Scientists Identify the Source of the Moon’s Water

Over the course of the past few decades, our ongoing exploration the Solar System has revealed some surprising discoveries. For example, while we have yet to find life beyond our planet, we have discovered that the elements necessary for life (i.e organic molecules, volatile elements, and water) are a lot more plentiful than previously thought. In the 1960’s, it was theorized that water ice could exist on the Moon; and by the next decade, sample return missions and probes were confirming this.

Since that time, a great deal more water has been discovered, which has led to a debate within the scientific community as to where it all came from. Was it the result of in-situ production, or was it delivered to the surface by water-bearing comets, asteroids and meteorites? According to a recent study produced by a team of scientists from the UK, US and France, the majority of the Moon’s water appears to have come from meteorites that delivered water to Earth and the Moon billions of years ago.

For the sake of their study, which appeared recently in Nature Communications, the international research team examined the samples of lunar rock and soil that were returned by the Apollo missions. When these samples were originally examined upon their return to Earth, it was assumed that the trace of amounts of water they contained were the result of contamination from Earth’s atmosphere since the containers in which the Moon rocks were brought home weren’t airtight. The Moon, it was widely believed, was bone dry.

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

However, a 2008 study revealed that the samples of volcanic glass beads contained water molecules (46 parts per million), as well as various volatile elements (chlorine, fluoride and sulfur) that could not have been the result of contamination. This was followed up by the deployment of the Lunar Reconnaissance Orbiter (LRO) and the Lunar Crater Observation and Sensing Satellite (LCROSS) in 2009, which discovered abundant supplies of water around the southern polar region,

However, that which was discovered on the surface paled in comparison the water that was discovered beneath it. Evidence of water in the interior was first revealed by the ISRO’s Chandrayaan-1 lunar orbiter – which carried the NASA’s Moon Mineralogy Mapper (M3) and delivered it to the surface. Analysis of this and other data has showed that water in the Moon’s interior is up to a million times more abundant than what’s on the surface.

The presence of so much water beneath the surface has begged the question, where did it all come from? Whereas water that exists on the Moon’s surface in lunar regolith appears to be the result of interaction with solar wind, this cannot account for the abundant sources deep underground. A previous study suggested that it came from Earth, as the leading theory for the Moon’s formation is that a large Mars-sized body impacted our nascent planet about 4.5 billion years ago, and the resulting debris formed the Moon. The similarity between water isotopes on both bodies seems to support that theory.

Near-infrared image of the Moon's surface by NASA's Moon Mineralogy Mapper on the Indian Space Research Organization's Chandrayaan-1 mission Image credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS
Near-infrared image of the Moon’s surface by NASA’s Moon Mineralogy Mapper on the Indian Space Research Organization’s Chandrayaan-1 mission. Credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS

However, according to Dr. David A. Kring, a member of the research team that was led by Jessica Barnes from Open University, this explanation can only account for about a quarter of the water inside the moon. This, apparently, is due to the fact that most of the water would not have survived the processes involved in the formation of the Moon, and keep the same ratio of hydrogen isotopes.

Instead, Kring and his colleagues examined the possibility that water-bearing meteorites delivered water to both (hence the similar isotopes) after the Moon had formed. As Dr. Kring told Universe Today via email:

“The current study utilized analyses of lunar samples that had been collected by the Apollo astronauts, because those samples provide the best measure of the water inside the Moon. We compared those analyses with analyses of meteoritic samples from asteroids and spacecraft analyses of comets.”

By comparing the ratios of hydrogen to deuterium (aka. “heavy hydrogen”) from the Apollo samples and known comets, they determined that a combination of primitive meteorites (carbonaceous chondrite-type) were responsible for the majority of water to be found in the Moon’s interior today. In addition, they concluded that these types of comets played an important role when it comes to the origins of water in the inner Solar System.

These images produced by the Lyman Alpha Mapping Project (LAMP) aboard NASA's Lunar Reconnaissance Orbiter reveal features at the Moon's northern and southern poles in the regions that lie in perpetual darkness. They show regions that are consistent with having large surface porosities — indicating "fluffy" soils — while the reddening is consistent with the presence of water frost on the surface. Credit: Southwest Research Institute
Images produced by the Lyman Alpha Mapping Project (LAMP) aboard NASA’s Lunar Reconnaissance Orbiter reveal features at the Moon’s northern and southern poles, as well as the presence of water frost. Credit: NASA/SwRI

For some time, scientists have argued that the abundance of water on Earth may be due in part to impacts from comets, trans-Neptunian objects or water-rich meteoroids. Here too, this was based on the fact that the ratio of the hydrogen isotopes (deuterium and protium) in asteroids like 67P/Churyumov-Gerasimenko revealed a similar percentage of impurities to carbon-rich chondrites that were found in the Earth’s coeans.

But how much of Earth’s water was delivered, how much was produced indigenously, and whether or not the Moon was formed with its water already there, have remained the subject of much scholarly debate. Thank to this latest study, we may now have a better idea of how and when meteorites delivered water to both bodies, thus giving us a better understanding of the origins of water in the inner Solar System.

Some meteoritic samples of asteroids contain up to 20% water,” said Kring. “That reservoir of material – that is asteroids – are closer to the Earth-Moon system and, logically, have always been a good candidate source for the water in the Earth-Moon system. The current study shows that to be true. That water was apparently delivered 4.5 to 4.3 billion years ago.

