DELTA 4 R/B

DELTA 4 R/B is a spent rocket body associated with United States, launched on 2003-03-11 from Cape Canaveral, Florida on the DSCS III A-3/IABS launch. With over 23 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 229 km and 17,500 km with an inclination of 25.3°. It travels at approximately 18,414 km/h (5.11 km/s), completing one full orbit every 5 hours 12 minutes — that’s roughly 4.61 orbits per day. Its orbital eccentricity of 0.5668 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. Spent rocket bodies like DELTA 4 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 4 R/B orbits at an average altitude of 8,865 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 4 R/B’s average altitude, there are currently 1 active payload and 8 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 25.3°, DELTA 4 R/B passes over latitudes between 25.3°N and 25.3°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.