Csomos 65 was the sixth Russian experimental meteorological satellite and the fourth launched from the Tyuratam site. Although the flight was at first thought to be part of the reconnaissance recoverable payload series, it was later revealed that the satellite carried supplemental experiments to test meteorological sensors and to obtain data in support of the operational weather satellite development program. The instrumentation included (1) a cloudcover photometer to measure the brightness characteristics of clouds in the 0.60- to 0.85-micron band, (2) a scanning IR radiometer to determine the angular, spectral, and latitudinal distribution of terrestrial IR radiation in the 0.8 to 45-micron band, (3) a UV spectrophotometer to measure the solar UV radiation reflected and scattered by the earth's atmosphere, and (4) a colorimeter to measure the radiation characteristics of the night airglow in the 0.25- to 0.60-micron band. The spin-stabilized satellite was in the form of a cylinder with hemispherical ends and was 5 m long and 2.44 m in diameter. Antennas were mounted on the ends of the satellite and operated on a frequency of 19.995 MHz. The satellite reentered the atmosphere on April 25, 1965, after nearly 8 days in orbit, and was successfully recovered. Similar flights were made by Cosmos 45 and 92.