SOLRAD 1 (GREB)

SOLRAD 1 (GREB) is an active satellite operated by NRL (United States), launched on 1960-06-22 from Cape Canaveral Space Force Station, United States. After more than 66 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 569 km and 849 km with an inclination of 66.7°. It travels at approximately 27,012 km/h (7.50 km/s), completing one full orbit every 99 minutes — that’s roughly 14.55 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~25–100 years. Orbital Radar tracks SOLRAD 1 (GREB) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

SOLRAD 1 (GREB) orbits at an average altitude of 709 km in the mid-LEO band, where atmospheric drag is minimal but radiation exposure remains manageable. Objects at this altitude persist for decades to centuries, making debris mitigation critical. This regime is popular for remote sensing constellations and scientific instruments that need stable, long-duration orbits. Within ±50 km of SOLRAD 1 (GREB)’s average altitude, there are currently 281 active payloads and 1,695 tracked debris or rocket body fragments — notable neighbours include TERRA, AQUA, ONEWEB-0179. With an inclination of 66.7°, SOLRAD 1 (GREB) passes over latitudes between 66.7°N and 66.7°S, covering most populated land masses in both hemispheres. This mid-inclination band balances global coverage with efficient launch energy requirements. United States operates approximately 13,279 active satellites in total, of which 86 share a similar altitude band with SOLRAD 1 (GREB).