The existence of water on the Moon has always been a source of excitement, particularly to those who hope to see a lunar base established there someday. By knowing the source of that water, we can also come to know more about the history of the Solar System and how it came to be. It will also come in handy when it comes time to search for other sources of water, which will always be a factor when trying to establishing outposts and even colonies throughout the Solar System.

Further Reading: Nature Communications

Herschel Spacecraft Won’t “Bomb” the Moon, But GRAIL Will

Artist concept of Ebb and Flow, the two GRAIL spacecraft in orbit of the Moon. Credit: NASA

The Herschel space telescope is slated to be decommissioned next March as the observatory’s supply of cryogenic helium will be depleted. One idea for “disposing” of the spacecraft was to have it impact the Moon, a la the LCROSS mission that slammed into the Moon in 2009, and it would kick up volatiles at one of the lunar poles for observation by another spacecraft, such as the Lunar Reconnaissance Orbiter. However, that idea has been nixed in favor of parking Herschel in a heliocentric orbit. But don’t be disappointed if you were hoping for a little lunar fireworks. There will soon be a double-barreled event as the twin GRAIL spacecraft will impact the moon’s surface on December 17, 2012.

NASA will be providing more information about the GRAIL spacecrafts’ impacts at a briefing on Thursday, but the Gravity Recovery and Interior Laboratory (GRAIL) team said last week that they were still formulating ideas for the impact scenario, and looking at the possibility of aiming the crashes so they are within the field-of-view of instruments on LRO. The two spacecraft are running out of fuel – Principal Investigator Maria Zuber said they have to do three maneuvers every day to keep the spacecraft from slamming into the Moon on their own – and earlier this year the duo were lowered from their prime mission orbit of 55 kilometers above the Moon to 23 km, and this week were lowered to 11 km to enable even higher resolution data.

The two spacecraft have been providing unprecedented detail about the Moon’s internal structure as they send radio signals to each other and monitor any changes in distance between the two as they circle the Moon. Changes as small as 50 nanometers per second have been measured, and last week the team detailed how they were able to create the most detailed gravity map of the Moon, as well as make determinations that the Moon’s inner crust is nearly pulverized.

We’ll provide more information about the GRAIL impacts when it becomes available, but preliminary details are that the impacts will take place on Dec. 17 at 19:28 UTC (2:28 p.m. EST).

The impact by LCROSS (Lunar Crater Observation and Sensing Satellite) confirmed the presence of water ice and an array of volatiles in a permanently shadowed crater at the Moon’s South Pole, and it is expected GRAIL would be targeted for similar observations.

Artist’s concept of Herschel at the L2 libration point one million miles from Earth. Credit: ESA

The Herschel team had said earlier this year that because the cryogenic superfluid helium coolant is running out — and the spacecraft needs to be at temperatures as low as 0.3 Kelvin, or minus 459 degrees Fahrenheit to make its observations — one idea of getting rid of the spacecraft would be to impact it on the Moon. This week, they posted on the Herschel website that ‘the lunar impact option is feasible, but carries an additional cost on top of that of the heliocentric orbit option. The ESA Executive has decided that the Herschel spacecraft will be “parked” indefinitely in heliocentric orbit.”

The Herschel operational large halo orbit around L2 is unstable, and so the orbit needs regular “maintenance,” and consequently, after end-of-helium (expected in March 2013), the spacecraft will need to be “parked” somewhere else with no need of orbit maintenance.

Herschel team member Chris North told Universe Today that the mission operators needed to get some engineering tests done to determine if the Moon impact was feasible. “Basically they hand it over to engineers who do things that are considered too risky during the scientific mission itself – e.g. test the attitude control to its limits to see what it can withstand!” North said via email. He added that most people he had spoken with were all for the impact, — having it “go out in a blaze of glory.”

But, surprisingly, the costs for impact are greater than leaving it in a parking orbit for a few hundred years. It’s orbit may have to be maintained again in the future, as some estimates put it at potentially impacting Earth at some point in several hundred years.

And for anyone worried that a lunar impact by the GRAIL spacecraft will “hurt” the Moon, one look at the Moon shows that it has been hit in the past and continues to get impacted by asteroids and meteoroids, with no adverse affect to its orbit.

As LCROSS principal investigator Tony Colaprete said about the LCROSS impact, “What we’re doing with the Moon is something that occurs naturally four times a month on the Moon, whether we’re there or not. The difference with LCROSS is that it is specifically targeted at a certain spot, Cabeus crater,” and that the laws of physics mean there will be a miniscule perturbation.

Even though the Centaur rocket stage that hit the Moon was expect to kick up about 350 tons of lunar regolith, “The impact has about 1 million times less influence on the Moon than a passenger’s eyelash falling to the floor of a 747 jet during flight,” Colaprete said.

The two GRAIL spacecraft are about the size of washing machines, much smaller than the Centaur rocket, so will have less of an impact.

Podcast: More From Tony Colaprete on LCROSS

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I had the chance to interview LCROSS principal investigator Anthony Colaprete about the latest findings released from the lunar impact of the spacecraft a year ago, and in addition to the article we posted here on Universe Today, I also did a podcast for the NASA Lunar Science Institute. If you would like to actually “hear” from Colaprete, you can listen to the podcast on the NLSI website, or you can also find it on the 365 Days of Astronomy podcast.

