Objective:

To demonstrate a new method for detecting signs of life in rocks analogous to those expected from Mars sample return missions, contributing to the development of protocols for handling extraterrestrial materials safely and effectively.

Approach:

• Methodology: The study utilized optical-photothermal infrared (O-PTIR) spectroscopy on 100-million-year-old basaltic rock cores from the South Pacific seafloor to detect microbial signatures, highlighting its significance for future Mars sample return missions.
• Comparison with Other Techniques: O-PTIR was compared with traditional methods like FT-IR microscopy and μ-Raman spectroscopy, emphasizing its advantages in sensitivity, minimal sample destruction, and ability to analyze thick rock sections without extensive preparation.

Key Findings:

• O-PTIR successfully detected microbial markers, including amide I and II bands indicative of peptides, and mineralogical contexts in basalt samples.
• Conventional FT-IR microscopy failed to identify microbial signals due to limited spatial resolution.
• μ-Raman spectroscopy was hindered by autofluorescence, masking potential biosignatures.

Interpretation:

O-PTIR provides high spatial resolution and can analyze thick rock sections without extensive sample preparation, making it suitable for Martian materials and essential for identifying potential biosignatures.

Limitations:

• O-PTIR is not a substitute for high-resolution techniques like TEM or NanoSIMS.
• Further validation is needed for older basalt rocks, around 2 billion years old, similar to those the Perseverance rover on Mars has already sampled.

Conclusion:

O-PTIR is a promising tool for detecting biosignatures in Martian samples, complementing existing methods while preserving precious materials for future analyses.

Sources:

• International Journal of Astrobiology