Do Moon Craters Harbor Caches Of Water Ice? A NASA rocket slammed into a lunar crater in October. A second spacecraft followed minutes later, taking inventory of kicked-up debris and sending data to Earth. Scientists have now analyzed those data, which may reveal whether the moon harbors significant quantities of water ice.
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Do Moon Craters Harbor Caches Of Water Ice?

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Do Moon Craters Harbor Caches Of Water Ice?

Do Moon Craters Harbor Caches Of Water Ice?

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This is SCIENCE FRIDAY from NPR News. Im Ira Flatow.

Last month, the headlines read like stuff from a science fiction movie: NASA finishes bombing run of the moon, the moon is bombed for water, NASA fires at moon twice. But all of this bombing business was at worst a media creation and at best a poor choice of words. Nothing exploded, no weapons were tested. NASA just trashed and crashed some space junk into the moon, something the U.S. and other countries have done in the past. All in the quest to answer one question: Are there deposits of water ice on the moon? Can we stir up the dust and gravel and dirt or whatever it is down there to see it?

Scientists have been analyzing the data from that crash over the last month. And my next guest is here to talk about these first results. Anthony Colaprete is a project scientist and principal investigator for the Lunar Crater Observation and Sensing Satellite, the LCROSS. Hes at the Ames Research Center in Moffett Field, California. Welcome to SCIENCE FRIDAY.

Dr. ANTHONY COLAPRETE (Principal Investigator, Lunar Crater Observation and Sensing Satellite, LCROSS): Hi. Thank you for having me.

FLATOW: I was watching your news conference today and you seemed to be saying there was plenty of water on the moon.

Dr. COLAPRETE: Well, certainly, was plenty of water where we were looking.

FLATOW: And that was?

Dr. COLAPRETE: Well, in the ejecta cloud and the vapor plume that came up from our impact in the crater Cabeus at the south pole of the moon. And we can only measure, of course, what we can see in our instruments fields of view. And in those fields of view we saw 100 plus kilograms potentially of water.

FLATOW: Thats about 25 gallons, something like that?

Dr. COLAPRETE: Yes. Something like that, right. And I think thats probably a lower limit. We - as I mentioned, its only what we can see in our fields of view. What we need to do next is really kind of reconstruct the entire event and almost reverse engineer the impact, stuff what we can see in our instruments back into ground to really understand the concentration of water in the crater we impacted.

FLATOW: Mm-hmm. So you - can you speculate whether that would be enough water to support astronauts that might be working on the moon?

Dr. COLAPRETE: Ive - that is - it would be speculation but its certainly enough water to make that case very interesting. You only need a percent or two to really make the effort worthwhile, going there and extracting the water and using it for whatever purposes you would. And I think were at that level. Were better than the percent level, I suspect. I dont know the exact level but were certainly over that threshold.

FLATOW: Mm-hmm. And the fact that this was hidden in a dark crater helped it survive?

Dr. COLAPRETE: Yes. We hit the coldest place, pretty much, in the crater. It was about minus 220 degrees below zero centigrade. And at those temperatures, all sorts of things can survive in a vacuum and stuffed under the dirt. We excavated probably a meter or two deep and the crater we made was 20 to 30 meters across, and so fairly large, and unearth a variety of things not just water. And were - and thats what makes this actually really interesting that since it is such a cold crater all kinds of volatiles in addition to water have been preserved there.

FLATOW: Such as?

Dr. COLAPRETE: Well, were still identifying the features that we in our - that we see in our spectra so I can - but I can give you some of the items were looking at as potential candidates. They include carbon dioxide, sulfur dioxide, methane, other things like methanol even, things you might find on a comet or a primitive body like an asteroid, an icy asteroid like a Trojan asteroid or Centaur asteroid. So its - in hindsight, you know, its not too surprising that you might see these things alongside the water. But we were really excited to see all of the other absorption lines and signatures of other species besides the water.

FLATOW: Now, we always talked about amino acids possibly arising from other places in the solar system. Could you detect that in this

Dr. COLAPRETE: We are certainly going to be looking for it. Hydrocarbons and organics could potentially be contributors to some of the signatures were seeing. We dont have any kind of positive identification of that right now but that is what we will be looking for and - both ultraviolet and visible spectroscopy that we have of the impact plume. There are a variety of emission lines that we have not identified yet, some of those may be as a result of organics or other hydrocarbons, we just dont know yet. Yeah.

FLATOW: Did you find any strange minerals or could you find any that you hadnt seen before?

Dr. COLAPRETE: That is potential - there is the potential for that too. Right now, we have been really focused on the water. That was our principal goal. We - everyday our - I think the entire team is impressed with the data set and the complexity and richness that exists in it. Weve identified a number of species that, I guess, you - one might expect at the moon, like sodium, for example. Theres a large sodium plume that did come up out of the crater after we impacted. And then, theres some other identifications that are very tentative right now that are maybe less expective(ph) and were looking at - into those. Typical things like potassium and iron, I think were going to find as we comb through our data.

