Researchers estimate ice content of crater at Moon's south pole

Jun 20, 2012 by Bill Steigerwald
Elevation (left) and shaded relief (right) image of Shackleton, a 21-km-diameter (12.5-mile-diameter) permanently shadowed crater adjacent to the lunar south pole. The structure of the crater's interior was revealed by a digital elevation model constructed from over 5 million elevation measurements from the Lunar Orbiter Laser Altimeter. Credit: NASA/Zuber, M.T. et al., Nature, 2012

(Phys.org) -- NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft has returned data that indicate ice may make up as much as 22 percent of the surface material in a crater located on the moon's south pole.

The team of NASA and university scientists using laser light from LRO's laser altimeter examined the floor of Shackleton crater. They found the crater's floor is brighter than those of other nearby craters, which is consistent with the presence of small amounts of ice. This information will help researchers understand crater formation and study other uncharted areas of the . The findings are published in Thursday's edition of the journal Nature.

"The brightness measurements have been puzzling us since two summers ago," said Gregory Neumann of NASA's Goddard Space Flight Center in Greenbelt, Md., a co-author on the paper. "While the distribution of brightness was not exactly what we had expected, practically every measurement related to ice and other on the moon is surprising, given the cosmically inside its polar craters."


This visualization, created using Lunar Reconnaissance Orbiter data, offers a view of Shackleton Crater located in the south pole of the moon. Thanks to these measurements, we now have our best-yet maps of the crater's permanently-shadowed interior! Note: This video contains no audio. Credit: NASA/Goddard/Ernie Wright

The spacecraft mapped Shackleton crater with unprecedented detail, using a laser to illuminate the crater's interior and measure its albedo or natural reflectance. The laser light measures to a depth comparable to its wavelength, or about a micron. That represents a millionth of a meter, or less than one ten-thousandth of an inch. The team also used the instrument to map the relief of the crater's terrain based on the time it took for to bounce back from the moon's surface. The longer it took, the lower the terrain's elevation.

In addition to the possible evidence of ice, the group's map of Shackleton revealed a remarkably preserved crater that has remained relatively unscathed since its formation more than three billion years ago. The crater's floor is itself pocked with several small craters, which may have formed as part of the collision that created Shackleton.

The crater, named after the Antarctic explorer Ernest Shackleton, is two miles deep and more than 12 miles wide. Like several craters at the moon's south pole, the small tilt of the lunar spin axis means Shackleton crater's interior is permanently dark and therefore extremely cold.

Researchers Estimate Ice Content of Crater at Moon's South Pole
This is an elevation map of Shackleton crater made using LRO Lunar Orbiter Laser Altimeter data. The false colors indicate height, with blue lowest and red/white highest. Credit: NASA/Zuber, M.T. et al., Nature, 2012

"The crater's interior is extremely rugged," said Maria Zuber, the team's lead investigator from the Massachusetts Institute of Technology in Cambridge in Mass. "It would not be easy to crawl around in there."

While the crater's floor was relatively bright, Zuber and her colleagues observed that its walls were even brighter. The finding was at first puzzling. Scientists had thought that if ice were anywhere in a crater, it would be on the floor, where no direct sunlight penetrates. The upper walls of Shackleton crater are occasionally illuminated, which could evaporate any ice that accumulates. A theory offered by the team to explain the puzzle is that "moonquakes"-- seismic shaking brought on by meteorite impacts or gravitational tides from Earth -- may have caused Shackleton's walls to slough off older, darker soil, revealing newer, brighter soil underneath. Zuber's team's ultra-high-resolution map provides strong evidence for ice on both the crater's floor and walls.


Video made using LRO data showing the illumination of Shackleton crater, a 21-km-diameter (12.5 mile-diameter) structure situated adjacent to the Moon's . The resolution is 30 meters (approximately 100 feet) per pixel. Frames are every hour from 01-Jun-2012 to 30-Jun-2012. Note: this video contains no audio. Credit: NASA/Zuber, M.T. et al., Nature, 2012

"There may be multiple explanations for the observed brightness throughout the crater," said Zuber. "For example, newer material may be exposed along its walls, while ice may be mixed in with its floor."

The initial primary objective of LRO was to conduct investigations that prepare for future lunar exploration. Launched in June 2009, LRO completed its primary exploration mission and is now in its primary science mission. LRO was built and is managed by Goddard. This research was supported by NASA's Human Exploration and Operations Mission Directorate and Science Mission Directorate at the agency's headquarters in Washington.

Explore further: The latest observations of interstellar particles

Related Stories

New lunar south polar maps from SMART-1

Mar 11, 2008

Newly-released images of the lunar south-polar region obtained by ESA’s SMART-1 are proving to be wonderful tools to zero-in on suitable study sites for potential future lunar exploration missions.

