SSETI-EXPRESS

SSETI-EXPRESS is an active satellite operated by ESA (European Space Agency), launched on 2005-10-27 from PKMTR. With over 21 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 666 km and 686 km with an inclination of 98.3°. It travels at approximately 27,075 km/h (7.52 km/s), completing one full orbit every 98 minutes — that’s roughly 14.65 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. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~10–25 years. Orbital Radar tracks SSETI-EXPRESS in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

SSETI-EXPRESS orbits at an average altitude of 676 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 SSETI-EXPRESS’s average altitude, there are currently 534 active payloads and 1,252 tracked debris or rocket body fragments — notable neighbours include TERRA, AQUA, LANDSAT 9. With an inclination of 98.3°, SSETI-EXPRESS passes over latitudes between 98.3°N and 98.3°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. ESA (European Space Agency) operates approximately 93 active satellites in total, of which 8 share a similar altitude band with SSETI-EXPRESS.