CLEMENTINE

CLEMENTINE is an active satellite operated by CNES / DGA (France), launched on 1999-12-03 from Guiana Space Centre, French Guiana on the Helios 1B launch. With over 27 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 433 km and 436 km with an inclination of 98.2°. It travels at approximately 27,551 km/h (7.65 km/s), completing one full orbit every 93 minutes — that’s roughly 15.44 orbits per day. Its near-polar, sun-synchronous orbit means it passes over any given point on Earth at approximately the same local solar time, ideal for consistent Earth observation lighting conditions. 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 ~1–3 years. Orbital Radar tracks CLEMENTINE in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

CLEMENTINE orbits at an average altitude of 435 km in a sun-synchronous orbit (SSO), a specialised subset of LEO where the orbital plane precesses to maintain a constant angle relative to the Sun. This provides consistent lighting conditions on every pass — essential for Earth observation, weather monitoring and environmental science. Within ±50 km of CLEMENTINE’s average altitude, there are currently 9,765 active payloads and 122 tracked debris or rocket body fragments — notable neighbours include ISS (ZARYA), STARLINK-1017, STARLINK-1039. This makes it one of the more crowded altitude bands, containing roughly 52.2% of all active satellites. With an inclination of 98.2°, CLEMENTINE passes over latitudes between 98.2°N and 98.2°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. France operates approximately 124 active satellites in total, of which 11 share a similar altitude band with CLEMENTINE.