Cave biosignature suites: microbes, minerals, and Mars

Area of Science:

• Astrobiology
• Geobiology
• Microbial Ecology

Background:

• Earth's subsurface, particularly caves, presents a prime analog environment for astrobiological research.
• Hostile surface conditions on planets like Mars necessitate subsurface exploration for potential life and biosignatures.

Purpose of the Study:

• To identify and characterize comprehensive biosignature suites in cave environments.
• To develop noninvasive techniques for biosignature detection applicable to planetary protection protocols and astrobiology.

Main Methods:

• Identification of macroscopic, microscopic, and geochemical cave biosignatures.
• Development of noninvasive and minimal-impact detection techniques.
• Analysis of mineralogical (manganese/iron oxides, calcite, sulfur), morphological, genetic, and isotopic data.

Main Results:

• Unequivocal biogenic biosignatures, including morphological fossils and mineral-coated filaments, were identified.
• Biosignature suites encompass mineralogy, biofabrics, microbial metabolism indicators (13C, 34S), genetic data, and elemental abundances.
• Techniques developed are analogous to planetary protection protocols, addressing challenges in fragile and extraterrestrial environments.

Conclusions:

• Cave environments serve as valuable models for subsurface astrobiology, offering suites of detectable biosignatures.
• The identified biosignature suites are robust, independently verifiable, and minimize reliance on specific life chemistries.
• The study validates subsurface exploration as a key strategy for detecting extraterrestrial life and biosignatures.