Proton-K

8K82K UR-500K

Mission Profile

Proton-K (8K82K, UR-500K) is the first orbital-capable variant of the Proton rocket family, adding a Blok D upper stage to the original two-stage Proton vehicle to achieve geostationary and lunar mission capability. Standing 44.3 meters tall with a 693,000 kg liftoff mass and 21,000 kg to LEO, it first flew on 16 November 1968 and launched the Zond lunar flyby missions, Salyut space stations, and numerous Gorizont geostationary communications satellites. Proton-K established the rocket as the Soviet Union's primary heavy-lift workhorse for decades.