Properties of martian slope streak populations

• We study slope streak activity in Viking/CTX overlap images.
• Most slope streaks have disappeared since 1977.
• Slope streak population is balanced in time.
• The turnover time of the slope streak population is estimated to be four decades.
• The number of discernible slope streaks increases with image resolution.

Slope streaks are down-slope mass movements on the surface of Mars that are among the few known examples of contemporary geologic activity on Mars. Here we study slope streak activity over three decades, based on overlapping images in the Lycus Sulci region taken by the Context Camera (CTX) 2007–2010 and the Viking Orbiter Camera in 1977. The number of disappeared slope streaks is nearly equal the number of newly formed slope streaks, suggesting the streak population is balanced. The turnover time of the population is estimated to be four decades. Slope streaks fade gradually over time, with islands of persistence. We also determine the number of observable slope streaks as a function of image resolution based on images by the High Resolution Imaging Science Experiment (HiRISE) camera, and find that the number of discernible slope streaks can increase rapidly with spatial resolution.