Combining Mars Data in GRASS GIS for Geological Mapping

Kurzfassung

GEO Information Systems (GIS) are standard tools in the Earth sciences whenever different geographic data sets must be combined. GIS became increasingly popular in the field of planetary research as well, due to the increasing amount of data from recent planetary missions, in particular to Mars. However, as the available GIS packages are designed for standard terrestrial coordinate systems, several obstacles have to be overcome to implement a geodetic accurate and consistent database for other solar system bodies. In the past decade, parameters describing the rotation and shape of Mars have changed several times. Therefore, today, the digital data products available to the science community incorporate several different reference surfaces and map projections. For example, while the gridded MOLA (Mars Orbiter Laser Altimeter) DTM (Digital Terrain Model) uses planetocentric latitudes and East longitudes, the traditional Viking maps use planetographic latitudes and West longitudes. In this paper we describe the required steps to integrate DTMs and images of Mars Global Surveyor, Viking mosaics, and supplementary geologic information in a single database unter de open source GIS GRASS (geographic Resources Analysis Support System) environment. The different possible reference frames - including their advantages and shortcomings - are discussed. The derived GIS database is currently being used to map the global distribution of tectonic faults on Mars. GIS also allows us to study statistical parameters (width, length, depth, and slopes) of outflow channels in the context of their spatial distribution. Finally, there are excellent prospects to use GRASS GIS for the upcoming analysis and geologic interpretation of image data from the High Resolution Stereo Camera aboard ESA's Mars Express. Other planetary science applications for GRASS GIS are presented and discussed at the conference. As the software and its source code is releases under a free license, scientists may take the opportunity to gather work experience with a planetary GIS at no costs and with the opportunity to modify the software to their specific needs.