Space might seem an empty, vast expanse, but satellites in Earth's orbit face the constant risk of collision - with other satellites, dead or alive, or with fragments of debris.

It is now routine for operators of spacecraft in busy highways to divert their mission out of harms way. In fact at ESA, each mission flown performs on average two 'collision avoidance manoeuvres' per year.

These manoeuvres are costly. Hours are spent on the ground monitoring the skies, calculating the risk and planning manoeuvres, not to mention the extra fuel spent and missed science and data collected while instruments are turned off.

Find out more in the joint ESA-UN podcast that narrates this space debris infographic series, with Benjamin Bastida Virgili and Hazuki Mori.