USGS ASTEROID RESOURCE ASSESSMENTS ARE FEASIBLE

USGS Open-File Report 2017-1041 presents the results of a feasibility study investigating the application of USGS resource assessment methods to water and iron-nickel alloys in near-Earth objects (NEOs). The conclusion is that only minor adjustments are required to translate Earth-based methods for use on asteroids. As one example, rather than using a spatial map as done on Earth, NEO “position” is more usefully measured in terms of the energy to reach them (delta-V). NEO numbers, sizes, and delta-V were calculated from data available through the Minor Planets Center. Spectral classification relied primarily on the SMASS catalog. Based on these spectra, the NEOs were placed in one of three compositional bins (carbonaceous, stony, and iron-rich). The water and iron abundance in each were derived from the meteorite compositions compiled by Nittler et. al (2004). The composite probabilities were computed using a simple Monte-Carlo model, resulting in probability distribution functions for the abundance of water and metal. While the feasibility study did not do an exhaustive investigation of uncertainties, it was complete enough to conclude that there certainly are vastly more resources in NEOs than the few current inhabitants of the International Space Station can use. It is important to note that extraction technologies were not investigated in this feasibility study - but the fact that the vast majority of the resources are in the larger NEOs may be relevant for those developing such technologies. Three areas of research are recommended to enable a formal USGS resource assessment of NEOs: (1) additional spectral characterization of NEOs, (2) a more systematic and complete petrologic characterization of meteorite samples on Earth, and (3) creating a more robust link between surface spectra and petrology through additional missions to NEOs like the Hayabusa missions and OSIRIS-REx.