Proton 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 2025, making it one of the most successful heavy boosters in the history of spaceflight. The components of all Protons are manufactured in the Khrunichev State Research and Production Space Center factory in Moscow and Chemical Automatics Design Bureau in 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.