Khrunichev Press Release:

A three–stage version of the Russia’s famous Proton launch vehicles family, known as the Proton –K, lifted off on its maiden flight on 10 March, 1967 from Baikonur Cosmodrome, Kazakhstan, carrying Russian Kosmos 146 spacecraft into a planned highly elliptical earth orbit. The first mission was successful.

Since then, Proton became well known as one of the most capable and reliable heavy launch vehicles in operation, with an outstanding reliability rating of about 96 percent and a total of 324 launches.

The Proton originally was introduced in 1965 as a booster for heavy military payloads and for space stations. It was designed by the Salyut Design Bureau and is manufactured by a Moscow –based Khrunichev State Research and Production Space Center.

Proton K is used in the basic three – stage configuration for heavy, LEO mission, while its four-stage configuration witha restartable Block DM fourth stage versions is used to lift heavy payloads into high-energy trajectories (geo-transfer, geosynchronous, geostationary, and interplanetary).   

Proton K has been used for most of important Soviet and Russia communications and deep–space missions, such as lunar and planetary probes. It launched the Ekran, Raduga, and Gorizont series of geostationary communications satellites (which provided telephone, telegraph, and television service within Russia and between member states of the Intersputnik Organization), as well as the Zond, Luna, Venera, Mars, Vega, and Phobos inter-planetary exploration spacecraft. The Proton has also launched the most of Glonass position location satellites. Proton launched the Salyut space stations, the Mir core segment and expansion segments, both Zarya and Zvezda modules for International Space Station.  Proton also launches commercial satellite, most of them being managed by International Launch Services (ILS), a joint Russia –USA venture. Since 1996, ILS performed 26 commercial missions on Proton K.

Over the years, Proton core vehicle underwent series of upgrading and modernization.  Proton M with Breeze M upper stage is the latest upgraded version of Proton vehicle. The upgrades provide enhanced performance, greater payload volume and increased mission design flexibility. The first vehicle in the Proton M series successfully lifted off on April 07, 2001, carrying a satellite for the Russian government.  

Proton currently is the largest Russian launch vehicle in regular operation and the heart of the space transportation system of Russia. Proton is expected to remain among the most capable and reliable launch vehicles in the world until 2010, at least.