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Above your head right now, thousands of dead satellites, spent rocket stages and shards of metal are circling the Earth at about 28,000 kilometres per hour. Most of them are junk — and the pile is growing faster than anyone is cleaning it up. According to figures from the European Space Agency, updated on July 31, 2026, about 46,160 objects are regularly tracked around Earth. Roughly 16,000 are working satellites. The other 30,000 are debris: dead spacecraft, empty rocket bodies and fragments from more than 660 break-ups, explosions and collisions.
The part we cannot see is far bigger
The tracked catalogue is only the visible part of the problem. According to reports from Space Daily and the Hindustan Times, ESA's models estimate another 54,000 objects larger than 10 centimetres, about 1.2 million pieces between one and 10 centimetres, and roughly 140 million fragments between one millimetre and one centimetre. A one-centimetre fragment is too small to track, but at orbital speeds it carries enough energy to disable a satellite — and a paint flake once cracked a Space Shuttle window. Since 1957, more than 7,320 rocket launches have placed about 27,490 satellites in orbit, and the combined mass of everything humans have left up there now exceeds 17,000 tonnes. Objects in low Earth orbit travel at roughly 7.8 kilometres per second, and in a head-on encounter the relative speed can reach 14 kilometres per second.
What Kessler syndrome really means
In 1978, NASA scientist Donald Kessler warned of a chain reaction that now bears his name: in a crowded orbital band, collisions create debris faster than atmospheric drag removes it, and each new fragment raises the chance of the next collision. It is not a single catastrophic afternoon, but a slow, self-reinforcing process — and some heavily used regions are already past the threshold, according to ESA's modelling. The evidence is in the catalogue. The 2009 collision between the working Iridium 33 satellite and the dead Russian Kosmos 2251 created more than 2,300 trackable fragments, and about 500 were still in orbit in February 2024. The deliberate destruction of China's Fengyun-1C weather satellite in 2007 produced more than 3,400 fragments, and Russia's destruction of Cosmos 1408 in 2021 added about 1,500 more. ESA's 2026 environment report says current trends would put the long-term collision risk at four times its proposed sustainability threshold, with collision probability in low Earth orbit up 20%. Its satellites now average two collision-avoidance manoeuvres per spacecraft each year.
Can anything be done about it?
The short answer is yes, but slowly. The US regulator adopted a rule requiring satellites to deorbit within five years of finishing their mission, effective from September 2024. ESA's ClearSpace-1 mission, scheduled to launch in 2029, will attempt to capture and deorbit a satellite launched in 2001 — the first active debris removal of its kind. NASA's 2026 review of deorbit systems lists propulsion, drag sails, tethers and active removal among the approaches available or in development, and its models suggest preventing a cascade in the busiest sun-synchronous band requires actively removing five to ten large objects a year. The harder problem is political: the 1967 Outer Space Treaty makes states responsible for their national space activities, including those of private firms, but there is still no binding global system for cleaning up orbit. Until there is, the sky above us keeps getting more crowded — and every launch adds to a bill that is already 17,000 tonnes heavy. For humanity's next steps beyond Earth, see our report on NASA hiring astronauts who could live and work on the Moon and the Atacama desert's biggest bloom in 30 years.