Understanding the Unusual LCROSS Ejecta Plume

LCROSS was an unusual mission, in that it relied on an impact in order to study a planetary body. Not only was the mission unusual, so was the ejecta plume produced by slamming a hollow Centaur rocket booster into the Moon.

“A normal impact with a solid impactor throws debris out more than up, like an inverted lampshade that gets wider and wider as it goes out,” said Pete Schultz, from Brown University and a member of the LCROSS science team. “But the configuration of a hollow impactor — the empty rocket booster — created a plume that had both a low angle plume but more importantly, also a really prominent high angle plume that shot almost straight up.”

This high plume elevated the debris enough so it was illuminated by sunlight, and could be studied by spacecraft.

Even though the plume wasn’t seen from Earth, as was advertised prior to the impact, it was seen by the both the LCROSS shepherding spacecraft and the Lunar Reconnaissance Orbiter. Using the spent Centaur was not so much by mission design as using what was available. But it turned out to be a great choice.

“I think we were quite fortunate,” Schultz told Universe Today in a phone interview this week. “I think another design, and we may have gotten a very different result. Not much debris may have come up into the sunlight and the plume would have been very temporary.”

In order for the debris to get high enough to come into sunlight, it had to rise up about a half mile above the bottom of the crater.

“To put this into perspective,” said Schultz, “we had to throw debris up twice the height of the Sears Tower, the tallest building in the US. Now the Moon has less gravity, so if we bring it back down to Earth and compare it, it is like trying to throw a ball to the top of the Washington Monument. So there is a lot of gravity to overcome, and it turns out that this impact did it because we used a hollow impactor.”

When the rocket booster hit and the crater began to form, the lunar surface collapsed and shot upwards – almost like a jet – towards the sunlight, carrying with it the volatiles that had been trapped in the regolith.

In order to figure out what the impact was going to look like, Schultz and his team, which included graduate student Brendan Hermalyn, did small scale impacts and modeling. Their tests were only done a couple of months before the actual impact, and used small half-inch projectiles into different surfaces.

“Most impacts, when we model them, we assume the impactors are solid,” Schultz said. “We did experiments, with both solid and hollow projectiles, and when we used the hollow projectile, we had a real surprise. We not only saw the debris moving outward, but also upward.”

“We really didn’t know exactly what we were going to see in the actual LCROSS impact, but our tests explained a lot,” Schultz continued, “explaining why we saw what we did and why we saw the plume for such a long time. If it had been coming out like an inverted lampshade or a funnel expanding, the debris would have come up and gone back down, and probably would have been done within about 20 seconds. Instead, it just kept on coming.”

But there were some expected moments. As the LCROSS shepherding spacecraft approached the lunar surface, Tony Colaprete and the team readjusted the exposures on the cameras and the team was able to actually see the surface of the Moon in the final seconds before impact.

“That was great,” Schultz said. “That means we got to see the crater, we were able to get an estimate on how big the crater was, and it made sense with what our predictions had said. But we were also able to see the remnants of this high angle plume still returning to the surface. This must have been shot almost straight up into space, and was now coming back to the Moon. We saw it as a very diffuse cloud, and saw the remaining portions of the regolith coming back down, like a fountain. To me, that was the most exciting part.”

Schultz said he was nervous during the impact.

“I have to confess, we were on pins and needles,” he said, “as this was something much bigger than the experiments of using half inch projectiles and we didn’t know if it was going to scale up. We were dealing with something that looked like schoolbus with no children aboard that was slamming into the Moon and we didn’t know if that was going to behave in the same way as our smaller models.”

And even though the plume did act like the models, there were plenty of surprises — both in the impact and what has now been discovered to exist in Cabeus Crater.

“We knew when it was going to hit the surface – we know how fast how we were going and where we were above the surface — and it turned out there was a delay before we saw the flash and that was really a surprise,” Schultz said. “It was about a half second delay and then it took about a third of second delay before it began to rise and get brighter. The whole thing took seven-tenths of a second before it began to get bright. That is hallmark of a fluffy surface.”

Schultz said they know that it was likely a “fluffy” surface from the experiments and modeling, and from comparisons with the Deep Impact mission, for which he was a co-investigator.

“One of the first things we realized was that this is not your normal regolith — what you usually think of for the Moon,” Schultz said. “We watched the flash, and we looked for what type of spectra we saw. The spectra has the fingerprints of the composition of the elements and compounds. We were expecting because of the low speed we actually wouldn’t get to see much. But instead we immediately got a couple of hits, we got to see a sudden emission of OH, which is a characteristic at this wavelength of a byproduct of heating of water. Then the next 2-second exposure was when things started emerging, the overall spectra got brighter which meant we were seeing more dust. But then we saw this big giant peak of sodium, just like a beacon, a very bright sodium line.”

And then there were two other lines that were very odd. “The best association we could find that is was silver,” said Schultz. “That was a surprise. Then all these other emission lines started emerging as more material got into sunlight. This suggests that we were throwing the dust into the sunlight, and the volatiles that had been frozen in time, literally, in the shadows of Cabeus were heating up and and being released.”

