MOST

MOST is an active satellite operated by Canadian Space Agency (Canada), launched on 2003-06-30 from PKMTR. With over 23 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 815 km and 827 km with an inclination of 98.7°. It travels at approximately 26,801 km/h (7.44 km/s), completing one full orbit every 101 minutes — that’s roughly 14.21 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 ~100–500 years. Orbital Radar tracks MOST in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

MOST orbits at an average altitude of 821 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 MOST’s average altitude, there are currently 389 active payloads and 2,279 tracked debris or rocket body fragments — notable neighbours include NOAA 20, ONEWEB-0179, ONEWEB-0455. With an inclination of 98.7°, MOST passes over latitudes between 98.7°N and 98.7°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. Canada operates approximately 67 active satellites in total, of which 7 share a similar altitude band with MOST.