On April 12, 1961, Gagarin took off from the Baikonur Cosmodrome in Soviet Kazakhstan. He became the first human to escape the bonds of gravity in his Vostok I capsule. He orbited the Earth once, in 108 minutes, before returning safely.
Gagarin never went into space again. He was killed in a military plane crash seven years later. His ashes were placed in the walls of the Kremlin.
The anniversary comes as Russia's leading space company, RKK Energiya, laid out plans to send manned missions to the moon by 2015 and to Mars between 2020 and 2030.