Microbialites at Gusev Crater, Mars

The Mars Exploration Rover Spirit investigated plains at Gusev crater, where sedimentary rocks are present. The Spirit rover's Athena morphological investigation shows microstructures organized in intertwined filaments of microspherules: a texture we ha also found on samples of terrestrial stromatolites and other microbialites. We performed a quantitative image analysis nto compare 45 microbialites samplings with 50 rover's ones (approximately 25.000/20,000 microstructures). Contours were extreacted and morphometric indexes obtained: geometric and algorithmic complexities, entropy, tortuosity, minimum and maximum diameters. Terrestrial and Martian textures resulted multifractals, while terrestrial abiogenic minerals showed a simple fractal structure. Mean values and confidence intervals from the Martian images overlapped perfectly with those from terrestrial samples. Our work show the presumptive evidence of microbialites in the Martian outcroppings explored by Opportunity at Meridiani Planum: unicellular life was widespread on the ancient Mars.