HR: 0800h
AN: P31B-0985    [Abstracts]
TI: The Search for Dune Movement on Mars
AU: * Williams, K K
EM: williamsk@nasm.si.edu
AF: Center for Earth and Planetary Studies, National Air and Space Museum Smithsonian Institution, Washington, DC 20013-7012 United States
AB: Although aeolian processes are active on Mars, questions remain about whether the current wind regime is adequate to cause dune movement. Early studies using Viking images might have detected movement in the northern erg, but that study was limited by image resolution. Since 1997, the Mars Orbiter Camera (MOC) on Mars Global Surveyor has been returning narrow angle (NA) images at resolutions of 1.5-12 m/pixel, and overlapping pairs of these images acquired at sufficiently spaced times can be used to search for dune movement. Whereas most images acquired during the Mapping Phase of the mission were near-nadir looking, images from the Extended and Relay portions of the mission often had look directions off nadir (ROTO images). This geometry causes parallax and complicates the search for dune movement but does not prevent it. Dune locations in MOC (and now THEMIS) images can also be compared to locations in Viking images, but movement would need to be on a larger scale because of the larger pixel sizes of Viking and THEMIS images. Results showing evidence for dune movement or for dune immobility would both be important for understanding the current martian aeolian setting and how it might have changed over time. The MSSS website and a USGS database of potentially overlapping MOC narrow angle images have been used to identify image pairs that could be used to determine whether dunes moved during the time spanned by the images. Of the over 150,000 MOC NA images released, only a small subset are overlapping pairs, and only a subset of those contain dunes. At this time, no definite dune movement has yet been detected, but the study is being expanded to cover more areas on Mars and to include more images as they become available.
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
DE: 5499 General or miscellaneous
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting