Printable Version of Topic

Click here to view this topic in its original format

Unmanned Spaceflight.com _ LRO & LCROSS _ NASA Briefs Preliminary Plume Findings from Moon Mission

Posted by: briv1016 Nov 10 2009, 09:26 PM

http://www.nasa.gov/home/hqnews/2009/nov/HQ_M09-215_LCROSS_briefing.html

Posted by: stewjack Nov 12 2009, 05:43 PM

http://www.nasa.gov/multimedia/nasatv/MM_NTV_Breaking.html

November 13, Friday
10 a.m. - Countdown Status Briefing - KSC (Public and Media Channels)
11 a.m. - ISS Expedition 21 Commentary - JSC (Public and Media Channels)
12 p.m. - LCROSS Science News Briefing – AMES (Public and Media Channels)

12 PM Eastern U.S. time = 17:00 GMT/UTC

Posted by: Holder of the Two Leashes Nov 13 2009, 04:59 PM

News conference is ready to start right now.

Edit: Water!

Posted by: Phil Stooke Nov 13 2009, 05:08 PM

NIR pic of the crater - nice!

Phil

Posted by: Holder of the Two Leashes Nov 13 2009, 05:21 PM

Infrared detection of water vapor and ice, ultraviolet detection of hydroxyl (OH). Lower limit of about 100 kg of water was detected. "Twelve buckets full". "Other stuff" found, too. No word yet on what.

Edit 38 minutes past the hour - CH type molecules present (possibilities are methane, CO2, etc.)

Posted by: glennwsmith Nov 13 2009, 05:45 PM

Cool!!!!!!!!!!!

And now I gotta run over to the "Earthlike Mars" thread to proclaim that there is almost certainly a frozen Oceanus Borealis under the dust of the northern plains of Mars!!!!

Posted by: bugs_ Nov 13 2009, 07:10 PM

Congratulations LCROSS team. Incredible. You guys sent up your own plume today!

Posted by: Webscientist Nov 13 2009, 07:45 PM

Great News from this not so boring moon!

Is this frozen water the outcome of a meteoritic or cometary impact?
Or is it the "ice tip of the iceberg"?
I'm in favour of the second hypothesis.

If confirmed, why not imagining a network of caves made of liquid water somewhere in the underground!

Posted by: remcook Nov 13 2009, 07:52 PM

Cool! smile.gif
Did they say why the hydroxyl signal levels went below the baseline in the end of that plot (bottom one here http://www.nasa.gov/mission_pages/LCROSS/main/LCROSS_results_images.html )? Just curious...

Posted by: Juramike Nov 13 2009, 08:40 PM

QUOTE (Holder of the Two Leashes @ Nov 13 2009, 12:21 PM) *
Edit 38 minutes past the hour - CH type molecules present (possibilities are methane, CO2, etc.)


CO2 won't have any C-H stretches.

Can someone post a link for that update?

Posted by: ustrax Nov 13 2009, 08:45 PM

From the press release: "there are hints of other intriguing substances"
http://www.nasa.gov/mission_pages/LCROSS/main/prelim_water_results.html

Colaprete at the conference: "and there's a whole lot more beyond the water so that's the exciting part in my mind, it's not only about the water, there's actually a lot more here that we're gonna be talking about in the months ahead looking" with the guy on his left with a monalisesque smile in his face...hmm...almost gives me the impression that they happier about that "extra" smile.gif
http://www.youtube.com/watch?v=QOpXMJdZGHc&feature=player_embedded#at=54

What can it be? Did I miss the answer to this?


Posted by: nprev Nov 13 2009, 08:47 PM

Apparently, there's evidence of at least simple organics, Rui. Perhaps that might bolster the cometary origin hypothesis, or imply capture of lunar outgassing products.

Posted by: P Hayne Nov 13 2009, 09:06 PM

QUOTE (remcook @ Nov 13 2009, 11:52 AM) *
Did they say why the hydroxyl signal levels went below the baseline in the end of that plot (bottom one here http://www.nasa.gov/mission_pages/LCROSS/main/LCROSS_results_images.html )? Just curious...

The hydroxyl band is seen in emission, so the drop below the baseline at the end is likely due to the fact that the shepherding spacecraft (SSC) passed through the plume, and was no longer picking up emission from the illuminated ejecta. A negative "band strength" probably just reflects the fact that the overall emission was dropping as the SSC dropped into the darkness of Cabeus.

Posted by: Holder of the Two Leashes Nov 13 2009, 10:01 PM

QUOTE (Juramike @ Nov 13 2009, 02:40 PM) *
CO2 won't have any C-H stretches. Can someone post a link for that update?


I mentioned it that way because that was how it was presented. Thirty-seven or so minutes into the briefing the question was asked about what else besides water. The fellow mentions "CH type" substances, and rattles off a list of possibilities in which carbon dioxide was included. Methane was another (I guess between it and CO2 you get an average of two), and methanol was also mentioned. I believe the possiblility of some kind of sulfur compound was raised, I can't remember the exact substance.

Posted by: ngunn Nov 13 2009, 10:23 PM

Before the specific mention of methane as a 'possibility' there was a comment about having found substance(s) that would evaporate at temperatures just 20-30 degrees warmer than ambient ground temperatures of -220C or -230C, possibly sublimed off a wider area around the crater by falling warm debris. Methane has a boiling point in this range - but are there other candidates?

Posted by: Beauford Nov 13 2009, 10:38 PM

QUOTE (ngunn @ Nov 13 2009, 04:23 PM) *
Before the specific mention of methane as a 'possibility' there was a comment about having found substance(s) that would evaporate at temperatures just 20-30 degrees warmer than ambient ground temperatures of -220C or -230C, possibly sublimed off a wider area around the crater by falling warm debris. Methane has a boiling point in this range - but are there other candidates?


There are quite a few that might move around by sublimation. Among the more interesting (and likely?) are formaldehyde, acetaldehyde, and ethylene oxide. ...the beginnings of a toolbox for organic chemists.

Posted by: SFJCody Nov 13 2009, 10:55 PM

QUOTE (ngunn @ Nov 13 2009, 10:23 PM) *
Before the specific mention of methane as a 'possibility' there was a comment about having found substance(s) that would evaporate at temperatures just 20-30 degrees warmer than ambient ground temperatures of -220C or -230C


They certainly seemed to hint at there being a lot of highly volatile materials down there. Makes me wonder whether we could get brief, regular bursts of cometary style activity by putting a huge reflective surface in lunar polar orbit. It would make boring old Luna look a bit like Enceladus! (entirely different mechanism, of course)

Posted by: stevesliva Nov 13 2009, 11:23 PM

QUOTE (Holder of the Two Leashes @ Nov 13 2009, 12:21 PM) *
Infrared detection of water vapor and ice, ultraviolet detection of hydroxyl (OH). Lower limit of about 100 kg of water was detected. "Twelve buckets full".


phew. That settles that, I hope. Glad it didn't end up the dry hole that was feared.

Any comments on the plume size versus any sort of modeling at this point?

Posted by: Fran Ontanaya Nov 13 2009, 11:38 PM

They said the plume was magnitude 8 and had a narrow, vertical and less dense part, which was only visible for a few seconds, and a wider, more dense part that lingered for a longer time. Since the Centaur created a nice crater, they speculated that the ice wouldn't be a solid surface. Overall it fit their models, it just didn't display much over the crater rim.

The 100kg figure would be based in what LCROSS could see from the plume, not the whole plume.

They said also that the analysis from the telescopes was going to take a longer time because their signal vs background wasn't so strong and, if I understood it right, that they have seen changes in the surrounding terrain due to the materials coming from the impact.

Posted by: elakdawalla Nov 13 2009, 11:46 PM

Re: what else other than water was in the plume: Colaprete said that he compared the spectra to those from Centaurs and Trojans and found a lot of similarities. There is probably a kitchen sinkful of crud at the poles that has accumulated there through billions of years of comets and asteroids bringing volatiles in that move around the lunar surface & get trapped at the poles. Centaurs & Trojans include water, CO2, CH4, SO2, methanol, ethanol, more complex organics; some of these are certainly present; but which ones and at what abundances are going to take lots and lots of modeling and comparisons among instruments and there may not be a unique model solution. He showed a model solution that was a pretty good fit, just to show that they are capable of fitting spectra, but he declined to indicate which species were in that model.

