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Greening Space: The Environmental Problem of Space Junk
 There are some pretty crazy environmental ideas out there – you may have heard the idea for human habitation of the Moon or Mars once human-induced environmental degradation makes the Earth too polluted to live on. But we may need to reconsider even this most drastic plan, because we’re already throwing our trash away into space, too! “Space junk” is the term used to describe the broken or disused satellites, pieces of rockets and other debris that are orbiting the Earth, left over from space missions.
NASA estimates that over 16,000 pieces of “space junk” bigger than 10cm litter the atmosphere around the earth. Since the space race, it has been assumed that space is so big that it is fine to leave “left overs” up there, or to wait thousands of years for the trash to be pulled back down to Earth itself, generally burning up in the atmosphere. However, whereas Space is indeed big, the orbit space around the Earth is not. Therefore, it is environmentally irresponsible to leave junk in space. By now, it’s also very hard to get rid of it. There are various options being explored, such as the CleanSpace One satellite that would intercept larger pieces of space junk and bring them back to Earth. Some organisations are also researching the possibility of creating large nets that could be dragged through the Earth’s orbit to pick up the space junk.
As well as tarnishing Space’s environment, even the smallest pieces of space junk can be very dangerous. The orbit speed of these bits of rubbish is around 28,000km/hr. Even a small bolt or a piece of metal can cause serious damage when it’s flying that fast since it is the speed at which two objects strike one another that determine the energy of the collision. A French satellite was damaged in 1996 by a piece of rocket, and an U.S. communications satellite was destroyed in 2009 in a collision with a defunct Russian satellite (this collision caused 2,000 more pieces of space junk). Scientists are particularly worried by the fact that one collision produces a lot of small fragments, as this causes more pieces of space debris that may collide into one another, causing ever more fragments! The Kessler Syndrome describes this process, with the end result that the Earth is surrounded by space junk and we can no longer safely enter Space. The International Space Station, the largest man-made object in Space, has already been playing ‘dodge’ with pieces of space debris for years, and has been forced to manoeuvre out of the way of space junk more than 10 times. It recently had a near miss with a piece of space junk, which luckily missed the Station by 250 metres.
International negotiations are underway between Space-exploring countries that would require any new satellites or rockets launched into Space to have mechanisms that would ensure that they returned to Earth. However, space is becoming commercialised and it is no longer the playground only of nations. More and more private companies are launching private space shuttles, such as SpaceX and Richard Branson’s Virgin. This will make it even harder to control what goes up into space, and in particular what comes back down.
Image courtesy of sweetie187 on flickr
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