Development of the VOILA LIBS instrument for volatiles scouting in polar regions of the Moon

In this paper, we report on the on-going development of a compact analytical instrument for future missions to the Moon, using the LIBS technique. The instrument, christened VOILA (Volatiles Identification by Laser Ablation), is part of the “LUVMI-X” scenario funded by the European Union’s Horizon 2020 programme which envisions the concept of a rover carrying a suite of instruments for detecting and characterizing volatiles as a component of lunar soil (“regolith”) at high latitudes on the Moon. Behaviour of the plasma created by LIBS target ablation depends on the prevalent atmospheric pressure. Mars atmospheric pressure is close to ideal for the LIBS technique. On bodies without atmosphere such as the Moon, the lack of confining pressure leads to the plasma dissipating quickly causing weaker signals. India has developed the first, modest LIBS instrument for operation on the Moon with however a number of limitations in its optical design. Moreover, the lander of the corresponding mission Chandrayaan-2 crashed during landing in 2019. Our VOILA is designed to be between the quite capable but large and massive Mars LIBS instruments of NASA (ChemCam on the CURIOSITY ANCE rover), and the very modest Indian LIBS for Chandrayaan- 2. The VOILA working range will vary between 0.3 and 0.5 m, with a laser pulse energy of ~15 mJ.