MICROSCALE OBSERVATIONS OF A POTENTIAL MARS ANALOG USING ROVER-INSPIRED METHODS

Much of the sedimentary history of a region may be contained in the microscale characteristics of the individual particles that make up its rocks and soil. When the study site is truly remote, such as Mars, examination at the handlens scale is critical both for extracting maximum information and for best utilizing finite analytical capabilities. We conducted fieldwork at Fort Rock tuff ring in central Oregon to test whether rover-inspired field methods would provide handlens-scale images that yield results similar to actual handlens work in the field.

Formations of interest were imaged for context at outcrop and unit scale, then specific features were imaged at 10 µm/pxl. To mimic rover operations, we chose features of interest through macroscale assessment, rather than examination of in situ samples with a handlens and limited the number of images examined to 2-5 per feature. In these images, we were able to identify characteristics of the hydrovolcanic nature of this tuff ring such as coarse-to-fine grained alternating layers and poorly-sorted angular clasts in a clast-supported matrix.

Among other results, we found that for one third of the features of interest the few pictures taken were ample for determining the likely nature of the ?feature as a tuff ring, but for two thirds, they were inadequate. At least 2-3 images at 667µm/pxl and another at 0.5 mm/pxl (imaging areas about 8 cm² and 65 cm² respectively) would have been required to eliminate or constrain other possible formation scenarios. For current and future Mars missions, taking "location" images at this intermediate scale would be a useful way to narrow down ideal sites for comprehensive analysis.

To assist in interpreting handlens-scale martian images in the future, 10µm/pxl images taken in this study are being incorporated into an image library, designed to stretch the utility of the limited number of images returned from Mars by providing terrestrial analog comparisons at appropriate resolution.