DELTA 1 R/B

DELTA 1 R/B is a spent rocket body associated with United States, launched on 1975-04-09 from Vandenberg Space Force Base, United States on the Geos C launch. After more than 51 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Low Earth Orbit (LEO) at altitudes between 770 km and 843 km with an inclination of 115.0°. It travels at approximately 26,828 km/h (7.45 km/s), completing one full orbit every 101 minutes — that’s roughly 14.26 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~100–500 years. Spent rocket bodies like DELTA 1 R/B are among the largest pieces of uncontrolled space debris and are priority targets for collision avoidance manoeuvres and future active debris removal efforts.

DELTA 1 R/B orbits at an average altitude of 807 km in the upper LEO band, where atmospheric drag is negligible and objects can persist for centuries to millennia. This altitude is used by broadband constellations like OneWeb and by scientific missions requiring stable orbits far from the densest debris bands. Within ±50 km of DELTA 1 R/B’s average altitude, there are currently 466 active payloads and 2,515 tracked debris or rocket body fragments — notable neighbours include NOAA 20, ONEWEB-0455. With an inclination of 115.0°, DELTA 1 R/B passes over latitudes between 115.0°N and 115.0°S, providing near-global coverage including the polar regions. Polar and near-polar orbits are used for reconnaissance, weather monitoring and Earth-observation missions that need to image every part of the planet. United States operates approximately 13,206 active satellites in total, of which 179 share a similar altitude band with DELTA 1 R/B.