BLOCK DM-SL R/B

BLOCK DM-SL R/B is a spent rocket body associated with Sea Launch, launched on 2008-03-19 from Sea Launch (ocean platform) on the DirecTV-11 launch. After 18 years in orbit, it continues to be tracked by global surveillance networks. It orbits in Medium Earth Orbit (MEO) at altitudes between 131 km and 14,887 km with an inclination of 0.5°. It travels at approximately 19,292 km/h (5.36 km/s), completing one full orbit every 4 hours 31 minutes — that’s roughly 5.31 orbits per day. Its orbital eccentricity of 0.5316 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. Spent rocket bodies like BLOCK DM-SL 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.

BLOCK DM-SL R/B orbits at an average altitude of 7,509 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 BLOCK DM-SL R/B’s average altitude, there are currently 3 active payloads and 13 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 0.5°, BLOCK DM-SL R/B passes over latitudes between 0.5°N and 0.5°S, concentrating coverage over equatorial and near-equatorial regions. Low-inclination orbits maximise revisit rates over specific tropical zones.