The surface of the Moon is a bleak and forbidding place that could be hiding a lot of water ice within the dusty landscape. However, most possible ice deposits don’t just stand out in an image. You need specialized mapping to find those deposits. So, scientists have devised another way to find the Moon’s frosty hidden reserves. They use seismic waves from moonquakes as locator beacons.

Geologists at the University of Maryland, Lawrence Berkeley National Laboratory, and the University of Hawai’i recently published a paper (cited below) that examines the role that seismic waves play in locating ice deposits on and in the Moon. Finding water ice is important because the users of future lunar laboratories and habitats will need a steady supply of water. In addition, ice can be used to create oxygen supplies and rocket fuels for getting around the Moon. It’s a far cheaper and more efficient source of water than bringing water and other supplies up from Earth.

A map of possible lunar water deposits around the south pole region of the Moon. Courtesy: Chandrayaan mission. Credit: ISRO.

How Did the Moon Get Water?

The origins of the lunar water caches remain something of a mystery, although the evidence points in a few directions. The most likely locations for substantial amounts of water are at the poles and other regions where some of the ice could have been delivered by comets or asteroids. There could be deposits in regions where volcanism transported water from inside the Moon to the surface, or via the solar wind or meteor showers. These bombard surface rocks, triggering chemical reactions that could release water molecules. The evidence for water is pretty substantial, based on studies of rocks brought back during the Apollo era, as well as studies made by such missions as the Chinese Chang’e 5 probe, the SOFIA project, and highly detailed images and impact modeling done by Chandrayaan scientists. It’s more likely that much of the proposed lunar water accumulated over millions or billions of years, rather than just one major delivery by a comet or asteroid impact.

Lunar water is likely some kind of briny mixture of materials from the Moon mixed with materials delivered by delivery of chondritic materials via impacts. It’s still possible that regions in the lunar interior could be warm enough to contain liquid water, although scientists need more data about the Moon’s core to prove that. Some analyses also suggest that some lunar water could date back to the time of the Moon’s formation during the impact between early Earth and a Mars-sized object. So, it’s clear that a better understanding of the nature of lunar water (as well as its locations) is in order.

These images show a very young lunar crater on the side of the moon that faces away from Earth, as viewed by NASA’s Moon Mineralogy Mapper on the Indian Space Research Organization’s Chandrayaan-1 spacecraft. On the left is an image showing brightness at shorter infrared wavelengths. On the right, the distribution of water-rich minerals (light blue) is shown around a small crater. Both water- and hydroxyl-rich materials were found to be associated with material ejected from the crater. Credits ISRO/NASA/JPL-Caltech/USGS/Brown Univ.

Future Uses of Lunar Ice

According to Nicholas Schmerr of the University of Maryland, the Artemis missions and others will rely on lunar ice deposits, no matter where they come from. “It’s crucial to identify any materials on the moon that an astronaut can make use of while they’re up there,” said Schmerr, who co-authored the team’s study. “Since they will be limited by the few resources they brought from Earth, anything they find on the moon will help them basically live off the land, especially for longer-term missions or outposts.”

Lunar ice also provides another avenue of planetary science research. Ice in the shadowed craters may well contain undisturbed deposits of ice from comets and other events from early solar system history. “The moon witnessed some of the most critical parts of the early solar system, including how water was delivered,” Schmerr said. “Studying the ice deposited there could reveal how water spread and ultimately how Earth’s oceans formed.”

Seismic Waves and Ice

Finding ice under the surface requires new thinking about how it can be located. The lunar surface is cold and dry. From studies here on Earth, scientists know that seismic waves behave differently depending on the types of material they pass through. When a quake occurs, it sends out these mechanical waves. They travel through all the materials beneath the surface, and their velocity changes depending on what they travel through at the time. The density and elasticity of materials are important factors. The velocity of a wave will tell us how deep the quake was, essentially where it occurred.

As an example, if a wave passes through an area that has a lot of ice, the waves travel two to three times faster than they would through dirt or sand. Areas with a lot of ice mixed in also see bounce back in the waves as they interact with the stiff, dense materials. If an area on the Moon has a lot of ice underground, scientists would expect to see changes in velocity of the earthquake waves as well as any possible bounce back. According to Schmerr, bounceback would also reveal other characteristics of the hidden ice. “We can use seismic waves to not just see whether ice is present but also roughly how much of it there is,” he explained.

