Strategy Page on the latest developments in tracking even smaller pieces of space junk in orbit around the Earth:
The U.S. Air Force is spending nearly $4 billion to build a S-Band radar on Kwajalein Island in the Pacific. This will make it easier and cheaper to find and track small (down to 10mm/.4 inch) objects in orbit around the planet. Such small objects are a growing threat and Space Fence will make it possible to track some 300,000 10mm and larger objects in orbit.
Getting hit by an object 100mm (4 inch wide), if it’s coming from the opposite direction in orbit, results in an explosion equivalent to 20 kg (66 pounds) of TNT. That’s all because of the high speed (7 kilometers a second, versus one kilometers a second for high-powered rifles) of objects in orbit. Even a 10mm object hits with the impact of 50-60 g (2 ounces) of explosives. In the last 16 years eight space satellites have been destroyed by collisions with one of the 300,000 lethal (10mm or larger) bits of space junk that are in orbit. As more satellites are launched more bits of space junk are left in orbit. Based on that, and past experience, it’s predicted that ten more satellites will be destroyed by space junk in the next five years. Manned space missions are at risk as well. Three years ago a U.S. Space Shuttle mission to fix the Hubble space telescope faced a one in 229 chance of getting hit with space junk (that would have likely damaged the shuttle and required a backup shuttle be sent up to rescue the crew). Smaller, more numerous, bits of space junk are more of a danger to astronauts (in space suits) working outside. The shuttle crew working outside to repair the Hubble satellite had a much lower chance of being killed by space junk because a man in a space suit is much smaller and the space suits are designed to help the person inside survive a strike by a microscopic piece of space junk.
