\n An artist\u2019s representation of satellites in orbit around Earth<\/p>\n yucelyilmaz\/Shutterstock<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n A collision would occur in just 2.8 days if all satellites lost their ability to dodge each other, highlighting how crowded Earth\u2019s orbit is becoming.<\/p>\n In the past seven years the number of satellites has more than tripled from 4,000 to nearly 14,000. The cause of this growth has mostly been SpaceX\u2019s Starlink constellation, which now numbers more than 9000 satellites in low Earth orbit between 340 and 550 kilometres above Earth.<\/p>\n This large increase means that satellites must constantly dodge out of the way of each other, known as a collision avoidance manoeuvre, to avoid crashes that would generate thousands of pieces of metal and potentially render parts of Earth\u2019s orbit unusable.<\/p>\n <\/p>\n From 1 December 2024 to 31 May 2025, SpaceX said in a biannual report that it performed 144,404 collision avoidance manoeuvres, equivalent to one manoeuvre every 1.8 minutes across its constellation. Only one collision in orbit has ever occurred. In 2009, an active satellite run by Iridium Communications hit a defunct Russian Cosmos satellite. Hundreds of pieces of debris from the event still orbit Earth.<\/p>\n Sarah Thiele at Princeton University in the US and her colleagues used public positional data of satellites to model how the increase in satellites has affected the collision risk. They came up with a new metric, called the CRASH Clock (Collision Realization And Significant Harm) to quantify the risk. The name invites comparisons with \u00a0the infamous Doomsday Clock that charts humanity\u2019s threat of nuclear war. \u201cWe definitely talked about that a lot,\u201d says Samantha Lawler at the University of Regina in Canada, a co-author on the paper.<\/p>\n They found that in 2018, prior to SpaceX\u2019s first Starlink launch in 2019, if all satellites suddenly lost their ability to manoeuvre there would have been a collision in 121 days. However, today the number is just 2.8 days because of the large number of satellites in orbit.<\/p>\n \u201cWe were shocked it was that short,\u201d says Thiele.<\/p>\n The 2.8-day figure presumes that there has been some event, such as a powerful solar storm, that has rendered all satellites unable to change course. In May 2024, a strong solar storm caused some Starlink satellites to ripple in a giant wave in response to the event. A repeat of the most powerful solar storm on record \u2013 the Carrington Event of 1859 \u2013 could cause significant problems, although Wineed Vattapally at SES Satellites in Luxembourg says it probably wouldn\u2019t render all satellites inoperable. \u201cIt\u2019s unlikely to knock them all out at the same time,\u201d he says.<\/p>\n <\/p>\n Experience the astronomical highlights of Chile. Visit some of the world\u2019s most technologically advanced observatories and stargaze beneath some of the clearest skies on earth.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n <\/span><\/p>\n A metric like the CRASH Clock is useful, says Hugh Lewis at the University of Birmingham, UK, to highlight how crowded Earth\u2019s orbit is becoming. \u201cCan we keep adding to that house of cards?\u201d he says. \u201cThe more cards that get added, the bigger the collapse is when things go wrong.\u201d<\/p>\n Tens of thousands more satellites are set to be launched in the coming years by SpaceX, Amazon, and several Chinese companies for their own mega constellations. That means it\u2019s likely the CRASH Clock will decrease further, raising the potential for collisions. \u201cIt\u2019s scary to think about,\u201d says Thiele.<\/p>\n Topics:<\/p>\n<\/section><\/div>\n![\"New](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/11\/28003449\/shutterstock_1102540808-scaled.jpg\")
\n <\/picture>\nThe world capital of astronomy: Chile<\/h3>\n