Remote Geochemical and Mineralogical Analyses under Venus Surface Conditions

The extreme Venus surface temperature (~740 K) and atmospheric pressure (~93 atm) create a challenging environment for surface geochemical and mineralogical investigations. Rapid analytical techniques are required to investigate the Venus surface within the several hour lifetime of the lander. The Venus Elemental and Mineralogical Camera (VEMCam) is a proposed integrated remote Raman - LIBS spectrometer capable of acquiring >1000 chemical and mineralogical measurements without the risks associated with collecting samples and bringing them into the lander. Wiens et al. [1], Sharma et al. [2] and Clegg et al. [3] demonstrated that both analytical techniques can be integrated into a single instrument similar to the SuperCam instrument on the Mars 2020 rover. This paper explores the capability of VEMCam instrument architecture to probe geologic samples and demonstrates quantitative analysis under Venus surface conditions.

Raman and LIBS are highly complementary analytical techniques capable of rapidly determining both mineralogy and composition of Venus surface samples. These techniques have the potential to profoundly increase our knowledge of the Venus surface composition, which is currently limited to geochemical data from the Venera and VEGA landers that collectively suggest a primarily tholeiitic basaltic [4] surface composition with some potentially more evolved compositions and, in some locations, K-rich trachyandesite. LIBS data reduction involves generating a regression model using known rock powder standards to quantitatively determine the elemental composition of unknown samples. Raman analyses have been conducted under supercritical CO₂ on single-mineral and mixtures of minerals and glasses. These experiments utilize a new 2 m long pressure chamber capable of simulating Venus surface temperature and pressure. Finally, computational fluid dynamics models have been used to characterize the transmission, power and beam quality of the laser through the Venus atmosphere and demonstrating the feasibility of this technique even under pessimistic surface conditions.