Soyuz-FG

The Soyuz-FG was an improved variant of the Soyuz-U launch vehicle from the R-7 rocket family, developed by the Progress Rocket Space Centre in Samara, Russia. It featured upgraded first and second stage engines, the RD-107A on the boosters and the RD-108A on the core, whose enhanced injector heads improved combustion efficiency and specific impulse. The FG in the name stands for forsunochnaya golovka, Russian for injector head. Introduced as a transitional solution while the more advanced Soyuz-2 was still in development, it made its maiden flight on 20 May 2001, delivering a Progress cargo spacecraft to the International Space Station, and from 2002 until its retirement in 2019 it was the primary vehicle for launching crewed Soyuz TMA, TMA-M and MS spacecraft from Gagarin's Start at the Baikonur Cosmodrome. For uncrewed missions it could fly with a Fregat upper stage. Soyuz-FG flew 70 times, with one failure, on 11 October 2018 during the launch of Soyuz MS-10, when a faulty sensor caused a booster to collide with the core stage and the crew safely returned to Earth after an emergency abort.