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 2015, 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 plant in Moscow, transported to the Baikonur Cosmodrome, brought to the launch pad horizontally, and raised into vertical position for launch.