ERS-1

ERS-1 is an active satellite operated by ESA (European Space Agency), launched on 1991-07-17 from Guiana Space Centre, Kourou. With over 35 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 737 km and 783 km with an inclination of 98.8°. It travels at approximately 26,915 km/h (7.48 km/s), completing one full orbit every 100 minutes — that’s roughly 14.39 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 ~25–100 years. Orbital Radar tracks ERS-1 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

ERS-1 operates in a sun-synchronous orbit (SSO), a special subset of LEO where the orbital plane precesses to keep a constant angle relative to the Sun. This means the satellite crosses any given latitude at approximately the same local solar time on every pass, providing consistent lighting conditions — essential for Earth observation, weather monitoring and environmental science. SSO orbits typically sit between 600 and 800 km altitude with inclinations near 97–99°.