Goddard Visualization Team Previews Lunar Impact

Oct 08, 2009

(PhysOrg.com) -- At 7:30 a.m. EDT on October 9, a two-ton rocket body will slam into a crater near the moon's south pole. By studying the resulting plume of gas and dust, scientists hope this grand experiment ...

Daybreak at Gale crater

Aug 25, 2011

This computer-generated images depicts part of Mars at the boundary between darkness and daylight, with an area including Gale Crater, beginning to catch morning light.

Recommended for you

Miranda: An icy moon deformed by tidal heating

6 hours ago

Miranda, a small, icy moon of Uranus, is one of the most visually striking and enigmatic bodies in the solar system. Despite its relatively small size, Miranda appears to have experienced an episode of intense ...

The latest observations of interstellar particles

12 hours ago

With all the news about Voyager 1 leaving the heliosphere and entering interstellar space you might think that the probe is the first spacecraft to detect interstellar particles. That isn't entirely true, ...

User comments : 21

Adjust slider to filter visible comments by rank

Display comments: newest first

axemaster
1 / 5 (4) Jun 20, 2012
The initial primary objective of LRO was to conduct investigations that prepare for future lunar exploration.

Why? The Moon has no potential for development like Mars. It has virtually no hydrogen available, and the radiation shielding required for growing plants is 10cm thick glass (incredibly expensive and heavy). Why aren't we gunning for Mars?

Mars could be reached and developed far more cheaply than the Moon, strange as that may sound. It has sufficient atmospheric shielding against radiation, and the atmosphere is 95% CO2, which means fuel can be produced on-site. Just carry some hydrogen there with you, and you can do chemical reactions with that CO2 to produce 38 times its weight in fuel. As a result you can carry enormous amounts of equipment with you to start building a base. Mars also has abundant mineral resources, meaning that all sorts of stuff can be produced using local resources. The soil has large amounts of water, enabling all sorts of tech.
axemaster
1.8 / 5 (4) Jun 20, 2012
Believe it or not, going to Mars and setting up the beginnings of a self sustaining civilization there would only cost about 12% of NASA's current budget annually. We could do so using conventional, proven rocket technologies, and if started today, the first rockets could be arriving 10 years from now.

If you don't believe me, read the book "The Case for Mars". The NASA leadership tried to get a program like this started about 10 years ago, but it was killed because of... surprise! Politics in Congress.
CapitalismPrevails
3.7 / 5 (6) Jun 20, 2012
The Moon has no potential for development like Mars. It has virtually no hydrogen available, and the radiation shielding required for growing plants is 10cm thick glass (incredibly expensive and heavy). Why aren't we gunning for Mars?


1. The orbital window for reaching mars is once every couple years. The window for reaching the moon is ofcourse much much smaller.

2. We haven't proved ourselves in creating any self sustaining environment for humans outside our magnetosphere. The moon would be sensible 1st place to start testing ourselves before venturing too far.

3. Who says we can't burrow green houses 10cm or deeper at the bottom of a crater?

4. Ofcouse the moon doesn't have "hydrogen" available. It has ICE available. We know sufficient ice exists there so why no use it to make hydrogen? If we can't use hydrogen for propellant, mass drivers may be an alternative. Using LFTRs for power generation is also possibility. http://www.youtub...zotsvvkw
axemaster
1 / 5 (3) Jun 20, 2012
The moon would be sensible 1st place to start testing ourselves before venturing too far.

But what's the point? There has to be a good reason to go to the Moon, beyond just testing tech for use on Mars - we can do the testing in vacuum chambers on Earth for a fraction of the cost. Moreover, we already have an immense amount of engineering knowledge already, more than sufficient for Mars missions. This isn't my opinion, it's NASA's opinion.

Who says we can't burrow green houses 10cm or deeper at the bottom of a crater?

Using sunlight to grow plants requires prohibitive radiation shielding. Not using sunlight entails the need for power generation on the MW scale. Either way, it's impractical.

Ofcouse the moon doesn't have "hydrogen" available. It has ICE available. We know sufficient ice exists there so why no use it to make hydrogen?

But again, what's the point? There's so little to be gained from going to the Moon. It's a dead-end destination.
Shelgeyr
4.8 / 5 (4) Jun 20, 2012
@CapitalismPrevails said:
The window for reaching the moon is of course much much smaller.


Did you mean "much much larger"? Wouldn't that make better sense?

Just wondering. I pretty much agree with your other points.
CapitalismPrevails
2.3 / 5 (3) Jun 20, 2012
Shelgeyr, LOL yes your correct. My bad.
javjav
5 / 5 (2) Jun 20, 2012
The Moon has no potential for development like Mars... Why aren't we gunning for Mars?


