Satellite collision


Strictly speaking, a satellite collision is when two satellites collide while in orbit around a third, much larger body, such as a planet or moon. This definition is typically loosely extended to include collisions between sub-orbital or escape-velocity objects with an object in orbit. Prime examples are the anti-satellite weapon tests. There have been no observed collisions between natural satellites, but impact craters may show evidence of such events. Both intentional and unintentional collisions have occurred between man-made satellites around Earth since the 1980s. Anti-satellite weapon tests and failed rendezvous or docking operations can result in orbital space debris, which in turn may collide with other satellites.

Natural-satellite collisions

There have been no observed collisions between natural satellites of any Solar System planet or moon. Collision candidates for past events are:
  • Impact craters on many Jupiter and Saturn's moons. They may have been formed by collisions with smaller moons, but they could equally likely have been formed by impacts with asteroids and comets during the Late Heavy Bombardment.
  • The far side of the Moon may have formed from the impact of a smaller moon that also formed during the giant impact event that created the Moon.
  • The objects making up the Rings of Saturn are believed to continually collide and aggregate with each other, leading to debris with limited size constrained to a thin plane. Although this is believed to be an ongoing process, this has not been directly observed.

Artificial-satellite collisions

Three types of collisions have occurred involving artificial satellites orbiting the Earth:

Spacecraft impacts with moons

Satellite collision avoidance

Satellite operators frequently maneuver their satellites to avoid potential collisions. One notable near collision was Sept 2019 between an ESA satellite and a SpaceX Starlink satellite, when ESA tweeted/complained at having to move to avoid the Starlink satellite.
A study from 2025, suggests that as of June 2025, if all LEO satellite operators stopped making any evasive maneuvers then a collision is likely to occur within 5.5 days. The researchers call this new metric "the CRASH Clock", and according to their calculations in January 2018 the CRASH clock was 164 days. They attribute the sharp reduction in the CRASH clock time to the launch of large satellite constellations such as Starlink.