DELTA 1 R/B

DELTA 1 R/B is a spent rocket body associated with United States, launched on 1969-01-30 from Vandenberg Space Force Base, United States on the Isis A launch. After more than 57 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Medium Earth Orbit (MEO) at altitudes between 574 km and 3,283 km with an inclination of 88.4°. It travels at approximately 24,949 km/h (6.93 km/s), completing one full orbit every 2 hours 6 minutes — that’s roughly 11.47 orbits per day. Its orbital eccentricity of 0.1632 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of 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 1,929 km in Medium Earth Orbit, the region between LEO and GEO (2,000–35,786 km). MEO’s higher altitude gives each satellite a much larger ground footprint than LEO, meaning fewer spacecraft are needed for global coverage — but signal latency is higher and radiation from the Van Allen belts is a significant design constraint. Within ±50 km of DELTA 1 R/B’s average altitude, there are currently 4 active payloads and 26 tracked debris or rocket body fragments. This is a relatively sparse altitude band, containing less than 1% of all active satellites. With an inclination of 88.4°, DELTA 1 R/B passes over latitudes between 88.4°N and 88.4°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.