Correlations Between Life-Detection Techniques and Implications for Sampling Site Selection in Planetary Analog Missions

Abstract We conducted an analog sampling expedition under simulated mission constraints to areas dominated by basaltic tephraof the Eldfell and Fimmvorðuhals 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 bioluminescenceassay showe...