Exploration missions to Mars rely on landers or rovers to perform multiple analyses over geographically small sampling regions, while landing site selection is done using large-scale but low-resolution remote-sensing data. Utilizing Earth analog environments to estimate small-scale spatial and temporal variation in key geochemical signatures and biosignatures will help mission designers ensure future sampling strategies meet mission science goals. Icelandic lava fields can serve as Mars analog sites due to conditions that include low nutrient availability, temperature extremes, desiccation, and isolation from anthropogenic contamination. This work reports analysis of samples collected using methods analogous to those of planetary missions to characterize microbial communities at different spatial scales in Mælifellssandur, Iceland, an environment with homogeneity at "remote imaging" resolution (overall temperature, apparent moisture content, and regolith grain size). Although microbial richness did not vary significantly among samples, the phylogenetic composition of the sediment microbiome differed significantly among sites separated by 100 m, which suggests distinct microbial signatures despite apparent homogeneity from remote observations. This work highlights the importance of considering microenvironments in future life-detection missions to extraterrestrial planetary bodies.
Keywords: Microbial ecology—Deglaciated environments—biosignatures—Martian analog—Extremophile—Amplicon sequencing.