Zenit (satellite)
Zenit 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
The basic design of the Zenit satellites was similar to the Vostok crewed spacecraft, sharing the return and service modules. It consisted of a spherical re-entry capsule in diameter with a mass of around. 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 and the total mass was between.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. The camera would either land on the ground or be recovered in midair by a modified Mil Mi-8 helicopter.
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 and an apogee between ; the missions usually lasted between 8 and 15 days.
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 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.
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".
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.
Many versions of the satellite were developed for different reconnaissance missions and flights continued until 1994.
Zenit variants
Zenit 2
Zenit 2 was the first version to be launched between 1961 and 1970.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, each frame held an image of a square. The ground resolution was stated to be 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.
Zenit 2s also carried ELINT equipment called Kust-12M to receive NATO radar signals. The satellites carried a parabolic antenna, around 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.
There were 81 Zenit 2 launches. 58 were successful and 13 were partially successful. There were 9 failed missions, 2 because of a satellite malfunction and 7 because of a failure in the launch vehicle.
| No. | Mission | Launch date | Landing date | COSPAR ID | Orbit | Duration | Outcome |
| 1 | - | 11 December 1961 09:39 | - | - | - | ||
| 2 | Kosmos 4 | 26 April 1962 10:02 | 29 April 1962 | 1962-014A | 285 x 317 km | ||
| 3 | - | 1 June 1962 09:38 | - | - | - | ||
| 4 | Kosmos 7 | 28 July 1962 09:18 | 1 August 1962 | 1962-033A | 197 x 356 km | ||
| 5 | Kosmos 9 | 27 September 1962 09:39 | 1 October 1962 | 1962-048A | 829 x 981 km | ||
| 6 | Kosmos 10 | 17 October 1962 09:00 | 21 October 1962 | 1962-054A | 178 x 376 km | ||
| 7 | Kosmos 12 | 22 December 1962 09:23 | 30 December 1962 | 1962-072A | 202 x 385 km | ||
| 8 | Kosmos 13 | 21 March 1963 08:30 | 29 March 1963 | 1963-006A | 214 x 303 km | ||
| 9 | Kosmos 15 | 22 April 1963 08:30 | 27 April 1963 | 1963-011A | 194 x 336 km | ||
| 10 | Kosmos 16 | 28 April 1963 08:50 | 8 May 1963 | 1963-012A | 201 x 379 km | ||
| 11 | Kosmos 18 | 24 May 1963 10:33 | 2 June 1963 | 1963-018A | 212 x 269 km | ||
| 12 | - | 10 July 1963 | - | - | - | ||
| 13 | Kosmos 20 | 18 October 1963 09:29 | 26 October 1963 | 1963-040A | 201 x 296 km | ||
| 14 | - | 28 November 1963 | - | - | - | ||
| 15 | Kosmos 24 | 19 December 1963 09:28 | 28 December 1963 | 1963-052A | 204 x 391 km | ||
