CONQUERING SPACE JUNK

Should we be worried about the debris we're leaving in orbit?

- Jonathan O'Callaghan

We humans aren't particularly good at cleaning up after ourselves on Earth, and it turns out we may be even worse when we leave our planet. In over 60 years of space exploration, we've rapidly filled Earth's orbit with junk, and that could become a serious problem in the not-too-distant future. The Soviet satellite Sputnik 1 became our first piece of space junk in October 1957 after it became the first human-made object ever to orbit Earth. By January 1958 its orbit had decayed enough that it re-entered our atmosphere and burned up, never to cause any trouble. But since then we've launched thousands of satellites into space, and many of them have been left in Earth orbit even after they have stopped working.

Space junk comes in all shapes and sizes, from bits as small as a fleck of paint to chunks as large as a satellite. More than 8,900 satellites have been launched since Sputnik, and over half are now defunct, orbiting Earth as junk. About 31,000 pieces of debris larger than a baseball are tracked in orbit, but it's estimated there are millions of smaller pieces. Travelling at speeds of more than 28,000 kilometres (17,400 miles) per hour, their size doesn't really matter - all space junk could cause devastating damage if it hit another object.