It is not one or the other. Moon resources could help in a travel to mars. The biggest problem for a travel to mars is launching from earth all the fuel, the radiation shield (hydrogen is the best material...), and the water. They account for at least 90% of the theoretical payload. Maybe it could be extracted from moon water. The launch from the moon is much easier.

What I miss in this article is a mention about other moon craters. Is this the only one containing ice or is it that other candidate craters have not been studied yet?
CapitalismPrevails
1 / 5 (2) Jun 20, 2012
Axemaster, we can't realistically test ourselves here on Earth because were not exposed to low gravity or space radiation. The moon is the best place to start. If we bring nuclear reactors up there(thorium), i'm there would be no problem with 24/7 access to MW power. BTW, thorium exists on the moon in abundance.
axemaster
not rated yet Jun 20, 2012
It is not one or the other. Moon resources could help in a travel to mars. The biggest problem for a travel to mars is launching from earth all the fuel, the radiation shield (hydrogen is the best material...), and the water. They account for at least 90% of the theoretical payload. Maybe it could be extracted from moon water. The launch from the moon is much easier.


Actually, the numbers have been done on that, and it's actually far cheaper and more practical to simply launch the hardware directly to Mars.

There's actually no need for a radiation shield - astronauts traveling to Mars on a 6 month transfer orbit will absorb only about 50 rem in total. That would increase their risk of dying from cancer by just 1%.

There's no point gathering water on the Moon since there is plenty on Mars.

There's also no point launching with "all the fuel" since the fuel can be made on Mars. This is 19th century technology folks.

The fuel can be reduced to ~10% of the payload as a result.
axemaster
not rated yet Jun 20, 2012
Axemaster, we can't realistically test ourselves here on Earth because were not exposed to low gravity or space radiation. The moon is the best place to start. If we bring nuclear reactors up there(thorium), i'm there would be no problem with 24/7 access to MW power. BTW, thorium exists on the moon in abundance.


The effects of radiation are extremely well documented and studied, and represent virtually no risk. There's no need to do more low gravity testing - the average stay time on the ISS is already 6 months, and the astronauts experience very limited ill effects.

And why do we care about how much thorium is on the Moon? What is the purpose of building a base there when there's nothing to use it for? All the objections raised so far have been solved already by NASA and others. Please, bring up a real issue worth addressing.
javjav
4 / 5 (5) Jun 20, 2012
it's actually far cheaper and more practical to simply launch the hardware directly to Mars.

What numbers? Do you have a link? I don't agree. The heaviest rocket in development (HLS) will only lift 70Ton. A mars travel would require a lot of them. The cost of sending everything directly is ridiculous.
There's actually no need for a radiation shield

What?. just one solar storm could be lethal without proper radiation shielding. Just to mention that space shuttle was directed to immediately cancel its mission in case of a solar storms, even if flying under Van Halen belt protection.
There's no point gathering water on the Moon since there is plenty on Mars.

Launching it from mars requires a lot of extra fuel, and the previous landing of big rockets for launching it later. It seems easier to send some fuel deposits from here or from the moon to mars orbit, to be used for the return trip
axemaster
1 / 5 (1) Jun 20, 2012
Unfortunately I don't have links, since my numbers are from the book "The Case for Mars", by Robert Zubrin. I strongly recommend reading it; it's very informative and lays out the results of about 20 years worth of R&D inside and outside NASA relating to Mars colonization.

I think it's worth noting that even though current boosters are ~70 tons, in the past much larger rockets have been used - and we still have the designs. In fact, there has been a proposal to do some very simple modifications to the Space Shuttle launch system that would allow it to lift 110-130 tons. So the mass isn't really a barrier in this case.

Solar storms aren't dangerous when you have 20-30 g/cm^2 of shielding, which would come from the structure of the ship.

Launching it from mars requires a lot of extra fuel, and the previous landing of big rockets for launching it later.

This is not true. As I have already explained, you can make fuel using the Martian air, using the methanation reaction.
axemaster
1 / 5 (1) Jun 20, 2012
A mars travel would require a lot of them. The cost of sending everything directly is ridiculous.


Actually, there wouldn't be very many of them. You send 1 unmanned fuel production system on ahead, and send the astronauts after it once it has landed and everything checks out. So that's just 2 launches in the 90-110 ton range to support a mission that would boast a 1.5 year surface exploration mission. As I said before, the math has been done, and it comes out to 12% of NASA's current annual budget - read the book if you want details.
axemaster
not rated yet Jun 20, 2012
Here's a link to a general description of the book:

http://www.nss.or...ars.html
Deesky
5 / 5 (3) Jun 20, 2012
What?. just one solar storm could be lethal without proper radiation shielding. Just to mention that space shuttle was directed to immediately cancel its mission in case of a solar storms, even if flying under Van Halen belt protection.

