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Zenit (satellite)

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Zenit
Zenit re-entry capsule, showing camera ports
ManufacturerOKB-1
Country of originSoviet Union
OperatorSoviet space program
ApplicationsPhoto reconnaissance
Production
StatusRetired
Launched688
Lost21
Maiden launch11 Dec 1961
Zenit 2-1
Last launch7 Jun 1994
Kosmos 2281
Last retirement8 Nov 2004
Zenit 8-103
Related spacecraft
Derived fromVostok

Zenit (Russian: Зени́т, IPA: [zʲɪˈnʲit], Zenith) was a series of military photoreconnaissance satellites launched by the Soviet Union between 1961 and 1994. To conceal their nature, all flights were given the public Kosmos designation.

Description[edit]

The basic design of the Zenit satellites was similar to the Vostok crewed spacecraft, sharing the return and service modules.[1] It consisted of a spherical re-entry capsule 2.3 metres (7.5 ft) in diameter with a mass of around 2,400 kilograms (5,300 lb). 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 metres (16 ft) and the total mass was between 4,600 and 4,740 kilograms (10,140 and 10,450 lb).[1]

Unlike the American CORONA spacecraft, the return capsule carried both the film and the cameras and kept them in a temperature-controlled pressurised environment. This simplified the design and engineering of the camera system but added considerably to the mass of the satellite. An advantage was that cameras could be reused.[1] The camera would either land on the ground or be recovered in midair by a modified Mil Mi-8 helicopter.[2]

Early Zenits were launched using the Vostok rocket; later versions used the Voskhod and the Soyuz rockets. The first flights were launched from Baikonur Cosmodrome but subsequent launches also took place at Plesetsk Cosmodrome.

Most Zenits flew in a slightly elliptical orbit with a perigee of around 200 kilometres (120 miles) and an apogee between 250 and 350 kilometres (160 and 220 miles); the missions usually lasted between 8 and 15 days.

History[edit]

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.) 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 crewed spacecraft. 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 uncrewed photo-reconnaissance satellite. This may have been a political manoeuvre that would enable him to continue the crewed space program and avoid diverting more of OKB-1's resources into Object OD-1.[1][3][4][5]

Despite bitter opposition from the military the Soviet government endorsed Korolev's approach and issued decrees on 22 and 25 May 1959 which ordered the development of three different spacecraft, all based on the same basic, Object OD-2, design. Spacecraft 1K would be a simplified prototype, 2K was to be a reconnaissance satellite and 3K was to be for crewed 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".[6]

The first Zenit launch attempt took place on 11 December 1961, but there was a fault in the rocket's third stage and the spacecraft was destroyed using its destruct charge. The second attempt — publicly referred to as Kosmos 4 — was successfully launched on 26 April 1962 and re-entered three days later. However a failure in the orientation system meant few useful pictures were obtained; usable pictures had a resolution of about 5 to 7 meters. Launch #3 on 1 June 1962 failed dramatically when one of the 8A92 booster's strap-ons shut down at liftoff and fell onto the pad, exploding on impact. The rest of the launch vehicle crashed 300 meters away. This accident caused considerable damage to Site 1, delaying the flights of Vostok 3 and Vostok 4 by two months.

On 28 July 1962, Site 1 was back in service to host the next Zenit flight, which performed successfully. Testing continued over the next year largely without incident but on 10 July 1963, another launch accident occurred in practically identical fashion to the June 1962 failure. Once again, one of the strap-ons shut down at liftoff, separated from the booster, and exploded on impact with the pad while the rest of the launch vehicle crashed a few hundred feet away.

