A Preliminary Control Net of Mars.

Describes the computation of an aerodetic net of Mars consisting of 112 reference points identified on the Mariner 6 and 7 flyby television pictures. Using geometrically restored pictures, the authors selected the control points, measured their positions, and computed their positions on Mars using the spacecraft trajectory data. The coordinates of an initial point are determined, and the near-encounter frames of Mariner 6 and the adjoining near-encounter frames of Mariner 7 are tied to this initial point. This computation involved 306 observations of 66 points on 16 pictures. The far-encounter frames were then tied to the near-encounter using common points; the solution involved 374 observations of 31 points on 35 pictures. The five Mariner 7 polar cap pictures were tied together using 104 observations of 21 points; however, none of the polar points could be identified on far-encounter frames, so this strip is not tied directly to the rest of the net. (To be published in the January 1971 Journal