Abstract

To be economically viable and sustainable, a long-term presence on the Moon, will require in situ resource utilization (ISRU) of a variety of resources, including regolith materials for manufacture of rocket fuel, power generation, and Moon base construction. Missions from NASA’s Artemis and China’s Chang’e programs are currently underway to explore, characterize, and evaluate the lunar water ice resource in polar areas. Rather than manufacture rocket fuel on Earth and incurring the tremendous cost of escaping Earth’s gravity well, it will be more cost-effective to manufacture rocket fuel on the Moon. Hydrogen resources for rocket fuel on the Moon are concentrated near the poles, where water ice and other volatiles exist in cold traps in permanently shadowed regions (PSRs) in crater floors. For most of the Moon’s long, 4.5 billion year (gigaannum [Ga]) history, volatiles such as water ice and ammonia, and a host of elements and other compounds such as methanol, sodium, carbon dioxide, carbon monoxide, ammonia, and sulfur dioxide accumulated in PSRs as ejecta from impacts of volatile-rich asteroids and comets. Local concentrations of water ice near the lunar South Pole locally exceed 5 wt%, although values of 0.5 to 4 wt% are more common. Estimates of the water ice resource at each pole vary from 100 million to 1 billion metric tons. This range reflects uncertainties in the actual thickness and depth of burial of the water ice and from the variety of imaging techniques that have been used.