Feasibility of Raman Optical Activity for In Situ Exploration of Europa and Ocean Worlds

Homochirality of biogenic amino acids and sugars is necessary for life and is observed in almost all organisms. Thanks to its ubiquity on Earth, astrobiologists have considered homochirality a potential biosignature for life in the solar system. Miniaturized Raman spectroscopy has proved to be a valuable in situ probe of both organics and minerals in planetary science, but these instruments are not sensitive to chirality. Raman optical activity (ROA) is a chiroptical technique that combines Raman spectroscopys versatility with the ability to detect chirality but has yet to be evaluated for planetary science. The possibility of a Europa lander mission provides an opportunity to examine this technique within an ocean world context. Given low nM organic concentrations in subglacial lakes on Earth, ROA should offer a similar sensitivity if it is to be used for Europa exploration [1]. We will conduct serial dilution experiments in water to determine ROAs limit of detection (LOD) for three commonly occurring amino acids: alanine, leucine, and valine. To mimic predicted Europan ocean chemistry, we will then create simulant samples composed of Europa-relevant salts such as NaCl, KCl, MgCl2, MgSO4, and CaSO4 and repeat the experiments. Salinity effects will be quantified by comparing the LODs across the various salt concentrations, determining ROAs sensitivity, and providing a starting point for further development with surface or resonance enhancement. References (1) Creamer, J. S.; Mora, M. F.; Willis, P. A. Analytical chemistry 2017,89,13291337.