Luch ('beam') satellites are an element of the second generation Soviet global command and control system, deployed in the first half of the 1980s. Analogous to the American TDRSS (Tracking and Data Relay Satellite System), they provided communications service to Mir, the Buran shuttle, Soyuz-TM spacecraft, military satellites, and the TsUPK ground control center. They also supported mobile fleet communications for the Soviet Navy. The modernized Luch-2 allows two high data rate channels to operate at once, enabling real-time TV transmissions from Mir. Each satellite is equipped with three transponders and has a nominal life of five years. By January 1999, five had been launched.