| 16 | Kosmos 28 | 4 April 1964 09:36 | 12 April 1964 | 1964-017A | 213 x 373 km | ||
| 17 | Kosmos 29 | 25 April 1964 10:19 | 2 May 1964 | 1964-021A | 203 x 292 km | ||
| 18 | Kosmos 32 | 10 June 1964 10:48 | 18 June 1964 | 1964-029A | 205 x 322 km | ||
| 19 | Kosmos 33 | 23 June 1964 10:19 | 1 July 1964 | 1964-033A | 205 x 279 km | ||
| 20 | Kosmos 35 | 15 July 1964 11:31 | 23 July 1964 | 1964-039A | 218 x 258 km | ||
| 21 | Kosmos 37 | 14 August 1964 09:36 | 22 August 1964 | 1964-044A | 208 x 240 km | ||
| 22 | Kosmos 46 | 24 September 1964 12:00 | 2 October 1964 | 1964-059A | 211 x 264 km | ||
| 23 | Kosmos 48 | 14 October 1964 09:50 | 20 October 1964 | 1964-066A | 204 x 284 km | ||
| 24 | Kosmos 50 | 28 October 1964 10:48 | 5 November 1964 | 1964-070A | 190 x 233 km | ||
| 25 | Kosmos 52 | 11 January 1965 09:36 | 19 January 1965 | 1965-001A | 203 x 298 km | ||
| 26 | Kosmos 64 | 25 March 1965 10:04 | 2 April 1965 | 1965-025A | 205 x 250 km | ||
| 27 | Kosmos 66 | 7 May 1965 09:50 | 15 May 1965 | 1965-035A | 285 x 397 km | ||
| 28 | Kosmos 68 | 15 June 1965 10:04 | 23 June 1965 | 1965-046A | 208 x 306 km | ||
| 29 | - | 13 July 1965 | - | - | - | ||
| 30 | Kosmos 78 | 14 August 1965 11:16 | 22 August 1965 | 1965-066A | 330 x 379 km | ||
| 31 | Kosmos 98 | 27 November 1965 08:24 | 5 December 1965 | 1965-097A | 205 x 547 km | ||
| 32 | Kosmos 99 | 10 December 1965 08:09 | 18 December 1965 | 1965-103A | 203 x 309 km | ||
| 33 | Kosmos 104 | 7 January 1966 08:24 | 15 January 1966 | 1966-001A | 195 x 379 km | ||
| 34 | Kosmos 105 | 22 January 1966 08:38 | 30 January 1966 | 1966-003A | 203 x 311 km | ||
| 35 | Kosmos 107 | 10 February 1966 08:52 | 18 February 1966 | 1966-010A | 216 x 313 km | ||
| 36 | Kosmos 112 | 17 March 1966 10:28 | 25 March 1966 | 1966-021A | 214 x 664 km | ||
| 37 | Kosmos 115 | 20 April 1966 10:48 | 28 April 1966 | 1966-033A | 189 x 283 km | ||
| 38 | Kosmos 117 | 6 May 1966 11:02 | 14 May 1966 | 1966-037A | 200 x 314 km | ||
| 39 | Kosmos 120 | 8 June 1966 11:02 | 16 June 1966 | 1966-050A | 201 x 331 km | ||
| 40 | Kosmos 124 | 14 July 1966 10:33 | 22 July 1966 | 1966-064A | 202 x 282 km | ||
| 41 | - | 16 September 1966 09:30 | - | - | - | ||
| 42 | Kosmos 129 | 14 October 1966 12:13 | 21 October 1966 | 1966-091A | 199 x 288 km | ||
| 43 | Kosmos 132 | 19 November 1966 08:09 | 27 November 1966 | 1966-106A | 202 x 257 km | ||
| 44 | Kosmos 136 | 19 December 1966 12:00 | 27 December 1966 | 1966-064A | 202 x 282 km | ||
| 45 | Kosmos 138 | 19 January 1967 12:39 | 27 January 1967 | 1967-004A | 190 x 273 km | ||
| 46 | Kosmos 143 | 27 February 1967 08:45 | 7 March 1967 | 1967-017A | 202 x 390 km | ||
| 47 | Kosmos 147 | 13 March 1967 12:10 | 21 March 1967 | 1967-022A | 195 x 298 km | ||
| 48 | Kosmos 153 | 4 April 1967 14:00 | 12 April 1967 | 1967-030A | 199 x 279 km | ||