Some of these compounds included not only water and OH, but also things like carbon monoxide, carbon dioxide, and methane, “things that we don’t think of when we talk about the Moon,” said Schultz. “Those are compounds we think of when we think about comets, so now we are in a position that maybe what we are seeing at the poles are the result of a long history of impacts that bring with them a lot of this type of material.” (Read our interview with Tony Colaprete for more about the recent LCROSS results.)

But no one is sure how the Moon can hold onto these volatiles and how they end up in the polar craters.

To figure that out, Schultz said more missions to the Moon are needed.

“Even though the Apollo astronauts were there, we’re now finding things 40 years later that are making our heads snap from all this the new information,” Schultz said. “It goes to show you, you can visit and think you know a place, but you have to go back and maybe even live there.”

Schultz said that as an experimentalist, one can never feel smug, but seeing how the actual plume behaved just like their models, he and his team were very happy. “Experiments are letting nature teach you lessons and that is why they are very interesting to do. We are humbled almost daily.”

Water on the Moon and Much, Much More: Latest LCROSS Results

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A year ago, NASA successfully slammed a spent Centaur rocket into Cabeus Crater, a permanently shadowed region at the lunar South Pole. The “shepherding” LCROSS (Lunar Crater Observation and Sensing Satellite) spacecraft followed close on the impactor’s heels, monitoring the resulting ejecta cloud to see what materials could be found inside this dark, unstudied region of the Moon. Today, the LCROSS team released the most recent findings from their year-long analysis, and principal investigator Tony Colaprete told Universe Today that LCROSS found water and much, much more. “The ‘much more’ is actually as interesting as the water,” he said, “but the combination of water and the various volatiles we saw is even more interesting — and puzzling.”

The 2400 kg (5200 pound) Centaur rocket created a crater about 25 to 30 meters wide, and the LCROSS team estimates that somewhere between 4,000 kilograms (8,818 pounds) to 6,000 kilograms (13,228 pounds) of debris was blown out of the dark crater and into the sunlit LCROSS field of view. The impact created both a low angle and a high angle ejecta cloud. (Read more about the unusual plume in our interview with LCROSS’s Pete Schultz).

The LCROSS team was able to measure a substantial amount of water and found it in several forms. “We measured it in water vapor,” Colaprete said, “and much more importantly in my mind, we measured it in water ice. Ice is really important because it talks about certain levels of concentration.”

With a combination of near-infrared, ultraviolet and visible spectrometers onboard the shepherding spacecraft, LCROSS found about 155 kilograms (342 pounds) of water vapor and water ice were blown out of crater and detected by LCROSS. From that, Colaprete and his team estimate that approximately 5.6 percent of the total mass inside Cabeus crater (plus or minus 2.9 percent) could be attributed to water ice alone.

Colaprete said finding ice in concentrations – “blocks” of ice — is extremely important. “It means there has to be some kind of process by which it is being enhanced, enriched and concentrated so that you have what is called a critical cluster that allows germ formation and crystalline growth and condensation of ice. So that data point is important because now we have to ask that question, how did it become ice?” he said.

In with the water vapor, the LCROSS team also saw two ‘flavors’ of hydroxyl. “We saw one that was emitting as it if it was just being excited,” Colaprete said, “which means this OH could have come from grains — it could be the adsorbed OH we saw in the M Cubed data, as it was released or liberated from a hot impact and coming up into view. We also see an emission from OH that is called prompt emission, which is unique to the emission you get when OH is formed through photolysis.”

Then came the ‘much more.’ Between the LCROSS instruments, the Lunar Reconnaissance Orbiter’s observations – and in particular the LAMP instrument (Lyman Alpha Mapping Project) – the most abundant volatile in terms of total mass was carbon monoxide, then was water, the hydrogen sulfide. Then was carbon dioxide, sulfur dioxide, methane, formaldehyde, perhaps ethylene, ammonia, and even mercury and silver.

“So there’s a variety of different species, and what is interesting is that a number of those species are common to water,” Colaprete said. “So for example the ammonia and methane are at concentrations relative to the total water mass we saw, similar to what you would see in a comet.”

The LCROSS NIR spectrometer field of view (green circle), projected against the target area in the crater Cabeus. Credit: Colaprete, et al.

Colaprete said the fact that they see carbon monoxide as more abundant than water and that hydrogen sulfide exists as a significant fraction of the total water, suggests a considerable amount of processing within the crater itself.

“There is likely chemistry occurring on the grains in the dark crater,” he explained. “That is interesting because how do you get chemistry going on at 40 to 50 degrees Kelvin with no sunlight? What is the energy — is it cosmic rays, solar wind protons working their way in, is it other electrical potentials associated with the dark and light regions? We don’t know. So this is, again, a circumstance where we have some data that doesn’t make entirely a lot of sense, but it does match certain findings elsewhere, meaning it does look cometary in some extent, and does look like what we see in cold grain processes in interstellar space.”

Colaprete said that finding many of these compounds came as a surprise, such as the carbon monoxide, mercury, and particularly methane and molecular hydrogen. “We have a lot of questions because of the appearance of these species, “ he said.