Lol, old rockers never die - they diversify into planetary protection systems! I think you meant Van Allen. :)
rubberman
5 / 5 (2) Jun 21, 2012
I think we should rename it the Van halen belt...
I also gotta go with Cap on this one, test our mettle with a moon base, then mars. Also with a lunar base, help isn't 6 months away if anything does go wrong enough to the point where a rescue mission is required.
El_Nose
not rated yet Jun 21, 2012
@axe

a few flaws in your logic.

1) Radiation shielding:

Neither has radiation shielding. On Earth radiation is reflected by the magnetosphere, UV is absorbed by ozone. Mars has neither of these features. Because it doesn't have a metallic core.

2) Power:

Setting up solar panels on the moon is a viable option. The main issue is the 14 days of darkness every place on the moon goes through... batteries

3) Logistics:

It is simply cheaper to get to the moon. Period. Less fuel, less flight time, faster communication, put up two satellites and you have constant communication with both sides.

4) Mass: IT's always a barrier to launches.

There is simply no way the space shuttles could ever lift 100 tons to orbit -- they were built to lift 16 tons MAX. If it were a simple fix to get 10x the capacity NASA would have done it -- even Congress would have approved that one. 120 ton lift has only been done with Saturn V

-- 6 months to Mars ??? -- what engine?
El_Nose
not rated yet Jun 21, 2012
@axe

The fuel used to achieve orbit is very very refined. It's not 19th century production methods its 20th century production methods. It took 25 years to get the quality good enough with infrastructure built on a planet with an atmosphere we can breathe -- you wanna built that infrastructure on a planet it takes 9 months to travel to. There is no infrastructure on the Mars -- or the moon -- so you go to the closest one first.

Mars is a lovely ideal - but the moon makes more sense. its cheaper faster, and we can experiment with mining easier on the moon. we can experiment with robotic construction techniques on the moon, we can experiment with every thing except terraforming on the moon.

Uses for a base on the moon are simply -- microgravity composites -- you can blend and mix metals in micro gravity that are impossible to create on earth. There has been no true mining effort on the moon because we don't really know what is deep inside of it. We do know its earthlike
axemaster
not rated yet Jun 21, 2012
Neither has radiation shielding. On Earth radiation is reflected by the magnetosphere, UV is absorbed by ozone. Mars has neither of these features.

Mars has an atmosphere. It is only 1% the effective mass shielding of Earth's, but it's still enough to block the vast majority of radiation.

Setting up solar panels on the moon is a viable option.

Not if you're using the power to grow plants. The amount of solar panels required would require dozens of heavy launches.

It is simply cheaper to get to the moon. Period. Less fuel, less flight time, faster communication, put up two satellites and you have constant communication with both sides.

It is, but you can't use it for anything meaningful. You can't build ships there because in-space manufacturing doesn't have enough quality control.

There is simply no way the space shuttles could ever lift 100 tons to orbit -- they were built to lift 16 tons MAX.

You can if there's no shuttle. Do your homework.
axemaster
not rated yet Jun 21, 2012
The fuel used to achieve orbit is very very refined. It's not 19th century production methods its 20th century production methods.

Good lord, you don't actually believe that do you? Methane oxygen is a perfectly good rocket fuel. It's trivial to make in bulk on Mars, since most of the mass can come from processing the CO2 atmosphere with a small amount of hydrogen you bring with you. You can make 38 times the amount of methane from the hydrogen you brought with you. The process also makes sufficient oxygen to burn it at high efficiency.

This fuel mix gives 380 isp. There are better mixes in existence on Earth, but you would have to carry them with you, reducing the effective isp into the double digits.

Mars is a lovely ideal - but the moon makes more sense.

So you want to build a $100 billions base on the Moon, to do... experiments? How does that make any sense? Shouldn't the experiments be on Mars? After all, the Moon is completely different from Mars.
El_Nose
not rated yet Jun 21, 2012
@axe

1) plants would still have to be grown in an indoor pressurized environment on Mars.

2) 10 tons of solar panels would provide somewhere in the neighborhood of way too much power to use

-- the 16 solar array panels on the ISS produce altogether, can generate 84 to 120 kilowatts of electricity -- enough to provide power to more than 40 homes ~quoted from nasa

they weigh in at about 6 tons, total.

3) your radiation numbers are a little off:

the experiments are about human livability in space. It takes 9 months to get to Mars and deep space radiation takes your chance of getting cancer very high.

The Mars probe to gather info on radiation in space burned out - due to high radiation!! it exceeded 50 millirads 5 times in one year due to space radiation it went literally off the scales once -- the scales are logarithmic!!

If you are in space and a solar storm happens u are messed up -- period

http://en.wikiped...periment