Proton M

Light and Medium variants

Proton Light and Proton Medium were two proposed variants with a lower payload capacity at a reduced price. Originally proposed end of 2016, Proton Light was cancelled in 2017 and Proton Medium was put on "indefinite hold" in 2018. The variants were designed to reduce the cost for launching medium and small commercial communications satellites into Geostationary Transfer Orbit (GTO). The variants were planned with a 2 + 1 stage architecture based on 3 stage Proton/Briz M, but dispensing with the 2nd stage and featuring minor lengthening of the other two stages. The Proton Light 1st stage was planned with 4 main engines and external tanks to the 6 used by Proton Medium and Proton-M. The cost was expected to be competitive with Ariane and SpaceX. The planned maiden flights were 2018 for Proton Medium and 2019 for Proton Light. They were expected to use Baikonur Cosmodrome Site 81/24 and would have required a new transporter-erector system and other ground infrastructure changes.