Examination of telemetry from the booster indicated that some sort of electrical failure occurred, but subsequent investigation took three months and finally concluded that a switch designed to cut power to the strap-ons at staging had malfunctioned, possibly due to liftoff-induced vibration. The electrical circuit in the 8A92 was redesigned and it never again experienced problems with the strap-ons shutting down at launch.[7]

Many versions of the satellite were developed for different reconnaissance missions and flights continued until 1994.[8][9]

Zenit variants[edit]

Zenit 2[edit]

Zenit 2 was the first version to be launched between 1961 and 1970 (there was no Zenit 1).[10][11]

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.[1]

Each camera had 1500 frames of film and from 200 km (120 mi), each frame held an image of a 60 by 60 km (37 by 37 mi) square. The ground resolution was stated to be 10 to 15 m (33 to 49 ft) 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. The Krasnogorsk factory, which had been producing a variety of optical equipment for the military since 1942, was also the manufacturer of the popular Zenit SLR cameras.[1]

Zenit 2s also carried ELINT equipment called Kust-12M (bush) to receive NATO radar signals. The satellites carried a parabolic antenna, around 1 m (3 ft 3 in) in diameter, that is associated with this equipment. 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.[1][12]

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.

Zenit 2M[edit]

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 rocket and Soyuz rockets. In common with Zenit 2 satellites this also had an ELINT payload.[12]

A total of 101 Zenit-2M satellites were launched between 1968 and 1979[13][14][15]

Zenit 4[edit]

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 metre.

The Zenit 4 had a mass of 6300 kg — around 1800 kg more than the Zenit 2. So, instead of the Vostok rocket, it was launched by the heavier Voskhod rocket. A total of 76 Zenit-4 satellites were flown between 1963 and 1970.[1][16][17]

Zenit 4 M[edit]

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. The mission duration was 13 days.

A total of 61 Zenit-4M satellites were launched between 1968 and 1974.[18][19]

Zenit 4 MK[edit]

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.

A total of 80 Zenit-4MK satellites were launched between 1969 and 1977.[20][21]

Zenit 4 MKM[edit]

Intended to replace the 4MK design, the 4MKM may have been a low altitude variant of the later Zenit-6U and have similar equipment to it[22]

