THEOS

THEOS is an active satellite operated by Geo-Informatics and Space Technology Development Agency (GISTDA) (Thailand), launched on 2008-10-01 from OREN. After 18 years in orbit, it continues to be tracked by global surveillance networks. It orbits in Low Earth Orbit (LEO) at altitudes between 824 km and 826 km with an inclination of 98.6°. It travels at approximately 26,793 km/h (7.44 km/s), completing one full orbit every 101 minutes — that’s roughly 14.20 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 THEOS in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

THEOS orbits at an average altitude of 825 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 THEOS’s average altitude, there are currently 381 active payloads and 2,250 tracked debris or rocket body fragments — notable neighbours include NOAA 20, ONEWEB-0179, ONEWEB-0455. With an inclination of 98.6°, THEOS passes over latitudes between 98.6°N and 98.6°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. Thailand operates approximately 13 active satellites in total, of which 2 share a similar altitude band with THEOS.