PHYSICAL WEATHERING OF MARTIAN ROCKS AS A RESULT OF DIURNAL HEATING AND COOLING

Recent studies in arid climates have shown that diurnal heating and cooling can play a significant role in the physical weathering of rocks. It is thought that diurnal variation in insolation creates thermal stresses that result in the formation and propagation of rock fractures. Due to the metronomic nature of this solar induced stress, cracks formed via this process exhibit a preferred orientation dictated by the overhead traverse of the Sun.

The Martian environment can be considered analogous to arid environments on Earth, so it follows that physical weathering in the Martian environment might also result from daily changes in the direction of insolation in conjunction with a large daily variation in temperature. If so, then cracks observed on Martian rocks should also exhibit a preferred orientation.

We have developed software that allows us to analyze, in a virtual field environment, 3-D data from NASA’s Spirit and Opportunity rovers. The accuracy of this software was tested by ground-truthing terrestrial LIDAR scans. To date, we have collected data for over 120 rocks, including rock size, total number of visible cracks, and spatial data such as crack length and orientation. Preliminary data suggests a potential preferred orientation of cracks, however, a non-uniform distribution of image orientations from the Spirit Rover introduces sampling bias and precludes simple analysis of the total dataset. Overall, our data has good potential to provide supporting evidence regarding the hypothesis that directional insolation is a significant contributor to the physical weathering of Martian rocks.