International Day of Human Space Flight The decision on the commemorative date "International Human Spaceflight Day" was taken at the 65th session of the UN General Assembly (Agenda item 50 - International cooperation in the peaceful uses of outer space) on April 7, 2011. The date is timed to coincide with the 50th anniversary of the first human spaceflight on April 12, 1961, which was performed by a citizen of the Soviet Union, cosmonaut Yuri Gagarin, on the Vostok-1 spacecraft.