Carbon Dioxide Cold Traps on the Moon

Water ice is expected to be trapped in permanently cold regions near the lunar poles. Other ices (“super‐volatiles”) are trapped at lower temperatures, close to the lowest temperatures measured within the lunar permanently shadowed regions (PSRs). Here, the thermal stability of solid carbon dioxide in the south polar region is determined by analysis of 11 years of temperature measurements by Diviner, a radiometer onboard the Lunar Reconnaissance Orbiter. Sublimation rates averaged over a draconic year are far lower than peak sublimation rates. Small spatially contiguous pockets of CO2 ice stability are found in the craters Amundsen, Haworth, de Gerlache, and others, over a cumulative area of roughly 200 km2. The LCROSS probe impacted one of those pockets and released CO2, serving as validation of the thermal stability calculations. Future surface missions can utilize this highly localized resource for the production of fuel, steel, and biological materials. Plain Language Summary Carbon‐bearing species would be essential for sustained robotic or human presence on the Moon, for use in rocket fuel and biological materials. Various volatiles can be cold‐trapped in permanently shadowed craters near the lunar poles. The existence of carbon dioxide cold traps has previously been surmised, but the required temperatures are near the lowest surface temperatures that have been reliably measured. Extensive and improved analysis of 11 years of orbital surface temperature measurements establishes the existence of carbon dioxide cold traps on the Moon, which potentially host high concentrations of solid carbon dioxide. Large CO2 cold traps are rare, however, and the geographic concentration of the resource will have policy implications. Key Points Time‐dependent sublimation rates for CO2 are calculated based on 11 years of Diviner temperature measurements Extensive data analysis establishes the existence of carbon dioxide cold traps in the south polar region of the Moon Solid carbon dioxide is expected to be highly localized