Modelling the survival of carbonaceous chondrites impacting the lunar surface as a potential resource

Introduction: The surface of our closest celestial neighbour is increasingly becoming a prime target for the next step in human exploration, with an emphasis on developing approaches for in situ resource utilisation (ISRU). Whilst the lunar surface may potentially provide an abundance of extractable metals [1,2], water [35], and potential construction materials for lunar habitats [6], there is a lack of a number of key elements in enough quantities needed to facilitate a long-term, sustainable human presence on the Moon [7]. Carbon and nitrogen are two such elements. These have been potentially delivered to the Moon in the form of carbonaceous chondrite (CC) meteorites [8,9]. The rich impact history of the Moon indicates that CC meteorites will have impacted the lunar surface at some point over geological time and could, therefore, be a source of these key elements if they survive [10, 11]. In the context of using CC material as a resource for lunar surface operations, it is important to consider where the material remains concentrated post-impact. If the material ‘survives’ (according to the pressure and temperature regimes recorded within the projectile), but is dispersed over a wide area after impact, it becomes less economical to collect and use as a resource. However, if a significant amount of material is concentrated within a small area surrounding the impact site (e.g., a few km), it could become an attractive resource and a potential target to establish a nearby lunar outpost. Investigation of both the temperature regimes and the location of CC material post-impact requires a suite of 3D impact models at a variety of impact angles and velocities. Here, we concentrate on the survival of carbon-bearing molecules as they are more abundant than nitrogen within CCs [9] and are more likely to survive impact due to their physical properties [8,9] (Table 1). Methods: Using iSALE-3D [12], we modelled the impact of a 1 km diameter CC-like asteroid into a single-layer, basaltic lunar surface. The simulation used a resolution of 16 cells per projectile radius, using the ANEOS equation of state (EoS) for serpentine [13] to best approximate CM CC-material and the ANEOS basalt EoS [14] to represent the lunar surface. Porosity was included in both impactor and target, with porosities chosen based on average values for CC parent bodies [15] (40%) and the lunar megaregolith [16] (10%). Impact velocities of 10 and 15 km/s were tested, with impact angles varied between 15 and 60o to the horizontal, at 15o increments. Lagrangian tracer particles were placed in each cell of the projectile to track temperature, pressure, and the location of the material over the course of the impact. Peak shock temperatures were then compared to vaporization temperatures for known carbon bearing molecules in CCs (Table 1).