The millions of fragments of debris in orbit today are the direct result of 'fragmentation events' in the past. Of the 550 events known to date, those caused by propulsion have created the greatest amount of space debris.

Energy left undisposed of on-board a satellite or rocket body can lead to explosions. For this reason, the international space debris mitigation guidelines require that satellites are 'passivated' at the end of their mission - for example by emptying fuel tanks and disconnecting batteries.

Because of these guidelines, and passivation technologies being developed by ESA and others, we expect a similar graph for the future to have far fewer propellant-fueled explosions in the future. However, as traffic in space rapidly increases, the number of collisions is expected to rise.

Find out how we know about the causes of debris-creating events, and how this can help us prevent them in the joint ESA-UN podcast that narrates this infographic.