Posted by: Gsnorgathon Nov 14 2009, 12:46 AM

Any idea what mass fraction that 100kg represents? Based on previous findings I'd guess "around 1%," but I'd love to know how much more (or less) it is.

Posted by: nprev Nov 14 2009, 01:11 AM

Rats. Swear I saw an estimate for the dimensions of Centaur Crater somewhere, but can't find it now. Anybody got that?

BTW, check out the Google homepage; a nice little surprise just popped up there within the last hour. smile.gif

Posted by: tanjent Nov 14 2009, 03:07 AM

Colaprete mentioned that at the time the target was switched from Cabeus A to Cabeus proper, all the Earth-based observers knew that their prospects for seeing the plume would be much diminished. They could have made that clearer to the general public at the time - it would have avoided the disillusionment when we saw those visuals with very little going on.

Regarding the effect of the water on the cost calculus of lunar exploration (I hope this is permitted...if not, by all means kill it) a useful metric would be to estimate the number of vehicle loads of infrastructure that would be needed to get the variable cost of rendering the local water down to the point where it is no more expensive than bringing water from Earth. If it were a matter of just filling plastic bags with volatiles and dragging them to a sunny slope, you could probably be in position to do that with virtually no heavy equipment. But the implication of twelve buckets from a thirty-meter crater would be that you'd have to set up a major factory to just take an occasional bath. In this case the scientific fascination with identifying all the volatiles, while it fully justifies the present mission, is not likely to translate into any speedup of the exploration timetable. Perhaps some beverage company will be interested to bring a little of the stuff back to Earth and bottle it? http://www.theonion.com/content/node/30505 .

Posted by: elakdawalla Nov 14 2009, 03:54 AM

The Centaur crater is 20 or 30 meters in diameter.

Posted by: nprev Nov 14 2009, 04:43 AM

Thanks, Emily.

Well, here's my (probably wrong) WAG. Assuming that the crater's only 5m deep & an average soil density of 3.5 g/cc, I get something like 2300 m^3 of material excavated for 8050 tonnes of mass.

They're inferring 100 kg of water from that, but of course that can't be interpreted as a full scan of all exhumed material.

All this says to me is that there's some water there. The means employed for detection really can't determine fine percentages of composition, IMO.

EDIT: Forgot to mention that I assumed crater diameter as 30m.

Posted by: ngunn Nov 14 2009, 09:03 AM

QUOTE (Gsnorgathon @ Nov 14 2009, 12:46 AM) *
Any idea what mass fraction that 100kg represents?


I did a rough estimate and came up with one part in 40000 of the excavated material.

Posted by: nprev Nov 14 2009, 09:41 AM

Actually, thinking about this some more, I don't know how that 100kg H2O figure could have been derived unless it was with respect to the mass of the plume itself, which has to be less than the total mass excavated due to sidescatter, oblique ejecta trajectories, etc.

If that's true, how then did they estimate the mass of the plume since it appeared to differ so significantly in many respects from the pre-impact models?

Posted by: Fran Ontanaya Nov 14 2009, 01:02 PM

It could be from the strength of the spectral signal against the background.

They said 100kg is the estimated lower limit in the field of view. Many volatiles were quickly vaporized and expanded away.

Posted by: centsworth_II Nov 14 2009, 05:41 PM

QUOTE (Fran Ontanaya @ Nov 14 2009, 08:02 AM) *
It could be from the strength of the spectral signal against the background.
Right. I thought the 100kg was an estimate of what was actually seen in a narrow field of view and that they are not ready to estimate what was in the entire plume or in the entire excavated area.

Posted by: remcook Nov 14 2009, 05:43 PM

My guess for the additional fitted gases in their plot ( http://www.nasa.gov/images/content/402265main_LCROSS_results9_full.jpg )
(They look like gases... for instance, the big 1.5 and 2 micron water ice features [ http://www.tng.iac.es/news/2001/02/05/trans-nep/images/fig-trans-nep.gif ] do not seem to be fitted):
CO2 at 2-2.1 micron:
http://vpl.astro.washington.edu/spectra/co2pnnlimagesmicrons.htm
ethane? or some other hydrocarbon at 1.7 micron
http://vpl.astro.washington.edu/spectra/c2h6pnnlimagesmicrons.htm
http://vpl.astro.washington.edu/spectra/ch3c2hpnnlimagesmicrons.htm
http://vpl.astro.washington.edu/spectra/c3h6bpnnlimagesmicrons.htm
...

edit - added link to NASA plot

Posted by: Zvezdichko Nov 14 2009, 06:08 PM

QUOTE (centsworth_II @ Nov 14 2009, 06:41 PM) *
Right. I thought the 100kg was an estimate of what was actually seen in a narrow field of view and that they are not ready to estimate what was in the entire plume or in the entire excavated area.


