were enrolled into a correspondence course programme at the Zhukovsky Air Force Engineering Academy. Gagarin enrolled in the programme in September 1960 and did not earn his specialist diploma until early 1968. Gagarin was also subjected to experiments that were designed to test physical and psychological endurance including oxygen starvation tests in which the cosmonauts were locked in an isolation chamber and the air slowly pumped out. He also trained for the upcoming flight by experiencing g-forces in a centrifuge. Psychological tests included placing the candidates in an anechoic chamber in complete isolation; Gagarin was in the chamber on 26 July – 5 August. In August 1960, a Soviet Air Force doctor evaluated his personality as follows: The Vanguard Six were given the title of pilot-cosmonaut in January 1961 and entered a two-day examination conducted by a special interdepartmental commission led by Lieutenant-General Nikolai Kamanin, the overseer of the Vostok programme. The commission was tasked with ranking the candidates based on their mission readiness for the first human Vostok mission. On 17 January, they were tested in a simulator at the M. M. Gromov Flight-Research Institute on a full-size mockup of the Vostok capsule. Gagarin, Nikolayev, Popovich, and Titov all received excellent marks on the first day of testing in which they were required to describe the various phases of the mission followed by questions from the commission. On the second day, they were given a written examination following which the special commission ranked Gagarin as the best candidate for the first mission. He and the next two highest-ranked cosmonauts, Titov and Nelyubov, were sent to Tyuratam for final preparations. Gagarin and Titov were selected to train in the flight-ready spacecraft on 7 April. Historian Asif Azam Siddiqi writes of the final selection: Vostok 1 On 12 April 1961, at 6:07 am UTC, the Vostok 3KA-3 (Vostok 1) spacecraft was launched from Baikonur Cosmodrome. Aboard was Gagarin, the first human to travel into space, using the call sign Kedr (, Siberian pine or cedar). The radio communication between the launch control room and Gagarin included the following dialogue at the moment of rocket launch: Gagarin's farewell to Korolev using the informal phrase Poyekhali! () later became a popular expression in the Eastern Bloc that was used to refer to the beginning of the Space Age. The five first-stage engines fired until the first separation event, when the four side-boosters fell