OAO 3 (COPERNICUS)

OAO 3 (COPERNICUS) is an active satellite operated by GSFC (United States), launched on 1972-08-21 from Cape Canaveral Space Force Station, United States on the OAO-C launch. After more than 54 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 688 km and 698 km with an inclination of 35.0°. It travels at approximately 27,042 km/h (7.51 km/s), completing one full orbit every 99 minutes — that’s roughly 14.60 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 ~10–25 years. Orbital Radar tracks OAO 3 (COPERNICUS) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

OAO 3 (COPERNICUS) orbits at an average altitude of 693 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 OAO 3 (COPERNICUS)’s average altitude, there are currently 305 active payloads and 1,489 tracked debris or rocket body fragments — notable neighbours include TERRA, AQUA, ONEWEB-0179. With an inclination of 35.0°, OAO 3 (COPERNICUS) passes over latitudes between 35.0°N and 35.0°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 13,276 active satellites in total, of which 80 share a similar altitude band with OAO 3 (COPERNICUS).