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Work began on the original Zenit spy satellite on 30 January 1956. After the success of Sputnik Sergei Korolev advocated that manned spaceflight should have first priority. After bitter disputes, a compromise solution was reached. Korolev was authorised to proceed with development of a spacecraft to achieve manned flights at the earliest possible date. However the design would be such that the same spacecraft could be used to fulfil the military's unmanned photo reconnaissance satellite requirement. The military resisted, but in November 1958 Korolev won, and the Council of Chief designers approved the Vostok manned space program, in combination with Zenit spy satellite program. This was formalised in a decree of 25 May 1959 that authorised development of the Zenit-2 and Zenit-4 spacecraft based on the Vostok design. This marked the end of the original Zenit configuration.
On 30 January 1956 work began in the Soviet Union on defining the requirements for satellites for military purposes. The system was defined incrementally throughout 1956 in a series of specification documents. In April the specification for a redundant restartable engine system for use in a variety of manoeuvrable satellites was released. The same month the requirements for research and development of an appropriate satellite guidance and control system were released. In May the technical requirements document was issued for a satellite that could be oriented in orbit by OPM MIAM. In July tests began of appropriate heat shield materials able to resist temperatures of 1,000 to 2,000 degrees C. A decree in August 1956 authorised design of a military reconnaissance satellite. In October the specification was issued for a comprehensive research program leading to manoeuvrable spacecraft, including investigations into launch methods, re-entry capsules, hypersonic aerodynamics, heat shields, thermodynamics, and parachute systems. By April 1957 the military issued a requirements document for experimental solar cell panels.
Design bureau work on the reconnaissance satellite began in 1957 in Section 3 of OKB-1 (Tikhonravov and Ryazanov). The first version designed consisted of an equipment section and a re-entry capsule. The equipment section included the camera, ELINT receivers, and control systems for orbital flight. The conical re-entry capsule contained the film cassettes to be returned to earth and the recovery systems. The capsule was deorbited by a separate TDU braking rocket. This spacecraft was initially sized at 1.5 tonnes total for launch by the basic R-7 rocket.
But early on it was decided that a long focal length camera (1.0 m) would be required, which tripled the estimated weight of the spacecraft.
By 2 July 1957 Tikhonravov had defined the necessary development tasks for the Zenit reconnaissance satellite as follows:
Design work starts on the Zenit, the first military photo-reconnaisance satellite. The necessary subsystems were defined incrementally throughout 1956 in a series of specification documents. In April the specifications for a redundant restartable engine and appropriate satellite guidance and control systems were released. In May the technical requirements document was issued for a satellite that could be oriented in orbit. In July tests began of appropriate heat shield materials.
Design was original concept of Zenit reconnaisance spacecraft. The effort would later be included in the Vostok program under the name of Zenit.
The decree formally authorised design of a military reconnaissance satellite. In October the specification was issued for a comprehensive research program leading to manoeuvrable spacecraft. By April 1957 the military issued a requirements document for experimental solar cell panels. Design bureau work on the reconnaissance satellite began in 1957 in Section 3 of OKB-1 (Tikhonravov and Ryazanov). This spacecraft was initially sized at 1.5 tonnes total for launch by the basic R-7 rocket.
Studies were undertaken for military reconnaissance satellites. Code names for these studies were: Shchit - military reconnaissance systems; Osnova - military reconnaissance equipment; Ediniy KIK - military reconnaissance control systems.
These included development of a three stage version of R-7, development of satellite guidance and control systems of the precision required for photography from orbit, satellite control equipment, ELINT sensors, guidance systems, film cassette return systems, and tracking systems for recovery of the re-entry vehicle with the film cassette.
Council of Chief Designers Decree 'On course of work on the piloted spaceship' was issued. Council of Chief designers approved the Vostok manned space program, in combination with Zenit spy satellite program Korolev was authorised to proceed with development of a spacecraft to achieve manned flights at the earliest possible date. However the design would be such that the same spacecraft could be used to fulfil the military's unmanned photo reconnaissance satellite requirement. The military resisted, but Korolev won. This was formalised in a decree of 25 May 1959.
Due to a bitter fight with the military over the nature and priority of the manned spacecraft and photo-reconnaissance space programs, the final decree for the Vostok manned spacecraft was delayed until seven months after drawing release began. This authorised production of a single design that could be used either as a manned spacecraft or as a military reconnaissance satellite. These were the Zenit-2 and Zenit-4 spacecraft based on the Vostok design. This marked the end of the original Zenit configuration.