R-7 Semyorka version
R-7 Semyorka Molniya (8K78)
A four-stage R-7 derivative born of a crash programme to launch planetary probes. It takes its name from the Molniya communications satellites it orbited, and it also carried the early Venera probes towards Venus.
- No
- Reusable
History
A rocket to leave low orbit
The 8K78 came out of a crash programme by the Korolev bureau to field a launcher for planetary probes. To the R-7 architecture it added a larger third stage and a fourth, Blok L, designed to fire in orbit and send the payload out of low Earth orbit — replacing the imprecise direct ascent of the first-generation Luna probes launched on the 8K72. Core and boosters received the uprated 8D74K engines.
Problems and fixes
Early 8K78s carried a faulty Blok I prone to vibration and pump cavitation. The stage was redesigned and the improved version first flew on 11 November 1963. The uprated 8K78M was introduced in 1965, although 8K78s kept flying into 1967. A minor revision, Molniya (E6), moved the guidance system for the whole vehicle onto the probe itself for the Luna E-6 series.
Data and record
It measured 43.44 m long and 10.30 m across the boosters and weighed 305,000 kg at lift-off, with four stages: Blok B, V, G and D with RD-107 engines; Blok A with an RD-108K; Blok I with an RD-0108; and Blok L with an S1.5400. Its record lists forty launches, twenty successful, nine failed and eleven partial: Soviet planetary exploration in the 1960s was paid for with a very high failure rate.