THOR DELTA 1 R/B

THOR DELTA 1 R/B is a spent rocket body associated with United States, launched on 1971-04-01 from Vandenberg Space Force Base, United States on the Isis B launch. After more than 55 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 1,352 km and 1,421 km with an inclination of 88.2°. It travels at approximately 25,805 km/h (7.17 km/s), completing one full orbit every 113 minutes — that’s roughly 12.69 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. Spent rocket bodies like THOR 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.

THOR DELTA 1 R/B orbits at an average altitude of 1,387 km in the uppermost reaches of Low Earth Orbit. At this altitude, orbital decay is effectively zero without active deorbiting, and coverage footprints are significantly larger than lower LEO, though at the cost of higher latency. Within ±50 km of THOR DELTA 1 R/B’s average altitude, there are currently 253 active payloads and 243 tracked debris or rocket body fragments. With an inclination of 88.2°, THOR DELTA 1 R/B passes over latitudes between 88.2°N and 88.2°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 12 share a similar altitude band with THOR DELTA 1 R/B.