Proton (rocket family)

Proton (Russian: Протон) (formal designation: UR-500) is an expendable launch system used for both commercial and Russian government space launches. The first Proton rocket was launched in 1965. Modern versions of the launch system are still in use as of 2019, making it one of the most successful heavy boosters in the history of spaceflight. All Protons are built at the Khrunichev State Research and Production Space Center factory in Moscow, transported to the Baikonur Cosmodrome, brought to the launch pad horizontally, and raised into vertical position for launch. As with many Soviet rockets, the names of recurring payloads became associated with the Proton. The moniker 'Proton' originates from a series of similarly named scientific satellites, which were among the rocket's first payloads. During the Cold War, it was designated the D-1/D-1e or SL-12/SL-13 by Western intelligence agencies. Launch capacity to low Earth orbit is about 22.8 tonnes (50,000 lb). Geostationary transfer capacity is about 6.3 tonnes (14,000 lb). Commercial launches are marketed by International Launch Services (ILS).The rocket is intended to be retired before 2030. As of June 2018, production on the Proton rocket is ceasing as the new Angara launch vehicle comes on line and becomes operational. No new launch service contracts for Proton are likely to be signed. Proton initially started its life as a 'super heavy ICBM'. It was designed to launch a 100-megaton (or larger) thermonuclear weapon over a distance of 13,000 km. It was hugely oversized for an ICBM and was never deployed in such a capacity. It was eventually used as a space launch vehicle. It was the brainchild of Vladimir Chelomei's design bureau as a foil to Sergei Korolev's N1 rocket, whose purpose was to send a two-man Zond spacecraft around the Moon; Korolev openly opposed Proton and Chelomei's other designs for their use of toxic propellants. The unusual appearance of the first stage results from the need to transport components by rail. The central oxidizer tank is the maximum width for the loading gauge of the track. The six tanks surrounding it carry fuel and serve as the attachment points for the engines. Despite resembling strap-on boosters, they are not designed to separate from the central oxidizer tank. The first and second stages are connected by a lattice structure. The second stage engine ignites shortly before separation of the first stage and the lattice allows the exhaust to escape.