Diviner data used to map the stability of ices at the lunar poles
A trio of new studies using Diviner data have been recently published confirming the existence of cold traps for various ices within the lunar polar regions. These discoveries have the potential to influence future robotic and human missions. Permanently shadowed regions in the polar regions of the Moon can reach extremely low temperatures, lower than the temperature of Pluto. These areas can trap volatiles such as water, carbon dioxide, and other compounds to form ice deposits.
Last month, a study mapping cold traps of carbon dioxide around the Moon’s South Pole was published in the journal Geophysical Research Letters. Over 11 years of Diviner data was used to generate maps of daily and seasonal temperatures which can be found on our published datasets page. Small pockets of carbon dioxide ice stability, where temperatures are persistently below 60 K (-352° F), were identified over a cumulative area exceeding 200 km2 (77 square miles) including the site of the LCROSS impact in Cabeus crater which was observed to release carbon dioxide.
This follows a previous paper that mapped the stability of water ice around the lunar South Pole published in the Planetary Science Journal. This study found the cold trapping area for water ice to be approximately 17,000 km2 (6500 square miles). That study also considered the stability of water ice below the surface. Even a thin layer of regolith or dust can protect ice from sublimation and loss to space. The area of ice stability at 2 cm (0.8 inches) depth was predicted to be double the size of the surface. However, such ice would need to be buried quickly to survive.
A paper published this week in the Planetary Science Journal expands on these previous studies. This latest study considered many key volatile species not mapped previously and expanded the area studied to both the north and south polar regions and went to much lower latitudes. Where lunar water ice and other species originate from is a mystery. Some of the volatiles mapped in this work have the potential to distinguish the source of polar ices such as volcanism, solar wind, and cometary impacts, if they are discovered by future landed missions.
Many of these ices would be an important resource for future surface missions and could be utilized for life support systems, fuel, and other manufacturing. Therefore their geographic concentration has implications for planning future exploration of the Moon including sending astronauts to the surface.
Figure: The locations of sulfur (yellow), water (blue), hydrogen cyanide (green), and CO2 (purple), at (a) Rozhdestvenskiy W crater at the north pole, (b) Haworth, Shoemaker, and Faustini craters at the south pole, and (c) Amundsen crater at the south pole.