The Moon and Mercury May Have Thick Ice Deposits


Earth’s Moon and Mercury, the closest planet to the Sun, may contain significantly more water ice than previously thought, according to a new analysis of data from NASA’s LRO and MESSENGER spacecraft.

The potential ice deposits are found in craters near the poles of both worlds. On the Moon, “We found shallow craters tend to be located in areas where surface ice was previously detected near the south pole of the Moon, and inferred this shallowing is most likely due to the presence of buried thick ice deposits,” said lead author Lior Rubanenko of the University of California, Los Angeles.

Conceptual illustration of permanently shadowed, shallow icy craters near the lunar south pole. Credits: UCLA/NASA
Conceptual illustration of permanently shadowed, shallow icy craters near the lunar south pole. Credits: UCLA/NASA

In the past, telescopic observations and orbiting spacecraft have found glacier-like ice deposits on Mercury, but as of yet not on the Moon. The new work raises the possibility that thick ice-rich deposits also exist on the Moon. The research may not only help resolve the question regarding the Moon’s apparent low ice abundance relative to Mercury, but it could also have practical applications: “If confirmed, this potential reservoir of frozen water on the Moon may be sufficiently massive to sustain long-term lunar exploration,” said Noah Petro, Lunar Reconnaissance Orbiter Project Scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The poles of Mercury and the Moon are among the coldest places in our solar system. Unlike Earth, the spin axes of Mercury and the Moon are oriented such that, in their polar regions, the Sun never rises high above the horizon. Consequently, polar topographic depressions, such as impact craters, never see the Sun. For decades it has been postulated these so-called permanently shadowed regions are so cold that any ice trapped within them can potentially survive for billions of years.

Previous observations of the poles of Mercury with Earth-based radar revealed a signature characteristic of thick, pure ice deposits. Later, MESSENGER – the MErcury Surface, Space ENvironment, GEochemistry and Ranging spacecraft – imaged these ice deposits. “We showed Mercury’s polar deposits to be dominantly composed of water ice and extensively distributed in both Mercury’s north and south polar regions,” said Nancy Chabot, instrument scientist for MESSENGER’s Mercury Dual Imaging System from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “Mercury’s ice deposits appear to be much less patchy than those on the Moon, and relatively fresh, perhaps emplaced or refreshed within the last tens of millions of years.”

Previous radar and imaging studies of the Moon, whose polar thermal environments are very similar to those of Mercury, found only patchy, shallow ice deposits. This outstanding difference served as the motivation for the UCLA researchers’ work – a comparative analysis of polar craters on Mercury and the Moon to delve into this difference between the two worlds. The research was published July 22 in Nature Geoscience.

The airless surfaces of Mercury and the Moon are scarred by many impact craters. These craters form when meteoroids or comets impact the surface. The team analyzed simple craters that are formed by smaller, less energetic impactors. These depressions are held together by the strength of the surface dust layer, or regolith and tend to be more circular and symmetrical than large craters. The UCLA scientists exploited this inherent symmetry to estimate the thickness of ice trapped within simple craters.

The study used elevation data obtained by MESSENGER and LRO to measure approximately 15,000 simple craters with diameters ranging from 2.5 km to 15 km (about 1.5 miles to 9.3 miles) on Mercury and the Moon. Researchers found that craters become up to 10% shallower near the north pole of Mercury and the south pole of the Moon, but not the north pole of the Moon.

The authors concluded that the most probable explanation for these shallower craters is the accumulation of previously undetected thick ice deposits on both worlds. Supporting this conclusion, the researchers found that the pole-facing slopes of these craters are slightly shallower than their equator-facing slopes, and that the shallowing is more significant in regions that promote ice stability because of Mercury’s orbit around the Sun. The topographic signal detected by the scientists is relatively more prominent in smaller simple craters, but does not preclude the possibility that ice may be more widespread in larger craters across the lunar pole.

Additionally, unlike Mercury, where the ice has been shown to be nearly pure, the deposits detected on the Moon are most likely mixed with the regolith, possibly in a layered formation. The typical age of the simple craters examined by the researchers indicates they could potentially accumulate ice that was later mixed with overlying regolith over long time scales. The scientists found that these inferred buried ice deposits are correlated with the locations of already detected surface ice. This finding could imply that the exposed ice deposits may be exhumed, or they could result from molecular diffusion from depth.

The research was funded by the LRO and MESSENGER missions. LRO is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington. Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the Moon. MESSENGER was managed by the Johns Hopkins University Applied Physics Laboratory. The spacecraft was launched Aug 3, 2004, and began orbiting Mercury on March 18, 2011. The mission ended with a planned impact on the surface of Mercury on April 30, 2015. NASA is leading a sustainable return to the Moon with commercial and international partners to expand human presence in space and bring back new knowledge and opportunities.

