Recomputation of the global Mars control-point network

This paper deals with the recomputation of the global control point network of the planet Mars. The existing Mars control point net is based on Viking data and consists of a large number of ground points, which can be easily identified in the imagery and whose three-dimensional (3D) object coordinates (e.g., latitude, longitude, and height with respect to a reference ellipsoid) are known. These coordinates were redetermined in order to eliminate several disadvantages of the former computations and to include the currently best available input data such as improved Viking trajectory information, the Viking occultation data, present rotational parameters, and the Mars Pathfinder lander data. Within a simultaneous 3D bundle block triangulation, seven interior orientation parameters, the position and attitude parametersof 1140 images, and the ground coordinates of 3739 tie points and one control point were estimated. The RMS values uX, uY, uZ of the theoretical standard deviations of the adjusted object coordinates amountto 750 m, 770 m, and 710 m, respectively, which is a significant improvement compared with former results (1 to 5 km). The accuracy of the ground point coordinates is close to the theoretical accuracy limitof 520 m in X, Y, and Z, where error-free orientation parameters areassumed. This new set of orientation parameters and ground points may now be used for local, regional, and global DTM generation; for thedetermination of reference bodies; for mapping purposes; as well as for current (Mars Global Surveyor 1996) and future (e.g., Mars Surveyor 1998 and 2001, Mars Express 2003) missions to Mars. [ABSTRACT FROM AUTHOR]