A mirror could be all we need to fetch water on the Moon

A giant mirror, some sunlight, and a trap to collect water could get us all the water we need on our Martian missions.
Amal Jos Chacko
Representational image of an astronaut on the moon.jpg
Representational image of an astronaut on the moon.

Nzoka John/iStock 

Space exploration has always faced a formidable challenge - acquiring the essential resources to sustain life beyond our planet. At the forefront of these resources is water, a precious and critical asset for human survival in the cosmos. 

As space agencies and scientists continue their quest for in-situ resource utilization, one ingenious idea stands out— “Thermal Mining of Ices on Cold Solar System Bodies.” 

Proposed by George Sowers, a space resource expert and Professor of Mechanical Engineering at the Colorado School of Mines (CSM), this concept could unlock large amounts of water from celestial bodies by harnessing the power of the Sun.

The concept is surprisingly simple yet revolutionary, akin to using a magnifying glass to direct sunlight to a specific spot as children might have done. 

Imagine you have a block of ice. If you put it in a vacuum, it will turn directly from a solid into a gas without first melting (sublimation) due to a lack of molecules in the vacuum carrying the heat away from the ice.

But if you can direct sunlight onto the ice with a giant mirror, the heat from the sunlight could cause the ice to sublimate even faster. The water vapor produced by the sublimating ice can then be captured and condensed into liquid water.

UniverseToday reports the basic system architecture of this concept to be simple, consisting of a few major components: a large mirror, or heliostat that directs sunlight, a giant tent that traps sublimated water, and a cold transport system that captures water as it escapes from the surface.

Moon: The Promising Frontier for Water Extraction

While the Thermal Mining concept holds potential for various celestial bodies like Mars, Ceres, and asteroids, it is the Moon that emerges as the most promising frontier for water extraction. 

Permanently Shaded Regions (PSRs) of the Moon are believed to harbor vast amounts of water, making it an ideal location to kick-start humanity's resource utilization in space.

The Moon's advantages over other celestial bodies include its manageable gravity, allowing the use of standard rovers for ice transportation, and the absence of an atmosphere that might impede solar thermal energy transfer. 

Additionally, the Moon's proximity to Earth makes it an enticing target for exploration and resource exploitation missions using the Thermal Mining technique.

Challenges and the Path Forward

As with any groundbreaking concept, Thermal Mining faces challenges that need to be addressed before it can become a reality. 

Dr. Sowers and his team encountered two notable issues during their proof-of-concept testing. The first challenge involved the setup itself, with the liquid nitrogen cooling system absorbing much of the intended heat, underlining the need to construct a larger test chamber to mitigate the effect.

The second, more complex challenge relates to the formation of a desiccated layer on the regolith's surface during the sublimation process which acts as a thermal barrier, hindering the escape of water vapor from deeper layers. 

Despite the challenges, the business case for Thermal Mining presents an enticing proposition. Dr. Sower's team estimates the total development cost for a lunar mining operation in the PSRs to be approximately $800M.

The Internal Rate of Return (IRR) makes the project viable, especially with the involvement of potential customers ranging from commercial sources to national space agencies like NASA.

Although still in the planning phase, the patented technology holds the promise of a future where humans can extract water and other resources from the Moon and beyond. 

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