New Idea: Use the Starship HLS to Create a Lunar Base!

Artist's impression of a modular lunar base built using the SpaceX Lunar Starship. Credit: ISU

Between the multiple space agencies planning to conduct crewed missions to the lunar surface, the many commercial entities who’ve contracted them to assist them, and proposals for lunar bases, the message of the modern space age is clear: We’re going back to the Moon. And this time, we intend to stay! Just like the efforts of the Apollo Era, this entails several challenges, ones that require “the best of our energies and skills.”

These challenges are leading to all sorts of innovative solutions, which recognize the need to leverage lunar resources to provide protection against the environment and see to peoples’ needs. A new proposal made by a team from the International Space University (ISU) has found a novel way to do just that. Their proposal? Use the SpaceX Starship Human Landing System (HLS) as the foundation for a lunar base.

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This is a 3D-Printed Steel Floor Prototype for a Lunar Habitat

Credit: ESA/MX3D

In this decade, multiple space agencies and commercial space entities will be taking us back to the Moon. But unlike the Apollo Era, the goal of these programs is not “footprints and flags,” but to establish the necessary infrastructure to keep going back. In particular, NASA, the ESA, Roscosmos, and China are all planning on establishing outposts that will allow for scientific research and a sustained human presence.

The ESA is currently showcasing what its outpost will look like at the 17th annual Architecture Exhibition at the La Biennale di Venezia museum in Venice. It’s known as the International Moon Village, which was designed by the architecture firm Skidmore, Owings & Merrill (SOM) with technical support from the ESA. This same company recently unveiled a prototype of the skeletal metal component that will one day be part of the Village’s lunar habitats.

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China and Russia Announce their Future Plans for the Moon, Including a Human Base

Credit: NASA

In the coming years, multiple space agencies will be sending astronauts to the Moon for the first time since the closing days of the Apollo Program. For NASA, this will represent the long-awaited “return to the Moon,” while every other space agency will see it as a tremendous step for their space programs. One thing they all have in common is that this time around, the goal is to build the necessary infrastructure that will allow for a long-term human presence.

However, amid all the excitement of this approaching moment in history are concerns about the lack of an international framework that will ensure our efforts are for the sake of “for all humankind.” Whereas NASA is seeking partners for its Artemis Program through bilateral agreements, Russia and China are pursuing an agreement of their own. They call it the International Lunar Research Station (ILRS), and they too are looking for partners in this endeavor.

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Conceptual Design for a Lunar Habitat

Between now and the end of this decade, multiple space agencies plan to send astronauts to the Moon for the first time since the Apollo Era. But whereas Apollo was a “footprints and flags” affair, the current proposals for lunar exploration call for the creation of infrastructure that allow for a sustained human presence there. In addition to NASA’s Artemis Program, the ESA is also working on a plan to create an “International Moon Village.”

For years, the ESA has released teasers as to what this “successor to the International Space Station” (ISS) might look like, the latest of which is on display at the La Biennale di Venezia museum in Venice. As part of the 17th International Architecture Exhibition, the architecture firm Skidmore, Owings & Merrill (SOM) showcased their design (with technical support from the ESA) for a semi-inflatable lunar habitat that could facilitate long-term lunar settlement.

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Astronaut Pee Will Help Build Bases on the Moon

Artist's impression of a lunar base created with 3-d printing techniques. Credits: ESA/Foster + Partners

In the next few decades, NASA, the European Space Agency (ESA), China, and Russia all plan to create outposts on the lunar surface that will allow for a permanent human presence. These proposals seek to leverage advances in additive manufacturing (aka. 3-D printing) with In-Situ Resource Utilization (ISRU) to address the particular challenges of living and working on the Moon.

For the sake of their International Moon Village, the ESA has been experimenting with “lunacrete” – lunar regolith combined with a bonding agent to create a building material. But recently, a team of researchers conducted a study (in cooperation with the ESA) that found that lunacrete works even better if you add a special ingredient that the astronauts make all by themselves – urine!

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The Blue Origins Founder Wants to Get to the Moon by 2024

Jeff Bezos and a mock-up of the Blue Moon lander. Credit: Blue Origin

Blue Origin is going to the Moon. In an hour-long presentation in Washington DC on May 9th, Jeff Bezos spelled out his plans for reaching the Moon, confirming what many guessed he was hinting at in a tweet from the previous week.

