Payload
Kessler syndrome
The runaway scenario where collisions in orbit generate debris that causes more collisions.
Donald Kessler argued in 1978 that above a certain density of objects in low Earth orbit, collisions would produce fragments faster than atmospheric drag removed them, and the debris population would grow on its own regardless of anything launched afterwards. Two events did most of the damage so far: a Chinese anti-satellite test in 2007 and the Iridium–Cosmos collision in 2009, which together roughly doubled the tracked debris in their altitude band. Fragments travel at several kilometres a second, so a centimetre of aluminium carries the energy of a hand grenade. The consequence is not a Hollywood cascade in an afternoon but a slow closing-off of specific altitudes over decades.
Where it has come up lately
Related terms
Sun-synchronous orbit
A near-polar orbit that crosses the equator at the same local time every day.
Geostationary orbit
The one orbit where a satellite appears to hang motionless over a fixed point.
Low Earth orbit
Everything from about 160 to 2,000 km up, where almost all spacecraft and all people are.
Orbital inclination
The angle between an orbit and the equator, which decides what ground the satellite ever sees.
Questions
What is Kessler syndrome?
The runaway scenario where collisions in orbit generate debris that causes more collisions.
Why does it matter?
Fragments travel at several kilometres a second, so a centimetre of aluminium carries the energy of a hand grenade. The consequence is not a Hollywood cascade in an afternoon but a slow closing-off of specific altitudes over decades.