By Dan May
On Our Land
Dan May
I enjoy winter. It is not my favorite season, but I like the cold and snow, including shoveling. The silhouettes of leafless trees provide new vantages of Orange’s hilly landscape, and with the growing season behind us, the levels of creeks, rivers and ponds all start to rise again.
The only things I dislike are the short days and the sun not rising very high in the sky. The low sun angle makes driving a challenge in the morning or evening; not to mention that it highlights the dust on surfaces in the house and neglected window washing. It also means that snow and ice will linger on the shady side of the house for days to weeks after the rest of the yard has thawed.
Low sun angles play a big part in NASA’s ongoing efforts to again land men and women on the Moon. The main goal of the Artemis/Orion missions is to establish a habitable operating station on the Moon. This station is almost certainly to be sited near the Moon’s south pole, close to features cryptically identified as permanently shaded regions, or PSRs. The PSRs are thought to contain the essential resource needed to support a long-term lunar station – ice.
We always see the same side of the Moon from Earth because it has an asymmetric structure, with the denser nearside gravitationally locked to face Earth. The lunar far side is also exposed to sunlight as the Moon orbits each month around Earth, but the Moon’s poles only ever receive sunlight at glancing low angles.
PSRs are deep meteorite impact craters near the poles where sunlight never reaches. They are also extremely cold, with temperatures of about –400 degrees Fahrenheit. Even in the absence of any significant atmosphere, this is frigid compared to a temperature of about 250 degrees Fahrenheit near the Moon’s equator when it is sunlit. The Apollo landing sites were all near the sunny lunar “tropics,” but the Artemis missions will explore some of the coldest parts of the Moon in search of ice.
Temperature in the vacuum of space is hard to comprehend for those of us who are Earthbound, but water ice and other ices of gases like ammonia and methane have accumulated in PSRs because they are so incredibly cold and permanently dark. The ices were delivered by impacts of meteorites and comets that struck the Moon, and their presence was confirmed by lunar satellite observations in the past decade. Among other scientific curiosities, ices in PSRs may be billions of years old and contain a record of the early solar system.
Water ice is a valuable resource for a habitable lunar station. In addition to consumption and cleaning needs, water is a component in materials required to construct shelters to protect life-supporting habitats from radiation and micrometeorites. It also can be broken down through the process of electrolysis to produce hydrogen and oxygen gas, both of which are fuel or energy sources. Ammonia would be useful to capture as well, as it could yield essential nitrogen fertilizer to grow crops in lunar greenhouses.
The first Artemis mission was completed successfully in December, with the unmanned Orion spacecraft splashing down in the Pacific after a test flight orbiting the Moon. The next mission will send astronauts into lunar orbit, with the goal of the third mission to land on the surface near the Moon’s south pole. This next generation of lunar astronauts is charged with finding, mining, analyzing and processing ices from the PSRs to begin the process of building a permanent station.
I am a geologist by training and started out in mining, so the challenge is personally fascinating. But even though I like winter, prospecting in the dark in a spacesuit at –400 degrees gives pause to 66-year-old me. These will be some of NASA’s most challenging tasks, but as the adage goes, “if we can do it there, we can do it anywhere.”
NASA’s overall mission is to push technology and creative ingenuity beyond convention. Having people establish artificial living environments on the Moon will highlight perceptions of Earth’s natural environments and perhaps provide improved approaches to manage Earthly resources.
Dan May is a geologist and professor of environmental science at the University of New Haven. He can be contacted at dmay@newhaven.edu.