Bezos and his company, Blue Origin, are developing a lunar lander capable of landing a large payload of 6.5 metric tons (14,330 lbs.) on the lunar surface. The lander is being called ‘Blue Moon’ and the target date for its rendezvous with the Moon is 2024.

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Lava Tube Openings Found Near the Moon’s North Pole

Artist's impression of a lunar base created with 3-d printing techniques. Credits: ESA/Foster + Partners

Between NASA, the Chinese National Space Agency, the European Space Agency and Roscosmos, there’s no shortage of plans for returning to the Moon and creating a permanent base there. Naturally, these plans have given rise to questions of where such bases should be built. So far, the top contenders have been lava tubes that have been spotted in various locations across the surface of the Moon and in the polar regions.

Whereas the polar regions are permanently shaded and appear to have abundant ice water, stable lava tubes would offer protection against the elements and harmful radiation. However, according to a new discovery presented at NASA’s Lunar Science for Landed Missions Workshop, it appears that there is a location on the Moon that ticks off both boxes – a possible lava tube that is located in the norther polar region!

This discovery was detailed in an abstract titled “Philolaus Crater: Exploring Candidate Lava Tubes And Skylights Near The Lunar North Pole“. The author was Pascal Lee, the co-founder and chairman of the Mars Institute, a planetary scientist at the SETI Institute, and the Principal Investigator of the Haughton-Mars Project (HMP) at NASA’s Ames Research Center.

NASA Lunar Reconnaissance Orbiter image showing some of the newly discovered lava tube skylight candidates at Philolaus Crater near the North Pole of the Moon. Credit: NASA/LRO/SETI Institute/Mars Institute/Pascal Lee

These pits were identified based on an analysis of imaging data from NASA’s Lunar Reconnaissance Orbiter (LRO). These images indicated the presence of small pits in the northeastern floor of the Philolaus Crater, a 70 km (43 mi)-diameter impact crater located about 550 km (340 mi) from the Moon’s North Pole. These pits could potentially be “skylights”, holes in the surface that lead to subterranean recesses.

Each pit appears to be a rimless depression measuring roughly 15 to 30 meters (50 to 11 ft) across and have shadowed interiors. Moreover, the pits are located along winding channels known as “sinous rilles” that are present along the floor of the Philolaus Crater. On the moon, these channels are thought to be the result of subterranean lava tubes that have since collapsed, or partially collapsed.

If water ice is present in the region, then these skylights could allow future explorers access to subsurface water ice that is less tainted by regolith. This presents a number of opportunities for research, and future long-term missions to the lunar surface. As Pascal Lee explained:

“The highest resolution images available for Philolaus Crater do not allow the pits to be identified as lava tube skylights with 100 percent certainty, but we are looking at good candidates considering simultaneously their size, shape, lighting conditions and geologic setting.”

In recent years, over 200 pits have been discovered by other researchers on the Moon, many of which were identified as possible skylights leading to underground lava tubes. However, this latest discovery is the first to place a possible skylight and lava tube within the Moon’s polar regions. These regions have become the focal point of research in recent years due to the fact that water ice is known to exist in the polar regions.

Within these permanently-shadowed cratered regions – particularly the South Pole-Aitken Basin – water ice is known to exist within the regolith. As a result, multiple proposals have been made to create lunar bases in the polar regions. However, there remains the challenge of how to get to that water (which would require drilling) and the fact that a permanently-shadowed region would not allow access to solar power.

This new discovery is therefore exciting for three reasons. For one, it would allow for much easier access to lunar polar ice that would be much more pure than anything drilled from the surface. Second, solar power would be available nearby, just outside each skylight. And third, these openings could provide access to a stable lava tube that contains water ice itself, much as lava tubes on Earth do.

Philolaus Crater also offers two additional bonuses when it comes a lunar settlement. Given that the crater formed in the Copernican Era (i.e. the last 1.1 billion years) it is relatively young as lunar craters go. As such, it would offer scientists with plenty of opportunities to study the Moon’s more recent geological history. Also, since the Philolaus Crater is on the near-side on the Moon, it would allow direct communications with Earth.

And as Lee added, a base in this location would also allow for some amazing views:

“We would also have a beautiful view of Earth. The Apollo landing sites were all near the Moon’s equator, such that the Earth was almost directly overhead for the astronauts. But from the Philolaus skylights, Earth would loom just over the crater’s mountainous rim, near the horizon to the southeast.”

