|Launch vehicle.||Vostok rocket.|
|Launch site.||Baikonur Cosmodrome.|
|Ceased operations.||Date unknown, but it was long ago, the orginal one probably came down in the early to mid 1960s.|
|Major contractor(s) .||OKB-1.|
|Is it still in orbit.||No.|
|Launch mass.||2,400 kg.|
The Zenit (Russian: Зени́т,English: Zenith) satellites were a series of over 500 related military photo-reconnaissance satellites launched by the Soviet Union between 1961 and 1991. They were used by the Soviets and Russians between 1991 and 1994. To conceal their nature, all flights were given the public Kosmos designation. Zenit 2 was the first version to be launched in 1961 (there was no Zenit 1 for an unknown resion.) First Zenit 2 flight – Kosmos 4, 1962, last zenit 2 flight – Kosmos 344, 1970.
When the the name of Yuri Gagarin's spacecraft became publicly known in 1961 as 'Vostok 2' reconnaissance satellite was renamed 'Zenit 2'.
At first they were launched using Vostok rockets; with later versions used the Voskhod and the Soyuz rockets. Launches were at first from from Baikonur Cosmodrome, but the subsequent launches also took place at Plesetsk Cosmodrome.
The 500 Zenits have all come down to earth over the years as planned and due to there shear numbers became the most numerous type of satellite used in the history of space-flight.
It is to be noted that modern services like Google Maps, hurricane tracking services and satellite TV all owe a debt to these early satellites.