Bill Steigerwald / Nancy Jones
NASA’s Goddard Space Flight Center, Greenbelt, Md.

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Joel O'Bryan
September 8, 2019 12:22 am

The Cassini lander, Huygens landed on Titan, a cryogenically cold methane moon of Saturn on January 14, 2005. Huygens found the temperature at the landing site was 93.8 K (−179.3 °C; −290.8 °F). It found a frozen slushy surface of methane ice. It’s warmer temperature meant it melted partially into the surface of it’s settled landing spot.

The Diviner instrument on NASA’s Lunar Reconnaissance Orbiter measured temperatures of 35 K (-396 °F , -238 °C) in craters at the lunar southern pole and 26 K (-413 F, -247 C) in a crater at the northern pole.

Any guesses if the technology exists to mine ice with a mechanical digger/transporter at those temps and not sink itself in melt water?

Samuel C Cogar
Reply to  Joel O'Bryan
September 8, 2019 5:02 am

Forget about any “melt water” …….. and mechanical thingys really don’t function very good at those temperatures.

Reply to  Samuel C Cogar
September 8, 2019 9:51 am

Samuel, we have mechanical systems which regularly operate at temperatures well below what you mention.
Deep space is very cold and we use that to our advantage. We even have to go so far as to shield our telescopes from even the faintest radiation.

Yes, it is hard, but we know how to do it.

Samuel C Cogar
Reply to  Rocketscientist
September 9, 2019 4:40 am

Rocketscientist, …… operating mechanical thingys is one thing, ……. “mining ice with a mechanical digger/transporter” is a whole new ballgame.

At -247 C, metal fatigue becomes a serious problem when subjected to pressure, strain, etc.

Tom Billings
Reply to  Samuel C Cogar
September 10, 2019 12:20 pm

““mining ice with a mechanical digger/transporter” is a whole new ballgame.”

Yes, it is, and it has been worked on for some time. As early as 1988 proposals were out for muckers on the lunar surface. While it may not be possible to use Manganese Steel at those temperatures, there are several interesting possibilities for mucker buckets and cables. I don’t have permission to discuss private work on that, however.

At -247 Cº things change, so we adapt to the changes. Interestingly enough, the Moon seems to have In Situ Resources to help us adapt to those needed changes. Extraction of those resources may begin on the same scale as an early iron master’s production facility (1,500 B.C.) to allow repair and replacement of equipment.

Tom Abbott
Reply to  Joel O'Bryan
September 8, 2019 7:23 am

A water jet could cut the ice into manageable chunks. There are plans to mine metal asteriods using water jets.

There should be plenty of good ideas about how to haul the ice chunks out of the crater without getting one’s feet wet.

Reply to  Tom Abbott
September 8, 2019 9:54 am

Laser jet cutting wouldn’t waste a valuable resource such as water. You need to think non-terrestrial. And you probably don’t want to start blowing dust around either.

Joel O'Bryan
Reply to  Rocketscientist
September 8, 2019 1:35 pm

Completely disagree with both liquid water jet or laser cutting a cryogenically cold ice. Any liquid water created is just going to immediately refreeze behind and around the fresh cut as you cut with heat (water or laser).

You do nothing at all to melt the ice until you get it to the processing facility.

A mechanical rotating carbide-tungsten cutting saw and then a reciprocating carbide 1 meter blade to finish the cut to the square corners, both kept at the 30-50 K temperature of the crater would be my suggested approach. And both a mechanical “sweeper” to move the cutting debris out of the way as quickly as possible. Once you’ve cut a 1 meter cube block (1000 kg mass weighing 366 lbs on the Moon), two mechanical screw augers (at 30 K themselves) on a lifting block drill into the top of the ice block to secure and lift it out of it hole with a crane. Set the ice block in a Dewar box for transport to a processing facility for melt and water separation from the regolith. All the mechanical stuff on movable, insulated kevlar-silicon and fiberglass matts stitched together with kevlar-nylon rope.

