Life Detection and Microbial Biomarker Profiling with Signs of Life Detector-Life Detector Chip During a Mars Drilling Simulation Campaign in the Hyperarid Core of the Atacama Desert

Abstract

The low organic matter content in the hyperarid core of the Atacama Desert, together with abrupt temperature shifts and high ultraviolet radiation at its surface, makes this region one of the best terrestrial analogs of Mars and one of the best scenarios for testing instrumentation devoted to in situ planetary exploration. We have operated remotely and autonomously the SOLID-LDChip (Signs of Life Detector-Life Detector Chip), an antibody microarray-based sensor instrument, as part of a rover payload during the 2019 NASA Atacama Rover Astrobiology Drilling Studies (ARADS) Mars drilling simulation campaign. A robotic arm collected drilled cuttings down to 80 cm depth and loaded SOLID to process and assay them with LDChip for searching for molecular biomarkers. A remote science team received and analyzed telemetry data and LDChip results. The data revealed the presence of microbial markers from Proteobacteria, Acidobacteria, Bacteroidetes, Actinobacteria, Firmicutes, and Cyanobacteria to be relatively more abundant in the middle layer (40–50 cm). In addition, the detection of several proteins from nitrogen metabolism indicates a pivotal role in the system. These findings were corroborated and complemented on “returned samples” to the lab by a comprehensive analysis that included DNA sequencing, metaproteomics, and a metabolic reconstruction of the sampled area. Altogether, the results describe a relatively complex microbial community with members capable of nitrogen fixation and denitrification, sulfur oxidation and reduction, or triggering oxidative stress responses, among other traits. This remote operation demonstrated the high maturity of SOLID-LDChip as a powerful tool for remote in situ life detection for future missions in the Solar System.

The Atacama Rover Astrobiology Drilling Studies (ARADS) Project

“…The SOLID instrument and its offline Life Detector Chip (LDChip) were participants in each of the four ARADS seasons, with initial rover and drill/arm integration as early as the 2017 season. As indicated in the work of Moreno-Paz et al ( 2023 ), the SOLID-LDChip immunoassay instrument assembly remote unequivocally detected microbial biosignatures associated with known species, in a changing pattern with depth (addressing the original ARADS H3 hypothesis). The LDChip antibody microarray results in this Special Collection paper are complemented with a comprehensive post-season laboratory analysis of the curated drilled field samples, including metaproteomics and DNA sequencing, as well as XRD, mass spectroscopy, and ion chromatography, which support ARADS H1 (near-surface heterogeneous distribution of organic compounds).…”

“…The prototype SOLID instrument (from the Instituto Nacional de Técnica Aeroespacial's [INTA] Centro de Astrobiología [CAB] in Spain) tested on ARADS and on a sister Life-detection Mars Analog Project (LMAP) lander (Sánchez-García et al, 2020 ) is divided into two main units: the sample preparation unit (SPU), which uses ultrasonication to extract biomolecules from sample into a buffer solution and is connected to the sample analysis unit (SAU) that bears the antibody microarray biosensor (the Life Detector Chip or LDChip) for immunological assays (Moreno-Paz et al, 2023 ). Figure 5 shows both parts of SOLID installed on the rover payload deck.…”