KH-8 Gambit 3

The KH-8 (BYEMAN codename Gambit-3)[1] was a long-lived series of reconnaissance satellites of the "Key Hole" (KH) series used by the United States from July 1966 to April 1984,[2] and also known as Low Altitude Surveillance Platform.[3] The satellite ejected "film-bucket" canisters of photographic film that were retrieved as they descended through the atmosphere by parachute. Ground resolution of the mature satellite system was better than 4 inches (0.10 m).[4] There were 54 launch attempts of the 3,000 kilogram satellites, all from Vandenberg Air Force Base, on variants of the Titan III rocket. Three launches failed to achieve orbit. The first one was satellite #5 on April 26, 1967, which fell into the Pacific Ocean after the Titan second stage developed low thrust. The second was satellite #35 on May 20, 1972, which suffered an Agena pneumatic regulator failure and reentered the atmosphere. A few months later, pieces of the satellite turned up in England and the US managed to arrange for their hasty return. The third failure was satellite #39 on June 26, 1973, which suffered a stuck Agena fuel valve. The Bell 8096 engine failed to start and the satellite burned up in the atmosphere. The KH-8 was manufactured by Lockheed. The camera system/satellite was manufactured by Eastman Kodak's A&O Division in Rochester, New York.

KH-8 GAMBIT
Schematics of GAMBIT-3 and Agena D
Mission typeImagery intelligence
OperatorNational Reconnaissance Office
Spacecraft properties
Manufacturer
Launch mass4100 kg (on orbit)
Dimensions14.75 m × 1.52 m (48.4 ft × 5.0 ft)
Start of mission
RocketTitan III
Launch siteVandenberg Air Force Base, SLC-4E
ContractorMartin Marietta
Orbital parameters
Reference systemSun-synchronous orbit
RegimeLow Earth orbit
Perigee altitude135 km (84 mi)
Apogee altitude305 km (190 mi)
Inclination110.5°
Main telescope
TypeAspheric reflector with five-element Ross corrector
Diameter1.1 m (3 ft 7 in)
Focal length4.46 m (14.6 ft)
Focal ratiof/4.09
Wavelengthsvisible light, Near-infrared
 

The Gambit codename was also used by the satellite's predecessor, the KH-7 Gambit.

Gambit 3 satellites were the same width as the Gambit 1 models, but also slightly longer – reaching about 29 feet (8.8 m) in length. They carried 12,241 feet (3,731 meters) of film and were designed for longer missions of up to 31 days.[5]

While Gambit was primarily designed and operated as a surveillance satellite, capturing high definition images of specific targets at low orbital altitudes, a single Gambit Block 3 mission was operated in 'dual-mode', orbiting first at a higher altitude to capture wide-area search imagery before lowering its perigee to capture normal surveillance imagery. The first film return capsule failed to separate correctly due to a new pyro mechanism failing to perform correctly. The contingency release mechanism separated the film bucket and parachute from its return capsule, and left the film bucket stranded in orbit. In September 2002, the film bucket re-entered over the South Atlantic into deep water. As the film bucket lacked its protective heatshield or the parachute needed to slow its descent, no attempt was made to recover it.[6]

Camera Optics Module
KH-8 GAMBIT-3 Photographic Payload Section
KH-8 Photographic Payload Section

The Camera Optics Module of KH-8 consists of four cameras.

The main camera of KH-8B (introduced in 1971) with a focal length of 175.6 in (4.46 m) is a single strip camera, designed to gather high-resolution images of ground targets. In the strip camera the ground image is reflected by a steerable flat mirror to a 1.21 m (48 in) diameter stationary concave primary mirror. The primary mirror reflects the light through an opening in the flat mirror and through a Ross corrector. At periapsis altitude of 75 nautical miles (139 km), the main camera imaged a 6.3 km wide ground swath on a 8.811 in (223.8 mm) wide moving portion of film through a small slit aperture, resulting in an image scale of 28 meter / millimeter.[7][8] The Astro-Position Terrain Camera (APTC) contains three cameras: a 75mm focal length terrain frame camera, and two 90mm focal length stellar cameras. The terrain frame camera takes exposures of Earth in direction of the vehicle roll position for attitude determination. The stellar cameras observed in 180 degree opposite directions and took images of star fields.[7]

