Earlier this week, the International Space Station (ISS) was forced to maneouvre out of the way of a potential collision with space junk. With a crew of astronauts and cosmonauts on board, this required an urgent change of orbit on November 11.

Over the station's 23-year orbital lifetime, there have been about 30 close encounters with orbital debris requiring evasive action. Three of these near-misses occurred in 2020. In May this year there was a hit: a tiny piece of space junk punched a 5mm hole in the ISS's Canadian-built robot arm.

This week's incident involved a piece of debris from the defunct Fengyun-1C weather satellite, destroyed in 2007 by a Chinese anti-satellite missile test. The satellite exploded into more than 3,500 pieces of debris, most of which are still orbiting. Many have now fallen into the ISS's orbital region.

To avoid the collision, a Russian Progress supply spacecraft docked to the station fired its rockets for just over six minutes. This changed the ISS's speed by 0.7 meters per second and raised its orbit, already more than 400km high, by about 1.2km.