Raman spectroscopy and planetary exploration: testing the ExoMars/RLS system at the Tabernas Desert (Spain)

TL;DR

This study demonstrates that Raman spectroscopy, tested in simulated Mars conditions at the Tabernas Desert, effectively identifies mineral and organic compounds, supporting its use in future planetary exploration missions like ExoMars.

Contribution

The paper presents a comprehensive field validation of the ExoMars RLS system, including portable emulators and laboratory comparisons, highlighting its capability to detect trace organics and minerals in arid environments.

Findings

Raman spectroscopy detected mineral phases not identified by XRD.

Organic functional groups indicative of extremophiles were identified.

RLS proved effective in simulated mission conditions for Martian exploration.

Abstract

ExoFit trials are field campaigns financed by ESA to test the Rosalind Franklin rover and to enhance collaboration practices between ExoMars working groups. During the first trial, a replicate of the ExoMars rover was remotely operated from Oxfordshire (United Kingdom) to perform a complex sequence of scientific operation at the Tabernas Desert (Spain). By following the ExoMars Reference Surface Mission (RSM), the rover investigated the Badlands subsoil and collected drill cores, whose analytical study was entrusted to the RLS (Raman Laser Spectrometer) team. The preliminary characterization of core samples was performed in-situ through the RLS Engineering and Qualification Model (EQM-2) and the Raman Demonstrator (RAD1), being this a new, portable emulator of the RLS. In-situ results where then complemented by laboratory analysis using the RLS ExoMars simulator and the commercial version of the Curiosity/CheMin XRD system. Raman data, obtained by closely simulating the operational constraints of the mission, successfully disclosed the mineralogical composition of the samples, reaching the detection of minor/trace phases that were not detected by XRD. More importantly, Raman analysis detected many organic functional groups, proving the presence of extremophile organisms in the arid sub-surface of the Tabernas Desert. In light of the forthcoming ExoMars mission, the results here presented proves that RLS could play a critical role in the characterization of Martian sub-surface environments and in the analytical detection of potential traces of live tracers.