Sulfate and iron oxide deposits at Rio Tinto (southwest Spain) are a terrane analog of the hematite-rich regions of early Mars. Understanding the distribution and drivers of microbial life in iron-rich environments could provide important clues to how to search for signatures of life on Mars.
Using a 1m-class planetary prototype drill mounted on a full-scale mockup of NASA’s Phoenix and Inside lander platforms, we simulated a robotic drilling mission to search for signs of life in the Martian subsurface. We demonstrated fully automated and aseptic drilling in iron- and sulfur-rich sediments along the Rio Tinto River, as well as sample transfer and delivery to sterile containers and analytical instruments.
As a ground-truth study, samples were analyzed in the field with a Life Detector chip immunoassay for microbial markers, followed by mineralogy in the laboratory with X-ray diffraction, gas chromatography/mass spectrometry for lipid composition, isotope-ratio. Mass spectrometry for isotopic ratios and 16S/18S rRNA genes for biodiversity.
The ubiquity of microbial biomarkers distributed in the 1m-deep subsurface is influenced by local mineralogy and geochemistry. The spatial heterogeneity of abiotic variables at the local scale highlights the importance of considering drill replicates in future Martian drilling missions.
A multi-analyte approach will allow molecular biomarkers that vary in compositional nature, preservation potential, and taxonomic specificities to be recovered from shallow drilling in iron-rich Martian analogs using an automated bio-detection lander prototype such as the proposed one. For NASA’s Icebreaker mission program.
Drilling and inspection on site. Map of the study area in the Río Tinto basin (southwest Spain), with regional map (b) showing the location of the LMAP esplanade (a) where the LMAP-2017 drilling and sampling campaign was conducted. Also shown are close-ups of the Mars robotic drill (c) and the manual coring drill (d) used to recover Mars-drill cuttings (M, yellow dot) and coring drill samples (G, blue dot). (a), it is noted that a previous drilling project (IPBSL-2015) was conducted 500 m northeast of the current sampling site (LMAP-2017). The black dashed shape in (b) highlights the white sulfate efflorescence arising in the stream. Satellite images are from Google Earth. LMAP, Life-Detection Mars Analog Project. Color images are available online. Astrophysics via PubMed
Astronomy