Vostok 5, launched 14 June 1963, was a joint mission with Vostok 6. It carried Valery Bykovsky on board and was originally planned to stay in orbit for 8 days. Bykovsky was ordered back to Earth after 5 days due to elevated levels of solar flare activity at that time. This remains today the record for the longest solo manned flight in Earth orbit.
Vostok 5 cover with special Kiev postmark 15 June 1963, signed by Gherman Titov & Valery Bykovsky.
Vostok 5 cover with special Poltava postmark 15 June 1963.
Vostok 6, launched 16 June 1963, was the first human spaceflight mission to carry a woman, cosmonaut Valentina Tereshkova, into space. During the mission, Tereshkova collected data on the female body's reaction to spaceflight. Her photographs of the horizon from space were later used to identify aerosol layers within the atmosphere. Vostok 6 was the last flight of a Vostok 3KA spacecraft.
Vostok 6 cover with special Donetsk postmarked on launch day 16 June 1963.
Vostok 6 cover with special Kiev postmark 18 June 1963.
Vostok 5 & 6 special Kiev postmark 19 June 1963, signed by Valery Bykovsky & Valentina Tereshkova.
Vostok 5 & 6 imperforated stamps on FDCs, postmarked June 20, 1963, Moscow, signed by Valery Bykovsky & Valentina Tereshkova.
Vostok 5 & 6 perforated stamps on covers with special Moscow postmark.
Vostok 5 & 6 commemorative stamps issued on 19 July 1963, signed by Valery Bykovsky & Valentina Tereshkova