BLOCK DM-SL R/B

BLOCK DM-SL R/B is a spent rocket body associated with Sea Launch, launched on 1999-10-10 from Sea Launch (ocean platform) on the DirecTV-1R launch. With over 27 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 2,634 km and 35,776 km with an inclination of 1.0°. It travels at approximately 14,212 km/h (3.95 km/s), completing one full orbit every 11 hours 19 minutes — that’s roughly 2.12 orbits per day. Its orbital eccentricity of 0.6479 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 19,205 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 7 tracked debris or rocket body fragments — notable neighbours include COSMOS 1492 (GLONASS), COSMOS 1594 (GLONASS). This is a relatively sparse altitude band, containing less than 1% of all active satellites. With an inclination of 1.0°, BLOCK DM-SL R/B passes over latitudes between 1.0°N and 1.0°S, concentrating coverage over equatorial and near-equatorial regions. Low-inclination orbits maximise revisit rates over specific tropical zones.