About Soyuz-U
The Soyuz-U2 was a Soviet, later Russian, carrier rocket. It was derived from the Soyuz-U, and a member of the R-7 family of rockets. It featured increased performance compared with the baseline Soyuz-U, due to the use of syntin propellant, as opposed to RP-1 paraffin, used on the Soyuz-U.