I already see a discussion on what 100kg means is going on. 100 kg per 20x20kms crater means it's quite dry. But a narrow field would require a whole new line of calculations and investigations, which I don't see it will happen in the next several weeks.

Posted by: nprev Nov 14 2009, 07:44 PM

Z, the crater diameter is actually 20-30 meters, not km.

Again, though, I can't see what these results really tell us other than that water & some other volatiles are in fact present. They may be able to set an upper limit on the amount present at this spot, but any further extrapolation would apparently require a number of assumptions.

That being said, it's still an important & exciting experiment. We are now certain that there is water in this region. How much is still anyone's guess.

Posted by: P Hayne Nov 14 2009, 07:44 PM

QUOTE (Zvezdichko @ Nov 14 2009, 10:08 AM) *
I already see a discussion on what 100kg means is going on. 100 kg per 20x20kms crater means it's quite dry. But a narrow field would require a whole new line of calculations and investigations, which I don't see it will happen in the next several weeks.

The crater diameter is about 20 meters. This gives roughly 1-10 ppm water by volume, if 100 kg represents the total amount of H2O in the ejecta (which is uncertain).

( 3.14*(10 m)^2 * (2 m) = 10^4 cubic meters; (100 kg H2O) * (1 m^3 / 1000 kg) = 0.1 cubic meter H2O; (0.1 cubic meter H2O) / (10^4 cubic meters total) = 10^-5 = 10 ppm H2O )
( changing the depth-to-diameter ratio from 1:10 to 1:5 gives roughly 1 ppm H2O. )

Posted by: ngunn Nov 14 2009, 08:33 PM

Well we've now got three estimates in the same ballpark. Converting to ppm: nprev 12ppm, myself 25ppm and P Hayne 1-10ppm.

I started wondering - if that were gold would we mine it? So with this thought here's a comparison from Wikipedia:

"Gold extraction is most economical in large, easily mined deposits. Ore grades as little as 0.5 g/1000 kg (0.5 parts per million, ppm) can be economical. Typical ore grades in open-pit mines are 1–5 g/1000 kg (1–5 ppm); ore grades in underground or hard rock mines are usually at least 3 g/1000 kg (3 ppm). Because ore grades of 30 g/1000 kg (30 ppm) are usually needed before gold is visible to the naked eye, in most gold mines the gold is invisible."

Posted by: Phil Stooke Nov 14 2009, 09:01 PM

I've put together a little finder guide to the LCROSS impact site with an estimate of the SSC impact location. All of the images are from LCROSS except the big one © which is part of a DIVINER (LRO) map.

Phil



PS Well duh! My 'C' in parenthesis gets automatically turned into a copyright sign. However, anything I post on UMSF is intended to be public domain in its posted form.

Posted by: Fran Ontanaya Nov 14 2009, 09:52 PM

But you are using estimates for pure, solid ice and a solid surface. Colaprete said that looking at the size of the crater that seemed unlikely.

Those 100kg minimum of H20 probably meant more than 0.1 cubic meters, and the average density of the ejected material could have been less than lunar rock.

Organics like methane yield water easily, their mass should count too.

Posted by: Holder of the Two Leashes Nov 14 2009, 10:27 PM

I really appreciated Colaprete being willing to openly mention the possible other volatiles they may be seeing, pending final proof. He would have been well within his rights to say he was holding comment until the analysis was definitive. Now we know that hydrogen compounds in addition to water are probably available, along with sources of carbon.

QUOTE (ngunn @ Nov 14 2009, 02:33 PM) *
I started wondering - if that were gold would we mine it?


Clever! One should also mention that it will be a lot easier to bake water out of lunar soil then to extract metal from ore. It can be certain that at this concentration it will be better to mine water than import it. Based on some studies done about mars sample returns that examined the use of refueling on the surface, and given the energy requirements for lunar sample return are similar but smaller, it's possible to speculate about a sample return probe with rover, where the rover processed ascent fuel in addition to gathering samples.

