Space Litter: When does the garbage pick up truck come?
It’s getting crowded up there: 15,000 pieces of junk plus 1000 active satellites, and counting.
• Sources include defunct satellites, rocket stages used to place satellites in orbit, bolts and other mission-related debris, and fragments from the intentional or accidental breakup of large objects. Also, the rare failed spacecraft that has stalled in orbit, such as the Russian Phobos–Grunt probe that just crashed to earth.
• The single largest debris generating event was in 2007, when China destroyed its polar orbiting satellite with a missile, resulting in 3000 trackable objects and 150,000 fragments of >1 cm size.The accidental collision of the Russian Cosmos 2251 and US Iridium 33 satellites in 2009 was responsible for another jump in space debris in 2009. Together, these two events effectively wiped out all space debris mitigation efforts until then (see graph, image 2).
• The risk of collision and damage at low earth orbit (<2000 km) is now at a few percent, comparable to other types of satellite failure like electrical defects. The Kessler syndrome describes a potential domino effect or feedback runaway (http://en.wikipedia.org/wiki/Kessler_syndrome). Space elevators, listed in the recent BBC poll as one of the top 20 predictions for the next 100 years, would almost certainly intersect with this debris.