The Kessler Syndrome

Gravity

If you haven't seen the movie yet, you ought to, it's not the best move ever made, it is entertaining, and it explores an interesting phenomenon known as the Kessler Syndrome.  The syndrome is named after Donald Kessler a NASA scientist who first speculated on the possibility of an ablative cascade in orbit, and it turns out the possibilities are not all that remote.

Rack'em!

Imagine if you would a game of pool in which every time the balls struck each other the broke into a number of smaller balls based on the speed of the impact.  The opening break may very well leave the table covered with marbles, put enough energy into it and you may wind up with the felt covered with BB's.

In 2007 the Chinese took out one of their own Fengyun weather satellites in the test of kinetic kill vehicle.  The impact turned a 750 kg satellite into roughly 2,300 pieces from the size of a golf ball on up, and 150,000 pieces smaller than a golf ball.

In 2009 a fourteen year old derelict Russian satellite known as Kosmos-2251 collided with a working Iridium (communications) satellite known as Iridium 33. The collision produced over 1,000 pieces four inches or larger, by 2011 as capabilities improved an additional 1,000 objects from the collision were added to the space catalog. 

It's not a matter of if another catastrophic collision occurs but when.  Satellite operators have to balance a limited on-board fuel supply against the probability of conjunction. In the Kosmos-Iridium case a conjunction of +/- 584 meters was predicted and either Iridium didn't get warning, or balanced the warning against the level of risk and chose not to maneuver.  In the end Iridium lost a $5M satellite.