Recurring slope lineae (RSL) are dark lines that appear on steep slopes, then lengthen, fade, and reappear, typically annually. Proposed explanations for their formation involve either the flow of liquid or dry sediment, with varying triggering mechanisms. McEwen et al.  report a significant increase in the number of RSL detections following the planet-encircling dust storm on Mars in 2018, compared to previous years. The latitudinal and seasonal range in which RSLs were detected was also expanded compared to previous years. These observations raise a new hypothesis about the potential role of dust mobilization and deposition in forming these features. Such a mechanism does not involve flowing water or brines, and if correct, diminishes the likelihood that RSLs represent modern-day habitable zones.
Citation: McEwen, A. S., Schaefer, E. I., Dundas, C. M., Sutton, S. S., Tamppari, L. K., & Chojnacki, M. . Mars: Abundant recurring slope lineae (RSL) following the planet‐encircling dust event (PEDE) of 2018. Journal of Geophysical Research: Planets, 126, e2020JE006575. https://doi.org/10.1029/2020JE006575
―A. Deanne Rogers, Editor, JGR: Planets