Space junk is the name for all human made material orbiting the Earth that no longer serves any useful purpose. This can be anything from a tiny fleck of paint to a whole defunct satellite.
There are an estimated 19,000 pieces of ‘large’ debris (more than 10cm across) whereas the number of pieces of ‘small’ debris (under 1 cm) has been estimated to be in the millions.
Cause for concern
The main concern with space debris is that it may hit an operational satellite such as a GPS satellite or the International Space Station. Flecks of paint less than 1cm in diameter sound harmless enough, but when they’re travelling at around 8km per second – faster than a rifle bullet – then they become lethal.
Every single space mission leaves space debris behind, whether from a satellite firing up its motor, the natural ageing of materials while in orbit or collisions between larger bits of debris, every piece that is added to the orbital skip adds to the headache of keeping operational satellites safe.
With over 6 000 rocket launches to date and many hundreds more launches planned over the next two years, the amount of space junk shows no sign of reducing.
Recent studies have suggested that lasers could be used in what might be the biggest clean-up operation ever known. The idea is that a high-powered pulsed laser system firing jets of plasma will cause the debris to slow down to the point where it re-enters Earth’s orbit, either burning up in the atmosphere or landing safely in the ocean.
One reservation, however, is that the laser system could end up being used by the military to sabotage or destroy their enemy satellites in attacks akin to those of a Bond villain.
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