How to Test for Lunar Ice

It’s one thing to study earthquake waves here on the home planet, but quite another to do it on the Moon. To figure out the best way to determine lunar ice deposits, the team, led by Harrison Lisabeth of Lawrence Berkeley National Laboratory, tried three approaches for detection. First, they took a volcanic rock from Arizona that is a close mimic of lunar rocks. If you crush that type of rock, it turns into an almost exact analog for lunar dust. They froze it and then X-rayed it to see how ice settled between dust grains. The second approach involved temperature models for the polar regions, where ancient ice deposits seem to exist undisturbed by sunlight. Finally, Schmerr ran computer simulations of minor moonquakes to see how they would interact with underground lunar ice. All three methods left very obvious signs of ice in the data.

Data from X-ray tomography of simulated lunar regolith showing a) the dry sample, b) a rendering of icy microstructures prepared with small amounts of water, c) grains with the ice removed, and d) ice with the grains removed. The ice acts like a cement in the pore spaces between the grains of dust. This test result showed how the ice could exist in the regolith of the Moon. Credit: Lisabeth, Schmerr, et al.

The results look very promising, and the research team was able to come up with some suggestions for further examinations of methods to find ice on the Moon. One approach is to study the microstructures of a wider array of lunar regolith analogs here on Earth. In addition, future computer models should take into account more accurate measurements of lunar topography. Finally, the team suggests that further seismic models and tests be made to determine more accurate locations and depths of ice.
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The hunt for lunar ice is a very real one and future explorers will need that resource. The team points out that recent spectroscopic data suggests that there is between 100 and 400 mg/g of water in the lunar soil. The job now is to identify deposits that are reasonably minable for industrial use by Artemis and other missions. Planned robotic and crewed missions to the moon in the next decade will provide opportunities to apply the tools of terrestrial near-surface geophysics to locating crucial lunar resources. The next viable mission is the Chinese Chang’e-7 is set to go to the Moon in …. and will carry a seismometer capable of looking for ice deposits in its landing site near Shackleton Crater. The 2028 Artemis mission should also be able to set a Lunar Environmental Monitoring Station that can also perform seismic studies.

For More Information

Scientists Use Moonquakes to Locate Lunar Ice

The Seismic Signature of Lunar Ice

Water on the Moon? New Study Narrows Down the Most Likely Suspects

Water and Ices on the Moon

Sacramento — The two candidates for California governor came to Sacramento on Tuesday offering policy agendas that were both sweeping and vague on details, with both warning of the dangers posed by their rival’s political party.

Democrat Xavier Becerra vowed to lower healthcare costs for Californians and teased two new policies on energy and artificial intelligence. Republican Steve Hilton pledged to slash gas prices and utility bills to help remedy his dystopian view of California under Democratic rule.

The two candidates will face off in the Nov. 3 election to succeed outgoing Gov. Gavin Newsom, and took time to deliver their campaign messages at an afternoon political forum in the state capital.

Hilton pointed to the size of the state budget, the homelessness crisis, high taxes, the cost of living, the unemployment rate and the business climate to argue that 15 years of Democratic control has proved disastrous in California.

“It’s just a complete failure on every front, and it seems to have been immune to any kind of challenge because it’s very powerful. The machine is very powerful, funded by government unions, and you’ve got this alliance of the government unions and nonprofits, and the Chamber of Commerce, and all of this,” he told hundreds of people at a convention center in Sacramento.

Becerra defended California’s Democratic leadership, which controls the state Legislature, the governor’s office and every other statewide political office, as a staunch bulwark against the ruthless agenda of the Trump administration and Republican-led Congress.

“We’re a state. We’re a family. You don’t blame just one parent when things go awry with one of the children,” he said in reference to more than a decade of Democratic governance in California. “We’re all in this together. We all have to work together. I could say that one of the members of the American family in Washington, D.C., has created more chaos than any Democrat in the state of California.”

After a chaotic and competitive June primary, Tuesday marked one of the few times the two men have addressed the same audience. They appeared at a forum hosted by the news organization Politico and sponsored by Airbnb, AT&T, energy company California Resources Corp., Google and the Western States Petroleum Assn.

