Proton

Proton (Russian: Протон, formal designation: UR-500) is a Russian hypergolic propellant expendable launch system operated by Roscosmos for commercial and state payloads. Developed by the Soviet space program, its first launch, a Proton-K variant, was in 1965. The modernized Proton-M is in use as of 2026, making it one of the most successful heavy boosters in the history of spaceflight.

Components are manufactured in the Khrunichev State Research and Production Space Center, Moscow, and Chemical Automatics Design Bureau, Voronezh, then transported to the Baikonur Cosmodrome, where they are assembled at Site 91 to form the launch vehicle. Following payload integration, the rocket is then brought to the launch pad horizontally by rail and raised into vertical position for launch. As with many Soviet rockets, the names of recurring payloads became associated with the launch vehicle itself. 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.