DIADEME 1

DIADEME 1 is an active satellite operated by CNES (France), launched on 1967-02-08 from Hammaguir, Algeria on the Diademe D-1C launch. After more than 59 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 502 km and 786 km with an inclination of 39.9°. It travels at approximately 27,137 km/h (7.54 km/s), completing one full orbit every 98 minutes — that’s roughly 14.75 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~10–25 years. Orbital Radar tracks DIADEME 1 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

DIADEME 1 orbits at an average altitude of 644 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 DIADEME 1’s average altitude, there are currently 886 active payloads and 1,065 tracked debris or rocket body fragments — notable neighbours include TERRA, AQUA, ONEWEB-0050. With an inclination of 39.9°, DIADEME 1 passes over latitudes between 39.9°N and 39.9°S, covering the tropical and temperate zones where most of the world’s population resides. Low-to-mid inclination orbits are efficient to reach from equatorial and mid-latitude launch sites. France operates approximately 124 active satellites in total, of which 45 share a similar altitude band with DIADEME 1.