KH-8 Gambit

The KH-8 (BYEMAN codename Gambit-3) 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, and also known as Low Altitude Surveillance Platform. 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). 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.

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 (9 m) in length. They carried 12,241 feet (3,731 meters) of film and were designed for longer missions of up to 31 days

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, 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. 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.

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