Of course, it would have to be a big sample return mission, and you'd have to be pretty patient with the rover, but there might be enough science here to justify it.

Posted by: PFK Nov 15 2009, 12:00 AM

Just out of interest - what would the total organic chemical content of the Centaur amount to? Plastics, wiring etc. Vapourise them via a collosal thud and all manner of fragments will fly.

Posted by: nprev Nov 15 2009, 12:08 AM

That's an excellent point.

Posted by: Phil Stooke Nov 15 2009, 01:13 AM

I don't know offhand but it's obviously very well characterized already. It's not a basis for doubting the results.

Phil

Posted by: P Hayne Nov 15 2009, 04:39 AM

QUOTE (Fran Ontanaya @ Nov 14 2009, 01:52 PM) *
But you are using estimates for pure, solid ice and a solid surface. Colaprete said that looking at the size of the crater that seemed unlikely.
Those 100kg minimum of H20 probably meant more than 0.1 cubic meters, and the average density of the ejected material could have been less than lunar rock.
Organics like methane yield water easily, their mass should count too.

The 100 kg reported was based on a column abundance (# per-square-meter), derived from the H2O band depths in the near-infrared spectra. This represents water molecules only. However, this number is derived from a model fit to the data, so uncertainties are large, as is typical for remote sensing spectroscopy. Regardless, the order of magnitude result will likely stand up, meaning the uppermost layers of the cold traps are about as "wet" as predicted (c.f. Campbell et al, Nature, 2006; Siegler et al, LPSC, 2009). That is, it's pretty dry, but not hopeless. Also, don't forget that we're only sampling the uppermost ~1-5 meters (including the ground-based radar results), so there could still be slabs of ice below.

Perhaps even more interesting are some of the other compounds, including several organic volatiles, that were observed in the ejecta plume. An interesting take on the smorgasbord of volatiles likely to accumulate at the lunar polar cold traps, is provided by Zhang and Paige, "Cold-trapped organic compounds at the poles of the Moon and Mercury: Implications for origins" Geophysical Research Letters 36, L16203.

Posted by: tanjent Nov 15 2009, 04:41 AM

Regarding the comparison of water to gold, remember that on the moon, water will be needed in much greater quantities than gold. This applies whether the need is for human consumption or, broken into its elemental components, as a fuel source. In the lunar environment, water would be more difficult to process than gold in one important respect - the gold wouldn't need to be constantly confined to prevent its escape to the vacuum of space. Any attempt to set up shop and utilize trace amounts of lunar water will have to invest heavily just in thermal insulation alone, otherwise those trace amounts are going to prove very difficult to corner. Remember those discarded Russian RTG's in Georgia that were located in the wintertime by hunters because they were surrounded by large circles of snow-free terrain? It's pretty hard to do industrial-scale work without generating waste heat, and at the local temperatures and vapor pressures prevailing in Cabeus, a little waste heat will quickly disrupt the delicate environmental balance that trapped the water in the first place.

This mission has told us a lot we didn't know. I'm intrigued by what these deposits can teach us when we determine where the water came from, and this should be answerable either by further work on the LCROSS data set or with some sort of sample return mission. But to significantly lower the costs of exploration we need at least a recognizable "dirty snowfield," not the Atacama desert.

Posted by: P Hayne Nov 15 2009, 04:44 AM

QUOTE (PFK @ Nov 14 2009, 04:00 PM) *
Just out of interest - what would the total organic chemical content of the Centaur amount to? Plastics, wiring etc. Vapourise them via a collosal thud and all manner of fragments will fly.

A serious concern is the presence of hydrazine fuel from the Centaur rocket, which does have some poorly-characterized absorption bands in the near-infrared. From what I have seen, it might be possible to reproduce one of the bands attributed to water, by using hydrazine, but not all of the water bands. If anyone can dig up (or measure!) a decent hydrazine absorption spectrum, that would be very helpful. The best I have seen was from the 1950's and was basically qualitative (can't recall the author).

Posted by: nprev Nov 15 2009, 04:47 AM

Did the Centaur actually have hydrazine? The main engines use LOX & LH2, and attitude control was provided during cruise by the LCROSS spacecraft itself.

