USA 81

USA 81 is an active satellite operated by United States, launched on 1992-04-25 from Vandenberg SFB, California. With over 34 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 782 km and 786 km with an inclination of 85.0°. It travels at approximately 26,870 km/h (7.46 km/s), completing one full orbit every 101 minutes — that’s roughly 14.32 orbits per day. Its near-circular orbit (eccentricity close to zero) means it maintains a very consistent altitude throughout each revolution. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~25–100 years. Orbital Radar tracks USA 81 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

USA 81 orbits at an average altitude of 784 km in the mid-LEO band, where atmospheric drag is minimal but radiation exposure remains manageable. Objects at this altitude persist for decades to centuries, making debris mitigation critical. This regime is popular for remote sensing constellations and scientific instruments that need stable, long-duration orbits. Within ±50 km of USA 81’s average altitude, there are currently 419 active payloads and 2,230 tracked debris or rocket body fragments — notable neighbours include NOAA 20, ONEWEB-0179, ONEWEB-0455. With an inclination of 85.0°, USA 81 passes over latitudes between 85.0°N and 85.0°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 12,360 active satellites in total, of which 155 share a similar altitude band with USA 81.