The Soviet space program, was the national space program of the Union of Soviet Socialist Republics (USSR) actived from 1930s until disintegration of the Soviet Union in 1991. The Soviet Union's space program was mainly based on the cosmonautic exploration of space and the development of the expandable launch vehicles, which had been split between many design bureaus competing against each other. Over its 60-years of history, the Russian program was responsible for a number of pioneering feats and accomplishments in the human space flight, including the first intercontinental ballistic missile (R-7), first satellite (Sputnik 1), first animal in Earth orbit (the dog Laika on Sputnik 2), first human in space and Earth orbit (cosmonaut Yuri Gagarin on Vostok 1), first woman in space and Earth orbit (cosmonaut Valentina Tereshkova on Vostok 6), first spacewalk (cosmonaut Alexei Leonov on Voskhod 2), first Moon impact (Luna 2), first image of the far side of the Moon (Luna 3) and unmanned lunar soft landing (Luna 9), first space rover (Lunokhod 1), first sample of lunar soil automatically extracted and brought to Earth (Luna 16), and first space station (Salyut 1). Further notable records included the first interplanetary probes: Venera 1 and Mars 1 to fly by Venus and Mars, respectively, Venera 3 and Mars 2 to impact the respective planet surface, and Venera 7 and Mars 3 to make soft landings on these planets.
Soyuz 7K-T No.39, also known as Soyuz 18a or Soyuz 18-1, was intended to be the next crewed mission to the Salyut-4 space station. The mission launched on April 5, 1975, 11:04:54 UTC, but due to a failure of the Soyuz launch vehicle during ascent it was aborted. Safety system initiated separation of the spacecraft, and the crew of commander Vasili Lazarev and flight engineer Oleg Makarov experienced overloads of up to 21.3 g. The capsule landed safely at 11:26:21 UTC, followed by a successful rescue of the crew members.