Looking ahead, Lee and his colleagues indicate that further exploration is needed to verify whether or not these pits are lava tube skylights and whether or not they contain ice. In the future, astronauts and robots could be sent to the polar regions of the Moon in order to seek out and explore caves that have been identified from orbit. As Lee explained, this will have benefits that go far beyond lunar exploration.

“Exploring lava tubes on the Moon will also prepare us for the exploration of lava tubes on Mars,” he said. “There, we will face the prospect of expanding our search for life into the deeper underground of Mars where we might find environments that are warmer, wetter, and more sheltered than at the surface.”

And as Bill Diamond – president and CEO of the SETI Institute – explained, this discovery highlights the true nature of exploration, which goes well beyond orbiters and robotic explorers:

“This discovery is exciting and timely as we prepare to return to the Moon with humans. It also reminds us that our exploration of planetary worlds is not limited to their surface, and must extend into their mysterious interiors”.

The Lunar Science for Landed Missions Workshop was convened by the Solar System Exploration Research Virtual Institute (SSERVI) at NASA’s Ames Research Center. The purpose of the workshop was to examine the range of scientific investigations that could be conducted on the Moon, including in-situ science, network science and sample return missions.

Further Reading: SETI

Stable Lava Tube Could Provide a Potential Human Habitat on the Moon

The Marius Hills Skylight, as observed by the Japanese SELENE/Kaguya research team. Image by: NASA/Goddard/Arizona State University

On October 5th, 2017, Vice President Mike Pence announced the Trump administration’s plan to return astronauts to the Moon. Looking to the long-term, NASA and several other space agencies are also intent on establishing a permanent lunar base there. This base will not only provide opportunities for lunar science, but will facilitate missions to Mars and beyond.

The only question is, where should such a base be built? For many years, NASA, the ESA and other agencies have been exploring the possibility of stable lava tubes as a potential site. According to new study by a team of international scientists, the presence of such a tube has now been confirmed in the Marius Hills region. This location is likely to be the site of future lunar missions, and could even be the site of a future lunar habitat.

In 2009, data provided by the Terrain Camera aboard JAXA’s SELENE spacecraft indicated the presence of three huge pits on the Moon. These pits (aka. “skylights”) were of particular interest since they were seen as possible openings to subsurface lava channels. Since then, the Marius Hills region (where they were found) has been a focal point for astronomers and planetary scientists hoping to confirm the existence of lava tubes.

Artist’s impression of a surface exploration crew investigating a typical, small lava tunnel, to determine if it could serve as a natural shelter for the habitation modules of a Lunar Base. Credit: NASA’s Johnson Space Center

The recent study, titled “Detection of intact lava tubes at Marius Hills on the Moon by SELENE (Kaguya) Lunar Radar Sounder“, recently appeared in the journal Geophysical Research Letters. The team consisted of members from JAXA’s Institute of Space and Astronautical Science (ISAS), Purdue University, the University of Alabama, AstroLabs, the National Astronomical Observatory of Japan (NOAJ) and multiple Japanese Universities.

Together, they examined data from the SELENE mission’s Lunar Radar Sounder (LRS) from locations that were close to the Marius Hills Hole (MHH) to determine if the region hosted stable lava tubes. Such tubes are a remnant from the Moon’s past, when it was still volcanically active. These underground channels are believed to be an ideal location for a lunar colony, and for several reasons.

For starters, their thick roofs would provide natural shielding from solar radiation, cosmic rays, meteoric impacts, and the Moon’s extremes in temperature. These tubes, once enclosed, could also be pressurized to create a breathable environment. As such, finding an entrance to a stable lava tube would the first step towards selecting a possible site for such a colony.

As Junichi Haruyama, a senior researcher at JAXA and one of the co-authors on the study, explained in a University of Purdue press release:

“It’s important to know where and how big lunar lava tubes are if we’re ever going to construct a lunar base. But knowing these things is also important for basic science. We might get new types of rock samples, heat flow data and lunar quake observation data.”

The city of Philadelphia is shown inside a theoretical lunar lava tube. A Purdue University team of researchers explored whether lava tubes more than 1 kilometer wide could remain structurally stable on the moon. Credit: Purdue University/courtesy of David Blair

Granted, the LRS was not specifically designed to detect lava tubes, but to characterize the origins of the Moon and its geologic evolution. For this reason, it did not fly close enough to the Moon to obtain extremely accurate information on the subsurface. Nevertheless, as SELENE passed near the Marius Hills Hole, the instrument picked up a distinctive echo pattern.

