Proton-K Blok D-1

8K82K Blok D-1 11S824F

Mission Profile

The Proton-K Blok D-1 (8K82K Blok D-1, 11S824F) was a four-stage Soviet/Russian heavy-lift launch vehicle in the Proton family, pairing the Proton-K with a Blok D-1 upper stage for geostationary and interplanetary missions. Standing 55.4 m tall with a 7.4 m diameter and a liftoff mass of 705 tonnes, it generated 9,870 kN of liftoff thrust and could deliver 5,500 kg to geostationary transfer orbit. First flying in October 1975, the Proton-K Blok D-1 launched Venera Venus probes, Vega Halley's Comet interceptors, and Phobos Mars spacecraft.