FDC Soviet Union Space for the 15th. anniversary of the Vosktok 2 flight made in 1961. The text on the envelop reads:”15th. anniversary of the space flight of the pilot cosmonaut G. Titov”.
Vostok 2 (Russian: Boctok 2) was a Soviet space mission which carried cosmonaut Gherman Titov into orbit for a full day on August 6, 1961 to study the effects of a more prolonged period of weightlessness on the human body. Titov orbited the Earth over 17 times, exceeding the single orbit of Yuri Gagarin on Vostok 1.