Ground-resolution distance achievable by KH-8

The films used by GAMBIT were provided by Eastman Kodak, and evolved through a series of successively higher definition films, starting with Type 3404 with a resolving power of 50 to 100 line pairs per mm.[9] Subsequent films used were Type 1414 high-definition film, SO-217 high-definition fine-grain film, and a series of films with silver-halide crystals of very uniform size and shape. The size of silver-halide crystals decreased from 1,550 angstrom in film Type SO-315, to 1,200 angstrom in SO-312, and ultimately to 900 angstrom in SO-409.[4] Under optimal conditions GAMBIT would thus have been able to record ground features as small as 0.28 to 0.56 m (0.92 to 1.84 ft) using the Eastman Kodak Type 3404 film. Using a film with a resolving power equivalent to the Kodak's Type 3409 film of 320 to 630 line pairs per mm, GAMBIT would have been able to record ground features as small as 5 cm to 10 cm (2" to 4").[10] The initial September 2011 release of "The Gambit Story" quotes "The mature system produced examples of imagery better than four inches ground-resolution distance". This number was again redacted in a later release.[4] Five to ten centimeters corresponds to the resolution limit imposed by atmospheric turbulence as derived by Fried[11] and, independently, Evvard[12] in the mid-1960s; remarkably, GAMBIT had reached a physical limit on resolution only a few years after the US launched its first reconnaissance satellite. GAMBIT was also able to record objects in orbit. The capability was developed to photograph Soviet spacecraft, but was first used to aid NASA engineers designing repairs for the damaged Skylab space station in 1973.[13][14]