Posted by: P Hayne Nov 15 2009, 04:55 AM

QUOTE (nprev @ Nov 14 2009, 08:47 PM) *
Did the Centaur actually have hydrazine? The main engines use LOX & LH2, and attitude control was provided during cruise by the LCROSS spacecraft itself.

Yes.

Posted by: Holder of the Two Leashes Nov 15 2009, 05:56 AM

As I recall from the blog site (someone correct me on this if I'm wrong), every bit of the hydrazine was successfully vented, or used.

QUOTE (tanjent @ Nov 14 2009, 10:41 PM) *
Any attempt to set up shop and utilize trace amounts of lunar water will have to invest heavily just in thermal insulation alone... But to significantly lower the costs of exploration we need at least a recognizable "dirty snowfield," not the Atacama desert.


I'm afraid I must disagree. In a vacuum, you don't have to invest heavily in thermal shielding. Proper reflection and disposal of waste heat (here, it would be upward toward the sky) and careful use of insulating materials in the proper location (thermally isolate the wheels on a rover, keep them cold) would enable the enviroment to be maintained as long as the rover didn't stay in one spot very long. Witness the Spitzer telescope, which maintains its innards during the current warm mission at 30 degree K, even in constant direct sunlight.

Earlier, use of the 100 ppm implanted regolith hydrogen was considered as a cost effective resource (by Harrison Schmidt, among others), even though it would require much higher roasting temperatures to obtain. Water ice will require less energy to get out.

As far as infrastructure, a landed vehicle could be refueled over time using its own propellant tanks for storage. You just need the rover dropping off its load multiple times.

Posted by: Geert Nov 16 2009, 06:26 AM

Last night we had quite a bit of rain here in the "jungle" of northeast Thailand, and rain in this time of the year is a bit exceptional.

However, our local radiostation just announced the reason in its hourly news bulletin: the rain was caused by the American moon rocket, crashing on the moon. It had taken the water a bit of time to reach Earth, but last night it arrived!

No kidding, this is the official news bulletin..

Posted by: nprev Nov 16 2009, 06:36 AM

Um...we're sorry? rolleyes.gif tongue.gif

Posted by: Stu Nov 16 2009, 06:41 AM

Better get under cover Geert; there should be a nasty shower of red rocks coming your way soon, knocked off Mars by the impact of Beagle 2. On behalf of the British people, I apologise in advance... wink.gif

Posted by: JohnVV Nov 16 2009, 07:20 AM

QUOTE
No kidding, this is the official news bulletin..

post a link
That is , sad to say, something i might expect to hear on the news these days .

Posted by: marsophile Nov 16 2009, 06:12 PM

One interesting question is: to what degree does the estimated concentration of hydrogen compounds in the plume match the concentration of hydrogen calculated from the neutron spectrometer measurements of Cabeus from LRO and Prospector? The neutron spectrometer measurements are averaged over a larger region, so if the concentration in the plume is smaller, it seems to imply larger patchy concentrations elsewhere in the crater. (I think Colaprete made this point in press conferences before the impact.) If the concentrations are about the same, then we can possibly extrapolate what the neutron spectrometer measurements mean in terms of specific compounds.

Posted by: Holder of the Two Leashes Nov 16 2009, 06:49 PM

I don't have the LRO results. http://fti.neep.wisc.edu/FTI/pdf/fdm1120.pdf, which interpreted everything in terms of implanted solar hydrogen, gave 1500 plus/minus 800 ppm by weight hydrogen from Prospector data.

If entirely in the form of water - just for the sake of argument - that would give you between 6.3 and 20.7 parts per thousand (or 6,300 to 20,700 ppm) by weight H2O. In reality we already know the hydrogen exists in various forms and compounds.

Posted by: PFK Nov 16 2009, 10:50 PM

Just to be clear, when I mentioned the organic content of the Centaur I certainly didn't mean to imply this would have implications for water measurements. I was thinking more of the "C-H" compounds they alluded to.
I'd agree entirely that it would be possible to make an inventory of this that would indicate how much "stuff" could be generated. And if this total is way below what is seen on the organic front then there's no issue - and I presume it is. Predicting what would be generated by such a powerful impact is, however, much harder. In reality, I suspect, all manner of small fragments will fly.

