The dream of building a permanent settlement on the Moon is a place where humans from all walks of life can come together and give rise to a new culture and identity. A place where vital scientific research and experiments can be conducted, lunar industries created, and people can go for a little adventure tourism. It has been in science fiction and speculative literature for over a century. It could become a reality in the coming years.
There are many challenges and opportunities for creative solutions. Astronomers have speculated for years that the best place to build a lunar colony is underground, in pits, caves, and stable lava tubes. Preliminary results show that the pits are remarkably stable compared to the surface.
The research was led by a graduate student from UC Boulder who presented his findings at the AGU Fall Meeting in New Orleans. The goal of the presentation is to provide new 3D thermal models to characterize the temperature environments within lunar pits and caves, with the ultimate goal of assessing the stability of a range of volatile species within these pits.
Thanks to missions like NASA's LRO, the twin Gravity Recovery and Interior Laboratory (GRAIL) satellites, and JAXA's SELenological and Engineering Explorer (SELENE), there are many more. Scientists understand that the Moon has many pits and caves. Stable lava tubes formed when the Moon was still volcanically active billions of years ago.
In many cases, these tubes have collapsed in one or more sections, creating holes from the surface into the interior. The sites are thought to have great potential for future research missions since they would provide insight into the volcanic and impact history of the Moon. The Chinese National Space Agency and the European Space Agency are being investigated by mission planners for future human exploration.
The pits and caves could provide resources for future human exploration, not the least of which are volatile elements. The ice could be used to provide astronauts with everything from drinking water to rocket fuel. The pits might be ideal for providing shelter from the hostile surface conditions that astronauts and even settlers would face on the lunar surface.
According to a recent press release from CU Boulder Today, they want to know what people should expect down there. To learn more about their suitability, Paul Hayne, an assistant professor in the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder and a co-author on the research, conducted a series of computer simulations to recreate what conditions are like below the Moon's surface.
Their initial findings show that the lunar pits and caves have stable temperature conditions that would help astronauts weather some of the Moon's most extreme weather. The same conditions would make it hard for them to find water ice. Most of the simulations hosted temperatures of -120 to 70 C (-184 to 94 F) throughout the entire lunar day.
Hayne and other scientists have shown that hidden troves of water ice may have accumulated in certain lunar cold traps over billions of years. Many lunar pits and caves are too warm to hold similar troves. The situation on the lunar surface is similar to this one because of the extreme temperature swings.
When you get close to the equator, the temperature can reach more than 100 degrees Celsius on the surface, and it will get down to zero at night.
The cratered polar regions are currently being looked at by most mission planners. Water ice has been observed in the permanently-shadowed areas because of the crater floors that act as cold sinks. The key to finding pits and caves with ice is geographical location and orientation.
Pits at higher latitudes may have the right geometry and temperatures for water ice to remain stable over time, compared to pits at low latitudes. The simulations showed that orientation was an important factor. If a cave pointed directly at the Sun rising, it would experience hot temperatures throughout the day, then plunge to frigid lows at night.
Hayne said that no one knows how many pits and caves are on the lunar surface. There may be more than 200 ranging between 5 meters and 900 meters in diameter. This research shows the need for knowledge of the thermal environments in lunar pits and presents some exciting possibilities for lunar habitats.
They are attractive options for establishing a long-term human presence on the moon. A protected base station could be located inside a lunar pit or cave near one of the polar craters. When conditions were right, astronauts could venture out to collect ice-rich soil.
The next iteration of their thermal simulations will include a statistical Monte Carlo hopping model that will be used to determine how long water can remain in the pits. The model will allow scientists to measure the role pit geometry and latitude play in trapping different types of volatile elements and predict the compositions of concentrated volatiles that may exist within lunar pits.
The lunar village is a group of structures on the rim of a crate. The credit is given to the European Space Agency.
The South Pole-Aitken Basin has been identified as a possible location for lunar bases by multiple space agencies. These bases would be able to harvest ice from the crater floor to fulfill their water needs and see to their power supply by positioning solar panels around the rim of the crater. Who says all bases will be established in these environments?
Others can still be found in the polar regions, but are located underground in lava tubes with large amounts of water ice. Who knows? When real estate becomes more sought after, settlers and commercial interests will have to build habitats in the pits and caves around the poles because there is little room left for surface habitats. It is possible to establish settlements in lava tubes large enough to house entire cities.
We are going back to the moon. We plan to stay indefinitely.
Further reading: AGU.
