Coarse-grained ripples investigated by the Opportunity rover on Meridiani Planum, Mars

Aeolian coarse-grained ripples have been found in all regions investigated by Mars rovers: Meridiani Planum, Gusev crater, Gale crater, and Jezero crater. Therefore, it can be assumed that coarse-grained ripples are one of the most common landforms on Mars. Studying their formation and evolution gives us the opportunity to determine past and current wind patterns. They are also crucial for understanding the formation and evolution of larger aeolian bedforms. Of all locations studied in situ on Mars, coarse-grained ripples in extensive (∼100 $km^{2}$) ripple fields were found only on Meridiani Planum. As coarse-grained ripples on Mars are not well characterized in the literature, in this work, the morphometry, morphology, spatial distribution, and orientation of coarse-grained ripples investigated along the 45 km long traverse of the Opportunity rover were analyzed. The obtained results allowed for a more precise definition of coarse-grained ripples and for distinguishing three classes of coarse-grained ripples on Meridiani Planum: small, medium, and large. The coarse-grained ripple activity on Meridiani Planum is now limited due to low material supply, and the relatively strong induration of the ripple surfaces. Even though most of the coarse-grained ripples on Meridiani Planum were formed thousands of years ago, some smaller coarse-grained ripples were formed by modern winds.