Investigating the Oldest Traces of Life by AFM/Confocal Raman Spectroscopy: Applications for the Analysis of Martian Rocks

The next European mission to Mars, ExoMars (2016), is dedicated to the search for past and/or present traces of life. This is one of the primary goals of exo/astrobiology. Similarities in the environmental conditions of early Mars and the early Earth mean that life forms on the early Earth are good analogues for potential martian life. However, the oldest traces of terrestrial life are extremely small and highly sophisticated scientific equipment is required to reveal their subtle traces. Instruments that could observe biosignatures on in situ missions are, however, limited in resolution. In this study, various techniques are used to analyse martian analogue rocks containing traces of life. These rocks are 3.5-3.3 billion-years old volcanic sediments from the Pilbara in Australia and Barberton in South Africa. High magnification instruments were used to demonstrate the biogenicity of the fossilised structures. Space-adaptable techniques were then used in order to investigate larger scale biosignatures. Special emphasis was placed on Raman spectroscopy. This technique is extremely promising in the search for traces of life in situ on Mars.