There were also differences in the abundances of all the species over the time – the short 4 minutes of time when they were able to monitor the ejecta cloud before the shepherding spacecraft itself impacted the Moon. “We actually can de-convolve, if you will, the release of the volatiles as a function of time as we look more and more closely at the data,” he said. “And this is important because we can relate what was released at the initial impact, what was released as grains sublimed in sunlight, and what was “sweated out” of the hot crater. So that’s where we’re at right now, it’s not just, ‘hey we saw water, and we saw a significant amount.’ But as a function of time there are different parts coming out, and different ‘flavors’ of water, so we are unraveling it to a finer and finer detail. That is important, since we need to understand more accurately what we actually impacted into. That is really what we are interested in, is what are the conditions we impacted into, and how is the water distributed in the soil in that dark crater.”

So the big question is, how did all these different compounds get there? Cometary impacts seem to offer the best answer, but it could also be outgassing from the early Moon, solar wind delivery, another unknown process, or a combination.

“We don’t understand it at all, really,” Colaprete said. “The analysis and the modeling is really in its infancy. It is just beginning, and now we finally have some data from all these various missions to constrain the models and really allow us to move beyond speculation.”

LCROSS was an “add-on” mission to the LRO launch, and the mission had several unknowns. Colaprete said his biggest fear going into the impact and going into the results was that they wouldn’t get any data. “I had fears that something would happen, there would be no ejecta, no vapor and we’d just disappear into this black hole,” he confessed. “And that would have been unfortunate, even though it would have been a data point and we would have had to figure out how the heck that would happen.”

But they did get data, and in an abundance that — like any successful mission — offers more questions than answers. “It really was exploration,” Colaprete said. “We were going somewhere we had absolutely never gone before, a permanently shadowed crater in the poles of the Moon, so we knew going into this that whatever we got back data-wise would probably leave us scratching our heads.”

Additional source: Science

Look for “Flood” of News This Week About Water on the Moon

LCROSS Mission

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Almost five months ago, the LCROSS spacecraft had an abrupt end to its flight when it impacted a crater on the Moon’s south pole. But that was only the beginning of the work of principal investigator Tony Colaprete and the rest of the science teams, who have since been working non-stop to get their initial results out to the public. Look for a flood of ‘water on the Moon’ news to be announced at the Lunar and Planetary Science Conference this week.

“The data set from LCROSS is a lot more interesting that we thought it would be,” said Colaprete, speaking on a “My Moon” webcast, sponsored by the Lunar and Planetary Institute. “A big part of our time has been making sure the data is properly calibrated. That takes a lot of time and effort, but the other side of the equation is understanding all the stuff you don’t understand in the data, and there was a lot we didn’t initially understand.”

The LCROSS team will present six papers, 11 posters and several oral sessions at the LPSC.
While the results are still under embargo, Colaprete was able to discuss the basics of what the science teams have found.

LCROSS impact site. Credit: NASA

One surprise for the teams was the low “flash” produced by the impact of the spacecraft. “We didn’t see a visible flash, even with sensitive instruments,” Colaprete said. “There was a delayed and muted flash and the impactor was essentially buried, with all the energy apparently deposited at a depth. So it is very likely that there were volatiles in the vicinity.”

The second surprise was the morphology of the impact plume. “We had reason to believe there would be high angle plume,” said Colaprete. “But we had a lower angle plume. We had a signal of a debris curtain in the spectrometers in LCROSS all the way down in the four minutes following the impact of the Centaur stage. That was corroborated with DIVINER measurements with LRO (a radiometer on the Lunar Reconnaissance Orbiter.) They were able to make some great observations of the ejecta cloud with DIVINER, and we had good signals with our instruments all the way down to impact.”

Most surprising, Colaprete said, was all the “stuff” that came up from the impact. “Everyone was really excited and surprised about all the stuff that we threw up with the impact.”

The LRO spacecraft was able to be tilted in orbit so the LAMP (Lyman-Alpha Mapping Project) instrument could observe impact plume. It observed a plume about 20 km tall, and observed a “footprint” of a plume up to 40 km above the Moon’s surface.
“They saw vapor cloud fill the ‘slit’ of the spectrometer’s observations at about 23 seconds after impact and it remained there through the entire flyby,” Colaprete said. “What that corresponds to is a hot vapor cloud of about 1000 degrees that was observed.”

A closer view of the moon as the LCROSS spacecraft approaches impact. Credit: NASA

Two exciting species found in the cloud were molecular hydrogen and mercury. “What is fantastic about that, is that there was an article written a couple of decades ago, regarding the possibility of mercury and water at the poles, and they said don’t drink the water!”

Colaprete said observing molecular hydrogen is spectacular because normally it doesn’t stay stable even at 40 Kelvin. The teams are still speculating how it was trapped and what form it was in. They found about 150 kg of molecular hydrogen in the plume.

All the elements found in the plume must be coming from cometary and asteroidal sources, Colaprete said. They also found water ice, sulfur dioxide, methane, ammonia, methanol, carbon dioxide, sodium and potassium. “We haven’t identified everything yet, but what we’re seeing is similar to what you would see in an impact of a comet, like what happened with the Deep Impact probe, which is exciting and surprising. The mineralogy in the dust itself that we kicked up corresponds to what was seen by M Cubed instrument, and also what we see in chondrite asteroids.”

