Gagarin, Yuri Alekseyevich (yo͞o`rē əlyĭksyā`yəvĭch gägä`rĭn), 1934–68, Russian astronaut (cosmonaut), b. near Gzhatsk, RSFSR. He was the first in history to be rocketed into orbital space flight. His flight on Apr. 12, 1961, lasted 1 hr. 48 min. and circled the earth once. The vehicle in which he traveled, named the Vostok [East], weighed over five tons; it reached a maximum altitude of 188 mi (303 km). All control over the spacecraft was handled from the ground, the pilot's reactions being carefully recorded. The success of this flight may be said to have opened the modern era of man in space. Gagarin was killed when a plane he was testing crashed.