EXPLORER 11

EXPLORER 11 is an active satellite operated by GSFC (United States), launched on 1961-04-27 from Cape Canaveral Space Force Station, United States. After more than 65 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Low Earth Orbit (LEO) at altitudes between 463 km and 1,170 km with an inclination of 28.8°. It travels at approximately 26,809 km/h (7.45 km/s), completing one full orbit every 101 minutes — that’s roughly 14.23 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~100–500 years. Orbital Radar tracks EXPLORER 11 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

EXPLORER 11 orbits at an average altitude of 817 km in the upper LEO band, where atmospheric drag is negligible and objects can persist for centuries to millennia. This altitude is used by broadband constellations like OneWeb and by scientific missions requiring stable orbits far from the densest debris bands. Within ±50 km of EXPLORER 11’s average altitude, there are currently 430 active payloads and 2,537 tracked debris or rocket body fragments — notable neighbours include NOAA 20, ONEWEB-0455. With an inclination of 28.8°, EXPLORER 11 passes over latitudes between 28.8°N and 28.8°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 13,279 active satellites in total, of which 162 share a similar altitude band with EXPLORER 11.