USSR 1963 Vostok 5 & 6

Vostok 5, launched on June 14, 1963, was piloted by Valery Bykovsky. This mission was part of a joint operation with Vostok 6; similar to the earlier pair of Vostok 3 and Vostok 4, the two Vostok spacecraft came close to each other in orbit and established a radio link. Vostok 5 returned to Earth on June 19, 1963. The mission faced several prelaunch delays, primarily due to concerns about elevated solar flare activity. At this early stage, the potential effects on the spacecraft and its occupant were not well understood, leading to the postponement of the original launch date from June 11.

A Vostok 5 cover featuring a special Kiev postmark dated June 15, 1963, signed by Gherman Titov and Valery Bykovsky.

A Vostok 5 cover featuring a special Poltava postmark dated June 15, 1963.

Vostok 6 marked the first human spaceflight to carry a woman, cosmonaut Valentina Tereshkova, into space on June 16, 1963. While Vostok 5 faced delays due to technical issues, Vostok 6 launched without any problems. The data gathered during this mission enhanced understanding of how the female body responds to spaceflight. Like other Vostok cosmonauts, Tereshkova kept a flight log, took photographs, and manually oriented the spacecraft. Her images of the horizon from space were later utilized to identify aerosol layers in the atmosphere. Initially, Vostok 6 was intended to be a joint mission with another Vostok carrying a female cosmonaut, but changes in the Vostok program led to cutbacks, paving the way for the transition to the Voskhod program. Vostok 6 ultimately became the final flight of a Vostok 3KA spacecraft.

A Vostok 6 cover featuring a special Donetsk postmark dated June 16, 1963, the day of the launch.

A Vostok 6 cover featuring a special Kiev postmark dated June 18, 1963.

A Vostok 5 and 6 cover featuring a special Kiev postmark dated June 19, 1963, signed by Valery Bykovsky and Valentina Tereshkova.

Vostok 5 and 6 covers featuring imperforate stamps on First Day Covers (FDCs), postmarked June 20, 1963, in Moscow, and signed by Valery Bykovsky and Valentina Tereshkova.

Covers, each showcasing a perforated stamp of Vostok 5 and Vostok 6, respectively, with a special Moscow postmark.

Vostok 5 and 6 commemorative stamps issued on July 19, 1963, signed by Valery Bykovsky and Valentina Tereshkova.