A Framework for Planetary Resource Classifications to Further Sustainability in Space Exploration Missions

The long-term impacts and overall sustainability of space exploration missions in the space environment were often unknown in past space missions. Historically, the space exploration vision of various space-faring agents refers to "planetary sustainability" as a synonym for mission assurance, rather than as an evaluation of long-term viability or as a means to ensure the sanctity of the space environment. Moreover, past missions have treated the space environment as an infinite frontier and not as a finite resource. NASA's Artemis program aims to return to the moon and achieve sustainable presence in lunarspace by 2028. Many planned future endeavors require resource extraction or in-situ resource utilization efforts. Resource prospecting is considered the first step in accessing resources in the lunarscape. Prospecting is a term utilized most in the mining and extractive industries and, by definition, is a means of experimental drilling and excavation. Prospecting, however, is not the same as classifying. Resource prospecting is more invasive than resource classification, although resource prospecting can advance resource classification efforts. When terrestrial (Earth-based) resources are evaluated on various measures – including availability, recoverability, accessibility – quantifying resource reserve estimates are a part of the evaluation; however, there is no framework established to characterize planetary resources on the basis of mission resource metrics. This investigation develops a framework to classify resources on the lunar surface, in response to the current, heightened interest in resource recovery and utilization in planetary resource-focused missions. Resource and risk classification methods established by the Society of Petroleum Engineers and General Electric will guide framework development. In the process, the investigation considers existing research proposals to establish resource limits and discusses how resource restrictions and risk thresholds are implemented in the final proposed framework. A novel resource classification framework is the final deliverable and is applied to geologic data from lunar fly-by and surface missions, thereby increasing the yield of existing mission data. Additionally, the framework integrates availability, recoverability, and accessibility metrics, while also addressing a composite sustainability metric. These four metrics are established as essential resource classification benchmarks to ensure that sustainable mission design is implemented early in the space systems engineering lifecycle by space systems engineers and mission designers in multidisciplinary teams.