Britain recently began a diplomatic campaign to draw up new rules for responsible behaviour in space; essentially it's a "don't litter" policy intended to reduce the threat posed by decades of irresponsible dumping in orbit. But what's the scale of the problem of space littering, and how might things go wrong? Adam Murphy spoke to John Zarnecki, emeritus professor of Space Sciences at the Open University... Like this podcast? Please help us by supporting the Naked Scientists