Soyuz-U2

The Soyuz-U2 (GRAU index 11A511U2) 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.

The increased payload of the Soyuz-U2 allowed heavier spacecraft to be launched, while lighter spacecraft could be placed in higher orbits, compared to those launched by Soyuz-U rockets. In 1996, it was announced that the Soyuz-U2 had been retired, as the performance advantage gained through the use of syntin did not justify the additional cost of its production. The final flight had occurred on September 28th 1995 from Baikonur Cosmodrome Site 31.

The Soyuz-U2 was primarily used to launch Yantar reconnaissance satellites, and Soyuz and Progress spacecraft to the Mir space station. Due to the similarity between the Soyuz-U and U2, the exact number of Soyuz-U2 launches is in doubt, with estimates ranging from 66 to 92 launches. It is also unclear how many launches failed, however most sources suggest there were either zero or two failures.