Today there are an estimated 18,000 pieces of trackable space junk in Earth鈥檚 orbit, which includes anything larger than a tennis ball. The largest group of these are pieces of exploded rockets left to drift around our planet. In close second-place, however, are more than 3000 pieces of debris left over from anti-satellite tests. Now a group of experts is calling for a ban on such tests, to stop the problem in its tracks before it has disastrous consequences.
The use of weapons in space has been ever-present in our relatively short history of spaceflight, and often shrouded in secrecy, but anti-satellite tests have been more brazenly conducted. Both the US and Soviet Union used missiles on several occasions to practice destroying their own satellites in the 20th Century, in anticipation of a full-blown conflict in space. Hundreds of pieces of dangerous debris remain from these tests, eclipsed by China鈥檚 infamous destruction of its Fengyun weather satellite in 2007 鈥� 2865 pieces of debris from that event are still orbiting Earth.
鈥淚t remains today, 15 years after it happened, the single biggest contributor to orbital debris,鈥� says at the Harvard-Smithsonian Center for Astrophysics in Massachusetts.
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In a letter to the United Nations today, experts from the Outer Space Institute 鈥� including former heads of state, astronauts and industry experts 鈥� are calling for a ban on such tests. Citing the significant orbital debris risks, and the rising number of satellites particularly from mega constellations such as SpaceX鈥檚 Starlink and the UK鈥檚 OneWeb, they say anti-satellite tests pose a substantial danger now more than ever.
鈥淭hese mega constellations, with tens of thousands of satellites going into orbit, change the risk profile dramatically,鈥� says at the University of British Columbia in Canada, the letter鈥檚 lead signatory. 鈥淸Banning anti-satellite tests] is no longer something that can be postponed.鈥�
A collision with even a small piece of space junk is enough to destroy a satellite, creating more debris. In turn, this could lead to rapidly rising levels of debris as more subsequent collisions take place, a cascade known as the Kessler syndrome. In a worst-case scenario, enough space debris could render parts of Earth鈥檚 orbit unusable, which could impact everything from Earth-imaging satellites involved in global food production to climate satellites that enable rapid responses to major disasters.
The timing of the letter comes as the US military is rumoured to be on the cusp of announcing a new space weapon, with speculation ranging from a kinetic anti-satellite vehicle to an electronic interference system. 鈥淚f we get into a live-fire open conflict situation, we鈥檙e going to accelerate the debris population very, very quickly,鈥� says at US think tank Secure World Foundation, who is a member of the UN Institute for Disarmament Research.
Efforts to halt anti-satellite tests alone, however, could take years. 鈥淭he US has always shut down these considerations,鈥� says , also at the Secure World Foundation. Even attempts to conduct anti-satellite tests more responsibly have had mixed results. In 2019 India destroyed a satellite at lower altitude than other tests, hoping the debris would re-enter the atmosphere in 45 days, but dozens of pieces remained after. 鈥淭here鈥檚 one piece still in orbit,鈥� says McDowell.
Neither China, the US nor Russia have conducted such a test in the last decade, but the danger remains ever-present. With the number of satellites in orbit set to increase 10 or even 100 times in the coming years, now more than ever we must champion a sustainable use of space 鈥� by, perhaps at the very least, banning anti-satellite tests. 鈥淚t鈥檚 a no-brainer,鈥� says McDowell. 鈥淒eliberately creating space debris is just egregious.鈥�
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