Missions
Ascent and Orbital events for GAMBIT-3 missions
N1 (rocket) imaged by KH-8 Gambit on 19 September 1968
KH-8 GAMBIT 3 (Block 1) main features
KH-8 GAMBIT 3 (Block 2) main features
KH-8 GAMBIT 3 (Block 3 & 4) main features
Name Block[15] Launch Date Alt. Name NSSDC ID No. Launch Vehicle Orbit Decay date
KH8-1 I 1966-07-29 OPS-3014 1966-069A Titan IIIB 158.0 km × 250.0 km, i=94.1° 1966-08-06[16]
KH8-2 I 1966-09-28 OPS-4096 1966-086A Titan IIIB
KH8-3 I 1966-12-14 OPS-8968 1966-113A Titan IIIB
KH8-4 I 1967-02-24 OPS-4204 1967-016A Titan IIIB
KH8-5 I 1967-04-26 OPS-4243 1967-F04, 1967-003X Titan IIIB no stable orbit 1967-04-26
KH8-6 I 1967-06-20 OPS-4282 1967-064A Titan IIIB
KH8-7 I 1967-08-16 OPS-4886 1967-079A Titan IIIB
KH8-8 I 1967-09-19 OPS-4941 1967-090A Titan IIIB
KH8-9 I 1967-10-25 OPS-4995 1967-103A Titan IIIB
KH8-10 I 1967-12-05 OPS-5000 1967-121A Titan IIIB
KH8-11 I 1968-01-18 OPS-5028 1968-005A Titan IIIB
KH8-12 I 1968-03-13 OPS-5057 1968-018A Titan IIIB
KH8-13 I 1968-04-17 OPS-5105 1968-031A Titan IIIB
KH8-14 I 1968-06-05 OPS-5138 1968-047A Titan IIIB
KH8-15 I 1968-08-06 OPS-5187 1968-064A Titan IIIB
KH8-16 I 1968-09-10 OPS-5247 1968-074A Titan IIIB
KH8-17 I 1968-11-06 OPS-5296 1968-099A Titan IIIB
KH8-18 I 1968-12-04 OPS-6518 1968-108A Titan IIIB
KH8-19 I 1969-01-22 OPS-7585 1969-007A Titan IIIB
KH8-20 I 1969-03-04 OPS-4248 1969-019A Titan IIIB
KH8-21 I 1969-04-15 OPS-5310 1969-039A Titan IIIB
KH8-22 I 1969-06-03 OPS-1077 1969-050A Titan IIIB
KH8-23 II 1969-08-23 OPS-7807 1969-074A Titan 23B
KH8-24 II 1969-10-24 OPS-8455 1969-095A Titan 23B
KH8-25 II 1970-01-14 OPS-6531 1970-002A Titan 23B
KH8-26 II 1970-04-15 OPS-2863 1970-031A Titan 23B
KH8-27 II 1970-06-25 OPS-6820 1970-048A Titan 23B
KH8-28 II 1970-08-18 OPS-7874 1970-061A Titan 23B
KH8-29 II 1970-10-23 OPS-7568 1970-090A Titan 23B
KH8-30 II 1971-01-21 OPS-7776 1971-005A Titan 23B 139.0 km × 418.0 km, i=110.8° 1971-02-09[17]
KH8-31 II 1971-04-22 OPS-7899 1971-033A Titan 23B 132.0 km × 401.0 km, i=110.9° 1971-05-13[18]
KH8-32 II 1971-08-12 OPS-8607 1971-070A Titan 24B 137.0 km × 424.0 km, i=111.0° 1971-09-03[19]
KH8-33 II 1971-10-23 OPS-7616 1971-092A Titan 24B 134.0 km × 416.0 km, i=110.9° 1971-11-17[20]
KH8-34 II 1972-03-17 OPS-1678 1972-016A Titan 24B 131.0 km × 409.0 km, i=111.0° 1972-04-11[21]
KH8-35 II 1972-05-20 OPS-6574 1972-F03 Titan 24B failed to reach orbit
KH8-36 II 1972-09-01 OPS-8888 1972-068A Titan 24B 140.0 km × 380.0 km, i=110.5° 1972-09-30[22]
KH8-37 III 1972-12-21 OPS-3978 1972-103A Titan 24B 139.0 km × 378.0 km, i=110.5° 1973-01-23[23]
KH8-38 III 1973-05-16 OPS-2093 1973-028A Titan 24B 139.0 km × 399.0 km, i=110.5° 1973-06-13[24]
KH8-39 III 1973-06-26 OPS-4018 1973-F04 Titan 24B failed to reach orbit (mix-up with KH8-38 in NSSDC)
KH8-40 III 1973-09-27 OPS-6275 1973-068A Titan 24B 131.0 km × 385.0 km, i=110.5° 1973-10-29[25]
KH8-41 III 1974-02-13 OPS-6889 1974-007A Titan 24B 134.0 km × 393.0 km, i=110.4° 1974-03-17[26]
KH8-42 III 1974-06-06 OPS-1776 1974-042A Titan 24B 136.0 km × 394.0 km, i=110.5° 1974-07-24[27]
KH8-43 III 1974-08-14 OPS-3004 1974-065A Titan 24B 135.0 km × 402.0 km, i=110.5° 1974-09-29[28]
KH8-44 III 1975-04-18 OPS-4883 1975-032A Titan 24B 134.0 km × 401.0 km, i=110.5° 1975-06-05[29]
KH8-45 III 1975-10-09 OPS-5499 1975-098A Titan 24B 125.0 km × 356.0 km, i=96.4° 1975-11-30[30]
KH8-46 III 1976-03-22 OPS-7600 1976-027A Titan 24B 125.0 km × 347.0 km, i=96.4° 1976-05-18[31]
KH8-47 III 1976-09-15 OPS-8533 1976-094A Titan 24B 135.0 km × 330.0 km, i=96.4° 1976-11-05[32]
KH8-48 IV 1977-03-13 OPS-4915 1977-019A Titan 24B 124.0 km × 348.0 km, i=96.4° 1977-05-26[33]
KH8-49 IV 1977-09-23 OPS-7471 1977-094A Titan 24B 125.0 km × 352.0 km, i=96.5° 1977-12-08[34]
KH8-50 IV 1979-05-28 OPS-7164 1979-044A Titan 24B 124.0 km × 305.0 km, i=96.4° 1979-08-26[35]
KH8-51 IV 1981-02-28 OPS-1166 1981-019A Titan 24B 138.0 km × 336.0 km, i=96.4° 1981-06-20[36]
KH8-52 IV 1982-01-21 OPS-2849 1982-006A Titan 24B 630.0 km × 641.0 km, i=97.4° 1982-05-23[37]
KH8-53 IV 1983-04-15 OPS-2925 1983-032A Titan 24B 124.0 km × 254.0 km, i=96.5° 1983-08-21[38]
KH8-54 IV 1984-04-17 OPS-8424 1984-039A Titan 24B 127.0 km × 235.0 km, i=96.4° 1984-08-13[39]

(NSSDC ID Numbers: See COSPAR)

Notable Missions

In May 1973 Gambit KH3-38 was used to observe the crippled Skylab space station, as part of the preparation for repairing it by the Skylab 2 mission.[14]

Cost

The total cost of the 54 flight KH-8 program from FY1964 to FY1985, without non-recurring costs, was US$2.3 billion in respective year dollars.[15]

