Abstract
Several important processes, from meteor disruption in Earth’s atmosphere and impact with the ground, to the comminution of boulders by thermal and impact processes and slope mechanics on the surface of an asteroid, to access and utilization of in-situ resources, depend on astromaterial properties including porosity, sound speed, thermal conductivity, and compressive strength. Whereas the bulk porosity of clay-rich meteorites is well established, the magnitude of their surface area and nano-scale porosity is poorly known. Here we apply the N2 BET gas adsorption method to measure the scale-distribution and net surface area of porosity in a range of clay-rich meteorites. Tarda (C2-ung) has high surface area, up to 82 m2/g, dominated by an interconnected network of ~ 3-nm-sized pores. In comparison, Ivuna and Orgueil (CI1) and Aguas Zarcas and Murchison (CM2) have bimodal nanopore-size distributions with a lower density of ~ 3-nm pores and broader size distributions around 40 nm, and corresponding lower surface areas ~ 14–19 m2/g. The high-surface-area of Tarda may indicate a high density of intra-tachoid pores among and between the nano-sized aggregates of poorly ordered clays. Samples from asteroids Ryugu and Bennu, mineralogically and texturally similar to Tarda, may have similarly interconnected nano-scale porosity with high surface area.