No water signs in samples as proof

[Jairo]

I read that lunar samples could be differenciated from Earth rocks because the first ones showed no signs of water.

I would like to know if it´s an evidence of if it´s a proof. Is it possible to find minerals wich show no signs of water contamination here on Earth? (To be clear: minerals that would show such signs if contaminated.)

[PhantomWolf]

firstly I wouldn't call Earth rocks "contaminated" with water, the water in them is chemically bonded into the clays and is part of the rock itself along with the silacates, carbonates and metal oxides.

Moon rock however doesn't have any bonded water in it. This is something quite significant. Firstly because it is virtually impossible to remove the water from Earth rocks and secondly because it was such a huge surprise. No-one expected to find waterless rocks and the discovery completely changed the theories behind the moon's formation. Had the rocks been "faked" there would have been no need to make them waterless simply because no-one would have considered it strange that they had water. Of course it would have been discovered quickly once the Soviet returns had been anlysised, but since Lunites (luna meteorites) were only discovered over 10 years after the Apollo missions because they matched the Apollo sample we have a major problem for those that claim artificality. If a Lunite can only be determined as such by careful chemical analysis based on what we learned from Apollo, how could the supposed fakers have known what to make their rocks look like chemically? It's a paradox.

[Jairo]

phantomwolf said:

...it is virtually impossible to remove the water from Earth rocks...

But is it possible to find Earth rocks that have no water to be removed?

[gwiz]

jairo said:

But is it possible to find Earth rocks that have no water to be removed?

Seeing the amount of steam that comes out of a volcano, I'd guess that even rocks formed underground would have a water content. However, I'm not a geologist and stand ready to be corrected.

[JayUtah]

I'm not sure we're looking for water itself so much as visible effects of water having been present during the rocks' formation. Rocks on Earth can be dry as a bone, but bear signs of water having participated in the formation of them millions of years ago. Sedimentary rock comes to mind, but I think you'd have to consult a qualified geologist. Lunar rocks don't appear to show any signs of having ever been in the presence of water.

[turbonium]

Hold on - what about ice detected by Clementine and the Lunar Prospector? This link nssdc.gsfc.nasa.gov/planetary/ice/ice_moon.html
claims there is ice on the moon. Lunar meteorites could therefore conceivably contain traces of water molecules.

[frenat]

I think the point is there may be ice or water there now but there wasn't any when the rocks were formed.

[PeterB]

The water detected there is only believed to exist in permanently shadowed parts of the Moon, expecially at the poles, and this is why these locations are being considered for Moon bases.

The origin of the water is believed to be comets which crashed at the poles. It's thus loose water ice which hasn't yet sublimed into space. What it isn't is water which is chemically bound into the crystals which make up the rocks.

[PhantomWolf]

Water inside of the rocks at formation bonds into the crystals and dictates the way they form, being very obvious to the eye of a geologist (or to anyone that knows what they are looking at.) There is a huge amount of water in the Earth's crust and so any rock that is formed, be they Igneous ( basalts, granites) Sedimentary (shales, linestones, sandstones) or Metamorphic (marbles, slates) does so with the effect of water. Sedimentary Rocks are the direct result of water as Jay stated above. Sandstones are produced when Ingneous (lava based) rocks are broken down by wave actions into sandy quartzs and claylike feldspars. This is then compressed into layers with clays and silts and hardens forming a soft gritty rock. This type of rock is very common in coastal areas about Earth and has been found by the rovers on Mars providing major evidence of water having been once on Mars. It wasn't found on the moon though. Neither was the second commonly found sedimentry rock. Shale cames directly from heated and compressed layers of slits and clays. Again numerous shales have been found on Mars, but not on the Moon. The final major type of Sedimentary rock in Limestone, the hardest of the three. This is a carbonite rock and is formed when the shells of crustaceans and animal skeletons are compressed together. While common in areas of Earth that were once under lakes or seas, this type of rock has not been found on either Mars or the Moon, indicating that there was never crustaceans or fish on either of these places. Metamorphic rock is Sedimentary rock that has been heated and compressed and changed into another form. Limestones become Marbles, shales become slate. Thus any of these types of rocks would indicate a large pressence of water and the internal structure and crystals are quite obviously water effected.

The lava based rocks, or Igneous rocks are what we mostly find on the moon. Generally they are basalts. Rocks come in many scales, but the two ends are Granites which have large crystals of quartz mixed with feldspar. They cool of very long periods of time. The feldspar and quartz crystals still can bond with water though and this can be seen by geologists. Basalts are rapidly cooled high metal, especially mgnesium, rocks. The moon really has two types of rocks. The lighter, long cooled granites which make to the ligther areas of the moon's surface and the darker basalts of the mares. By studying the feldspar and quartz in the moon granites and basaltys, geologists found that there is no water bound into the crystals, nor has it had a presence in the formation of the crystals. It's probably easier to show it with images because the distictions is quite apparent visually, but I'd have to search for some, so I'm not going too right now. What it does show however is that absence of any water bonding into the crystals shows that there was no water during their formation and the lack of sedimentary or metamorphic rocks show that there has been no liquid water about either.

As to the Ice. Well while there is some evidence of large amounts of bonded hyrodren, the impact of the Lunar Prospector resulted in a negitive finding for ice crystals, so whether there really is ice of not is still a question up in the air. It is believed that any ice there is from comet impacts though, and so the affect they would have had on any rocks wuld be about the same as blasting them with a hose. