Prof. Shubhadip Chakraborty

Detailed characterisation of returned lunar samples suggests a significant effect of shock metamorphism. The continuous churning due to impacts driven shock waves influences the chemical composition and volatiles on the topmost layer of the regolith. More specifically, volatile elements such as Na and H2O may vary due to impact-induced processes. Shock induced regolith modification is still scarce due to limited returned samples mainly from equatorial and complex geological regions. The goal of this work is to investigate the influence of shock induced modification to lunar analogues and understand the formation of volatiles in airless planetary bodies like Moon and Mercury. We will present preliminary results of shock induced modification of Sittampundi anorthosite (SA) and JSC-1 lunar analogues, simulants. The results are derived using newly established hypersonic shock wave facility at the GITAM Bengaluru under an ongoing ISRO RESPOND project. The analogue materials were sieved to different grain sizes, and powder XRD (p-XRD), Infrared reflectance (IRR) measurements and Raman microscopy was performed to determine their structural and optical properties. p-XRD and Raman analysis revealed the crystalline nature of the samples as reported in the published literature. Scanning electron microscopy (SEM) study revealed irregular morphology and the elemental analysis was performed to quantify the presence of various elements. We found these results are in close accordance with actual Lunar samples obtained from previous Apollo missions. Following, the SA samples were subjected to controlled shock exposure of a Mach number varying from 2.5 to 7 with a calculated reflected shock temperature varying from approximately 2400K to 7000K. The resulting changes in the morphology, microstructure, and surface properties of those samples are presently being analysed by SEM, p-XRD, IRR. This shock induced results will be compared with the before shock characteristics of samples and the outcomes will be discussed and put in the context of volatiles study of the Moon.