Reply to  Joel O'Bryan
September 8, 2019 9:48 am

There is no atmosphere to transmit heat, only radiation and conduction. Thermal shielding can eliminate almost if not all of the radiated heat and isolated feet will virtually eliminate any conductive heat transfer.
We know how to handle heat and were’t not as sloppy as roughnecks.
I will flabbergasted if the ice is found in large blocks of blue ice. It will more likely be mined as chunks of frozen conglomerate (regolith with ice cementing it together) which will need to be processed to extract any water. And if I recall the wettest frozen lunar concrete is drier than the driest bag of readimix here on earth.
Gravity on the Moon is only 1/6 that of Earth. Lifting heavy chunks will not be an issue. Transportation will be another issue. We don’t know the drivablilty of most of the lunar surface and since we NEED friction to drive we don’t want to spin out and bury our vehicle up to their axles (which did happen often with the lunar rovers). Rail transport might be the eventual solution, with rail gun launches into orbit.
I’ve looked into several “hopper” transporters which use propulsive power to lift, transport and land cargo. No atmosphere, no drag, no wind. Easier than a helicopter. Just a pop and its up and away.

But, mostly the water on the moon will be used as rocket fuel, not for life support.
We may transport it up to L1 where the assembly and refueling stations will be. there it can be made into radiation shielding until its used for life support and eventually fuel.

Reply to  Joel O'Bryan
September 8, 2019 8:56 pm

“The Diviner instrument on NASA’s Lunar Reconnaissance Orbiter measured temperatures of 35 K (-396 °F , -238 °C) in craters at the lunar southern pole and 26 K (-413 F, -247 C) in a crater at the northern pole.

Any guesses if the technology exists to mine ice with a mechanical digger/transporter at those temps and not sink itself in melt water?”

Melting the water may be the only extractive technology at those temperatures.
The metals used on Earth to extract minerals would likely shatter trying to break ice with metallic similarities. Dust, pebbles, rocks etc. would perform similarly to pebble filled concrete mix.

Bulldozers and other earth moving equipment have a difficult time in Earth’s polar zones.

September 8, 2019 12:33 am

So, could be there is lots lunar ice which have high concentration of water buried under meters of regolith in lunar southern region. And in fairly small craters [couple km in diameter].
No instruments could have measured it, and is inferred due to significantly shallower craters floors as compared to other craters.
No estimate of how much.
But say, billions of tons frozen water??

Joel O’Bryan
Reply to  gbaikie
September 8, 2019 1:11 am

600 billion metric tonnes is the rough ball park estimate, mostly south pole.
Even if just 1% is recoverable by robotic diggers, 6 billion cubic meters of water is a lot of water.

Reply to  Joel O’Bryan
September 8, 2019 10:19 am

To mine lunar water, I think you need about 20,000 tons of recoverable water at a site.
Or need in first decade, about 1000 tons per year, and first 5 years will critical time period to demonstrate, you can make and sell lunar rocket fuel, if you can you have company which worth billions dollars. The hard part is selling 1000 tons of rocket fuel per year- you need to create such market demand.

You start with about 100 tons, and double production per year, and you bootstrap by using the rocket fuel to lower capital cost of getting the infrastructure needed to get to 1000 tons per year production level, but need “external demand” of 1000 tons per year {or more} to be profitable.
Or lunar water needs to be about $500 per kg, but if water can extracted more easily it could be $100 to $200 per kg.
It seems main advantage of cheaper lunar water, is one does not need as much demand. So instead of 1000 tons per year, 500 ton per year might end being profitable. But faster one can get more demand, like say 5000 tons per year, it’s on path being a trillionaire, but selling 1000 tons of rocket fuel per year within 5 years, is not easy, and 5000 tons per year within 5 year, seems close to impossible.
5000 tons per year within 2 to 3 decades is different story.
So cheaper lunar water doesn’t require as much sold in early years to avoid going bankrupt. But in 50 years, lunar water could sold for say $50 kg and could selling more than 20,000 tons per year, by that time you would selling lunar rocket fuel in LEO.
Now, not heard there being 500 billion tonnes of water in Lunar polar region- what means to me, is lunar settlements- towns in lunar polar region, and lunar water being less than $1 per kg, or lunar water less than 1000 times cost of water on Earth- less than $1 per ton.
Or with Mars settlements one needs +10 billion tonnes of available water, or 50 billion tons within 50 km, would good place for a town on Mars, and one could have lakes on Mars. 500 billion tonnes at lunar polar region, means one could also have lakes on the Moon.
Or 1 billion tons is 1 cubic km of water, 500 is 500 cubic km of water, 500 square km with 1 km thick ice. I think you meant 500 million tons. Or 5 billion tonnes.
Paul Spudis said there could be 10 billion tons of water at both poles, or 5 billion at each pole. And in terms of recoverable lunar water hundreds of million of tons.

Or 1 square km 1 meter deep is 1 million cubic meter, and if 10% or 100,000 tons water, it’s should mineable. If 20% or 200,000 tons, a lot easier. But if had 20% under 1 meter lunar regolith which less than 5% water, the 10% surface might more mineable. Though if had 50% under about 2 meter depth of dry regolith, probably much more mineable than 10% at surface.
So article is about perhaps nearly pure ice under meters of dry regolith- frozen ponds/lakes under lunar dirt, which is interesting, but in terms lunar water mining in the first decade, I would think high water concentration near/at surface
would better place to start.

