Application of Raman Spectroscopy as in situ Technology for the search for life

Abstract

Raman microscopy is a nondestructive in situ technology appropriate to identify organic compounds and mineral products. It is a well-established technology and applied in various areas like pharmacy, biology, and mineralogy. Measurements could also be taken on other planetary bodies of our Solar System via future spacecrafts. The range for application reaches from acquiring discriminating bands (e.g., Raman reporter molecules like pigments) to the complex evaluation of spectral fi ngerprints. For the chemical characterization of biological samples as well as biomaterial-containing samples, chemometrical methods and pattern recognition need to be used for a reliable identi fi cation. Databases of Raman spectra established beforehand support the identi fi cation of the observed material. The ExoMars Mission in 2018 is the fi rst mission for which a Raman spectrometer is part of the planned payload. In preparation to this and further missions, it is necessary to study the circumstances one could be faced with when performing Raman measurements in a non-Earth-like environment. The differences and difficulties compared to the established measurement approaches on Earth (Sect. 2 ) need to be recognized, and solutions must be found. As an example for a space application in Mars exploration, the identification of b-carotene in cyanobacteria on Mars-analogue material by Raman spectroscopy is presented (Sect. 3 , based on Böttger et al., 2012 ) . A procedure was developed to optimize the detection of cyanobacteria embedded in different types of martian soils.