FLATOW: Right. If we were to be in that crater and were able to walk around, would it feel like we were walking on icy ground there, you know, like in a tundra or something like that?

Dr. COLAPRETE: Well, it didnt look very strong. No. This is something that were going to, again, try to answer going forward. But the fact that we made a fairly large crater means that the ground was probably not very strong. It didnt have a lot of strength to it. It was probably unconsolidated, maybe fluffy material. So these crystals - if it was - if theres a variety of volatiles that are frozen, they arent necessarily frozen into some kind of hard conglomerate that would feel like walking on tundra or frozen ground. But, again, were talking about concentrations, perhaps, in the one, two, three, four percent level. And at that level, well, you still dont quite get as a solidifying of the materials.

FLATOW: Mm-hmm. When the crash occurred, was it strong enough to turn any of that ice into liquid water, a vapor, or any of that stuff?

Dr. COLAPRETE: It certainly turned into the vapor and thats the predominant signature we see is water vapor and other vapors. There are - the series of events that - as far as we understand it right now - is that at impact two plumes occurred, two ejecta plumes. One plume had a high angle and was composed of vapors and fine debris, and it was fairly warm and its probably about 600 or 700 degrees centigrade. And it rose quickly vertically upward. Some of this vapor reached as high as 20 to 30 to 40 kilometers even. At the same time, a lower-altitude, slower-moving, more lateral ejecta curtain rose into sunlight and moved much more laterally outward from the impact site and we see that in the images and in the spectroscopy. And that was debris dust that got into sunlight and was reflecting back sunlight to us. So that debris cloud got as large as 10, 12, even 15 kilometers across, 20 or 30 seconds after impact. And we could see it as long as about 30 or 40 seconds after impacting in our cameras and actually could then actually see the reflectance of material, solar sunlight reflecting off the material as late as two minutes after impact. So it was there was this quite extensive cloud that we made around the impact site.

FLATOW: So you had like this low-level smog thing

Dr. COLAPRETE: Yeah. Yeah.

FLATOW: hanging close to the ground for a while.

Dr. COLAPRETE: Well, some of that might have been - may be hanging closer to ground or this higher angle plume that got very high just took a long time to fall back down and basically just kind of rained - there was a continuous raining down of material for two or three or four minutes even, after the impact.

FLATOW: Now, are there other areas on the moon that might be as fruitful and

Dr. COLAPRETE: Yes. Cabeus, we picked, because of its - the data ring now is really indicating a lot of hydrogen-bearing species there, that's why we went there ultimately. But there are a variety of other places in the south pole and at the north pole that show also strong hydrogen concentrations in various instruments. And the two instruments in particular are the neutron spectrometers that flew on - one flew on Lunar Prospector back - about 12 years ago, and the current neutron spectrometer on the Lunar Reconnaissance Orbiter, which is orbiting the moon now.

Both those instruments were really - the Lunar Prospector measurements were the ones that really told us something was interesting - really interesting was going on at the poles of the moon because it showed this increase of hydrogen at the poles. But we didn't know what it was.

FLATOW: Is it possible that anywhere but the poles, if you dig down far enough

Dr. COLAPRETE: Mm-hmm.

FLATOW: you might find?

Dr. COLAPRETE: Yeah. It's really - it matters - the dominant physical parameter that probably matters most is temperature.

FLATOW: Right.

Dr. COLAPRETE: And where we hit it was really cold, so it's a very good trap. But you can find places where it only gets sunlight a few days out of the month, and so is down below the surface, 10 centimeters or 20 centimeters below the surface, it's still below 100 degrees Kelvin or -170 degrees centigrade. So in those areas, they're much more extensive than these really cold traps but they still are cold enough to trap water, for example.

FLATOW: Yeah. And that might be the - if you're going to be permanently based some place, those spots might be a place to go.

Dr. COLAPRETE: Much more accessible, you're in sunlight still and, yes, you can extract then material from just below the - just below the surfaces. That's right.

FLATOW: So what do you do for an encore now?

Dr. COLAPRETE: Well, we've got a lot more data to work through. This was really a status update. There was an incredible amount of interest in the mission and so we were really compelled to keep people up to date as possible as we went forward. We're working on our current list of publications now on these current findings to get those out. But really identifying everything else we saw in the spectra and define all these other materials is really important and - because that actually will help us understand the sources and sinks for this hydrogen is - this combined with the earlier measurements from the moon mineralogical map or on (unintelligible) and the other observations from other spacecraft, we really start to put together a new picture of the moon with a water cycle, a hydration cycle that is active, currently taking place but also could really harbor some really interesting things that may be a billion years old.

FLATOW: Dr. Colaprete, thank you for taking time to be with us today.

Dr. COLAPRETE: Oh, my pleasure. Thank you.

FLATOW: Good luck to you. Anthony Colaprete is project scientist for the LCROSS there at Moffett Field at Ames Research Center. We're going to take a break and talk about solar sail. Stay with us. We'll be right back. I'm Ira Flatow. This is SCIENCE FRIDAY from NPR News.

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