There’s an awful lot of space debris that we humans have put into space, and most is still orbiting the Earth.
Its estimated that there are tens of millions of pieces of space debris.
Most of this comprised of small particles, less than 1 centimetre…
- These include dust from solid rocket motors, surface degradation products such as paint flakes, and coolant released by nuclear powered satellites.
- The damage that these particles will cause is similar to sandblasting, and can be partly prevented through things like “meteor bumpers” which are widely used on spacecraft such as the International Space Station.
- However, not all parts of a spacecraft can be protected. Solar panels, telescopes etc are subject to constant wear by debris (and to a much lesser extent, micrometeoroids).
- BUT… a 2mm piece of debris can rip a lethal hole in an astronaut’s spacesuit. The chance of such an object hitting an astronaut during a six-hour spacewalk is 31,000 to one.
- A much smaller number of the debris objects are larger, over 10 centimetres.
- The only protection against these objects is to manoeuvre the spacecraft to avoid a collision.
- If a collision does occur, most of the resulting fragments will cause additional collision risk!
- The chance of being hit by space junk on Earth is 20 billion to one. In 1997, a Lottie Williams was hit but unharmed by a 13cm piece of a Delta II rocket.
Vanguard 1, launched by the USA back in 1958, is the oldest piece of space junk. It stopped operating in 1964, but will continue orbiting Earth for 240 years.
The length of time junk stays in orbit before re-entering the atmosphere is only a few days when it’s below 200km, but increases to a few years between 200 and 600km.