Experimental Simulations of Recurring Slope Lineae on the Surface of Mars

By: Elizabeth Eddings '15

Advising Faculty: Douglas Thompson

Recurring Slope Lineae (RSL) are active surface features found on rocky Martian slopes commonly in the southern hemisphere equatorial to mid-latitude regions. These low albedo, dark streaks on Mars demonstrate seasonal characteristics; they appear and grow darker and longer in warm months and fade to possible disappearance in colder months. One proposed mechanism for the formation and evolution of these features by McEwen et al. (2011) is the melting of subsurface water on Mars. The goal of this study was to test this hypothesis by reconstructing features similar to RSL in the lab that display the same seasonal characteristics as a result of freezing and thawing cycles creating a source of subsurface liquid. Laboratory experiments were conducted at both the Arkansas Center for Space and Planetary Sciences and at Connecticut College using small open-topped and insulated boxes filled with saturated regolith. The two main constraints that were identified in these simulations were the effects of topographic distribution of regolith and of large boulders on the overall thawing of the system and production of features. Results showed that dark wet streaks could appear along the slope as a result of capillary rise through a thin dry overburden of sediment, but there must be some sort of anisotropy introduced into the system in order for the dark line to occur in a linear trend, such as the generation of a small channel extending down the slope. Additional results indicated that different heat transfer properties of larger particles could initiate subsurface thawing from a point along the slope. The lack of recurrence of slope lineae in these experiments suggests a need for larger scale varying topography experiments or a possible limitation due to the size of the small boxes not reaching the critical length necessary for features to form.

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Related Fields: Physics