HR: 17:30h
AN: P34A-05    [Abstracts]
TI: Regional Differences in Gully Occurrence on Mars: A Comparison Between the Hale and Bond Craters Using HRSC, THEMIS-IR and MOC Data
AU: * Reiss, D
EM: dennis.reiss@dlr.de
AF: Institute of Planetary Science, German Aerospace Center, Rutherfordstr. 2, Berlin, 12489 Germany
AU: Stephan, K
EM: katrin.stephan@dlr.de
AF: Institute of Planetary Science, German Aerospace Center, Rutherfordstr. 2, Berlin, 12489 Germany
AU: van Gasselt, S
EM: vgasselt@zedat.fu-berlin.de
AF: Remote Sensing of the Earth and Planets, Freie Universitaet Berlin, Malteserstr. 74-100, Berlin, 12249 Germany
AU: Hauber, E
EM: ernst.hauber@dlr.de
AF: Institute of Planetary Science, German Aerospace Center, Rutherfordstr. 2, Berlin, 12489 Germany
AU: Jaumann, R
EM: ralf.jaumann@dlr.de
AF: Institute of Planetary Science, German Aerospace Center, Rutherfordstr. 2, Berlin, 12489 Germany
AU: Neukum, G
EM: gneukum@zedat.fu-berlin.de
AF: Remote Sensing of the Earth and Planets, Freie Universitaet Berlin, Malteserstr. 74-100, Berlin, 12249 Germany
AB: Gullies on Mars indicate liquid water in the recent past. The strong latitude-dependence suggests a climatic control on their formation. However, in some regions many gullies occur in one crater and do not in another crater nearby. This is the case for the Hale (gullies) and Bond (no gullies) crater, respectively. These regional differences have been interpreted as an argument against climatically controlled deposition and melting of volatiles. The formation of gullies on Earth depends on rainfall and/or melting of snow as well as on several parameters such as (1) the presence of steep slopes, (2) sufficient amounts of fines/debris and (3) low or no vegetation. We investigated the Hale/Bond region (325$^\circ$E and 35$^\circ$S) with High Resolution Stereo Camera (HRSC) images, which covers this region with a resolution of $\sim$25 m/pxl in the nadir channel, 100 m/pxl in color (blue, green, red, near infrared) and HRSC stereo data (100 m/pxl). The color images and derived products show regional variances in surface reflectance, which correlate well with differences in the thermophysical surface properties derived from nighttime THEMIS-IR images. The gully regions in the Hale crater show low nighttime temperatures (unconsolidated material), while higher temperature slopes (consolidated material) occur in the Bond Crater. These different surface properties of unconsolidated (gullies) and consolidated (no gullies) material is confirmed by the morphology as analysed in MOC--images. The morphology indicates debris slopes in the Hale crater in contrast to Bond crater where the material seems to consist of cemented mantle deposits. Furthermore, the Bond crater is highly degraded and the rim slopes derived from HRSC stereo data vary between 10$^\circ$ to 20$^\circ$ in contrast to the more pristine Hale crater with slopes in the range of 20$^\circ$ to 30$^\circ$. We conclude that the occurrence of gullies in the Hale/Bond region depends on the distribution of unconsolidated material and/or steep slopes. The regional and local gully distribution is likely to vary because of differences in topography and surface material composition.
DE: 5415 Erosion and weathering
DE: 5420 Impact phenomena (includes cratering)
DE: 5470 Surface materials and properties
DE: 6207 Comparative planetology
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting