Present-day gully activity on Mars provides new evidence for transient liquid water. Reiss et al. study images of the Russell crater dune field on Mars taken by the High Resolution Imaging Science Experiment from November 2006 to May 2009.
The authors observe that the length of a 2-meter (6.56 feet) wide gully channel had increased by about 50 m (164 ft) in one year and about 120 m (394 ft) within the second year. On the basis of the morphology of the channel and other factors, the researchers believe that these changes in the length of the gully are best explained by erosional processes triggered by the melting of small amounts of water ice.
Title:Evidence for present day gully activity on the Russell crater dune field, Mars, D. Reiss, G. Erkeling, K. E. Bauch, H. Hiesinger: Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Münster, Germany; Geophysical Research Letters DOI: 10.1029/2009GL042192