One of the most pleasing aspects of this scientific process, Colaprete said, was the different teams being able to verify what other teams were finding.

“The concentration of hydrogen we saw in the regolith was higher than expected,” Colaprete said. “We ran the numbers again, and we said, ‘Oh, we can’t wiggle out of this answer.’ Then the PI for the LEND (Lunar Exploration Neutron Detector on LRO, which can acquire high-resolution neutron datasets) instrument confirmed that their numbers were entirely consistent with what we got. It was surprising because it wasn’t what we expected. But that is why you make measurements.”

“This should be a fun year as we pull this all together, and get it released to the public so we can get a lot more neurons looking at this,” Colaprete said. “I think this will really change our understanding of the Moon and how we think about it.”

Water on the Moon

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Water has long been suspected to exist in the permanently shadowed polar craters on the Moon, and now the LCROSS impact has allowed scientists to make a direct and definitive finding of this precious resource in a place NASA and other space agencies are considering exploring with human expeditions. Many say this could be a game-changing discovery for the future of lunar science and exploration. Unlike the previous announcement in September of water on the Moon, where water exists diffusely across the moon as hydroxyl or water molecules adhering to the surface in low concentrations, this new discovery could mean underground reservoirs of water ice. “There is too much water to be just absorbed in the soil,” said Anthony Colaprete of the LCROSS mission at Friday’s press conference. “There has to be real solid ice there. You could melt it and drink it.”

But could you really drink it? “Well, not if it has methanol in it. We need to sort out the flavor of the water,” said Colaprete, “meaning we need to find out if it is water, ice, or vapor. We still need to do that math.”

Colaprete said from the amount of water the spectrometers on the LCROSS spacecraft detected, initial indications are it is ice. However, Colaprete added that the impacting Centaur upper stage didn’t hit appear to hit something hard and frozen, from the images of the crater.

If someone was walking on the Moon and was able to walk in Cabeus crater where the impact took place, would the regolith there look different compared to other places on the Moon? “That’s a good question – and we’ve been talking about that,” Colaprete said. “It would be an interesting place to walk around. With our near infrared camera we can relate the the data to what the human eye can see, and try to understand what the terrain looks like. We never saw the crater floor before impact, but now we can see what the floor looks like.”

Did they find anything else in the plume created by the impact? “We’re seeing a lot of stuff,” Colaprete said. “I think there’s a little bit of everything. We’re seeing other emission lines in the spectroscopic data we haven’t completely identified. We’re still working on those — I don’t know what all else is in there just yet. We’ve been focusing on the water quest so far.”

As to whether they’re seeing any organics, the team couldn’t yet say definitively. Colaprete said they are seeing compounds similar to those seen previously in asteroids and comets.

“This is only another snapshot in time of our understanding of the moon,” said Mike Wargo, NASA’s chief lunar scientist, ” and we’ll be continuing to work to get more details on the water and everything else. We’re not done yet.”

LCROSS Confirms “Buckets” of Water on the Moon



The LCROSS team announced today the mission successfully uncovered water during the Oct. 9, 2009 impacts into the permanently shadowed region of Cabeus cater near the moon’s south pole. “Indeed yes, we found water. We didn’t find just a little bit we found a significant amount,” said Tony Colaprete, principal investigator for LCROSS at a press conference. The team was not able to put a concentration of how much water is held in the lunar regolith, but in a fraction of the 20-30 meter crater the impact made, they were able to observe about 25 gallons (95 liters) of water with spectroscopic data. Colaprete held up a 2-gallon (7 liter) bucket, to demonstrate how much they found.

Data from the down-looking near-infrared spectrometer. The red curve shows how the spectra would look for a "grey" or "colorless" warm (230 C) dust cloud. The yellow areas indicate the water absorption bands. Credit: NASA
Asked if the team had “eureka” moment of when they found the water signature, Colaprete said, “It’s been a ‘holy cow!’ moment every day since impact. About two weeks ago we meet as a team and went through the entire data set. That’s when we came to the conclusion that we definitively found water.”

Colaprete said they also found signatures of other compounds as well, including sodium and carbon dioxide, which they are still analyzing.

While earlier findings this year of water on the Moon with the Moon Mineralogy Mapper on the Chandrayaan-1 spacecraft compared the lunar regolith to being drier than deserts on Earth, at Cabeus crater, there appears to be more.

“If you were standing on the 20 meter ‘beach,’ of the crater we created from the impact, it is wetter than some deserts on Earth,” Colaprete said.

Since the impacts, the LCROSS science team has been working almost nonstop analyzing the huge amount of data the spacecraft collected. The team concentrated on data from the satellite’s spectrometers, which provide the most definitive information about the presence of water. A spectrometer examines light emitted or absorbed by materials that helps identify their composition.

Data from the ultraviolet/visible spectrometer taken shortly after impact showing emission lines (indicated by arrows). These emission lines are diagnostic of compounds in the vapor/debris cloud. Credit: NASA
Data from the ultraviolet/visible spectrometer taken shortly after impact showing emission lines (indicated by arrows). These emission lines are diagnostic of compounds in the vapor/debris cloud. Credit: NASA

The 95 liters was the amount of what was in the field of view of the spectrometers. To find out how much total water is inside the crater will take a “reconstruction” of the crater by the team. “We need to take the amount of ejecta, along with the size of crater and reconstruct the event to understand how it all fits back in the ground to understand everything in its entirety,” said Colaprete. “We know it was important to the public for us to come out with the results, and to provide some sort of quantifiable amount but we still have a lot of work to do to see the total picture.”

