In-situ sample handling and chemical analysis of lunar regolith by laser ablation ionisation mass spectrometry

Abstract

With NASA's emphasis on lunar exploration through the Artemis program, novel scientific objectives have been formulated to enhance our understanding of the Solar System's historical context, particularly the evolution of the Earth-Moon system. Simultaneously, the establishment of a permanent human presence on the Moon is proposed as a primary objective within the Artemis program, with the achievement of this goal hinging on in-situ resource utilization (ISRU) of lunar materials. Effective ISRU needs methodologies for chemical analysis and selecting appropriate lunar materials in-situ. To facilitate these tasks, the deployment of sensitive instrumentation capable of determining the element and isotope composition of lunar materials is imperative. In this contribution, we present the current progress in developing a reflectron-type time-of-flight laser ablation ionisation mass spectrometer (RTOF-LIMS) to allow for direct sensitive chemical microanalysis of lunar regolith grains in-situ on the lunar surface. This LIMS system will operate in the lunar south pole region on a CLPS mission within NASA’s Artemis program. The contribution will provide a general overview of the instrument and focus primarily on the design and operations of the sample handling system (SHS). Furthermore, we will discuss the results of experiments conducted on lunar regolith simulant. These experiments were performed using a prototype LIMS system to validate the feasibility of the SHS. This prototype system has capabilities representative of the flight instrument currently in development regarding the mass analyser and optical sub-system. The laboratory and flight optical sub-systems are based on a microchip Nd:YAG laser system (~ 1.5 ns pulse width, λ = 532 nm, 100 Hz laser pulse repetition rate, laser irradiance ~ 1 GW/cm2), and custom-made laser optics to achieve a focal spot on the sample surface of ~20 μm. Consequently, the conducted measurements can serve as a qualification baseline for the flight instrument during ground-based tests. (1) P. Keresztes Schmidt et al., Sample handling concept for in-situ lunar regolith analysis by laser-based mass spectrometry, IEEE Aerospace Conference, 2024, submitted(2) P. Wurz et al., In Situ Lunar Regolith Analysis by Laser-Based Mass Spectrometry, IEEE Aerospace Conference, 2023, 1-10(3) P. Keresztes Schmidt, A. Riedo, P. Wurz, Chimia 2022, 76, 257(4) A. Riedo, A. Bieler, M. Neuland, M. Tulej and P. Wurz, J. Mass Spectrom., 2013, 48, 1-15(5) P. Wurz, M. Tulej, A. Riedo, V. Grimaudo, R. Lukmanov, and N. Thomas, IEEE Aerospace Conference, 2021, 50100, 1-15.