CALIPSO

CALIPSO is an active satellite operated by Centre National d'Etudes Spatiales (CNES)/NASA (France), launched on 2006-04-28 from Vandenberg SFB, California. With over 20 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 662 km and 664 km with an inclination of 98.5°. It travels at approximately 27,100 km/h (7.53 km/s), completing one full orbit every 98 minutes — that’s roughly 14.69 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 ~10–25 years. Orbital Radar tracks CALIPSO in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

CALIPSO orbits at an average altitude of 663 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 CALIPSO’s average altitude, there are currently 649 active payloads and 1,121 tracked debris or rocket body fragments — notable neighbours include TERRA, AQUA, LANDSAT 9. With an inclination of 98.5°, CALIPSO passes over latitudes between 98.5°N and 98.5°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 115 active satellites in total, of which 43 share a similar altitude band with CALIPSO.