R-7 Semyorka

The R-7 Semyorka (Russian: Р-7 Семёрка, lit.'number seven', GRAU index: 8K71) was a Soviet missile developed during the Cold War, and the world's first intercontinental ballistic missile. The basis for the R-7 rocket family, it was adapted into the world's first orbital launch vehicle, Sputnik, and the crewed orbital launch vehicles Vostok. R-7 derivatives are the most launched rocket family ever with over 2,000 flights as of 2026, primarily Soyuz variants.

Developed by OKB-1 under Sergei Korolev, the R-7 used a kerolox propellant, with a 37 meter-tall core stage powered by the four-chamber RD-108 engine, and four boosters each powered by one four-chamber RD-107 engines. It carried a thermonuclear warhead of between three and five megatons, based on the RDS-37 design. The R-7 made 28 launches between 1957 and 1961. A derivative, the R-7A, was operational from 1960 to 1968. Western Cold War espionage did not discover the R-7 until its launch, later giving it the NATO reporting nameSS-6 Sapwood. In August 1957, it was first tested successfully, flying 6,000 km from Baikonur Cosmodrome to Kura Missile Test Range.

Up to six R-7 units were operationally deployed from late 1959, by the newly-formed Strategic Rocket Forces, at five launch sites, one launch pad at Baikonur and four at Plesetsk Cosmodrome. The Soviet Armed Forces initially planned to deploy fifty launch pads for the Soviet nuclear forces. However, the missile's preparation time of 20 hours, maximum alert duration of 24 hours due to liquid oxygen usage, and American Lockheed U-2 spy plane flights, made this infeasible; experts have called its ICBM role as a "blunder" and a "monster". Instead it was R-16 ICBM, developed by the OKB-586 bureau under Mikhail Yangel, which was the first Soviet ICBM deployed en masse, with over 200 units by 1965.

Despite its weakness as an ICBM, some American intelligence reports estimated hundreds of R-7s within a few years, beginning fears of a missile gap. The US responded with a Strategic Air Command continuous 24/7 nuclear alert, which lasted another 34 years until 1991, its first ICBM deployment, the SM-65D Atlas, and the deployment of PGM-17 Thorintermediate-range ballistic missiles in the United Kingdom within range of Moscow.

It became the basis for the R-7 family which includes Sputnik, Luna, Molniya, Vostok, and Voskhodspace launchers, as well as later Soyuz variants. These produced the bulk of early Soviet Space Race achievements, such as the Luna 2 and Luna 3 Moon probes. Various modifications are still in use and it has become the world's most reliable space launcher.