In Situ Lunar Regolith Analysis by Laser-Based Mass Spectrometry

Abstract

We are developing laser-based mass spectrometry (LIMS) for the in situ investigation of the chemical and mineralogical composition of the lunar regolith. The current development of our LIMS instrument is for an application on a robotic mission within the Artemis CLPS program of NASA. The CLPS lander will be placed in the south polar region. The LIMS system consists of a time-of-flight mass analyzer (TOF-MS), a laser system (LSS) providing nano-second laser pulses focused to um spots on the sample surface, electronics (ELU) for operating the LIMS system, and a sample handling system (SHS). The TOF-MS, LSS, and ELU are according to our established design presented earlier. The SHS is specially designed for the CLPS lander to collect regolith grains from the lunar surface in the vicinity of the lander. The SHS design foresees rotating steel brushes that free regolith grains from the surface into ballistic trajectories. A conveyor belt collects these grains, which is electrically biased to improve its collection efficiency. Adjusting the speed of the brushes and the voltage on the conveyor belt allow to optimize the collection efficiency of the grains. The conveyor belt transports the grains to the entrance of the mass analyzer where grain by grain analysis will be performed. The main scientific objective for the LIMS instrument is the geochemical analysis of the lunar regolith, by the analysis of individual regolith grains and assessing their mineralogical diversity. In addition, this investigation will also address technical aspects of sampling a planetary surface at or near a landed spacecraft, i.e., the effect the plume of the retrorockets has on the regolith underneath the lander. Of particular interest is the chemical contamination of the surface by the spent fuel, and the amount of removal grains by the gas drag.