Proton version
Proton Proton-K (8K82K)
The version that carried the Soviet space programme for forty-five years: it launched every Salyut station, almost every Mir module and the Zarya and Zvezda modules of the International Space Station. 50 m tall, 19,760 kg to low Earth orbit and 310 launches to 2012.
- March 10, 1967
- First launch
- 19,760 kg
- LEO capacity
- No
- Reusable
History
A hypergolic rocket
The Proton-K burns unsymmetrical dimethylhydrazine and nitrogen tetroxide, hypergolic propellants that ignite on contact: no ignition system is needed, they store at ambient temperature and the rocket can sit on the pad indefinitely. The unusual look of its first stage — a central oxidiser tank ringed by six fuel tanks that resemble boosters but never separate — comes from a railway constraint: the central tank is the widest the track loading gauge allows.
Upper stages
The fourth stage came in several versions depending on the mission. The simplest, Blok D, served interplanetary missions and had no guidance module, relying on the probe itself. Three Blok DM versions (DM, DM2 and DM-2M) worked high Earth orbits. Blok D and its derivatives were unusual in storing fuel in a toroidal tank around the engine. When the space station programme began in 1971, Protons started flying with the Blok D removed as a heavy low-orbit lifter.
Record
The maiden flight, on 10 March 1967, carried a Soyuz 7K-L1 of the Zond programme, part of the uncrewed circumlunar tests with which the USSR hoped to beat Apollo. Through the 1970s and 1980s it launched every Venera and Mars probe with its Blok D fourth stage and, in three-stage form, all seven Salyut stations. From 1986 it orbited six of the seven Mir modules and, from 1998, the Zarya and Zvezda modules of the ISS Russian segment; the vehicle's payload record, 22,776 kg, belongs to Zvezda itself. Its 310th and final flight came on 30 March 2012, replaced by the Proton-M.