extended stay

Human life on the Moon could depend on a substance deadly to animals on Earth

The solid carbon dioxide could be used as fuel for a sustainable human presence on the Moon.

An overhead view of the moon's south pole.
NASA/GSFC/Arizona State University

For planned future missions to the Moon, making that 238,855 mile trip to the lunar surface is only half the battle.

The goal is not only to get there but to maintain a human presence on the Moon, which will require astronauts to generate resources on the lunar surface. And a recent discovery may help future astronauts spend quite a bit of time hopping on its terrain.

Scientists recently confirmed the presence of carbon dioxide cold traps at the Moon’s poles, which could be used as a crucial resource to produce fuel, as well as biomaterials and even steel.

“Carbon is an important element to have — it’s an essential element,” Norbert Schorghofer, senior scientist at the Planetary Science Institute and lead author of the new study, tells Inverse.

Schorghofer and colleagues detailed their discovery in a paper published in the Geophysical Research Letters.

HERE’S THE BACKGROUND — It’s been more than 50 years since humans took a small step on the Moon with the Apollo mission, but NASA is planning quite the giant leap back to the lunar surface.

The space agency is planning on not only returning humans to the Moon, but on establishing a sustainable presence and building a lunar base on the surface. To do that, future astronauts have to live off the land.

In 2018, scientists discovered evidence of water ice on the Moon's surface, mainly at a lunar crater in the Moon's southern pole. Some water ice was also apparent at the northern pole, where temperatures never reach above -250 degrees Fahrenheit.

Two years later, NASA confirmed the discovery, adding that the water ice was much more abundant than previously believed. But other resources are needed to sustain a human presence on the Moon. That’s where the cold traps come in.

This photo of Apollo 12 astronaut Alan Bean on the Moon.

NASA./Corbis Historical/Getty Images

WHAT’S NEW — In 2009, NASA’s Lunar Crater Observation and Sensing Satellite detected carbon dioxide in a plume of material that erupted from the Moon’s Cabeus crater.

Scientists had always predicted that the Moon would have carbon dioxide cold traps, but the temperatures needed to be extremely cold in the regions where it would exist.

“The cold traps are regions cold enough for solids or liquids to accumulate,” Schorghofer says. “As long as there is a source of that, then it should have carbon dioxide.”

For the latest research, Schorghofer and colleagues used 11 years’ worth of temperature data from the Diviner Lunar Radiometer Experiment, an instrument aboard NASA’s Lunar Reconnaissance Orbiter.

The data showed permanently shadowed areas near the Moon’s poles where temperatures would be low enough to sustain the carbon dioxide cold traps.

The Moon undergoes seasons, and although these seasonal changes do not affect the entire surface of the Moon, they are significant in those permanently shadowed areas. During the winter months, temperatures dip low enough for the cold traps to exist while the carbon is lost to space for a brief period during the summer months.

The carbon dioxide cold traps cover around 204 square kilometers total, and the largest area of cold traps lies in the Amundsen Crater and extends about 82 square kilometers wide.

In these areas, temperatures remain below -350 degrees Fahrenheit.

WHY IT MATTERS — Carbon dioxide can act as an essential resource on the Moon. Astronauts could convert it into breathable oxygen or use the carbon into a solid form for building materials and other resources.

The rockets that SpaceX is planning to use for the mission to the Moon run on a mixture of liquid oxygen and methane, with methane being partially made of carbon and hydrogen. It could also aid in steel production from materials gathered on the Moon.

WHAT’S NEXT — The paper suggests that not only is there carbon dioxide on the Moon but there’s also an abundance of it.

“It’s expected to be a high concentration,” Schorghofer says. “And the higher the concentration, the easier it is to extract it.”

Although a specific technique to extract the carbon from the Moon’s cold traps has yet to be developed, it would be similar to mining resources here on Earth.

“The challenge is to operate in permanent darkness,” Schorghofer says. “It’s a very challenging environment, but it’s still much easier than having to bring it from Earth.”

Transporting the carbon from Earth would be much more expensive as well as it costs about $10,000 to put a pound of payload in Earth’s orbit. Therefore, having local resources sounds like a much better option.

Space agencies still have some time to develop a way to mine carbon dioxide. The Artemis crewed landing on the Moon was recently pushed back to the year 2025.

“I think there’s a lot of enthusiasm about [sustainable human presence on the Moon],” Schorghofer says. “But I think it’s very expensive to do it so it remains to be seen whether it’s viable or not.”

“It’s achievable, it’s just very, very expensive,” he adds.

Abstract: 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.
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