The impact created by the LCROSS Centaur upper stage rocket created a two-part plume of material from the bottom of the crater. The first part was a high angle plume about 10-12 meters across of vapor and fine dust and the second a lower angle ejecta curtain of heavier material. This material has not seen sunlight in billions of years.

Colaprete said the crater floor is normally about -230 C, but the impact heated things up to about 1000 K, or 700 C, which is cold for an impact, but what was expected for the low density Centaur rocket that slammed into the Cabeus Crater.

Where the water came from is yet to be determined, whether it was delivered there by comets and meteorite hits or if some process within the Moon or on the surface is creating the water.

Mike Wargo, NASA’s chief lunar scientist, said the cold traps in the permanently shadowed craters of the Moon are like the dusty attics or junk drawers of the solar system. “They collect stuff from the whole evolution of the solar system, at least form the past few billion years. We’re only just begun to tap into our understanding.”

“This has really turned our understanding of lunar water on its head,” said Greg Delory. We should keep our minds open of what this is telling us. It’s not Apollo’s Moon, its our Moon.”

Source: NASA press conference
For more information see NASA’s press release

Moon Crash Plume Visible to Spacecraft But Not Earth Telescopes

Nine science instruments on board the LCROSS spacecraft captured the entire crash sequence of the Centaur impactor before the spacecraft itself impacted the surface of the moon. But from Earth, any evidence of the plume was hidden by the rim of a giant impact basin, a 3 kilometer-high (2-mile) mountain directly in the way for Earth telescopes trained on the impact site, said Dr. Peter Schultz, co-investigator for LCROSS. Additionally, the crater created by the impact was only about 28 meters across (92 feet) but Schultz said the best resolution Earth telescopes can garner is about 180 meters (200 yards) across.

The science team is analyzing the data returned by LCROSS, and Anthony Colaprete, principal investigator and project scientist, said “We are blown away by the data returned. The team is working hard on the analysis and the data appear to be of very high quality.”

The team hopes to release some of their preliminary findings within the next several weeks, Schultz said at in webcast with students and teachers this week.

During the Oct. 9 crash in to the Moon’s Cabeus crater, the nine LCROSS instruments successfully captured each phase of the impact sequence: the impact flash, the ejecta plume, and the creation of the Centaur crater.

Within the ultraviolet/visible and near infra-red spectrometer and camera data was a faint, but distinct, debris plume created by the Centaur’s impact.

“There is a clear indication of a plume of vapor and fine debris,” said Colaprete. “Within the range of model predictions we made, the ejecta brightness appears to be at the low end of our predictions and this may be a clue to the properties of the material the Centaur impacted.”

The magnitude, form, and visibility of the debris plume add additional information about the concentrations and state of the material at the impact site.

From images and data, the team was able to determine the extent of the plume at 15 seconds after impact was approximately 6-8 km in diameter. Schultz said the Moon’s gravity pulled down most of ejecta within several minutes.

The LCROSS spacecraft also captured the Centaur impact flash in both mid-infrared (MIR) thermal cameras over a couple of seconds. The temperature of the flash provides valuable information about the composition of the material at the impact site. LCROSS also captured emissions and absorption spectra across the flash using an ultraviolet/visible spectrometer. Different materials release or absorb energy at specific wavelengths that are measurable by the spectrometers.

the locations of the Diviner LCROSS impact swaths overlain on a grayscale daytime thermal map of the Moon’s south polar region. Diviner data were used to help select the final LCROSS impact site inside Cabeus Crater, which sampled an extremely cold region in permanent shadow that can serve as an effective cold trap for water ice and other frozen volatiles. Credit NASA/GSFC/UCLA
the locations of the Diviner LCROSS impact swaths overlain on a grayscale daytime thermal map of the Moon’s south polar region. Diviner data were used to help select the final LCROSS impact site inside Cabeus Crater, which sampled an extremely cold region in permanent shadow that can serve as an effective cold trap for water ice and other frozen volatiles. Credit NASA/GSFC/UCLA

Additionally, the Lunar Reconnaissance Orbiter’s Diviner instrument also obtained infrared observations of the LCROSS impact. LRO flew by the LCROSS Centaur impact site 90 seconds after impact at a distance of ~80 km. Both science teams are working together to analyze the their data.

The LCROSS spacecraft captured and returned data until virtually the last second before impact, Colaprete said, and the thermal and near-infrared cameras returned excellent images of the Centaur impact crater at a resolution of less than 6.5 feet (2 m).

“The images of the floor of Cabeus are exciting,” said Colaprete. “Being able to image the Centaur crater helps us reconstruct the impact process, which in turn helps us understand the observations of the flash and ejecta plume.”

Sources: LCROSS, LCROSS webcast

Moon Impact Data and Images from LCROSS: First Glance

Even without big explosions or bright plumes of ejecta, for all intents and purposes it appears LCROSS’s impact on the Moon was a smashing success. While the mainstream media and the public seemed disappointed in the lack of visual data, mission managers said the mission has garnered plenty of spectroscopic data, and that’s where the real science can be found. “There was an impact and we saw the crater with spectroscopic data,” said LCROSS principal investigator Tony Colaprete. “We have the data we need to address the questions we set out to answer.” The big question is whether the impact kicked up any signatures of water ice, but it could take days, weeks or months to analyze all the data.

