Spatial Variation in Results of Biosignature Analyses of Apparently Homogeneous Samples from Mars Analogue Environments in Iceland

Abstract

The search for signs of life on Mars and beyond is time consuming and labor-intensive; hence, it is critical to understand how to design sampling strategies that can maximize the likelihood of success. Two distinct Mars analogue environments in Iceland were selected to represent volcanic resurfacing and glacial environments where characterization of different biosignatures at various spatial scales (100 m, 10 m, 1 m, 10 cm) was performed. This study serves the twofold purposes of (1) understanding the different levels of biosignature distributions in these analogue environments and (2) the spatial distributions of biosignatures in these environments, with an overarching goal of drawing lessons from low biomass Mars analogue environments to inform the best sampling strategies for sample collection strategies on Mars. Our results show that samples should be collected for analysis at large (at least 100 m spacing) to capture most differences within an apparently homogeneous environment of the aged resurfaced volcanic region like Mælifellssandur, whereas a smaller spacing at 10 m scale is necessary for younger glacial–volcanic environments like Fimmvörduháls. This study also illustrates the importance of understanding the variability across spatial scales in sampling design for future planetary missions.

The Vacant Niche Revisited: Using Negative Results to Refine the Limits of Habitability

“…Both sampling small areas and increasing the scale of experiments—at the cost of resolution—can convey an inaccurate sense of homogeneity across an environment. This makes the choice of sampling scale crucial in life detection, particularly in oligotrophic or low biomass regions 30, 31, 32, 33 .…”

Laboratory and field analogs of the Martian (sub)surface

“…Sampling in fresh basaltic environments can help us discern between lifeless samples and those with low biomass and poor biosignature preservation, an issue we may encounter in upcoming Mars missions (Cockell and McMahon, 2019). Biosignature detection strategies have been tested in Icelandic hydrothermal areas (Muñoz-Iglesias et al, 2022) and volcanic resurfacing and glacial environments with low biomass (Tan et al, 2022). Newly formed basaltic terrain post volcanic eruptions also allows us to study the primary colonizers of an abiotic environment (e.g., Carrillo et al (2022)).…”