This pattern was characterized by a decrease in echo power followed by a large second echo peak. These two echoes correspond to radar reflections from the Moon’s surface, as well as the floor and ceiling of the open lava tube. When they analyzed this pattern, the research team interpreted it is evidence of a tube. They found similar echo patterns at several locations around the hole, which could indicate that there is more than one lava tube in the region.

To confirm their findings, the team also consulted data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission. Consisting of two spacecraft, this collaborative effort collected high-quality data on the Moon’s gravitational field between 2011 and 2012. By using GRAIL data that identified mass deficits under the surface, which are evidence of caverns, the team was able to narrow down their search.

Jay Melosh, a GRAIL co-investigator and Distinguished Professor of Earth, Atmospheric and Planetary Sciences at Purdue University, was also a co-author on the paper. As he explained:

“They knew about the skylight in the Marius Hills, but they didn’t have any idea how far that underground cavity might have gone. Our group at Purdue used the gravity data over that area to infer that the opening was part of a larger system. By using this complimentary technique of radar, they were able to figure out how deep and high the cavities are.”

Arched passages in the main tube show the classic lava tube shape. The floor was the crust on a former lava lake that fell inward as it drained from beneath. Credit: Dave Bunnell/Under Earth Images/Wikipedia Commons

On Earth, stable lava tubes have been found that can extend for dozens of kilometers. To date, the longest and deepest to be discovered is the Kazumura Cave in Hawaii, which is over a kilometer (3,614 feet) deep and 65.5 km (40.7 mi) long. On the Moon, however, lava tubes are much larger, due to the fact that the Moon has only a fraction of the Earth’s gravity (0.1654 g to be exact).

For a lava tube to be detecting using gravity data, it would need to be several kilometers in length and at least one kilometer in height and width. Since the tube in Marius Hills was detectable, it is likely big enough to house a major city. In fact, during a presentation at the 47th Lunar and Planetary Conference, researchers from Purdue University showed GRAIL data that indicated how the tube beneath the MHH could be large enough to house Philadelphia.

This most recent study was also the subject of a presentation at the 48th Lunar and Planetary Conference. Similar evidence of possible stable lava tubes in the Sea of Tranquility was also obtained by the Lunar Reconnaissance Orbiter (LRO) back in 2010. However, this latest combination of radar and gravity data has provided the clearest picture yet of what a stable lava tube looks like.

Similar evidence of lava tubes has also been discovered on Mars, and possible even Mercury. On Mars in particular,  chains of pit craters, broad lava fans, skylights and partially collapsed lava tubes all indicate the presence of stable tubes. Based on this latest study, future mission to the Red Planet (which could include the creation of a habitat) might also entail the investigation of these features.

In fact, lava tubes could become the means through which a human presence is established throughout the Solar System someday!

Further Reading: Purdue University, Geophysical Research Letters

Settle the Moon Before Mars, Says Astronaut Chris Hadfield

Chris Hadfield recently explained how humanity should create a Moon base before attempting to colonize Mars. Credit: Foster + Partners is part of a consortium set up by the European Space Agency to explore the possibilities of 3D printing to construct lunar habitations. Credit: ESA/Foster + Partners

In the coming decades, NASA has some rather bold plans for space exploration. By the 2030s, they hope to mount their “Journey to Mars“. a crewed mission that will see astronauts traveling beyond Earth for the first time since the Apollo era. At the same time, private companies and organizations like SpaceX and MarsOne are hoping to start colonizing Mars within a decade or so.

According to Chris Hadfield, these mission concepts are all fine and good. But as he explained in a recent interview, our efforts should be focused on renewed exploration of the Moon and the creation of a lunar settlement before we do the same for Mars. In this respect, he is joined by organizations like the European Space Agency (ESA), Roscosmos, the Chinese National Space Agency (CNSA), and others.

When it comes to establishing a base on the Moon, the benefits are rather significant. For starters, a lunar outpost could serve as a permanent research base for teams of astronauts. In the same respect, it would present opportunities for scientific collaboration between space agencies and private companies – much in the same way the International Space Station does today.

