High Quality Content by WIKIPEDIA articles! Vostok (Russian , translated as "East") was a family of rockets derived from the Soviet R-7 Semyorka ICBM designed for the human spaceflight programme but later used for other satellite launches. It was a subset of the R-7 family of rockets.On March 18, 1980 a Vostok-2M rocket exploded on its launch pad at Plesetsk during a fueling operation, killing 48. An investigation into a similar but avoided accident revealed that the substitution of lead-based for tin-based solder in hydrogen peroxide filters had resulted in the breakdown of the H2O2 and the resulting explosion.