Graveyard orbit

A graveyard orbit, also called a junk orbit or disposal orbit, is an orbit that lies significantly away from common operational orbits, where spacecraft are intentionally placed at the end of their operational life. Most commonly, it refers to a supersynchronous orbit that lies significantly above synchronous orbit. It is a measure performed in order to reduce the probability of collisions with operational spacecraft and of the generation of additional space debris (known as Kessler syndrome). After moving a spacecraft to a graveyard orbit, it will typically be passivated.

A graveyard orbit is used when the change in velocity required to perform a de-orbit maneuver is too large. De-orbiting a geostationary satellite requires a delta-v of about 1,500 metres per second (4,900 ft/s), whereas re-orbiting it to a graveyard orbit only requires about 11 metres per second (36 ft/s).

For satellites in geostationary orbit and geosynchronous orbits, the graveyard orbit is a few hundred kilometers above the operational orbit. The transfer to a graveyard orbit above geostationary orbit requires the same amount of fuel that a satellite needs for approximately three months of stationkeeping. It also requires a reliable attitude control during the transfer maneuver. While most satellite operators try to perform such a maneuver at the end of the operational life, only one-third succeeded in doing so as of 2005. However, as of 2011, the majority of recently decommissioned geosynchronous spacecraft were said to have been relocated to a graveyard orbit.