Enhancing Operational Efficiency of the Raman Laser Spectrometer (RLS) in the ExoMars Rosalind Franklin Mission: A Comprehensive Qualitative Analysis of Key Parameters in the Sample Acquisition and Measurement Strategies

Abstract

The Raman Laser Spectrometer (RLS), part of the Pasteur analytical suite onboard the ExoMars 2028 Rosalind Franklin rover, is designed to perform structural and compositional analyses of powdered subsurface samples on Mars. Its fully autonomous operation within the constraints of the Pasteur Analytical Laboratory-limited by time, energy, and sample availability-requires an efficient balance between scientific performance and operational viability. This study presents a qualitative analysis of RLS operations under mission-representative conditions using the Flight Spare (FS) model, focusing on the impact of key parameters-number of accumulations, autofocus frequency, and analyzed spots per sample-on the system's detection capabilities. Experimental campaigns were conducted using ESA-selected analog samples representative of Oxia Planum geology. Performance was evaluated using both the RLS FS and the ExoMars Simulator. Results show high consistency (90-95%) in mineral detection between systems, confirming the robustness of the RLS FS under representative scenarios. The instrument demonstrated its ability to identify key phases, including oxides, silicates, carbonates, hydrated sulfates, and amorphous carbon, highlighting its relevance to geological and astrobiological investigations. Operational tests confirmed that reducing the number of accumulations or autofocus activations-under appropriate sample conditions-does not compromise spectral quality. These findings support a flexible strategy that adapts operational parameters to the scientific context, optimizing resource use and preserving long-term instrument reliability. The results will contribute to the refinement of nominal activity plans for ExoMars and reinforce the use of the RLS FS as a critical asset for validating future configurations of the flight model.