ln August 2016, engineers at the European Space Agency (ESA) realised that something was wrong with their most important observation satellite. They quickly worked out that the satellite, orbiting 35 000 kilometres from the earth, had been hit by a tiny piece of debris. ’lt could have been something like a piece of soap,’ says one engineer. ’That might seem strange, but all sorts of things have been left in space and they travel at very high speeds over ten kilometres per second.’ Fortunately, the engineers were able to carry out repairs. Satellites and spacecraft require millions of dollars of investment, however, and the incident was a reminder that one day a very expensive piece of technology could be destroyed by space litter.
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| MAN-MADE SPACE DEBRIS |
Sputnik, the first ever man-made satellite was launched in 1957, and since then, over 5000 satellites have been sent into space. However, only about 1200 of them are currently working; the rest are no longer used and just orbit the earth like large pieces of junk. It’s not so surprising that these ’dead satellites,’ and even large parts of broken spacecraft, are a form of space pollution. But there are thought to be about 150 million man-made objects larger than one millimetre in size, and many of them are things that most people wouldn’t imagine were in space. Bits of paint and old batteries have been reported, and while they may not seem significant, they can be very dangerous.
’There is so much space debris,’ says one ESA engineer, ’that some sections of space may eventually become unusable.’ Scientists at the ESA are currently working on plans for spacecraft which function as space garbage trucks; these would pick up rubbish and bring it back to earth. Projects like this are costly and difficult, however, and experts stress the need for international agreements about dealing with man-made objects in space.
'Satellites and other spacecraft are equipped with radars and cameras which detect large objects, so they can avoid them says the ESA engineer. ’But the systems can't always detect objects of a more limited scale like a bit of unused fuel or even a tool lost by an astronaut during a space-walk. There’s also the fact that, at some point, human life may be at risk. Don’t forget that there are people working on the international Space Station and in other spacecraft, and their numbers are likely to grow.’
Unfortunately, the near future is likely to become even more complicated. Large companies are planning to launch several thousand new satellites into space in order to provide improved communications and internet access for all parts of the world. This makes the need to deal with space debris even more urgent. One possible solution relates to the design of satellites: when a satellite becomes out-of-date, it should automatically return to earth.
Dealing with smaller waste is, in some ways, more complicated. A research project in the USA is . aiming to develop laser beams, which would push rubbish out of orbit. Another proiect Japan is building a giant net that would collect small waste over a period of time. It would then be directed back to earth and its contents would burn up upon entering the Earth’s atmosphere.
Some of the ideas being considered are difficult to imagine, but solutions for dealing with man-made space litter are clearly needed.
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