Mars Television Camera
Two television cameras, one of medium resolution (wide angle) and the other of high resolution (narrow angle), were part of the Mariner 6 scientific instrumentation. The wide-angle camera, which had a field of view of 11 deg by 14 deg and a focal length of 50 mm, encompassed 100 times more surface area than the narrow-angle camera and was used only for near-encounter pictures. The narrow-angle camera, which was used for both near- and far-encounter pictures, had a focal length of 508 mm and provided 10 times the linear resolution of the wide-angle camera. Camera shutters were alternated and timed to provide overlapping of the wide-angle and narrow-angle pictures, providing 75 pictures from the two systems (26 near-encounter and 49 far-encounter, plus a 50th fractional far-encounter image). The near-encounter pictures were taken between 13 min 59 s before encounter and 2 min 55 s after encounter along a track that crossed the equatorial zones of the planet and included many known light and dark features of the Martian surface. The far-encounter pictures were obtained in two series of operations. In the first series, 33 pictures were obtained between 48 h and 28 h before encounter. In the second series, 17 pictures were obtained between 22 h and 7 h from closest approach. The picture data were encoded and recorded within the onboard television and data storage subsystems. For each picture produced by the cameras, three separate encoded versions were transmitted to earth -- a composite analog video (CAV) picture, a digital video (DV) picture, and an every twenty-eighth (ETE) digital picture. Video reconstruction consisted of combining the three data streams (CAV, DV, and ETE). This generated video data as they existed coming out of the camera heads. The telemetered video magnetic tapes were displayed on a CRT and photographed on 70-mm film to produce the raw images. They were also digitally processed by an IBM 360/44 computer for enhancement and by an IBM 360/75 for noise removal to obtain the versions contained in data sets -01C through -01H. Detailed information on the digital processing procedures can be found in "Digital Processing of the Mariner 6 and 7 pictures," T. C. Rindfleish et al, J. Geophys. Res. , v. 76, p. 394-417, January 1971. Accurate trajectory and related geometrical data can be found in Mariner Mars 1969 Simulated TV Pictures (Final), J. K. Campbell, 1970, which was issued by JPL.