DMSP 5D-3 F17 (USA 191)

DMSP 5D-3 F17 (USA 191) is an active satellite operated by United States, launched on 2006-11-04 from Vandenberg SFB, California. With over 20 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 836 km and 849 km with an inclination of 98.7°. It travels at approximately 26,761 km/h (7.43 km/s), completing one full orbit every 102 minutes — that’s roughly 14.15 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. It is part of the Weather constellation group. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~100–500 years. Orbital Radar tracks DMSP 5D-3 F17 (USA 191) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

DMSP 5D-3 F17 (USA 191) 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°.