Initial video and images from the event – taken by LCROSS itself and a wide variety of space- and ground-based telescopes – did not show much as far as a visible impact or the anticipated ejecta plume.

Was that a surprise to the science team? “I guess I’m not necessarily surprised,” said Colaprete. “Impacting the Moon is tricky business, and you learn to expect what you’re not going to expect. I’m not convinced we haven’t seen the ejecta. I want to go back to images and look at them carefully. We’ve had just 15-20 minutes of our efforts so far with images. So stay tuned. I certainly hope we can dig something out that will be telling. Our emphasis was on the spectra, that’s where the information is.”

Mid Infrared Camera flash detection of Centaur impact. Credit: NASA
Mid Infrared Camera flash detection of Centaur impact. Credit: NASA


Just two and a half hours after impact, mission managers spent most of Friday morning’s press conference explaining how little chance they had to look at the data – and that they wouldn’t even approach the topic of whether water had been detected yet — and how the impact doesn’t end the mission. “This is just the beginning,” said Michael Wargo, NASA’s chief lunar scientist. “We’ve got an enormous amount of data, not only from LCROSS from assets around the world. This is going to change the way we look at the Moon scientifically and change the way we do future exploration.”

High praise was given to the operations and observation campaign teams, as well as the spacecraft itself. “I’m happy to report spacecraft performed beautifully and the operations team did very well,” said Dan Andrews, LCROSS Project Manager. “It takes awhile to comb through the data to make sure we are reporting accurate and correct data, but we wanted to give you all an update on how things went.”

Here’s what they know so far:

They saw a flash at impact with the near infrared camera on LCROSS, and were able to see that an impact occurred, and even see the crater itself. “We had a very good high signal to noise data on the LCROSS spectrometer, probably the highest we could hope for,” said Colaprete. “The fact that we saw a remnant crater and that we got data as far down as we did, it’s very promising. Just on my initial eyeballing, the crater looked to be about the size we were predicting; about 18-20 feet or more. It filled a whole pixel of the camera.”

A closer view of the moon as the LCROSS spacecraft approaches impact.  Credit: NASA
A closer view of the moon as the LCROSS spacecraft approaches impact. Credit: NASA


“The cameras worked very well and we were able to track the Centaur all the way to the end of the mission” Colaprete continued, and then addressed a possible reason why the ejecta plume wasn’t more visible. “There was a flicker from the Centaur that might have been from a tumbling action. We wanted to avoid a perfectly end-on or perfectly flat impact, and it’s possible that happened. But we have the information we can go back now and look at everything.”
This image was taken by the Palomar Observatory at the time of impact.  Credit: Palomar Observatory
This image was taken by the Palomar Observatory at the time of impact. Credit: Palomar Observatory


Data from several other spacecraft and telescopes were just starting to trickle in, as well.

On the Lunar Reconnaissance Orbiter, which was observing the impact event from lunar orbit, the LAMP instrument (UV spectrometer) and the Diviner instrument (imaging radiometer) confirmed detection of the ejecta plume. The LRO teams have begun analyzing their data.

The Hubble Space Telescope also observed the event, but not in visible light. “HST was highly focused on spectroscopy, which is where the science is,” Colaprete said. “HST cannot look at the moon except for the very narrow filters because it is so bright. It took long integration stares just off to the side of the Moon.”

Other assets observing the event included IKONOS, GeoEye 1, ODIN — a Swedish radio telescope – all in Earth orbit, and Keck Observatory on Mauna Kea, the Palomar Observatory and MMTO.

Jennifer Heldmann who led the LCROSS observation campaign described some of the data obtained by a all the different telescopes and spacecraft: “We have images, we have video, we have graphs with squiggly lines, which scientists love.”

One surprise is that in the initial data, sodium was seen in the spectroscopic data, and Colaprete said sodium exists in the Moon’s tenuous atmosphere called the exosphere, and perhaps something got thermalized during the impact excite the sodium atoms to where strong visible emission lines showed up in the data.
The LCROSS visible spectrometer swept across the sunlit rim of Cabeus crater before the impact, then into darkness, whereupon the reflectance drops very sharply to a flat low. Then it swept across the impact site, where it detected a tiny "blip" from the impact. The sharp peak following that results from a known instrument artifact that had yet to be calibrated out in this early version of the data. Credit: NASA / GSFC / annotations by Emily Lakdawalla

Other “blips” in the data showed up, and while Colaprete said he couldn’t say what they meant, he was just glad there were there.

“As of now, this has just been a real-time mission,” he said. “We laid it all out there by having streaming video, but here we are at 2 hours. Our primary objective was finding out about the hydrogen that’s been observed at the lunar poles, and honestly, our initial visual images didn’t answer that question. But the answers are in the spectra and we’ve got something there. It could be days, weeks, or months until we can give you an answer. We’ll look at data, scratch our heads, fight over who gets to look at which data, and hopefully from that we can make a public announcement of what we’ve found.”

Source: LCROSS press conference.