Other U.S. imaging spy satellites

References
  • Mark Wade (August 9, 2003). KH-8. Encyclopedia Astronautica. Accessed April 23, 2004.
  • KH-8 Gambit. GlobalSecurity.org
  1. "GAMBIT 3 KH-8 Reconnaissance Satellite". National Museum of the U.S. Air Force. Retrieved August 10, 2022.
  2. Richelson, Jeffrey (1987). American espionage and the Soviet target. W. Morrow. p. 195. ISBN 978-0-688-06753-3.
  3. Global Security Space Systems IMINT Overview LASP
  4. "The GAMBIT Story". National Reconnaissance Office. June 1991. Archived from the original on September 15, 2012. Retrieved September 26, 2011.
  5. "Declassified US Spy Satellites from Cold War Land in Ohio". Space.com. January 28, 2012. Retrieved October 11, 2015.
  6. "GAMBIT_Dual_Mode". www.nro.gov. Retrieved February 19, 2021.
  7. "KH-8 Camera System". National Reconnaissance Office. 1970. Archived from the original on September 15, 2012. Retrieved September 26, 2011.
  8. Day, Dwayne A. (November 29, 2010). "Ike's gambit: The development and operations of the KH-7 and KH-8 spy satellites". www.thespacereview.com. Retrieved January 25, 2009.
  9. "KODAK PLUS-X AERECON II Film 3404" (PDF). Kodak. November 28, 2005. Archived from the original (PDF) on November 6, 2013.
  10. "KODAK AERECON High Altitude Film 3409" (PDF). Kodak. November 28, 2005. Archived from the original (PDF) on January 10, 2014.
  11. Fried, David (1966). "Limiting Resolution Looking Down Through the Atmosphere". Journal of the Optical Society of America. 56 (10): 1380–1384. Bibcode:1966JOSA...56.1380F. doi:10.1364/josa.56.001380.
  12. Evvard, John (December 1, 1968). "Atmospheric Turbulence Limits on the Observational Capabilities of Aerospacecraft". NASA Technical Note. NASA-TN-D-4940. Retrieved June 18, 2015.
  13. Day, Dwayne Allen (June 11, 2012). "Out of the black". The Space Review. Retrieved June 11, 2012.
  14. Day, Dwayne (May 20, 2013). "Those magnificent spooks and their spying machine: The spies help rescue Skylab". The Space Review. Retrieved July 10, 2020.
  15. "The GAMBIT story". National Reconnaissance Office. June 1991. Archived from the original on October 7, 2017. Retrieved September 25, 2011.
  16. "KH 8-01". NASA National Space Science Data Center. October 8, 2010.
  17. "KH 8-30". NASA National Space Science Data Center. October 8, 2010.
  18. "KH 8-31". NASA National Space Science Data Center. October 8, 2010.
  19. "KH 8-32". NASA National Space Science Data Center. October 8, 2010.
  20. "KH 8-33". NASA National Space Science Data Center. October 8, 2010.
  21. "KH 8-34". NASA National Space Science Data Center. October 8, 2010.
  22. "KH 8-36". NASA National Space Science Data Center. October 8, 2010.
  23. "KH 8-37". NASA National Space Science Data Center. October 8, 2010.
  24. "KH 8-38". NASA National Space Science Data Center. October 8, 2010.
  25. "KH 8-40". NASA National Space Science Data Center. October 8, 2010.
  26. "KH 8-41". NASA National Space Science Data Center. October 8, 2010.
  27. "KH 8-42". NASA National Space Science Data Center. October 8, 2010.
  28. "KH 8-43". NASA National Space Science Data Center. October 8, 2010.
  29. "KH 8-44". NASA National Space Science Data Center. October 8, 2010.
  30. "KH 8-45". NASA National Space Science Data Center. October 8, 2010.
  31. "KH 8-46". NASA National Space Science Data Center. October 8, 2010.
  32. "KH 8-47". NASA National Space Science Data Center. October 8, 2010.
  33. "KH 8-48". NASA National Space Science Data Center. October 8, 2010.
  34. "KH 8-49". NASA National Space Science Data Center. October 8, 2010.
  35. "KH 8-50". NASA National Space Science Data Center. October 8, 2010.
  36. "KH 8-51". NASA National Space Science Data Center. October 8, 2010.
  37. "KH 8-52". NASA National Space Science Data Center. October 8, 2010.
  38. "KH 8-53". NASA National Space Science Data Center. October 8, 2010.
  39. "KH 8-54". NASA National Space Science Data Center. October 8, 2010.
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