Soviet automated rendezvous and docking system overview

The Soviets have been performing automated rendezvous and docking for many years. It has been a reliable mode of resupply and reboost. During the course of the Soviet space program, the autodocking system has evolved. The earlier IGLA system was replaced with the current KURS system. Both systems are radar-based. The variation in strength between antennas is used for computing relative positions and attitudes. The active spacecraft has a transponder. From discussions with Soviet engineers, it seems the docking process can be controlled either from the ground or from the active (docking) spacecraft's onboard computer. The unmanned Progress resupply ships regularly dock with the current MIR Space Station. The Soyuz T spacecraft incorporated the IGLA system, and the later Soyuz TM and Progress M Series spacecraft incorporated the KURS. The MIR Complex has both systems installed. The rear port and the KVANT docking port have the IGLA system installed to support earlier Progress ships that use the IGLA. The first Soyuz TM docking occurred in May of 1986, while the first Progress M docked in September of 1989.