In a state with a pronounced Democratic tilt, Becerra, a former U.S. Health and Human Services secretary, is the front-runner in the race. Nearly 45% of the state’s voters are registered Democrats, while 25% are Republicans, according to a May report by the secretary of state’s office. Becerra has raised millions of dollars more than Hilton and benefited from well-funded independent groups that spent millions supporting his campaign.

Becerra repeatedly said he would not promise anything he could not deliver, saying that voters “want to see actual outcomes.”

“That’s also why I think you can’t do pie in the sky, inflated promises, because people want to see you deliver, and you can talk a great game, but unless you can deliver, people are going to crucify you,” he said.

He said he could not promise to build 3 million new housing units, as Newsom did eight years ago as a candidate for governor.

“That’s an inflated promise. But I will tell you, we will build, and I will tell you, there will be more Californians who own a home,” Becerra said.

Later, he told reporters he was not specifically referring to the figure Newsom had promised. “I could have said 2 million. I could have said 5 million. What I was saying is, it’s gonna be something that’s realistic,” he said.

Becerra was willing to make some big promises on healthcare.

“Am I going to promise you that I can drop the price of prescription drugs? Yes, because I did it before, and I know I can do it again. Am I telling you that I can keep Californians insured for healthcare, even though the guy in the White House stripped a trillion dollars out of the healthcare system? Yes, because I know how much money is in the healthcare system,” he said.

Pressed for specifics on how he would prevent people from losing their health insurance, Becerra hinted that the solution could be within the healthcare industry itself.

“There’s money in them there hills,” he said. “Healthcare is more expensive in California than anywhere else in the country, and healthcare is more expensive in the U.S. than it is anywhere else in the world. There is money that’s being spent that does nothing to dispense healthcare to you, and we’ve got to stop that game.”

Hilton acknowledged the long odds he faces in the November general election.

“I know I’m probably the only person in this room that actually thinks I can win this election,” he said.

Since the June primary, Hilton has been a constant presence on the campaign trail, crisscrossing the state, holding town halls and news conferences, making speeches and giving media interviews. Becerra has been far less visibly active.

Hilton argued that California is at a crossroads, pointing to residents and businesses moving out of the state.

“I’m here to say we can turn them around,” he said. “It’s an absolute crisis that we’re in if we don’t change direction.”

Hilton has vowed to cut gas prices to $3 per gallon, reduce utility bills, eliminate income taxes for Californians making under $150,000, increase the supply of starter homes and overhaul the business climate, particularly in the entertainment and agricultural industries. Just how Hilton would deliver on his agenda, given that Democrats control the California Legislature, remains unclear.

While he did not make any formal policy announcements at the summit, Becerra said there is “a lot of room to expand” on regulations and protections on AI, and he signaled support for a government-purchased stake in AI companies. “We can make it so they can prosper, but we prosper with them,” he said.

Hilton, who has released several AI-generated campaign ads, criticized Sam Altman of OpenAI and Anthropic’s Dario Amodei for doing little to earn the public’s trust on the fast-emerging technology. He also said there is space to both regulate and give AI more freedom.

“I think we’re in danger of both over- and under-regulating at the same time. I think we’re under-regulating some of the harms, for example, in relation to children and in relation to the creative community and their output, but we’re in danger of over-regulating some of the potential benefits,” including in the medical field, he said.

When asked whether the state’s voters are “stupid” for continuing to vote for Democrats, Hilton replied that they are not, but rather had not been offered a clear, positive alternative.

“There is a sense of inevitability about it, and I think that’s infected perhaps a lot of the political discourse in California,” he said. The notion that “it’s California. Democrats are always going to be in charge. What can you do?”

He said he believes he has a shot in the November election because he has a positive message, similar to that which helped propel the right-leaning Tories to a 14-year reign in the United Kingdom when he was a senior advisor to then-Prime Minister David Cameron.

Hilton labeled Becerra “unqualified” and didn’t discuss his endorsement by President Trump, which propelled his advancement to the general election.

“We’ve got everything going for us in California. We’ve got incredible assets and resources. We’ve got natural beauty, the best weather, great universities, amazing people, the incredible innovation ecosystem, the kind of startup hustle rebel spirit,” he said. “We just need, I think, a proactive, pro-business governor [who] recognizes that we’ve just ended up …, often with good intentions, frankly, in a situation where we’ve just got this massive, bloated bureaucratic government that’s stifling the spirit of California.”