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Zenit re-entry capsule, showing camera ports.
Zenit re-entry capsule, showing camera ports.
For other uses, see Zenit (disambiguation).

Zenit (Russian: Зени́т, Zenith) is the name of a series of military spy satellites launched by the Soviet Union between 1961 and 1994. Russian ( transliteration:,) is the most geographically widespread language of Eurasia, the most widely spoken of the Slavic languages A spy satellite (officially referred to as a reconnaissance satellite) is an Earth observation satellite or Communications satellite deployed for The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 Year 1961 ( MCMLXI) was a Common year starting on Sunday (link will display full calendar of the Gregorian calendar. Year 1994 ( MCMXCIV) was a Common year starting on Saturday (link will display full 1994 Gregorian calendar) To conceal their nature, all flights were given the public Kosmos designation. For the Cosmos 1 solar sail &mdash not part of this series &mdash see Cosmos 1. Over a 33 year period, over five hundred Zenits were flown making it the most numerous type of satellite in the history of spaceflight.

Contents

Description

The basic design of the Zenit satellites was similar to the Vostok manned spacecraft. The Vostok ( Russian: Восток, translated as East) was a type of Spacecraft built by the Soviet Union 's space programme for It consisted of a spherical re-entry capsule 2. 3 m in diameter with a mass of around 2400 kg. This capsule contained the camera system, its film, recovery beacons, parachutes and a destruct charge. In orbit, this was attached to a service module that contained batteries, electronic equipment, an orientation system and a liquid fuelled rocket engine that would slow the Zenit for re-entry, before the service module detached. The total length in orbit was around 5 m and the total mass was between 4600 kg and 6300 kg.

Unlike the American Corona spacecraft, the return capsule carried both the film and the cameras and kept them in a temperature controlled pressurised environment. Corona was a US military Reconnaissance satellite system operated by the CIA Directorate of Science & Technology with substantial assistance from the This simplified the design and engineering of the camera system but added considerably to the weight of the satellite. An advantage was that cameras could be reused.

Early Zenits were launched using the Vostok rocket; later versions used the Voskhod and the Soyuz rockets. Vostok 8K72K specifications Stage Number 1 - Strap-on Boosters 4 x Vostok 8K72K-0 Gross Mass 43300 kg Empty Mass 3710 kg The Voskhod rocket (Russian Восход translated as "Sunrise") was a derivative of the Soviet R-7 ICBM designed for the The Soyuz launch vehicle (Western designation A-2 is an Expendable launch system manufactured by TsSKB-Progress in Samara Russia. The first flights were launched from the Baikonur Cosmodrome but subsequent launches also took place at the Plesetsk Cosmodrome. The Baikonur Cosmodrome ( Kazakh: Байқоңыр ғарыш айлағы, Bayqoñır ğarış aylağı; Russian: Космодром Plesetsk Cosmodrome ( Russian: Космодром «Плесецк») is a Russian

Most Zenits flew in a slightly elliptical orbit with a perigee of around 200 km and an apogee between 250 km and 350 km; the missions usually lasted between 8 and 15 days. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from

History

In 1956 the Soviet government issued a secret decree that authorised the development of 'Object D' which led to the program to launch Sputnik 3 (Sputnik 1 was a simplified spin-off of the Object D program. Year 1956 ( MCMLVI) was a Leap year starting on Sunday (link will display full calendar of the Gregorian calendar. See also Sputnik program modified R-7/SS-6 ICBM List of unmanned spacecraft by program Sputnik 1 ( "Спутник-1", "Satellite-1" ПС-1 ( PS-1, i ) The text of the decree remains secret, but it apparently authorised another satellite program – ‘Object OD-1’ - which was to be used for photo-reconnaissance from space.

By 1958, the OKB-1 design bureau was simultaneously working on Object OD-1 and Object OD-2—an early design for the Vostok manned spacecraft. Year 1958 ( MCMLVIII) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar. SP Korolev Rocket and Space Corporation Energia ( Russian: ru Ракетно-космическая корпорация "Энергия" им The Vostok ( Russian: Восток, translated as East) was a type of Spacecraft built by the Soviet Union 's space programme for The development of Object OD-1 was experiencing serious difficulties so the head of OKB-1,Sergei Korolev, initiated work to see if a design based on Object OD-2 could be used for an unmanned photo-reconnaissance satellite. Sergey Pavlovich Korolyov (often Transliterated as Sergei Korolev) (Серге́й Па́влович Королёв Сергій Павлович Корольов This may have been a political manoeuvre that would enable him to continue the manned space program and avoid diverting more of OKB-1’s resources into Object OD-1.

