LIBS for Volatile Detection in the Lunar Polar Region

Abstract

The Moon has recently come into the focus of attention of international space agencies again. Concepts for the establishment of a long-term human presence on the Moon have been proposed, such as the Moon Village concept championed by ESA and NASAs lunar outpost concepts as part of the Artemis program. One reason for this renewed interest in the Moon was the discovery of water ice in the lunar polar regions by the Chandrayaan-1 mission. Water and other volatiles are important resources both for life support and for potential applications as fuels and propellants for spacecraft. In-situ resource utilization (ISRU) of volatiles could significantly reduce the costs of a sustained presence on the Moon and could also be beneficial for the future human exploration of the solar system. The detection of volatiles like water is therefore an important scientific goal for future robotic missions to the Moon. The LUVMI-X project (Lunar Volatiles Mobile Instrumentation Extended) is developing an initial system design as well as payload and mobility breadboards for the detection of volatiles in the lunar polar region on a small, lightweight rover. One of them is the LIBS instrument VOILA (Volatiles Identification by Laser Analysis). LIBS is a technique that requires only optical access to its target. A LIBS spectrum is obtained within seconds, making it well-suited for quick analyses of multiple targets in proximity to the rover. LIBS was first used in space by the ChemCam instrument on board Curiosity of NASAs Mars Science Laboratory mission. With SuperCam on board NASAs Mars2020 rover and MarsCoDe on board Chinas HX-1 rover, two more LIBS instruments are headed for Mars in 2020. The first LIBS instrument on the Moon was supposed to operate on board the Pragyan rover of Indias Chandrayaan-2 mission, but the lander crashed onto the lunar surface during descent in September 2019. In this study, we demonstrate the potential of LIBS for the detection of volatiles on the lunar surface. The influence of instrument parameters such as the pulse energy of the laser and the spectral coverage of the spectrometer on the obtained spectra is analyzed and the feasibility of hydrogen quantification is investigated in mixed samples of varying composition.