PROSPERO (BLACK ARROW)

PROSPERO (BLACK ARROW) is an active satellite operated by RAE (United Kingdom), launched on 1971-10-28 from WOMRA on the X-3 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 525 km and 1,250 km with an inclination of 82.0°. It travels at approximately 26,678 km/h (7.41 km/s), completing one full orbit every 103 minutes — that’s roughly 14.02 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~100–500 years. Orbital Radar tracks PROSPERO (BLACK ARROW) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

PROSPERO (BLACK ARROW) orbits at an average altitude of 888 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 PROSPERO (BLACK ARROW)’s average altitude, there are currently 249 active payloads and 1,839 tracked debris or rocket body fragments. With an inclination of 82.0°, PROSPERO (BLACK ARROW) passes over latitudes between 82.0°N and 82.0°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 Kingdom operates approximately 725 active satellites in total.