1962-05-28 USSR Kosmos 5

A cover commemorating the launch of Kosmos 5, postmarked in Stanislav with a hand cancel on May 29, 1962, one day after the spacecraft’s launch.

Kosmos 5, also designated 2MS No. 2 and sometimes referred to in Western sources as Sputnik 15, was a Soviet scientific research and technology-demonstration satellite launched on May 28, 1962. It was the fifth spacecraft to receive the Kosmos designation and the second and final spacecraft of the 2MS series, following Kosmos 3. The 2MS spacecraft were developed by OKB-1 as small, solar-powered research satellites. Their objectives included testing spacecraft systems and equipment for future missions and studying cosmic rays, radiation, and the near-Earth space environment.

A significant objective of the mission was to investigate artificial radiation around Earth. Kosmos 5 was among the satellites affected by the enhanced radiation environment produced following the U.S. Starfish Prime high-altitude nuclear test on July 9, 1962. The resulting artificial radiation belt damaged or disabled several spacecraft, and Kosmos 5 ceased communications on that date. Although contact was lost after about six weeks, the spacecraft itself remained in orbit for almost a year. Kosmos 5 reentered Earth's atmosphere on May 2, 1963, after approximately 339 days in orbit.