Space Research & Planetary Sciences Division Web Site

McEwen et al. have identified a set of darkish streaks which appear every late spring on southern hemisphere slopes. They are reproducible and often leave behind a brighter deposit. There are called Recurring Slope Lineae (RSL) and may be related to liquid water.


A color-enhanced image of the inside rim of Newton Crater on Mars, showing dark streaks, called Recurring Slope Lineae (RSL).

Although we are co-authors on the paper here, our main contribution is studying the photometric effects of traces of water on Martian simulants. The darkening of sand and dust samples when wet is common knowledge but there are other subtle effects that occur when the sample is dried out again. We are investigating some of these slightly esoteric issues with our goniometer set-up.


A wet (left) and dry (right) sample of JSC-1 Mars simulant.


  • McEwen, A.S., C.M. Dundas, S. S. Mattson, A.D. Toigo, L. Ojha, J.J. Wray, M. Chojnacki, S. Byrne, S.L. Murchie, and N. Thomas, (2013), Recurring Slope Lineae in Valles Marineris, Mars, Nature Geoscience 7, 53-58.
  • McEwen, A.S., L. Ojha, C.M. Dundas, S.S. Mattson, S. Byrne, J.J. Wray, S.C. Cull, S.L. Murchie, N. Thomas, and V.C. Gulick, (2011), Seasonal Flows on Warm Martian Slopes, Science, Science, 333, 740.

Space Research & Planetary Sciences Division Web Site