SOLRAD 11A/B PKM

SOLRAD 11A/B PKM is a spent rocket body associated with United States, launched on 1976-03-15 from Cape Canaveral Space Force Station, United States on the LES 8 launch. After more than 50 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 36,238 km and 102,751 km with an inclination of 21.7°. It travels at approximately 8,252 km/h (2.29 km/s), completing one full orbit every 57.8 hours — that’s roughly 0.42 orbits per day. Its orbital eccentricity of 0.4384 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. At geostationary altitude, there is no meaningful atmospheric drag — this object will remain in orbit indefinitely unless actively deorbited. Spent rocket bodies like SOLRAD 11A/B PKM are among the largest pieces of uncontrolled space debris and are priority targets for collision avoidance manoeuvres and future active debris removal efforts.

SOLRAD 11A/B PKM orbits at an average altitude of 69,495 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. With an inclination of 21.7°, SOLRAD 11A/B PKM passes over latitudes between 21.7°N and 21.7°S, covering the tropical and temperate zones where most of the world’s population resides. Low-to-mid inclination orbits are efficient to reach from equatorial and mid-latitude launch sites. United States operates approximately 13,206 active satellites in total.