On top of that, a lunar outpost could serve as a refueling station, facilitating missions deeper into the Solar System. According to estimates prepared by NexGen Space LLC (a consultant company for NASA), such a base could cut the cost of any future Mars missions by about $10 billion a year. Last, but not least, it would leverage key technologies that have been developed in recent years, from reusable rockets to additive manufacturing (aka. 3D printing).

And as Chris Hadfield stated in an interview with New Scientist, there are also a number of practical reasons for back to the Moon before going to Mars – ranging from distance to the development of “space expertise”. For those interested in science and space exploration, Chris Hadfield has become a household name in recent years. Before becoming an astronaut, he was a pilot with the Royal Canadian Air Force (RCAF) and flew missions for NORAD.

After joining the Canadian Space Agency (CSA) in 1992, he participated in two space missions – STS-74 and STS-100 in 1995 and 2001, respectively – as a Mission Specialist. These missions involved rendezvousing with the Russian space station Mir and the ISS. However, his greatest accomplishment occurred in 2012, when he became the first Canadian astronaut to command an ISS mission – Expedition 35.

During the course of this 148-day mission, Hadfield attracted significant media exposure due to his extensive use of social media to promote space exploration. In fact, Forbes described Hadfield as “perhaps the most social media savvy astronaut ever to leave Earth”. His promotional activities included a collaboration with Ed Robertson of The Barenaked Ladies and the Wexford Gleeks, singing “Is Somebody Singing? (I.S.S.) via Skype.

Canadian astronaut Chris Hadfield, the first Canadian to serve as commander of the ISS. Credit: CTV

The broadcast of this event was a major media sensation, as was his rendition of David Bowie’s Space Oddity“, which he sung shortly before departing the station in May 2013. Since retiring from the Canadian Space Agency, Hadfield has become a science communicator and advocate for space exploration. And when it comes to the future, he was quite direct in his appraisal that the we need to look to the Moon first.

According to Hadfield, one of the greatest reasons for establishing a base on the Moon has to do with its proximity and the fact that humans have made this trip before. As he stated:

“With long-haul space exploration there is a whole smorgasbord of unknowns. We know some of the threats: the unreliability of the equipment, how to provide enough food for that length of time. But there are countless others: What are the impacts of cosmic rays on the human body? What sort of spacecraft do you need to build? What are the psychological effects of having nothing in the window for months and months? And going to a place that no one has ever been before, that can’t be discounted.”

In that, he certainly has a point. At their closest – i.e. when it is at “opposition with the Sun”, which occurs approximately every two years – Mars and Earth are still very far from each othre. In fact, the latest closest-approach occurred in 2003, when the two planets were roughly 56 million km (33.9 million miles) apart. This past July, the planets were again at opposition, where they were about 57.6 million km (35.8 million miles) apart.

Using conventional methods, it would take a mission between 150 and 300 days to get from the Earth to Mars. Whereas a more fuel-efficient approach (like ion engines) would cost less but take much longer, a more rapid method like chemical rockets would could cost far more. Even with Nuclear Thermal Propulsion (NTP) or the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept, the journey could still take 5 to 7 months.

During this time, astronauts would not only be subjected to a great deal of cosmic radiation, they would have to contend with the affects of microgravity. As studies that have been conducted aboard the ISS that have shown, long-term exposure to a microgravity environment can lead to losses in bone density, muscular atrophy, diminished eyesight, and organ damage.

Recent studies have also shown that exposure to radiation while on the surface of Mars would be quite significant. During its journey to Mars, the Curiosity rover recorded that it was subjected to average dose of 1.8 millisieverts (mSv) per day from inside its spaceship – the Mars Science Laboratory. During its first three hundred days on the surface, it was exposed to about 0.67 millisieverts (mSv) per day.

This is about half and one-fifth (respectively) of what people are exposed to during an average here on Earth. While this falls outside of NASA’s official guidelines, it is still within the guidelines of other space agencies. But to make matter worse, a new study from the University of Nevada, Las Vegas, concluded that exposure to cosmic rays could cause cell damage that would spread to other cells in the body, effectively doubling the risk of cancer.

The risks of going to the Moon, in contrast, are easy to predict. Thanks to the Apollo missions, we know that it takes between two and three days to travel from the Earth to the Moon. The Apollo 11 mission, for example, launched from the Cape Kennedy on July 16th, 1969, and arrived in lunar orbit by July 19th, 1969 – spending a total of 51 hours and 49 minutes in space. Astronauts conducting this type of mission would therefore be subject to far less radiation.

