1962-04-26 USSR Kosmos 4

A cover commemorating the launch of Kosmos 4, postmarked in Stanislav with a hand cancel on April 27, 1962, one day after the spacecraft’s launch.

Kosmos 4, also designated Zenit-2 No. 2 and sometimes referred to in Western sources as Sputnik 14, was a Soviet military reconnaissance satellite launched from Baikonur Cosmodrome Site 1/5 aboard a Vostok-K rocket on April 26, 1962. It was the fourth spacecraft to receive the Kosmos designation and the first Soviet reconnaissance satellite to successfully reach orbit. The Zenit-2 spacecraft was derived from the Vostok crewed spacecraft, using a recoverable capsule that allowed its photographic payload and film to be returned to Earth.

The mission had both reconnaissance and scientific objectives. Its primary purpose was photographic reconnaissance, while its instruments also measured the radiation environment around Earth. In particular, Kosmos 4 was intended to collect radiation measurements before and after planned U.S. nuclear tests associated with Project Starfish Prime. Telemetry systems transmitted scientific and spacecraft data to ground stations. Although an orientation-system malfunction shortened the mission, the spacecraft was successfully deorbited and recovered in Kazakhstan on April 29, making Kosmos 4 the first Soviet reconnaissance satellite to successfully reach orbit and return its payload to Earth.