DELTA 1 R/B

DELTA 1 R/B is a spent rocket body associated with United States, launched on 1983-01-26 from Vandenberg SFB, California on the IRAS launch. With over 43 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 845 km and 875 km with an inclination of 100.1°. It travels at approximately 26,728 km/h (7.42 km/s), completing one full orbit every 102 minutes — that’s roughly 14.10 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 860 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 231 active payloads and 1,872 tracked debris or rocket body fragments — notable neighbours include NOAA 20, ONEWEB-0455. With an inclination of 100.1°, DELTA 1 R/B passes over latitudes between 100.1°N and 100.1°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 12,511 active satellites in total, of which 39 share a similar altitude band with DELTA 1 R/B.