SPECTROSCOPIC TECHNIQUES FOR THE IN SITU DETECTION OF MOLECULAR SIGNATURES INDICATIVE OF HABITABILITY AND LIFE IN PLANETARY ANALOGS

Life detection in the solar system relies on the identification of signatures of habitability and life. Terrestrial field studies in planetary analog environments provide natural settings where known biosignatures can be studied using field portable instrumentation relevant to life detection missions. In conjunction with signatures for organic compounds, environmental indicators such as secondary minerals or elemental variations that differ from the host rocks can be evidence of biological activity. With the lack of intact organic materials on solar system bodies, and the ambiguity in their origins, such environmental indicators are key in identifying signatures of life. This puts an increased importance on the ability to readily decipher the differences between the microbially and geochemically induced mineral products. While many analytical techniques are capable of identifying such biosignatures, few techniques are not limited by their need for molecular specificity, inability to non-destructively probe samples, and lack of portability. Raman spectroscopy is a field-portable, non-destructive, and rapid vibrational spectroscopic technique whose measurements provide structural information to identify organic and inorganic compounds. In natural samples, however, structural commonalities between compounds can result in similar peak positions of many co-occurring minerals and organic compounds, resulting in the misinterpretation of spectra and possible misidentification of biosignatures. In recent years the interpretation of Raman spectroscopic data in this context has been facilitated by the additional detail in elemental chemistry provided by Laser Induced Breakdown Spectroscopy (LIBS). New advancements in spectroscopic technologies have pushed the capabilities of LIBS even further to identify complex molecular compounds in MWIR and LWIR, increasing the chances for accurately identifying compounds specific to life. Here we present data collected from multiple analog sites in which slight variations in secondary minerals and microbial communities are particularly distinguishable using the combination of UVN-LWIR LIBS and VIS-NIR Raman spectroscopy.