Zenit-4MKM (Gerakl)[23][24]
No. Mission Launch date
(GMT) 		Landing date COSPAR ID Orbit Duration
(in orbit) 		Outcome
1 Kosmos 927 12 July 1977
09:00 		25 July 1977 1977-063A 153 x 361 km 13 days Success
2 Kosmos 932 20 July 1977
07:35 		2 August 1977 1977-069A 150 x 358 km 13 days Success
3 - 10 August 1977
10:40 		- - (Suborbital) - Failure
4 Kosmos 938 24 August 1977
14:30 		6 September 1977 1977-078A 181 x 340 km 13 days Success
5 Kosmos 953 16 September 1977
14:30 		29 September 1977 1977-089A 180 x 330 km 13 days Success
6 Kosmos 957 30 September 1977
09:46 		13 October 1977 1977-098A 171 x 361 km 13 days Success
7 Kosmos 964 4 December 1977
12:00 		17 December 1977 1977-110A 171 x 362 km 13 days Success
8 Kosmos 969 20 December 1977
15:50 		3 January 1978 1977-120A 180 x 317 km 14 days Success
9 Kosmos 974 6 January 1978
15:50 		19 January 1978 1978-001A 178 x 334 km 13 days Success
10 Kosmos 986 24 January 1978
09:50 		7 February 1978 1978-010A 172 x 318 km 14 days Success
11 Kosmos 987 31 January 1978
14:50 		14 February 1978 1978-013A 189 x 322 km 14 days Success
12 Kosmos 989 14 February 1978
09:30 		28 February 1978 1978-017A 169 x 318 km 14 days Success
13 Kosmos 993 10 March 1978
10:42 		23 March 1978 1978-027A 190 x 325 km 13 days Success
14 Kosmos 999 30 March 1978
07:50 		12 April 1978 1978-033A 174 x 352 km 13 days Success
15 Kosmos 1003 20 April 1978
15:30 		4 May 1978 1978-040A 178 x 328 km 14 days Success
16 Kosmos 1007 16 May 1978
10:40 		28 May 1978 1978-048A 168 x 350 km 13 days Success
17 Kosmos 1021 10 June 1978
08:35 		23 June 1978 1978-057A 173 x 313 km 13 days Success
18 Kosmos 1022 12 June 1978
10:30 		25 June 1978 1978-059A 171 x 344 km 13 days Success
19 Kosmos 1029 29 August 1978
15:00 		8 September 1978 1978-082A 194 x 316 km 10 days Success
20 Kosmos 1031 9 September 1978
15:00 		22 September 1978 1978-085A 182 x 329 km 13 days Success
21 Kosmos 1042 6 October 1978
15:30 		19 October 1978 1978-092A 179 x 299 km 13 days Success
22 Kosmos 1047 15 November 1978
11:45 		28 November 1978 1978-104A 171 x 354 km 13 days Success
23 Kosmos 1049 21 November 1978
12:00 		4 December 1978 1978-107A 169 x 338 km 13 days Success
24 Kosmos 1059 7 December 1978
15:30 		20 December 1978 1978-110A 180 x 338 km 13 days Success
25 Kosmos 1068 26 December 1978
15:30 		8 January 1979 1978-123A 191 x 389 km 13 days Success
26 Kosmos 1071 13 January 1979
15:30 		26 January 1979 1979-002A 179 x 339 km 13 days Success
27 Kosmos 1073 30 January 1979
15:15 		12 February 1979 1979-006A 182 x 328 km 13 days Success
28 Kosmos 1078 22 February 1979
12:10 		2 March 1979 1979-016A 168 x 280 km 8 days Success
29 Kosmos 1080 14 March 1979
10:50 		28 March 1979 1979-023A 169 x 294 km 14 days Success
30 Kosmos 1098 15 May 1979
11:40 		28 May 1979 1979-040A 170 x 354 km 13 days Success
31 Kosmos 1113 10 July 1979
09:00 		23 July 1979 1979-064A 173 x 330 km 13 days Success
32 Kosmos 1117 25 July 1979
15:20 		7 August 1979 1979-068A 177 x 325 km 13 days Success
33 Kosmos 1120 11 August 1979
09:15 		24 August 1979 1979-073A 170 x 362 km 13 days Success
34 Kosmos 1128 14 September 1979
15:30 		27 September 1979 1979-081A 173 x 328 km 13 days Success
35 Kosmos 1148 28 December 1979
13:00 		10 January 1980 1979-106A 170 x 340 km 13 days Success
36 Kosmos 1165 21 February 1980
12:00 		5 March 1980 1980-017A 170 x 350 km 13 days Success
37 Kosmos 1170 1 April 1980
08:00 		12 April 1980 1980-025A 178 x 379 km 11 days Success
38 Kosmos 1173 17 April 1980
08:30 		28 April 1980 1980-029A 174 x 352 km 11 days Success
39 Kosmos 1214 10 October 1980
13:10 		23 October 1980 1980-082A 170 x 347 km 13 days Success

Zenit 4 MKT[edit]

Another variant of the Zenit-4 design equipped with a Priroda-3 camera, intended for the investigation of natural resources in the interests of the Soviet economy and international cooperation.[25]

A total of 27 Zenit-4MKT satellites were launched between 1975 and 1985.[26][27]

Zenit 4 MT[edit]

A special version of the Zenit 4M intended for topographical photography. It carried an SA-106 topographic camera, a laser altimeter and Doppler apparatus.

