Lunar Reconnaissance Orbiter (LRO).
Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab

 

The existence of carbon dioxide (CO2) cold traps on the Moon has been confirmed. That finding offers a potential resource for future exploration of the lunar surface.

However, large CO2 cold traps are rare and the geographic concentration of the resource will have policy implications.

As pointed out in new research, carbon-bearing species would be essential for sustained robotic or human presence on the Moon, for use in rocket fuel and biological materials.

South polar region of the Moon. Areas that act as CO2 cold traps are colored. Black contours show the boundaries of H2O cold traps. The background map is shaded relief.
Credit: Norbert Schorghofer

Improved analysis

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.

The new research makes use of extensive and improved analysis of 11 years of orbital surface temperature measurements that establishes the existence of carbon dioxide cold traps on the Moon, which potentially host high concentrations of solid carbon dioxide.

“Carbon Dioxide Cold Traps on the Moon” is a new paper appearing in Geophysical Research Letters, led by Tucson, Arizona-based Planetary Science Institute (PSI) senior scientist Norbert Schorghofer.

Diviner Lunar Radiometer Experiment.
Credits: NASA’s Goddard Space Flight Center/Debbie McCallum

Important resource

“After water, carbon is probably the most important resource on the Moon. It can be used for the production of rocket fuel, but also for biomaterials and steel. If we have to bring carbon or fuel from Earth, it drives up the cost of sustained presence,” Schorghofer explains in a PSI statement.

It’s part of “living off the land,” or in-situ resource utilization, Schorghofer said.

“Extensive and improved analysis of 11 years of orbital surface temperature measurements by the Diviner Lunar Radiometer Experiment on board NASA’s Lunar Reconnaissance Orbiter (LRO) establishes the existence of carbon dioxide cold traps on the Moon, which potentially host high concentrations of solid carbon dioxide, Schorghofer said.

“Our work has established the existence of CO2 cold traps, where theory predicts solid CO2 should have accumulated,” Schorghofer added. “Our work does not show that there actually is CO2 in these areas, but it is a reasonable expectation, especially since CO2 was detected in the LCROSS (NASA’s Lunar Crater Observation and Sensing Satellite) impact plume in 2009.”

LRO image of Amundsen crater. Credit: NASA/GSFC/ASU

Many terabytes of data

In the new study, many terabytes of Diviner data were processed to capture the full time dependence of surface temperatures.

The Diviner Lunar Radiometer Experiment (DLRE) onboard LRO is built to identify cold traps — areas cold enough to preserve ice for billions of years — and potential ice deposits as well as rough terrain, rock abundance, and other landing hazards.

Diviner was built and developed by the University of California, Los Angeles, and NASA’s Jet Propulsion Laboratory in Pasadena, Calif

Exploration target

According to the paper, the total area of CO2 cold traps in the south polar region of the Moon is about 200 square kilometers.

For comparison, water ice cold traps cover nearly 14,000 square kilometers.

Concentrated CO2 is an extremely scarce resource, only found at a few places, and a large portion of its cold trap area resides on the floor of Amundsen crater on the Moon.

That feature, which is relatively accessible, may be a promising exploration target. In this area, temperatures never exceed negative 350 degree Fahrenheit, so it will definitely be a technological challenge to explore these extremely cold and permanently dark places.

“The fact that this resource is highly concentrated geographically has implications for the governance of the lunar surface. Moreover, the interaction of carbon with galactic cosmic rays can produce organic compounds,” the paper points out.

To view the paper – “Carbon Dioxide Cold Traps on the Moon” – go to:

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2021GL095533

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