Evidence for present day gully activity on the Russell crater dune field, Mars

On the basis of High Resolution Imaging Science Experiment (HiRISE) images of two successive years we observed changes of a gully on the Russell crater dune field. Within the first year the length of a ∼2 m wide incised gully channel grew about 50 m downslope, and ∼120 m within in the second year. Gully activity occurred in early spring between LS ∼198° and ∼218° in the first year and between LS ∼192° and ∼221° in the second year. Based on the channel morphology, spectral data and modeled surface temperatures, the changes can be best explained with transient melting of small amounts of H2O‐ice triggering slurry flows consisting of sand mixed with liquid water.