Posted by: nprev Nov 17 2009, 12:35 AM

Most of the organics on the booster would presumably be wire insulation: PTFE, Kapton, etc. Would it be reasonable to assume that most of this stuff was subjected to high heat & subsequently decomposed into simple organics almost instantaneously during the impact?

IIRC, there's a fair amount of carbon in lunar soil already, and definitely a lot of oxygen. There might be a detectable excess of hydrogen and nitrogen from breakdown of the booster's wire insulation, but according to Phil this has been "tared out" of the observations.

Posted by: Phil Stooke Nov 17 2009, 01:29 AM

There is also a lot of doubt about how a manufactured object behaves in an impact. A rock hitting the Moon at several km per second behaves in ways we understand fairly well, but how does an impacting rocket stage behave? Some of its kinetic energy is used up bending metal. The top end of the impactor may not hit the surface at the same speed the bottom end did due to the complex behaviour of the structure. It's not as simple as a shock wave moving through a rock. I am not so sure that a bundle of insulated wires is going to be vaporized. We don't know a lot about this situation. I think these kinds of uncertainty generally act to reduce contamination of the type discussed here, but I expect we'll see more experiments on the ground to try to get a better handle on it.

Phil

Posted by: Greg Hullender Nov 17 2009, 05:25 AM

Note that the impact was at only 2.5 kps.

http://lcross.arc.nasa.gov/rationale.htm

And it was not expected to vaporize more than 10% of the ice. Instead, they were counting on the Sun to do that.

--Greg


Posted by: marsbug Nov 20 2009, 03:52 PM

New scientist has confused me. I know I shouldn't put too much faith in what they report these days but they've said:

QUOTE
The solar wind is expected to form water in minute amounts, amounting to concentrations of no more than 1 per cent in the lunar soil.

LCROSS team members are still analysing the data, but calculations suggest the concentration of water is higher than that. "The data are consistent with a total hydrogen content in the range of several per cent," says Colaprete.


This is from their report on the Lunar Exploration Analysis Group meeting, so I was hoping for some interesting tidbits, but I'm just confused! Is the water content several percent, or the hydrogen content? Does anyone know of any other reports from the Lunar Exploration Analysis Group?

Posted by: mcaplinger Nov 20 2009, 04:01 PM

QUOTE (marsbug @ Nov 20 2009, 07:52 AM) *
New scientist has confused me.

I'll spare you my opinion of the subject publication...

I think it's premature to discuss the LCROSS results before a peer-reviewed paper is published. IMHO, the LCROSS team didn't do anyone any favors announcing their preliminary results at a press conference.

Posted by: marsbug Nov 20 2009, 04:11 PM

I think you're right!

Posted by: marsophile Nov 20 2009, 06:20 PM

QUOTE (mcaplinger @ Nov 20 2009, 09:01 AM) *
I think it's premature to discuss the LCROSS results before a peer-reviewed paper is published. IMHO, the LCROSS team didn't do anyone any favors announcing their preliminary results at a press conference.


I disagree. The press conference did no harm and gave the public, who paid for the mission, exactly what they needed. This mission was funded, by the way, by the Exploration Systems Mission Directorate, not the Science Mission Directorate. The papers and conference reports, when they appear, will give the science community what they need.

The New Scientist article seems to plainly say that the hydrogen concentration, not the water concentration, was several percent, but obviously any report in a popular magazine should be viewed with due skepticism.

Posted by: mcaplinger Nov 20 2009, 06:52 PM

QUOTE (marsophile @ Nov 20 2009, 10:20 AM) *
The press conference did no harm and gave the public, who paid for the mission, exactly what they needed.

Well, I have some residual concerns about the detection methodology, and I don't think anyone knows if the amount of water detected was useful for resource exploitation or just a scientific curiosity. I'd think the public deserves the answer to that basic question.

Posted by: Ron Hobbs Nov 20 2009, 06:53 PM

I think you all may find the comments of William Marshall of Ames Research Center, as published in the New York Times, interesting.

http://www.nytimes.com/2009/11/20/opinion/20marshall.html

I was particularly intrigued by the statement, "Almost as surprising as NASA's announcement is the lack of attention it has received."

Neat graphic as well.

Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)