Spectroscopic Investigation of Synthetic Martian Analog Mineral Mixtures Relevant to Gale and Jezero Craters Exploration

We produced several mineral mixtures and measured their reflectance in the VNIR range (350–2,500 nm) with the aim of reproducing the spectral features observed by the rovers Perseverance and Curiosity in the Jezero and Gale Crater respectively. We chose two specific case-study spectra of the rovers namely the Bellegarde #5 abrasion patch in Jezero and the Voyageurs target drill in Gale. After selecting a number of mineral components representative of the two sites we first produced several binary (two components) mixtures and measured their reflectance. The binary mixtures are characterized by systematic variations of mineral proportions and were used to assess specific aspects of the relationships between spectral properties and mineralogical composition of mineral mixtures. Based on the results from the binary mixtures we then produced multicomponent (4, 5 or 6 components) mixtures through an iterative approach in which the spectrum of each produced mixture is compared with a target spectrum and its mineralogical composition is adjusted to match the target spectrum as closely as possible. The retrieved mineral composition of the final mixtures was eventually used to infer the conditions of formation of the investigated target emphasizing how the mineralogical composition of a laboratory mixture can give insights into the environmental conditions experienced by the target rock.