IMS-1

IMS-1 is an active satellite operated by ISRO (India), launched on 2008-04-28 from Satish Dhawan Space Centre, India on the PSLV Rideshare 01 launch. After 18 years in orbit, it continues to be tracked by global surveillance networks. It orbits in Low Earth Orbit (LEO) at altitudes between 548 km and 555 km with an inclination of 98.0°. It travels at approximately 27,317 km/h (7.59 km/s), completing one full orbit every 96 minutes — that’s roughly 15.05 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 ~3–10 years. Orbital Radar tracks IMS-1 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

IMS-1 orbits at an average altitude of 552 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 IMS-1’s average altitude, there are currently 1,688 active payloads and 407 tracked debris or rocket body fragments — notable neighbours include STARLINK-1184, STARLINK-1276, ONEWEB-0050. This makes it one of the more crowded altitude bands, containing roughly 9% of all active satellites. With an inclination of 98.0°, IMS-1 passes over latitudes between 98.0°N and 98.0°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. India operates approximately 109 active satellites in total, of which 19 share a similar altitude band with IMS-1.