Artist’s impression of a lunar base created with 3-d printing techniques. Credits: ESA/Foster + Partners

Granted, the surface of the Moon is still exposed to significant amounts of radiation since the Moon has no atmosphere to speak of. But NASA estimates that walls which are 2.5 meters in thickness (and made from lunar regolith) will provide all the necessary shielding to keep astronauts or colonists safe. Another good reason to go to the Moon first, according to Hadfield, is because expertise in off-world living is lacking.

“There are six people living on the International Space Station, and we have had people there continuously for nearly 17 years,” he said. “But the reality is we have not yet figured out how to live permanently off-planet. So I think if we follow the historically driven pattern then the moon would be first. Not just to reaffirm that we can get there, but to show that we can also live there.”

But perhaps the best reason to settle the Moon before moving onto Mars has to do with the fact that exploration has always been about taking the next step, and then the next. One cannot simply leap from one location to the next, and expect successful results. What are required is baby-steps. And in time, sufficient traction can be obtained and the process will build up speed, enabling steps that are greater and more far-reaching. Or as Hadfield put it:

“For tens of thousands of years humans have followed a pattern on Earth: imagination, to technology-enabled exploration, to settlement. It’s how the first humans got to Australia 50,000 or 60,000 years ago, and how we went from Yuri Gagarin and Alan Shepherd orbiting Earth to the first people putting footprints on the moon, to people living in orbit.

Based on this progression, one can therefore see why Hadfield and others beleive that the next logical step is to return to the Moon. And once we establish a foothold there, we can then use it to launch long-range missions to Mars, Venus, and beyond. Incremental steps that eventually add up to human beings setting foot on every planet, moon, and larger body in the Solar System.

On the subject of lunar colonization, be sure to check out our series on Building a Moon Base, by Universe Today’s own Ian O’Neill.

Further Reading: New Scientist

Good News for Future Moon Bases. There’s Water Inside the Moon

Evidence from ancient volcanic deposits suggests that lunar magma contained substantial amounts of water, bolstering the idea that the Moon's interior is water-rich. Credit: Olga Prilipko Huber

Since the Apollo program wrapped up in the early 1970s, people all around the world have dreamed of the day when we might return to the Moon, and stay there. And in recent years, however, that actual proposals for a lunar settlement have begun to take shape. As a result, a great deal of attention and research has been focused on whether or not the Moon has indigenous sources of water.

Thanks to missions like Chandrayaan-1 and the Lunar Reconnaissance Orbiter (LRO), scientists know that there are vast amounts of surface ice on the Moon. However, according to a new study, researchers from Brown University have found evidence of widespread water within volcanic deposits on the lunar surface. These findings could indicate that there are also vast sources of water within the Moon’s interior.

For their study – titled “Remote Detection of Widespread Indigenous Water in Lunar Pyroclastic Deposits” – Brown researchers Ralph E. Milliken and Shuai Li combined satellite data with new thermal profiles to search for signs of water away from the polar regions. In so doing, they addressed a long-standing theory about the likelihood of water in the Moon’s interior, as well as the predominant theory of how the Moon formed.

Lunar Crater as imaged by NASA’s Moon Mineralogy Mapper. Credit: SRO/NASA/JPL-Caltech/USGS/Brown Univ.

As noted, scientists have known for years that there are large amounts of frozen water in the Moon’s polar regions. At the same time, however, scientists have held that the Moon’s interior must have depleted of water and other volatile compounds billions of years ago. This was based on the widely-accepted hypothesis that the Moon formed after a Mars-sized object (named Theia) collided with Earth and threw up a considerable amount of debris.

Essentially, scientists believed that it was unlikely that any hydrogen – necessary to form water – could have survived the heat of this impact. However, as of a decade ago, new scientific findings began to emerge that cast doubt on this. The first was a 2008 study, where a team of researches (led by Alberto Saal of Brown University) detected trace amounts of water in samples of volcanic glass that were bought back by the Apollo 15 and Apollo 17 missions.

This was followed by a 2011 study (also from Brown University) that indicated how crystalline structures within those beads contained as much water as some basalt mineral deposits here on Earth. These findings were particularly significant, in that they suggested that parts of the Moon’s mantle could contain as much water as Earth’s. The question though was whether these findings represented the norm, or an anomaly.

