The Moon has both a South and North Pole, but just how cold are they? For context, Antarctica's coastal temperatures average around 14°F (-10°C), while the interior drops to -76°F (-60°C), making Earth's South Pole one of the coldest places on the planet. Recent research shows that the South Pole of the Moon experiences even more extreme temperature fluctuations and freezing conditions.
New research out of The University of New Mexico showcases exploring, sampling, and interpreting of lunar volatiles in polar cold temperatures on the Moon. The team of researchers looked at the surface of the Moon and analyzed permanently shadowed regions that have temperatures of 25 to 50 degrees Kelvin or -400°F.
Within these shadowed regions, there are cold traps that capture and preserve volatiles, such as water, carbon dioxide, and other elements. Charles Shearer, a research scientist in the Institute of Meteoritics (IOM) and research professor in the Department of Earth and Planetary Sciences (EPS) at UNM, was the lead author, along with UNM's Zachary Sharp, who co-authored the piece and the Lunar and Planetary Institute's (LPI) Julie Stopar. The research was published in the National Academy of Science (PNAS) as a special issue.
"There are potential resources on the Moon that could be utilized for human activity on the lunar surface and beyond," explained Shearer. "We all need water. It could also provide oxygen for humans to breathe, and some of the materials could be used for fuels for transporting humans around the surface of the Moon or going beyond the moon."
This research has implications for NASA's Artemis mission to return humans to the Moon. Artemis I, which launched in November 2022, carried an unmanned spacecraft that flew past the moon, orbited it, and then returned to Earth.
Artemis II plans to follow a similar route, this time with humans aboard, orbiting the moon and returning safely to Earth. Artemis III will be the first crewed mission to the moon's surface since Apollo 17, landing at the lunar South Pole to explore its surface, collect samples and return to Earth.
Julie Stopper, from Lunar and Planetary Institute, looked at the orbital data and provided information about the permanently shadowed regions in terms of stability fields. She looked at what could there be in terms of volatiles, temperature ranges, and showed permanently shadowed regions where they are located.
Sharp, the director of the Center for Stable Isotopes (CSI) at UNM, specializes in stable isotopes of hydrogen, oxygen, and a wide range of other elements that can determine and provide a print of where those volatiles came from.
"No human has been to the south region that is permanently shadowed, so we really don't know yet what's actually in there," stated Sharp. "We have good ideas, but in detail, we don't know the quantities of water, CO2, other gases, methane, or sulfur. It's just not completely known."
This Artemis missions will take samples in sealed containers and return them to Earth for further analysis. During the initial Artemis missions, the samples will be kept at higher temperatures than the extreme cold of the lunar cold traps. The questions addressed in this study is what information can be gained from these samples and equally importantly, what information will be lost by allowing them to warm to some degree.
One of the main challenges of even sampling this particular region of the Moon is the extreme temperature. The permanently shadowed regions of the southern pole on the moon can reach temperatures of -423°F and can make it very difficult for humans to explore.
Bringing these samples back to Earth at higher temperatures than the extreme cold of the lunar south pole will result in changes of these elements from solids to liquids or gases, which could result in the loss of important information and data.
"One of the main efforts of our work was to say how are we going to return these samples at different temperatures (super cold, cold, and room temperature). What information will be lost for these different storage conditions and which storage conditions will showcase the closest to the Moon," said Sharp.
Shearer and Sharp were able to consider different scenarios with different temperature ranges to investigate what information might be lost. Their research also provided step by step ideas for how to eventually collect these samples to represent how they are on the Moon.
Another challenge in collecting these samples is that when the gases are sealed, they could vaporize and reach extremely high pressures, potentially becoming toxic for human transportation. Additionally, the appropriate portion size needs to be determined.
"There needs to be portions of whether going to the Moon, Mars, or sampling from comets, you need to have the proper engineering, the proper tools to sample, and preserve those volatiles. And if you don't preserve them correctly, you lose information," said Shearer.
This research presented the fundamental questions that need to be addressed by the science teams for future missions.
NASA has decided to emphasize the South Pole region for a variety of reasons from engineering to scientific. One reason is that humans have never been to that sort of terrain. The South Pole on the Moon contains shadowed regions along with some of the oldest crust on the Moon and one of the largest impact basins in the Solar System.
"Returning these materials that are derived from that impact event and dating them will tell us about the impact history of the inner solar system, including the Earth," explained Shearer. "It can also tell us a little bit about the migration and the movement of some of the larger planets in the Solar System, like Jupiter and Saturn."
Sharp was the first person to analyze gases from the Apollo 17 mission that had never been opened. This made The University of New Mexico the first university to ever analyze those gases in 2022.
The University of New Mexico has created a seamless enterprise when it comes to this research by working through different departments (EPS, Institute of Meteoritics, etc.) The University is equipped with high technology for analyzing these kinds of materials. Sharp explained that the university has invested in an advanced transmission electron microscope, stable isotope lab radiogenic isotope labs, electron microscopes, X-ray diffraction, X-ray Computed Tomography (XCT) and more.
"We have our small group out here that focuses on planetary materials, but reaching out to biology, engineering, physics and astronomy, and a lot of other departments on campus to really define space exploration and infrastructure on campus," said Shearer.
Shearer also mentioned that New Mexico is a space-faring state and has a growing space exploration infrastructure. Spaceport America, the Very Large Array, and the various National Labs are great examples. There are also numerous private sector companies, all within New Mexico, that are investing in space technology.
"Billions are being invested now to develop the space economy of the Moon-Earth, system. It's extremely valuable to New Mexicans to be involved in the space economy to varying degrees," said Shearer. "The purpose of this is also to reach out to the private sector and the national labs to involve them and help develop this New Mexico space economy. UNM has championed these activities through the Sustainable Space Research Grand Challenge. Further, NASA has supported many of our research programs on the UNM campus."
"This research is putting us on the ground floor and we're addressing some fundamental questions," said Sharp.
Ultimately, the goal is for the samples to be returned and allocated to premier labs in order to analyze and interpret the data.
"In the publication, we talk about the volatile species that we expect to return from the Artemis mission and how we might curate and sample those to curate the most information possible about the moon," said Sharp.
The LPI looks at photographic imagery from satellites orbiting the moon and makes maps of the temperature profiles of the whole region. While these indications help to map out the moon, Shearer and Sharp both conclude that futher missions will only confirm what's actually there.
"We are just in the very early exploratory phase of space exploration, and we don't quite know what's there yet. We don't know how dangerous it is, how cold it is, or what we're going to find. Each mission will give us new information that will enable missions to become more sophisticated as we move forward in the exploration of the Moon," concluded Sharp.
