NATO 4A R/B(PAM-D)

NATO 4A R/B(PAM-D) is a spent rocket body associated with United States, launched on 1991-01-08 from Cape Canaveral, Florida on the NATO 4A launch. With over 35 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 793 km and 35,424 km with an inclination of 26.1°. It travels at approximately 14,527 km/h (4.04 km/s), completing one full orbit every 10 hours 36 minutes — that’s roughly 2.27 orbits per day. Its orbital eccentricity of 0.7073 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. Spent rocket bodies like NATO 4A R/B(PAM-D) are among the largest pieces of uncontrolled space debris and are priority targets for collision avoidance manoeuvres and future active debris removal efforts.

NATO 4A R/B(PAM-D) orbits at an average altitude of 18,109 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 NATO 4A R/B(PAM-D)’s average altitude, there are currently 2 active payloads and 23 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 26.1°, NATO 4A R/B(PAM-D) passes over latitudes between 26.1°N and 26.1°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 12,413 active satellites in total.