The Parus satellites form a network of military satellites which, for a quarter of a century, has provided navigational information and store-dump radio communications for Russian/Soviet naval forces and ballistic missile submarines. Being the operational successor to Tsyklon, Parus is also known as Tsyklon-B. Flight trials of the new satellites began in 1974 and the system was accepted into military service in 1976. From 1974 to the present, there have been about 90 launches in the series, all by Cosmos-3M rockets from Plesetsk, into roughly circular orbits with an altitude of about 1,000 kilometers and an inclination of 83°.