We conducted an analog sampling expedition under simulated mission constraints to areas dominated by basaltic tephra of the Eldfell and Fimmvörðuháls lava fields (Iceland). Sites were selected to be “homogeneous” at a coarse remote sensing resolution (10–100 m) in apparent color, morphology, moisture, and grain size, with best-effort realism in numbers of locations and replicates. Three different biomarker assays (counting of nucleic-acid-stained cells via fluorescent microscopy, a luciferin/luciferase assay for adenosine triphosphate, and quantitative polymerase chain reaction (qPCR) to detect DNA associated with bacteria, archaea, and fungi) were characterized at four nested spatial scales (1 m, 10 m, 100 m, and >1 km) by using five common metrics for sample site representativeness (sample mean variance, group F tests, pairwise t tests, and the distribution-free rank sum H and u tests). Correlations between all assays were characterized with Spearman's rank test. The bioluminescence assay showed the most variance across the sites, followed by qPCR for bacterial and archaeal DNA; these results could not be considered representative at the finest resolution tested (1 m). Cell concentration and fungal DNA also had significant local variation, but they were homogeneous over scales of >1 km. These results show that the selection of life detection assays and the number, distribution, and location of sampling sites in a low biomass environment with limited a priori characterization can yield both contrasting and complementary results, and that their interdependence must be given due consideration to maximize science return in future biomarker sampling expeditions. Key Words: Astrobiology—Biodiversity—Microbiology—Iceland—Planetary exploration—Mars mission simulation—Biomarker. Astrobiology 17, 1009–1021.

We conducted a planetary exploration analogue mission at two recent lava fields in 19Iceland, Fimmvörðuháls (2010) and Eldfell (1973), using a specially developed field laboratory. 20We tested the utility of in-field site sampling down selection and tiered analysis operational 21 capabilities with three life detection and characterization techniques: fluorescence microscopy 22 (FM), adenine-triphosphate (ATP) bioluminescence assay, and quantitative polymerase chain 23 reaction (qPCR) assay. The study made use of multiple cycles of sample collection at multiple 24 distance scales and field laboratory analysis using the synchronous life-detection techniques to 25 heuristically develop the continuing sampling and analysis strategy during the expedition. 26Here we report the operational lessons learned and provide brief summaries of scientific 27 data. The full scientific data report will follow separately. We found that rapid in-field analysis 28 to determine subsequent sampling decisions is operationally feasible, and that the chosen life 29 detection and characterization techniques are suitable for a terrestrial life-detection field mission. 30In-field analysis enables the rapid obtainment of scientific data and thus facilitates the 31 collection of the most scientifically relevant samples within a single field expedition, without the 32 need for sample relocation to external laboratories. The operational lessons learned in this study 33 could be applied to future terrestrial field expeditions employing other analytical techniques and 34 to future robotic planetary exploration missions. 35 3 2 Introduction 36Extreme environments on Earth are used as analogs to inform both the science and 37 operations of future planetary exploration missions (Amils et al., 2007, Amato et al., 2010, Billi 38 et al., 2013. In particular, Icelandic lava fields have an especially good heritage as Mars analog 39 sites (Farr, 2004, Warner and Farmer, 2010, Cockell et al., 2011, Cousins and Crawford, 2011, 40 Mangold et al., 2011, Ehlmann et al., 2012, Cousins et al., 2013. Lava fields are relevant for 41 astrobiological science due to the presence of extreme conditions, including desiccation, low 42 nutrient availability, temperature extremes (e.g. due to high elevation or close proximity to 43 fumaroles), relatively young ages, and their isolation from anthropogenic contamination (Allen 44 et al., 1981, Bagshaw et al., 2011. From an operational perspective, many Icelandic lava fields 45 are remote enough to require that field expeditions address several sampling operational 46 constraints that are also experienced in robotic planetary exploration (Arena et al., 2004, Preston 47 andDartnell, 2014). 48Terrestrial field campaigns designed to conduct scientific studies of planetary analogs can 49 also serve as operational analogs for robotic planetary missions. Field campaigns typically 50 involve in situ sampling, followed by preservation of any collected samples and subsequent 51 return to an institutional laboratory where ...