constellations were polluting the night sky, with light reflecting off the satellites and interfering with radio-telescopes.

"Currently there is zero regulation of this process," he said. "We have to decide between the benefits of these mega-constellations to our society and of preserving a pristine night sky."

However Rolf Densing, ESA operations director, warned against vilifying Starlink. "It seems at first sight that Elon Musk is the evil guy who is polluting space but I must congratulate them on developing this idea of mega-constellations," he said. "They are not as bad as it sometimes looks."

Although there have been at least two near misses since 2019 involving Starlink satellites, Densing said the company was generally adhering to space debris guidelines and beginning to address astronomers' concerns.

Manuel Metz, representing the Inter-Agency Space Debris Co-ordination Committee which brings together the world's main space bodies, said they were working on improving guidelines for reducing the risk of collisions and preventing further accumulation of orbital junk.

"The first guidelines published 20 years ago are still workable but they need improvement," he said. "Constellations are a dramatic change in the way space is being used."

Agencies and governments are moving to strengthen guidelines and overhaul international space law to tackle space waste by ensuring that all new satellites are designed to deactivate themselves and burn up safely in the atmosphere at the end of their life, said Luisa Innocenti, head of ESA's Clean Space Office.

Agencies are also investing in new technologies, including automated collision avoidance systems and waste clearance spacecraft.

The first such ESA mission is due to launch in 2025. The ClearSpace satellite will use robotic arms to grab a redundant rocket stage, the discarded part of a launcher, at an altitude of 800km and send the 100kg metal object hurtling downward to incinerate itself in the atmosphere.

- Financial Times