Zenit-4MT (Orion)[28][29]
No. Mission Launch date
(GMT) 		Landing date COSPAR ID Orbit Duration
(in orbit) 		Outcome
1 Kosmos 470 27 December 1971
14:04 		6 January 1972 1971-118A 192 x 259 km 10 days Success
2 Kosmos 502 13 July 1972
14:30 		25 July 1972 1972-055A 203 x 262 km 12 days Success
3 Kosmos 541 27 December 1972
10:30 		8 January 1973 1972-105A 218 x 348 km 12 days Success
4 Kosmos 576 27 June 1973
11:50 		9 July 1973 1973-044A 204 x 332 km 12 days Success
5 Kosmos 616 17 December 1973
12:00 		28 December 1973 1973-102A 206 x 332 km 11 days Success
6 Kosmos 664 29 June 1974
12:50 		11 July 1974 1974-049A 205 x 341 km 12 days Success
7 Kosmos 693 4 November 1974
10:40 		16 November 1974 1974-088A 219 x 243 km 12 days Success
8 Kosmos 720 21 March 1975
06:50 		1 April 1975 1975-019A 212 x 273 km 11 days Success
9 Kosmos 759 12 September 1975
05:30 		23 September 1975 1975-084A 231 x 276 km 11 days Success
10 Kosmos 811 31 March 1976
12:50 		12 April 1976 1976-030A 206 x 338 km 12 days Success
11 Kosmos 855 21 September 1976
11:40 		3 October 1976 1976-095A 221 x 321 km 12 days Success
12 Kosmos 916 10 June 1977
08:00 		21 June 1977 1977-046A 255 x 304 km 11 days Success
13 Kosmos 988 8 February 1978
12:15 		20 February 1978 1978-015A 201 x 335 km 12 days Success
14 Kosmos 1046 1 November 1978
12:00 		13 November 1978 1978-102A 202 x 324 km 12 days Success
15 Kosmos 1069 28 December 1978
16:30 		10 January 1979 1978-124A 254 x 289 km 13 days Success
16 Kosmos 1119 3 August 1979
10:45 		15 August 1979 1979-071A 213 x 245 km 12 days Success
17 Kosmos 1139 5 October 1979
11:30 		18 October 1979 1979-088A 199 x 329 km 13 days Success
18 Kosmos 1180 15 May 1980
05:35 		26 May 1980 1980-038A 245 x 279 km 11 days Success
19 Kosmos 1211 23 September 1980
10:30 		4 October 1980 1980-077A 211 x 236 km 11 days Success
20 Kosmos 1239 16 January 1981
12:00 		28 January 1981 1981-004A 210 x 231 km 12 days Success
21 Kosmos 1309 18 September 1981
09:30 		1 October 1981 1981-092A 212 x 257 km 13 days Success
22 Kosmos 1332 12 January 1982
12:30 		25 January 1982 1982-002A 207 x 251 km 13 days Success
23 Kosmos 1398 3 August 1982
11:30 		13 August 1982 1982-077A 211 x 231 km 10 days Success

Zenit 6U[edit]

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 a total of 97 Zenit-6U satellites launched between 1976 and 1984.[30][31]

Zenit 8[edit]

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-DK No.1" designation.

A total of 102 Zenit-8 satellites were launched between 1984 and 1994, in addition to one sent into a suborbital trajectory during the maiden flight of the Soyuz-2 rocket in 2004.[32][33][34][35]

In popular culture[edit]

A Zenit satellite was mentioned in the movie Mission: Impossible – Dead Reckoning Part One.

References[edit]

