DIAPASON (D1-A)

DIAPASON (D1-A) is an active satellite operated by CNES (France), launched on 1966-02-17 from Hammaguir, Algeria on the Diapason D-1A launch. After more than 60 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Medium Earth Orbit (MEO) at altitudes between 497 km and 2,293 km with an inclination of 34.1°. It travels at approximately 25,791 km/h (7.16 km/s), completing one full orbit every 114 minutes — that’s roughly 12.67 orbits per day. Its orbital eccentricity of 0.1156 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. Orbital Radar tracks DIAPASON (D1-A) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

DIAPASON (D1-A) orbits at an average altitude of 1,395 km in Medium Earth Orbit, the region between LEO and GEO (2,000–35,786 km). MEO’s higher altitude gives each satellite a much larger ground footprint than LEO, meaning fewer spacecraft are needed for global coverage — but signal latency is higher and radiation from the Van Allen belts is a significant design constraint. Within ±50 km of DIAPASON (D1-A)’s average altitude, there are currently 295 active payloads and 265 tracked debris or rocket body fragments. With an inclination of 34.1°, DIAPASON (D1-A) passes over latitudes between 34.1°N and 34.1°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.