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COMBINING MARS DATA IN GRASS GIS FOR GEOLOGICAL MAPPING
C. Deuchler?, M. Wàühlisch*' , S. Gehrke^, E. Hauber®, J. Oberst®, R. Jaumann®
* DLR, German Aerospace Center, Institute for Planetary Research, Rutherfordstrasse 2, D-12489 Berlin, Germany
marita.waehlisch@dir.de
^ Technical University of Berlin, Sekr. EB9, Strafe des 17. Juni 135, D-10623 Berlin, Germany
Commission IV, WG IV/9
KEY WORDS: Extra-terrestrial, Planetary, Exploration, GIS, Cartography
ABSTRACT:
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 the 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.
In this paper we describe the required steps to integrate Digital terrain Models (DTMs) and images of Mars Global Surveyor, Viking
mosaics, and supplementary geologic information in a single database under the open source GIS GRASS (Geographic Resources
Analysis Support System) environment. The different possible reference frames are discussed. The derived GIS database is
currently being used to map the global distribution of tectonic faults on Mars. Finally, there are excellent prospects to use GRASS
GIS for the analysis and geologic interpretation of image data from the High Resolution Stereo Camera aboard Mars Express. As the
software and its source code are released 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.
1. INTRODUCTION - .* "Planetocentric/east": -90° to +90° north planeto-
centric latitude / 0° to 360° east longitude.
The past decade has seen an increasing number of planetary e “Planetographic/west”: -90° to +90° north planeto-
space missions, returning large volumes and various types of graphic latitude / 0° to 360° west longitude.
scientific data. Therefore, GIS technology became increasingly
popular in this field owing to its ability to create multilayered Earth, Moon and Sun do not match with this definition for
databases for comparison studies (e.g. [3]-[5]). Our goal was to traditional reasons [8]. For Mars cartography, the
create a global GIS database for planet Mars incorporating the planetographic/west system was used until recently. There is a
various datasets available to date. The database relies on the recommendation of the Mars Geodesy/Cartography Working
GRASS software, which is available as open source from the Group (MGCWG) to only employ the planetocentric/east
internet [13]. system in future products [2].
2.2 Horizontal Reference
2. CARTOGRAPHIC STANDARDS ON MARS
The IAU reports also state the parameters necessary to define
Beginning in 1976, the definitions of the body-fixed coordinate the geodetic base of the Mars GIS. In particular these are: the
systems of all planets and satellites along with size and shape angle Wy, defining the prime meridian in respect to the inertial
parameters for mapping are updated and published by the coordinate system (see [8]) and the radii of the biaxial ellipsoid.
Working Group of Cartographic Constants and Rotational ^ These values have been updated several times during the last
Elements of the Planets and Satellites of the International decades (Table 1).
Astronomical Union (IAU) on a regular basis [8].
2.3 Vertical Reference
2.1 Coordinate systems The MOLA team released a planetary radii model and a
topographic elevation model (elevation above the areoid, i.e.
There are two coordinate systems approved and recommended the geoid for Mars) [10]. The two datasets have been approved
by IAU for planetary mapping: by IAU to be the reference surface models for Mars [9].
*
Corresponding author
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