Historians have settled on a simple fact about the morning of 12 April 1961: a 27-year-old Soviet Air Force pilot named Yuri Alekseyevich Gagarin became the first human being to leave the planet, completing a single orbit of Earth in 108 minutes aboard Vostok 1. He would die in a training crash near Kirzhach on 27 March 1968, at 34, his death never definitively explained.
Gagarin was born in Klushino, in the Smolensk Oblast. He studied at the Saratov Industrial Technical School and the Saratov Aeroclub, graduated from the Orenburg Military Pilot School in 1955, and flew MiG-15s in the Soviet Air Force. He was selected for cosmonaut training in 1960.
Vostok 1 launched from Baikonur at 06:07 UTC on 12 April 1961, reaching a 169 × 327 km orbit. The descent module re-entered the atmosphere, with a failure of the attitude control system causing a tumble that ended during descent. Gagarin ejected at about 7 km altitude and parachuted to a soft landing near Engels at 07:55 UTC. The flight profile (ejection before landing) was dictated by the absence of a soft-landing system on the Vostok descent module.
Gagarin toured the world in 1961–62 and trained for further flights, but never flew in space again. His death in a MiG-15UTI crash, with flight instructor Vladimir Seryogin, has never been definitively explained; a 2013 declassification produced no firm cause. The city of Gzatsk was renamed Gagarin in 1968, and 12 April is now the UN International Day of Human Space Flight.
For the rest of Soviet space program article and the space race overview.