MOSCOW, September 13. /TASS/. Russia’s Khrunichev center has developed a "medium" model of the heavy space rocket Proton-M, capable of putting in obit a payload of 2.2 tonnes, the press-service of the Russian space corporation Roscosmos said. The first launch is due in 2018.

"The Khrunichev center is determined to achieve the first launch of the two-stage medium configuration of the Proton rocket in 2018. This rocket will have a standard Proton-M configuration," the news release says.

The rocket’s nose cone measures four meters in diameter.

Roscosmos said the light Proton rocket would be launched in 2019. This modification will have four first stage engines and the nose cone’s diameter will be the same, four meters. Both rockets will be equipped with the upper stage Briz-M.

Both will be used only for commercial launchers under contracts concluded by the Khrunichev center’s daughter company International Launch Services.

The medium and light models of the rocket will be two-stage ones. The light one will have four laterally installed first stage engines, and the medium one, six. The light rocket will be able to put payloads of 1.45 tonnes in geo-stationary orbits, and the "medium" one, 2.2 tonnes. The current model of the Proton-M rocket is capable of taking 3.3-tonne payloads to this altitude.

Earlier, Khrunichev’s general designer, Aleksandr Medvedev, told TASS in an interview a light version of the Proton-M had been developed. The first launch of such a rocket, he said, might take place no later than 2019. No test launches will be needed. All of the rocket’s components had been used in different configurations already.