Despite bitter opposition from the military, the Soviet government endorsed Korolov’s approach and issued decrees on 22 May and May 25, 1959 that ordered the development of three different spacecraft, all based on the same basic, Object OD-2, design. Events 334 BC - The Greek army of Alexander the Great defeats Darius III of Persia in the Battle of the Granicus. Events 1085 - Alfonso VI of Castile takes Toledo Spain back from the Moors. The year 1959 ( MCMLIX) was a Common year starting on Thursday (link will display full calendar of the Gregorian calendar. Spacecraft 1K would be a simplified prototype, 2K was to be a reconnaissance satellite and 3K was to be for manned flights. The name Vostok was also initially used for all three of these craft. But in 1961 the name became publicly known as the name of Yuri Gagarin's spacecraft so the 'Vostok 2' reconnaissance satellite was renamed 'Zenit 2'.

The first Zenit launch attempt took place on the 11 November 1961, but there was a fault in the rocket’s third stage and the spacecraft was destroyed using its destruct charge. Events 308 - The Congress of Carnuntum: Attempting to keep peace within the Roman Empire, the leaders of the Tetrarchy declare Year 1961 ( MCMLXI) was a Common year starting on Sunday (link will display full calendar of the Gregorian calendar. The second attempt—publicly referred to as Cosmos 4—was successfully launched on the 26 April 1962 and re-entered three days later. Events 1467 - The miraculous image in Our Lady of Good Counsel appear in Genazzano, Italy. Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar. However a failure in the orientation system meant no useful pictures were obtained. The third Zenit (Kosmos 7) was launched on the 28 July 1962 and successfully returned with pictures eleven days later. Events 1540 - Thomas Cromwell is executed at the order of Henry VIII of England on charges of Treason. Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar. A further ten flights (including two more launch failures) took place before the system was considered operational.

Many versions of the satellite were developed for different reconnaissance missions and flights continued until 1994. Year 1994 ( MCMXCIV) was a Common year starting on Saturday (link will display full 1994 Gregorian calendar)

Zenit variants

Zenit 2

Zenit 2 was the first version to be launched in 1961 (there was no Zenit 1. )

The arrangement of cameras varied, but most flights carried four cameras of 1000 mm focal length, and one of 200 mm focal length. The single lower resolution camera was intended to provide low-resolution pictures that would help give a context to the high-resolution pictures.

Each camera had 1500 frames of film and from 200 km, each frame held an image of a 60 km by 60 km square. The ground resolution was stated to be 10-15 m although some unofficial sources claim it was much better—one source claims the number of cars in a car park could be counted. The cameras were developed at the Krasnogorsk Optical-Mechanical factory near Moscow. Krasnogorsk (Красного́рск is a town in Moscow Oblast, Russia, adjacent to the north-western boundary of Moscow, on the Moskva River Moscow (Москва́ romanised: Moskvá, IPA: see also other names) is the Capital and the largest city of Curiously, this was also where the popular Zenit SLR cameras were made. This article is about the Russian camera brand For the astronomic or geodetic instruments directed to the zenith see Zenith camera.

Zenit 2s also carried ELINT equipment to receive NATO radar signals. The North Atlantic Treaty The satellites carried a parabolic antenna, around 1 meter in diameter, that is associated with this equipment. The parabolic antenna is a high-gain reflector antenna used for radio television and data communications and also for radiolocation ( RADAR) on the UHF and However, it is unclear if the antenna transmitted recorded signals to the ground or was for intercepting radar signals. In the latter case they would have been recorded on magnetic tape, to be retrieved after the return capsule landed.

There were 81 Zenit 2 launches, 58 were successful and 11 were partially successful. There were 12 failed missions, 5 because of a satellite malfunction and 7 because of a failure in the launch vehicle.

First flight - Kosmos 4, 1962. Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar. Last flight - Kosmos 344, 1970. Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar.

Zenit 2M

Improvements included a new camera system and the addition of solar panels. As the spacecraft mass was increased to 6300 kg, the Vostok rocket was replaced by the Voskhod and Soyuz rockets.

