This week, the US became the first country to ban anti-satellite missile tests, in an effort to protect Earth’s orbit from dangerous space debris. There could be millions of pieces of old satellites and spent rockets zooming around above our atmosphere, at speeds where collisions can be catastrophic. Guardian science editor Ian Sample talks to Prof Don Pollacco and Prof Chris Newman about the threat posed by space junk, and how we can tackle the problem. Help support our independent journalism at theguardian.com/sciencepod