In 2009, the American and Russian satellites Iridium-33 and Cosmos 2251 collided 800km over Siberia.
The collision resulted in two massive debris clouds encircling the globe, critically endangering other satellites in Lower Earth Orbit—an already dangerously overcrowded place. The collision shone a light on the growing problem of space debris. It wasn’t the first collision in orbit, and it won’t be the last, as the problem is self-perpetuating. It’s become known as Kessler Syndrome.
Of all the man-made satellites in Low Earth Orbit, 95% are junk known as space debris. Rocket thrusters, derelict satellites, and most of all, fragments of debris from collisions and explosions. Earth’s orbits are facing an environmental crisis that’s almost completely invisible to us, but which may carry dire consequences for our infrastructure and the future of spaceflight if left unchecked.
The worst case scenario is that you end up creating enough debris that it’s not cost-effective to depend on space. Now, that may take a long time, but because it’s a non-reversible process, once you’ve reached a certain threshold where you’re generating debris from these collisions faster than it can be cleaned out, it’ll just continually get worse unless you can do something drastic.
—Donald Kessler, Astrophysicist and former Head of the Orbital Debris Program Office at NASA
If we continue operating the way we do today, we will have a disaster in 50 years, in 100 years. It compares quite nicely to the CO2 issue, and the climate on ground, so it’s not our generation suffering from all the CO2 released into the atmosphere, it is future generations, but it is our generation that has to take the action. And the space debris problem is quite similar.
—Holger Krag, Head of the Space Debris Office at the European Space Agency
Written, Animated, Edited, and Narrated by
Special thanks to
Donald Kessler & Holger Krag
Mom & Dad
Blue Dot Sessions
Footage, Images, and Assets
European Space Agency
University of Surrey (RemoveDebris demonstration)
AGI (Iridium–Cosmos collision model)
tashtego (ENVISAT 3D model)
unaipl2003 (Dawn satellite model)
See all catalogued and tracked space debris in orbit: stuffin.space
NASA overview of space debris and its risk to human spacecraft
A detailed chronology of orbital debris (1995)
NASA presentation about orbital debris management and risk mitigation
A comprehensive overview of the history and terminology of the space debris problem
Donald Kessler’s 1978 paper introducing what became known as Kessler Syndrome