September 8, 2019 3:00 am

After watching the BBC show, planet’s by brian coxs, I’ve always wondered wondered how there could be any ice on mercury, considering how close it is to the sun?

Reply to  Sunny
September 8, 2019 3:39 am

Mercury is tide locked to the sun so the far side never sees the sun.

Reply to  F.LEGHORN
September 8, 2019 4:54 am

F.LEGHORN. wouldn’t the sheer heat of the sun radiate around mercury? Mercury is only 57.91 million miles from the sun, that’s close

Reply to  Sunny
September 8, 2019 8:33 am

Mercury rotates in a way that is unique in the Solar System. It is tidally locked with the Sun in a 3:2 spin-orbit resonance, meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun. As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two Mercurian years. (It’s Wikipedia, but this is the kind of subject that can be dispassionately handled there.)

Reply to  Sunny
September 8, 2019 10:31 am

Nope, probably couple meter under regolith, it’s less than 0 C.
Solid rock conducts more heat, but think of kiln, it be 1000 C but not much heat conducted thru the brick walls of kiln- and they don’t 1 meter thick walls.
Or couple meter sold rock might warmer than 0 C, but 10 meters, less than 0 C.
Lunar and Mercury regolith have very good insulation properties.

Reply to  F.LEGHORN
September 8, 2019 10:22 am

Nope, it’s:
” It is tidally locked with the Sun in a 3:2 spin-orbit resonance, meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun”- wiki

September 8, 2019 4:03 am

The first conclusive evidence came from NASA instrument M3 on Indian satellite Chandrayaan-1.
Yesterday the Chandrayaan-2 lander, Vikram, lost contact on its way to actually check that water ice.
NASA’s Artemis is heading for that south polar region. Water accessibility is critical.

Nick Schroeder
September 8, 2019 6:54 am

But the “average” temperature requires the “water ice” to be evenly distributed across the entire surface.

September 8, 2019 12:57 pm

With little to no atmospheric pressure keeping Hydrogen fused with Oxygen, there is no “usable”water nor ice on either of them…nor anywhere else in this solar system.
We’ve never even gotten ANY “fuel” from ANY water on this freakin planet which 70% of the stuff!!!!

-GAWD I’m tired of this bullcrap…

Johann Wundersamer
Reply to  Patvann
September 9, 2019 3:03 am

Patvann, nevertheless: WATER on the Moon is “significantly” more common than scientists have previously assumed.

September 8, 2019 5:21 pm

Patvann, I’m[ not sure of the source of your complaint. Tell me which if these you are frustrated with:
1) “Non usable water”. Do you mean because we can’t use it now it is not usable? Or are you saying that without an atmosphere, there is no water? Ice does not count as water? Most ice comets have no “atmosphere until the solar wind starts stripping away the molecules of ice as they approach the sun. So, there is clearly ice, and the conversion process is merely heat.

2) “We’ve never even gotten ANY “fuel” from ANY water”. In my high school science classes, we split the molecules very simply into O2 and H2. Granted, more energy went into the process of splitting water than we got out. There is a lot of sun on the moon – easily planned for since there is no winter and there are no clouds. It is usable, and not attenuated by an atmosphere. The results of our high school experiment yielded a two gases that we could combust, although we didn’t need to use the O2 because there was sufficient in the atmosphere. H2 is fuel. There are many cars that use it now. H2 powered cars are sold commercially by major manufacturers.

3) This planet is not 70% water. About 70% of the surface is covered by water, but according to USGS water is only about 2.3% water by volume (Earth 1.44E+10 cu miles, water 3.38E+08 cu miles).

September 8, 2019 10:16 pm

Unlike Earth, the spin axes of Mercury and the Moon are oriented such that, in their polar regions, the Sun never rises high above the horizon.

The moon part of that claims looks spurious. Lunar rotation is tidally locked to Earth and always presents the same face with just a little libration. The axis of the lunar obital plane is the same as earth’s rotational axis +/-5.8 degrees. On average polar exposure must be the same as Earth’s, but sometimes a little more; sometimes less.

September 8, 2019 10:19 pm

Oops. Lunar orbital plane is the ecliptic +/- 5.8 degrees. So indeed poles much less exposed.

September 9, 2019 3:18 am

The aliens that occupy our hollow moon probably use the ice resources to convert the ice to hydrogen to run day to day operations of the moon. Recycled ice?

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