CAT 4

CAT 4 is an active satellite operated by ESA (European Space Agency), launched on 1981-12-20 from Guiana Space Centre, French Guiana on the Marecs A launch. With over 45 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 259 km and 25,022 km with an inclination of 10.6°. It travels at approximately 16,484 km/h (4.58 km/s), completing one full orbit every 7 hours 15 minutes — that’s roughly 3.31 orbits per day. Its orbital eccentricity of 0.6513 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. Orbital Radar tracks CAT 4 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

CAT 4 orbits at an average altitude of 12,641 km in Medium Earth Orbit, the region between LEO and GEO (2,000–35,786 km). MEO’s higher altitude gives each satellite a much larger ground footprint than LEO, meaning fewer spacecraft are needed for global coverage — but signal latency is higher and radiation from the Van Allen belts is a significant design constraint. Within ±50 km of CAT 4’s average altitude, there are currently 1 active payload and 1 tracked debris or rocket body fragment. This is a relatively sparse altitude band, containing less than 1% of all active satellites. With an inclination of 10.6°, CAT 4 passes over latitudes between 10.6°N and 10.6°S, concentrating coverage over equatorial and near-equatorial regions. Low-inclination orbits maximise revisit rates over specific tropical zones. ESA (European Space Agency) operates approximately 93 active satellites in total.