HR: 11:50h
AN: P22A-07    [Abstracts]
TI: Dark Streaks on Mars : Systematic Mapping of Geometric, Surface Properties and Rate of Formation From HRSC, THEMIS and MOC images.
AU: * Baratoux, D
EM: david.baratouxd@cnes.fr
AF: Observatoire Midi-Pyren\'ees, Laboratoire Dynamique Terrestre et Plan\'etaire, UMR 5562, 14 Avenue Edouard Belin, TOULOUSE, F-31400 France
AU: Mangold, N
EM: mangold@geol.u-psud.fr
AF: Orsay-Terre, FRE 2566, OrsayTerre, Bat 509 Universit\'e Paris-Sud, Orsay, F-91405 France
AU: Pinet, P
AF: Observatoire Midi-Pyren\'ees, Laboratoire Dynamique Terrestre et Plan\'etaire, UMR 5562, 14 Avenue Edouard Belin, TOULOUSE, F-31400 France
AU: Masson, P
EM: masson@geol.u-psud.fr
AF: Orsay-Terre, FRE 2566, OrsayTerre, Bat 509 Universit\'e Paris-Sud, Orsay, F-91405 France
AU: Chevrel, S
EM: serge.chevrel@cnes.fr
AF: Observatoire Midi-Pyren\'ees, Laboratoire Dynamique Terrestre et Plan\'etaire, UMR 5562, 14 Avenue Edouard Belin, TOULOUSE, F-31400 France
AU: Forget, F 3
EM: forget@lmd.jussieu.fr
AF: Laboratoire de M‚t‚orologie Dynamique, UMR 8539, Institut Pierre Simon Laplace Universit‚ Paris 6, BP 99, 4 place Jussieu, Paris, F-75252 France
AU: Daydou, Y
EM: yves.daydou@cnes.fr
AF: Observatoire Midi-Pyren\'ees, Laboratoire Dynamique Terrestre et Plan\'etaire, UMR 5562, 14 Avenue Edouard Belin, TOULOUSE, F-31400 France
AU: Jehl, A
EM: augustin.jehl@cnes.fr
AF: Observatoire Midi-Pyren\'ees, Laboratoire Dynamique Terrestre et Plan\'etaire, UMR 5562, 14 Avenue Edouard Belin, TOULOUSE, F-31400 France
AU: Neukum, G
EM: gneukum@zedat.fu-berlin.de
AF: Department of Earth Sciences, Institute of Geosciences, Remote Sensing of the Earth and Planets, Freie Universit\"at Berlin Malterserstr. 74-100, Building D , Berlin, D-12249 Germany
AU: Greeley, R
EM: greeley@asu.edu
AF: Department of Geological Sciences, Arizona State University, Box 87104, Tempe, AZ 85287 United States
AB: Dark slope streaks are among the only processes which are active at the present time on the Martian surface. While their mechanism of formation and triggering is still debated, they may involve liquid water. The HRSC experiment (Mars Express) provides new key data for the study of the mechanism of formation of these objects. The resolution and covering of HRSC images permit a systematic mapping of the geometric properties of these objects (width, length and orientation) which was not possible with MOC or THEMIS-VIS data. We present a systematic mapping of about 800 dark streaks in a region north of Olympus Mons. The mapped area extends from $28^o$N to 38$^o$N from 220$^o$E to 224$^o$E. From these data, it is possible to investigate geographical variations of the density of dark streaks. Few dark streaks occur north of $33^oN$. The density of dark streaks increases rapidly from $32^oN$ and values up to 0.05 dark streaks per $km^2$ are observed. The ubiquitous boundary observed around $33^o$N indicates a possible correlation between the formation of dark streak and surface temperature, a correlation which has been previously reported at the planetary scale [1] giving supports to the role of liquid water in the process of formation. The number of dark streaks varies also with longitude. These variations can be related to surface roughness properties (at the kilometer scale) and surface thermal properties. The orientations of dark streaks have been systematically mapped from the direction of the flow along the slope. The dark streaks at the highest latitude are preferentially oriented on south facing slopes. This result implies a dependence to the sun exposition. At lower latitude, the orientation of dark streaks becomes progressively more randomly distributed, with the exception of an area on the slope of the aureole of Olympus Mons, where a population of dark streaks is emplaced preferentially on west facing slopes. This preferential orientation can not be explained by any particular organization of the topography or slopes. We propose that winds could be involved in the formation of dark streaks by the accumulation of dust particles at hill crests. The comparison of HRSC, THEMIS-VIS and MOC images allow the detection of new dark streaks. These observations are promising for the estimation of possibly geographic variations of rates of formation which will have implications concerning the transport and deposition of dust on Mars. [1] Schorghofer, et. al. Slope streaks on mars: Correlations with surface properties and the potential role of water. Geoph.l Res. Let., 29(23):41-1,41-4.
DE: 5415 Erosion and weathering
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting