ERS 15

ERS 15 is an active satellite operated by USAF SSD (United States), launched on 1966-08-19 from Vandenberg Space Force Base, United States on the Midas RTS-I F2 launch. After more than 60 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 3,686 km and 3,698 km with an inclination of 90.3°. It travels at approximately 22,657 km/h (6.29 km/s), completing one full orbit every 2 hours 48 minutes — that’s roughly 8.59 orbits per day. Orbital Radar tracks ERS 15 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

ERS 15 orbits at an average altitude of 3,692 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 ERS 15’s average altitude, there are currently 8 active payloads and 5 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 90.3°, ERS 15 passes over latitudes between 90.3°N and 90.3°S, providing near-global coverage including the polar regions. Polar and near-polar orbits are used for reconnaissance, weather monitoring and Earth-observation missions that need to image every part of the planet. United States operates approximately 13,276 active satellites in total, of which 8 share a similar altitude band with ERS 15.