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KH-8 Gambit-3 (Block 3)

KH-8 48 [USAF]

KH-8 (Keyhole-8) or Gambit-3 was the second generation of Gambit high resolution reconnaissance satellites. The KH-8 Block 3 were the third iteration of this design, introducing an improved roll joint.

KH-8 Block 3 had the same basic layout as the KH-8 (Block 2) series. The forward part was joint via a roll joint with the Agena-D. The major subsystems of the satellite included a photographic-payload section (PPS), a satellite-control section (SCS), and the booster vehicle. The payload section contained a camera module and two satellite recovery-vehicles (SRV). The control section included the command system, the orbit-adjust module, an attitude-control subsystem, a back-up stabilization system (BUSS), and the power supply.

The next 11 satellites of the KH-8 Block 3 series (KH-8 37 to 47) featured an improved roll joint capable of 18000 maneuvers per mission,increasing greatly the agility of the imaging system. Also the film capacity was increased. The block 3 satellites were able to perform satellite-to-satellite (SSquared) imaging.

The camera system was strip camera coupled to an optical system a focal length of 4.46 m. In the optical system the ground image is reflected by a steerable flat mirror to a 1.21 m diameter stationary concave primary mirror. The primary mirror reflects the light through an opening in the flat mirror and through a Ross corrector. At perigeum, the main camera imaged a 6.3 km wide ground swath on a 223.8 mm wide moving portion of film through a small slit aperture. The ground resolution was as small as 0.1 m or better, near the theoretical physical e resolution limit imposed by atmospheric turbulence.

The Astro-Position Terrain Camera (APTC) contained three cameras: a 75 mm focal length terrain frame camera, and two 90 mm 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 opposite directions and took images of star fields.

This series used the stretched Titan-3(24)B Agena-D version as launch vehicle.

KH-8 39 was lost due to fuel valve failure of the Agena during ascent.

The KH-8 Block-3 satellites were succeeded by the improved KH-8 Block 3 satellites featuring a number of improvements, including solar arrays.

Nation: USA
Type / Application: Reconnaissance, photo (film return type)
Operator: US Air Force (USAF)
Equipment: ?
Configuration: Agena-D, 2 SRVs
Propulsion: Bell 8096, SPS
Power: Batteries
Lifetime: 30 to 45 days
Orbit: (typical)
Satellite COSPAR Date LS Launch Vehicle Remarks
KH-8 37 (Gambit-3 37, Mission 4337, OPS 3978) 1972-103A 21.12.1972 Va SLC-4W Titan-3(24)B Agena-D
KH-8 38 (Gambit-3 38, Mission 4338, OPS 2093) 1973-028A 16.05.1973 Va SLC-4W Titan-3(24)B Agena-D
KH-8 39 (Gambit-3 39, Mission 4339, OPS 4018) 1973-F04 26.06.1973 Va SLC-4W F Titan-3(24)B Agena-D
KH-8 40 (Gambit-3 40, Mission 4340, OPS 6275) 1973-068A 27.09.1973 Va SLC-4W Titan-3(24)B Agena-D
KH-8 41 (Gambit-3 41, Mission 4341, OPS 6889) 1974-007A 13.02.1974 Va SLC-4W Titan-3(24)B Agena-D
KH-8 42 (Gambit-3 42, Mission 4342, OPS 1776) 1974-042A 06.06.1974 Va SLC-4W Titan-3(24)B Agena-D
KH-8 43 (Gambit-3 43, Mission 4343, OPS 3004) 1974-065A 14.08.1974 Va SLC-4W Titan-3(24)B Agena-D
KH-8 44 (Gambit-3 44, Mission 4344, OPS 4883) 1975-032A 18.04.1975 Va SLC-4W Titan-3(24)B Agena-D
KH-8 45 (Gambit-3 45, Mission 4345, OPS 5499) 1975-098A 09.10.1975 Va SLC-4W Titan-3(24)B Agena-D
KH-8 46 (Gambit-3 46, Mission 4346, OPS 7600) 1976-027A 22.03.1976 Va SLC-4W Titan-3(24)B Agena-D .
KH-8 47 (Gambit-3 47, Mission 4347, OPS 8533) 1976-094A 15.09.1976 Va SLC-4W Titan-3(24)B Agena-D


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