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 785 km with an inclination of 85.0°. It travels at approximately 26,871 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 occupies the mid-LEO band between 600 and 1,000 km, where atmospheric drag is minimal but radiation exposure remains low. This altitude range balances orbital longevity (decades to centuries) with reasonable ground coverage, making it popular for remote sensing constellations, scientific instruments and weather satellites. Debris concerns are significant here because objects persist far longer than in lower orbits.