The Proton rocket (Прото́н) (formal designation: UR-500) is a rocket used in an expendable launch system for both commercial and Russian government launches. The first Proton was launched in 1965 and the launch system is still in use as of 2009, which makes it one of the most successful heavy boosters in the history of spaceflight. All Protons are built at the Khrunichev plant in Moscow. They are transported for launch to the Baikonur Cosmodrome, where they are brought to the launch pad horizontally and then raised into vertical position for launch.
The name "Proton" originates from a series of large scientific Proton satellites, which were among the rocket's first payloads. It is also known as the D-1/ D-1e or SL-12/SL-13. Like many Soviet boosters, the name of the recurring payloads became associated with their launchers.
Launch capacity to low Earth orbit is about 22 tonnes (44,000 lb). Interplanetary transfer capacity is about 5–6 tonnes (11,000–13,000 lb). Commercial launches are marketed by International Launch Services (ILS). In a typical launch of a commercial communications satellite destined for geostationary orbit, a Proton M/Breeze M can place a spacecraft with mass at separation of 4,140 kg into an orbit with an apogee of 35,786 kilometers, a perigee of 6,257 kilometers and an inclination of 19.7°.
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