| 49 | Kosmos 157 | 12 May 1967 10:30 | 20 May 1967 | 1967-044A | 249 x 262 km | ||
| 50 | Kosmos 164 | 8 June 1967 13:00 | 14 Jun 1967 | 1967-057A | 185 x 317 km | ||
| 51 | Kosmos 168 | 4 July 1967 05:59 | 12 July 1967 | 1967-067A | 223 x 230 km | ||
| 52 | - | 1 September 1967 10:30 | - | - | - | ||
| 53 | Kosmos 177 | 16 September 1967 06:06 | 24 September 1967 | 1967-088A | 201 x 267 km | ||
| 54 | Kosmos 180 | 26 September 1967 10:20 | 4 October 1967 | 1967-093A | 206 x 350 km | ||
| 55 | Kosmos 181 | 11 October 1967 11:30 | 19 October 1967 | 1967-067A | 198 x 325 km | ||
| 56 | Kosmos 193 | 25 November 1967 11:30 | 3 December 1967 | 1967-117A | 745 x 756 km | ||
| 57 | Kosmos 195 | 16 December 1967 12:00 | 24 December 1967 | 1967-124A | 204 x 352 km | ||
| 58 | Kosmos 199 | 16 January 1968 12:00 | 1 February 1968 | 1968-003C | 206 x 363 km | ||
| 59 | Kosmos 205 | 5 March 1968 12:30 | 13 March 1968 | 1968-016A | 197 x 293 km | ||
| 60 | Kosmos 210 | 3 April 1968 11:00 | 11 April 1968 | 1968-024A | 200 x 373 km | ||
| 61 | Kosmos 216 | 20 April 1968 10:30 | 28 April 1968 | 1968-034A | 198 x 267 km | ||
| 62 | Kosmos 223 | 1 June 1968 10:50 | 9 June 1968 | 1968-045A | 221 x 317 km | ||
| 63 | Kosmos 231 | 10 July 1968 19:49 | 18 July 1968 | 1968-058A | 206 x 311 km | ||
| 64 | Kosmos 235 | 9 August 1968 07:00 | 17 August 1968 | 1968-067A | 201 x 281 km | ||
| 65 | Kosmos 240 | 14 September 1968 06:50 | 21 September 1968 | 1968-075A | 203 x 283 km | ||
| 66 | Kosmos 247 | 11 October 1968 12:05 | 19 October 1968 | 1968-088A | 199 x 345 km | ||
| 67 | Kosmos 253 | 13 November 1968 12:00 | 18 November 1968 | 1968-102A | 216 x 337 km | ||
| 68 | Kosmos 255 | 29 November 1968 12:40 | 7 December 1968 | 1968-105A | 197 x 317 km | ||
| 69 | Kosmos 258 | 10 December 1968 08:25 | 18 December 1968 | 1968-111A | 205 x 298 km | ||
| 70 | Kosmos 263 | 12 January 1969 12:10 | 20 January 1969 | 1969-003A | 200 x 325 km | ||
| 71 | Kosmos 266 | 25 February 1969 10:20 | 5 March 1969 | 1969-015A | 202 x 336 km | ||
| 72 | Kosmos 273 | 22 March 1969 12:15 | 30 March 1969 | 1969-027A | 200 x 336 km | ||
| 73 | Kosmos 278 | 9 April 1969 13:00 | 17 April 1969 | 1969-034A | 198 x 310 km | ||
| 74 | Kosmos 281 | 13 May 1969 09:15 | 21 May 1969 | 1969-042A | 191 x 303 km | ||
| 75 | Kosmos 287 | 24 June 1969 06:50 | 2 July 1969 | 1969-054A | 189 x 265 km | ||
| 76 | Kosmos 290 | 22 July 1969 12:30 | 30 July 1969 | 1969-060A | 195 x 332 km | ||
| 77 | Kosmos 301 | 24 September 1969 12:15 | 2 October 1969 | 1969-081A | 203 x 271 km | ||
| 78 | Kosmos 309 | 12 November 1969 11:30 | 20 November 1969 | 1969-098A | 185 x 364 km | ||
| 79 | Kosmos 325 | 4 March 1970 12:14 | 12 March 1970 | 1970-015A | 200 x 327 km | ||
| 80 | Kosmos 326 | 13 March 1970 08:00 | 21 March 1970 | 1970-018A | 208 x 232 km | ||
| 81 | Kosmos 344 | 12 May 1970 10:10 | 20 May 1970 | 1970-038A | 204 x 326 km |