A Novel Controlled Environment Study of Prebiotic Organic Material in the Tagish Lake Meteorite Using Raman and Fluorescence Spectroscopy: Implications for Asteroid-Return Sample Analysis

Several ambitious missions such as OSIRIS-REx, Hayabusa2 and Mars Sample Return are currently collecting or planning to collect the most pristine planetary samples to analyze on Earth since the Apollo missions. Therefore, it is essential to create instrumentation that will allow preliminary compositional analysis of these materials without the need for sample preparation and in a minimally destructive way, while preventing oxidation, alteration, or contamination from Earth’s environment. At York University, a small, transportable environmental chamber with temperature, pressure, and atmosphere control has been integrated on an optical table with a combined UV (266 nm) and Green (532 nm) Raman, laser-induced fluorescence, and time-resolved laser-induced fluorescence instrument. This system can collect high-resolution 2D spectroscopic maps, long accumulation point analysis and time-resolved fluorescence ‘fingerprinting’ of minerals and organics. The sample chamber is capable of pressures < 10E-4 mbar, temperatures < -20C, and different atmosphere compositions such nitrogen, argon or carbon dioxide via gas hookup. The intended use of the system is to detect and identify minerals and organics within sensitive or fragile planetary samples using minimally destructive laser-based techniques, while maintaining specific environmental conditions to preserve and maintain the pristineness of the material being analyzed, such as samples returned from planetary missions. To validate the functionality of the system as a laboratory tool for samples returned from space or for planetary science research, several experiments were conducted using different materials to showcase the different modalities of the instrumentation. One such experiment is conducted on a non-pristine piece of the Tagish Lake meteorite, containing some of the most primitive materials in our solar system. The meteorite fragment was kept frozen and in an inert atmosphere during Raman (UV and green) and Fluorescence (UV) analyses. These spectroscopic techniques resulted in high-resolution 2D maps of the surface of the meteorite fragment, showing mineral localities and groupings, as well as organic constituents present. UV-Raman in particular results in spectra containing aromatic and aliphatic hydrocarbon, ketones, and cyano radical peaks, all of which are the basic building blocks of important organic constituents like amino acids which play an integral role in biotic life on Earth. The detection of such compounds in the Tagish Lake meteorite using UV-Raman spectroscopy is novel and provides a unique tool to analyze organic constituents within sensitive materials in a very minimally destructive way with no sample preparation.