Formation of Martian Slope Streaks: Implications for Aqueous Processes

Dark slope streaks are features that were first found by the Viking Orbiter and are now being studied by the Mars Global Surveyor (MGS) spacecraft. The streaks have no distinct topographic relief of their own and follow the surrounding terrain which includes moving around obstacles and flowing downward from crater rims, valley walls, and shield volcano scarps. Slope streaks are young features found at equatorial latitudes and are not overlain by craters, ejecta or debris. The streaks are about a few meters wide to a kilometer long and appear in wedge, anastomosing, and braided shapes. Because they occur on slopes, it is suggested that the mechanism forming the streaks is gravitationally driven. New slope streaks are darker than the surrounding terrain and brighten over time, perhaps due to dust mantling. We have studied periodic pictures taken by the Mars Orbiter Camera (MOC) on MGS that show changes in old streaks and formation of new slope streaks to determine if the streaks were formed by wet or dry processes. Two overlapping image pairs are calibrated and reprojected to the same viewing geometry and resolution to accurately compare new slope streaks. Images examined include a slope streak with dune morphology, horseshoe vortices, possible permafrost in highland knobs, and comparison of seasonal melt. Supported by NSF award number AST-0552751, Research Experiences for Undergraduates Program.