First flight - Kosmos 208, 1968. Year 1968 ( MCMLXVIII) was a Leap year starting on Monday (link will display full calendar of the Gregorian calendar. Last flight - Kosmos 1044, 1978. Year 1978 ( MCMLXXVIII) was a Common year starting on Sunday (link displays the 1978 Gregorian calendar)

Zenit 4

Unlike Zenit 2, little information on Zenit 4 has been released. The Zenit 4 was intended for high resolution photography and carried one camera of 3000 mm focal length as well as a 200 mm camera. The focal length of the main camera was greater than the diameter of the capsule so the camera made use of a mirror to fold the light path. The ground resolution is not publicly known but it is believed to have been 1-2 m.

The Zenit 4 weighted 6300 kg—around 1500 kg more than the Zenit 2. So, instead of the Vostok rocket, it was launched by the heavier Voskhod rocket. A probable total of 76 Zenit 4’s were flown.

First flight - Kosmos 22, 1963. Year 1963 ( MCMLXIII) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar. Last flight - Kosmos 355, 1970. Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar.

Zenit 4 M

An improved version of the Zenit 4, the Zenit 4M carried a new camera, solar panels, and a restartable engine so the satellite’s orbit could be altered during the course of its mission. Mission duration was 13 days.

First flight - Kosmos 251, 1968. Year 1968 ( MCMLXVIII) was a Leap year starting on Monday (link will display full calendar of the Gregorian calendar. Last flight - Kosmos 667, 1974. Year 1974 ( MCMLXXIV) was a Common year starting on Tuesday (link will display full calendar of the 1974 Gregorian calendar.

Zenit 4 MK / Zenit 4 MKM

These may have been versions of the Zenit 4 designed specifically to fly in lower orbits to improve image resolution. Some sources claim they were fitted with devices to compensate for aerodynamic drag and to withstand the effects of aerodynamic heating. Aerodynamic heating is the heating of a solid body produced by the passage of fluid (such as air over a body such as a Meteor, Missile, or Airplane.

First flight - Kosmos 371, 1970. Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar. Last flight - Kosmos 1214, 1980. Year 1980 ( MCMLXXX) was a Leap year starting on Tuesday (link displays the 1980 Gregorian calendar)

Zenit 4 MT

A special version of the Zenit 4M intended for topographical photography. Topography ( topo-, "place" and graphia, "writing" is the study of Earth 's Surface features or those of Planets It carried a SA-106 topographic camera, a laser altimeter and Doppler apparatus.

First flight - Kosmos 470, 1971. Year 1971 ( MCMLXXI) was a Common year starting on Friday (link will display full calendar of the 1971 Gregorian calendar. Last flight - Kosmos 1398, 1982. Year 1982 ( MCMLXXXII) was a Common year starting on Friday (link displays the 1982 Gregorian calendar)

Zenit 6U

A ‘universal’ version of the Zenit, intended for both low-altitude, high-resolution missions and higher-altitude, general observation missions. All flights used the Soyuz launch vehicle. There were 96 launches.

First flight - Kosmos 867, 1976. Year 1976 ( MCMLXXVI) was a Leap year starting on Thursday (link will display full calendar of the Gregorian calendar. Last flight - Kosmos 1685, 1985. Year 1985 ( MCMLXXXV) was a Common year starting on Tuesday (link displays 1985 Gregorian calendar)

Zenit 8

This was intended for military cartographic photography. It used a Soyuz launch vehicle and launches took place from both Baikonur and Plesetsk. It had a 15 day orbital life. Similar satellites were referred to using the ‘Resurs’ designation.

Kosmos 2281, was the last Zenit flight.

First flight - Kosmos 1571, 1984. Year 1984 ( MCMLXXXIV) was a Leap year starting on Sunday (link displays the 1984 Gregorian calendar) Last flight - Kosmos 2281, 1994. Year 1994 ( MCMXCIV) was a Common year starting on Saturday (link will display full 1994 Gregorian calendar)

Following the end of the programme, one Zenit-8 satellite was launched on the maiden flight of the Soyuz-2 rocket, as a DemoSat. Soyuz 2 is the collective designation for the new generation versions of the Russian Soyuz Rocket. A DemoSat is a boilerplate spacecraft used to test a Carrier rocket without risking a real satellite on the launch The satellite was placed on a sub-orbital trajectory, and intentionally impacted the Pacific Ocean shortly after launch. The Pacific Ocean is the largest of the Earth 's Oceanic divisions [1]

References

External links

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