Watch out for the space junk

Computer-generated images of objects in orbit around the Earth. These are objects, not shown to scale, that are large enough (at least 5 cm across) to be tracked by the US Space Surveillance Network. Some 95% are junk, i.e. not functioning satellites, with most occupying a low Earth orbit up to an altitude of 2000 km (left). Those items of junk in a geostationary orbit some 36 000 km high (right) form a clear ring, since they are located directly over the equator and have the same orbital period as the Earth. (Courtesy:NASA)

By Hamish Johnston

It’s finally happened — a very expensive telecommunications satellite has been destroyed by a piece of space junk. On Tuesday, one of 66 satellites that cover the Earth for the phone company Iridium was taken out by a defunct Russian satellite.

Although space is a big place, humans have managed to put lots of junk up there since the first satellite was launched in 1957 — as you can see in the illustrations above.

The pictures come from an article by Edwin Cartlidge — “Our orbiting junk-yard” — that appeared in the October 2007 issue of Physics World. I’m afraid that the full article is not available on physicsworld.com, but if your library subscribes to the Physics World Archive, you can read Edwin’s article here

Members of the Institute of Physics can read an online version of the Physics World. Simply login here and follow the Physics World link.