As Milliken, an associate professor in Brown’s Department of Earth, Environmental, and Planetary Sciences (DEEPS) and the co-author on the paper, summarized in a recent Brown press release:

“The key question is whether those Apollo samples represent the bulk conditions of the lunar interior or instead represent unusual or perhaps anomalous water-rich regions within an otherwise ‘dry’ mantle. By looking at the orbital data, we can examine the large pyroclastic deposits on the Moon that were never sampled by the Apollo or Luna missions. The fact that nearly all of them exhibit signatures of water suggests that the Apollo samples are not anomalous, so it may be that the bulk interior of the Moon is wet.”

A false colour composite of the distribution of water and hydroxyl molecules over the lunar surface. Credit: ISRO/NASA/JPL-Caltech/Brown Univ/USGS

To resolve this, Milliken and Li consulted orbital data to examine lunar volcanic deposits for signs of water. Basically, orbiters use spectrometers to bounce light off the surfaces of planets and astronomical bodies to see which wavelengths of light are absorbed and which are reflected. This data is therefore able to determine what compounds and minerals are present based on the absorption lines detected.

Using this technique to look for signs of water in lunar volcanic deposits (aka. pyroclastic deposits), however, was a  rather difficult task. During the day, the lunar surface heats up, especially in the latitudes where volcanic deposits are located. As Milliken explained, spectronomers will therefore pick up thermal energy in addition to chemical signatures which this can throw off the readings:

“That thermally emitted radiation happens at the same wavelengths that we need to use to look for water. So in order to say with any confidence that water is present, we first need to account for and remove the thermally emitted component.”

To correct for this, Milliken and Li constructed a detailed temperature profile of the areas of the Moon they were examining. They then examined surface data collected by the Moon Mineralogy Mapper, the spectrographic imager that was part of India’s Chandrayaan-1 mission. They then compared this thermally-corrected surface data to the measurements conducted on the samples returned from the Apollo missions.

Colored areas indicate elevated water content compared with surrounding terrains. Yellows and reds indicate the richest water content. Credit: Milliken lab/Brown University

What they found was that areas of the Moon’s surface that had been previously mapped showed evidence of water in nearly all the large pyroclastic deposits. This included the deposits that were near the Apollo 15 and 17 landing sites where the lunar samples were obtained. From this, they determined that these samples were not anomalous in nature, and that water is distributed across the lunar surface.

What’s more, these findings could indicate that the Moon’s mantle is water-rich as well. Beyond being good news for future lunar missions, and the construction of a lunar settlement, these results could lead to a rethinking of how the Moon formed. This research was part of Shuai Li’s – a recent graduate of the University of Brown and the lead author on the study – Ph.D thesis. As he said of the study’s findings:

“The growing evidence for water inside the Moon suggest that water did somehow survive, or that it was brought in shortly after the impact by asteroids or comets before the Moon had completely solidified. The exact origin of water in the lunar interior is still a big question.

What’s more, Li indicated that lunar water that is located in volcanic deposits could be a boon for future lunar missions. “Other studies have suggested the presence of water ice in shadowed regions at the lunar poles, but the pyroclastic deposits are at locations that may be easier to access,” he said. “Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward, and our results suggest a new alternative.”

The blue areas show locations on the Moon’s south pole where water ice is likely to exist. Credit: NASA/GSFC

Between NASA, the ESA, Roscosmos, the ISRO and the China National Space Administration (CNSA), there are no shortage of plans to explore the Moon in the future, not to mention establishing a permanent base there. Knowing there’s abundant surface water (and maybe more in the interior as well) is therefore very good news.  This water could be used to create hydrazine fuel, which would significantly reduce the costs of individual missions to the Moon.

It also makes the idea of a stopover base on the Moon, where ships traveling deeper into space could refuel and resupply – a move which would shave billions off of deep-space missions. An abundant source of local water could also ensure a ready supply of drinking and irrigation water for future lunar outposts. This would also reduce costs by ensuring that not all supplies would need to be shipped from Earth.

On top of all that, the ability to conduct experiments into how plants grow in reduced gravity would yield valuable information that could be used for long-term missions to Mars and other Solar bodies. It could therefore be said, without a trace of exaggeration, that water on the Moon is the key to future space missions.

The research was funded by the NASA Lunar Advanced Science and Exploration Research (LASER) program, which seeks to enhance lunar basic science and lunar exploration science.

Further Reading: Brown University