  1. ^ a b c d e f g h Peter A. Gorin (1997). "Zenit:Corona's Soviet Counterpart". In Robert A. McDonald (ed.). Corona Between the Sun and the Earth: the first NRO reconnaissance eye in space. Bethesda, MD: The American Society for Photogrammetry and Remote Sensing. pp. 84–107.
  2. ^ "[1.0] Mi-8 Variants".
  3. ^ James Harford (1997). Korolev: How One Man Masterminded the Soviet Drive to Beat America to the Moon. John Wiley. ISBN 0-471-32721-2.
  4. ^ Peter A. Gorin (1997). "Zenit – The First Soviet Photo-Reconnaissance Satellite". Journal of the British Interplanetary Society. 50: 441.
  5. ^ Dwayne Day, ed. (1998). Eye in the Sky: Story of the Corona Spy Satellites. Smithsonian. ISBN 1-56098-773-1.
  6. ^ Mark Wade. "Zenit-2 satellite". Encyclopedia Astronautica. Retrieved 6 June 2024.
  7. ^ Timothy Varfolomeyev (1998). "Soviet Rocketry That Conquered Space: Part 8:Successes and Failures of a Three-Stage Launcher". Archived from the original on 3 March 2016. Retrieved 22 February 2013.
  8. ^ Sven Grahn. "Soviet/Russian reconnaissance satellites page at Sven's Space Place". Archived from the original on 2 May 2021. Retrieved 15 July 2005.
  9. ^ Robert Christy. "Complete Zenit Chronology". Zarya.info. Archived from the original on 23 October 2020. Retrieved 2 May 2013.
  10. ^ Gunter D. Krebs. "Zenit-2 (11F61)". Gunter's Space Page. Retrieved 12 May 2013.
  11. ^ Robert Christy. "Zenit-2 Missions". Zarya.info. Archived from the original on 1 October 2020. Retrieved 12 May 2013.
  12. ^ a b Bart Hendrickx (2005). "Snooping on Radars: A History of Soviet/Russian Global Signals Intelligence". Journal of the British Interplanetary Society. 58, supplement 2: 97–113.
  13. ^ Gunter D. Krebs. "Zenit-2M (Gektor, 11F690)". Gunter's Space Page. Retrieved 12 May 2013.
  14. ^ Gunter D. Krebs. "Zenit-2M/NKh (Gektor-Priroda, 11F690)". Gunter's Space Page. Retrieved 12 May 2013.
  15. ^ Robert Christy. "Zenit-2M Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  16. ^ Gunter D. Krebs. "Zenit-4 (11F69)". Gunter's Space Page. Retrieved 12 May 2013.
  17. ^ Robert Christy. "Zenit-4 Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  18. ^ Gunter D. Krebs. "Zenit-4M (Rotor, 11F691)". Gunter's Space Page. Retrieved 12 May 2013.
  19. ^ Robert Christy. "Zenit-4M Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  20. ^ Gunter D. Krebs. "Zenit-4MK (Germes, 11F692)". Gunter's Space Page. Retrieved 7 June 2024.
  21. ^ Robert Christy. "Zenit-4MK Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  22. ^ Mark Wade. "Zenit-4MKM". Encyclopedia Astronautica. Retrieved 7 June 2024.
  23. ^ Gunter D. Krebs. "Zenit-4MKM (Gerakl, 11F692M)". Gunter's Space Page. Retrieved 7 June 2024.
  24. ^ Robert Christy. "Zenit-4MKM Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  25. ^ Mark Wade. "Zenit-4MKT". Encyclopedia Astronautica. Retrieved 7 June 2024.
  26. ^ Gunter D. Krebs. "Zenit-4MKT (Fram, 11F635)". Gunter's Space Page. Retrieved 12 May 2013.
  27. ^ Robert Christy. "Zenit-4MKT Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  28. ^ Gunter D. Krebs. "Zenit-4MT (Orion, 11F629)". Gunter's Space Page. Retrieved 12 May 2013.
  29. ^ Robert Christy. "Zenit-4MT Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  30. ^ Gunter D. Krebs. "Zenit-6U (Argon, 11F645)". Gunter's Space Page. Retrieved 12 May 2013.
  31. ^ Robert Christy. "Zenit-6 Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  32. ^ Gunter D. Krebs. "Zenit-8 (Oblik, 17F116)". Gunter's Space Page. Retrieved 12 May 2013.
  33. ^ Robert Christy. "Zenit-8 Missions". Zarya.info. Archived from the original on 28 September 2020. Retrieved 12 May 2013.
  34. ^ Mark Wade. "Soyuz-2-1A". Encyclopedia Astronautica. Retrieved 7 January 2010.
  35. ^ Gunter D. Krebs. "Zenit-8-Dummy (Oblik-Dummy, 17F116ML)". Gunter's Space Page. Retrieved 7 June 2024.
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