Jonathan McDowell is an astrophysicist at the Harvard Smithsonian Center for Astrophysics, who studies black holes, quasars and X-ray sources in galaxies, as well as supporting the development of data analysis software for the X-ray astronomy community. In addition to his research Jonathan runs `Jonathans Space Report', which is a newsletter that has been running since 1989 that reports on recent space launches, International Space Station activities and space craft developments. In this episode of the podcast Jonathan discusses space junk, where it comes from, why it is a problem, and possible solutions for cleaning it up.