Instrumentation for laser ablation ionisation mass spectrometry on the lunar surface

Abstract

With NASA’s increased focus on exploration of our Moon within the Artemis program, new scientific goals have been formulated to expand our knowledge on the history of our Solar System, including the evolution of the Earth-Moon system. Additionally, establishing a permanent human presence on the Moon has been declared a goal of the Artemis program, the success of which will inevitably depend on in-situ resource utilization (ISRU) of lunar material. In turn, successful ISRU requires methods capable of analysing and selecting suitable materials in place. To support these tasks, sensitive instrumentation capable of determining the elemental and isotope composition of geological samples from the lunar surface is essential. Consequently, defining and determining the technical requirements of such instrumentation, constructing it accordingly, and verifying its performance are all crucial steps in maximising the scientific return of such a mission. Furthermore, NASA’s Artemis program also aims to facilitate future human exploration of Mars, which implies that instrumentation applied successfully on the Moon might find its application on the Martian surface in the future. We present our progress in designing, constructing and testing a prototype miniature laser ablation ionisation mass spectrometer (LIMS) for in-situ measurements on the lunar surface. The finalised instrument will be deployed on the Commercial Lunar Payload Service (CLPS) mission CP-22 scheduled for launch in late 2026 and land in the lunar south pole region. Our miniature reflectron-type time-of-flight mass analyser (160 mm x Ø 60 mm) designed for in-situ space applications was coupled to a pulsed Nd:YAG microchip laser system (SB1 series, Bright Microlaser Srl, Italy) operating at 532 nm (max. laser pulse energy of 40 µJ, pulse repetition rate of 100 Hz). The laser source and the optics were mounted colinearly to the optical axis of the instrument assembly into a cage system. This construction is modelled after the envisioned flight design, and therefore used to determine the required optical and electronic performance characteristics of the future flight instrument. The current flight design will be presented as well. Furthermore, validation of the technical implementation and verification of the scientific requirements will be discussed through the results of laser ablation experiments conducted on lunar regolith simulant.