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Cosmos 1629



Cosmos 1629 was part of a Soviet constellation of satellites comprised of the first echelon of the Missile Attack Warning System (SPRN), which was operated by the Air Defense Forces of the Ministry of Defense. According to Soviet officials, the early warning satellites could detect missile launches within 20 seconds of lift-off.

Each satellite possessed a perigee of about 600 km, an apogee of nearly 40,000 km, and an inclination of 63 degrees. This orbit was superfically similar to that employed by the Molniya communications satellites but was distinguished by initial argument of perigee 316-319 degrees, including to the Molniya 280-288 degree arguments of perigee. The seemingly minor difference significantly affected the shape of the satellite's groundtrack in the Northern Hemisphere.

Russian early warning spacecraft were more affected by gravitational perturbations due to their higher argument of perigee and, therefore, performed periodic station-keeping maneuvers to maintain an acceptable groundtrack. In addition, the argument of perigee migrated slightly over time (due to inclination variations), causing an alteration in the shape of the groundtrack. Instead of expending additional propellant to prevent the argument of perigee shift, Russian spacecraft controllers altered the satellite's ascending node. This had the effect of "stabilizing" the apogee point about which surveillance operations were performed.

Alternate Names

  • 15574
  • Cosmos1629

Facts in Brief

Launch Date: 1985-02-21
Launch Vehicle: Proton-K
Launch Site: Tyuratam (Baikonur Cosmodrome), U.S.S.R
Mass: 2000 kg

Funding Agency

  • Unknown (U.S.S.R)


  • Surveillance and Other Military

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office

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