Composite image not to scale. Not even close. Background image: NASA
Staring up on a clear starry night, you wouldn't think that you are looking at a junkyard, but there are more than 9,000 pieces of manmade debris, weighing over 5-million kg (5,500 tons), unassumingly orbiting earth.
"Currently there is no easy and inexpensive way to remove objects from space," NASA researcher Jer Chyi Liou said via e-mail.
The figure includes more than 1,500 discarded rocket bodies and almost 3,000 objects that were once payload on space missions, such as now-defunct satellites.
Currently the International Space Station and space shuttle do their work in a zone between 400 and 600 km (250 and 375 miles) above Earth's surface, while the debris is concentrated between 885 and 1000 km (550 and 625 miles) away. So, for now, the risk of a potential collision with the junk is greater for commercial satellites and research missions, such as the recent unmanned NASA expedition to Pluto.
Even though the junk cloud is out of reach, NASA researchers have mapped, catalogued and tracked every item larger than 10 cm. The debris will eventually fall out of orbit and burn up as it enters the Earth's atmosphere. But that isn't happening fast enough.
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A paper in the January 20th issue of Science says that even if we don't launch any additional rockets or satellites, fragments of space refuse (which break off as a result of periodic collisions) will increase the total amount of interstellar debris. Collisions alone could cause the number of objects to triple over the next two centuries. New fragments would increase the probability of further collisions by a factor of 10.
Lead-author Liou cautions that the Science paper describes a best case scenario, because it assumes no future launches.
"In reality, as we continue to launch satellites and rocket bodies into space, it will only get worse."
NASA researchers hope their research will spur efforts to engineer economically viable ways to clean up the mess. That work is still largely in the theoretical phase; proposed options include a real-life version of Space Invaders which uses ground-based lasers to zap the junk out of orbit.