sciencesoup:

Space Fence: Watching Over Us

Earth is surrounded by a dense population of orbiting man-made junk, such as derelict spacecraft, obsolete satellites and rubble and shards from explosions or collisions. NASA estimates that there are 22,000 pieces of junk bigger than a softball orbiting us, 500,000 pieces bigger than a marble, and hundreds of millions of pieces smaller than 1cm. This junk is dense and fast-moving, and collisions with current operational satellites could be devastating—not to mention the International Space Station—so the US-based “Space Fence” program is being developed to improve the way we detect, track, measure and catalogue this debris. It will replace the aging Air Force Space Surveillance System (installed in 1961), and with ground-based radars at different geographical sites, the Space Fence program will be able to detect smaller microsatellites and debris than current systems allow. It’s expected to track 200,000 objects in a search area 220,000 times the volume of Earth’s oceans, helping us differentiate between potential and actual threats and therefore protect satellites vital to the functioning of GPS, banking, and communication. Lockheed Martin is developing the radar system for the US Air Force, and the program is expected to go live in 2017.