OPS 1127 (DMSP 4B F3)

OPS 1127 (DMSP 4B F3) is an active satellite operated by SAMSO (United States), launched on 1969-07-23 from Vandenberg Space Force Base, United States on the DAPP 7421 launch. After more than 57 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Low Earth Orbit (LEO) at altitudes between 763 km and 824 km with an inclination of 98.4°. It travels at approximately 26,852 km/h (7.46 km/s), completing one full orbit every 101 minutes — that’s roughly 14.30 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 OPS 1127 (DMSP 4B F3) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

OPS 1127 (DMSP 4B F3) orbits at an average altitude of 794 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 OPS 1127 (DMSP 4B F3)’s average altitude, there are currently 446 active payloads and 2,494 tracked debris or rocket body fragments — notable neighbours include NOAA 20, ONEWEB-0455. With an inclination of 98.4°, OPS 1127 (DMSP 4B F3) passes over latitudes between 98.4°N and 98.4°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. United States operates approximately 13,279 active satellites in total, of which 193 share a similar altitude band with OPS 1127 (DMSP 4B F3).