TOPEX/POSEIDON

TOPEX/POSEIDON is an active satellite operated by United States, launched on 1992-08-10 from Guiana Space Centre, Kourou. With over 34 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 1,331 km and 1,343 km with an inclination of 66.0°. It travels at approximately 25,888 km/h (7.19 km/s), completing one full orbit every 112 minutes — that’s roughly 12.81 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 thousands of years. Orbital Radar tracks TOPEX/POSEIDON in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

TOPEX/POSEIDON orbits at an average altitude of 1,337 km in the uppermost reaches of Low Earth Orbit. At this altitude, orbital decay is effectively zero without active deorbiting, and coverage footprints are significantly larger than lower LEO, though at the cost of higher latency. Within ±50 km of TOPEX/POSEIDON’s average altitude, there are currently 12 active payloads and 161 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 66.0°, TOPEX/POSEIDON passes over latitudes between 66.0°N and 66.0°S, covering most populated land masses in both hemispheres. This mid-inclination band balances global coverage with efficient launch energy requirements. United States operates approximately 12,339 active satellites in total, of which 4 share a similar altitude band with TOPEX/POSEIDON.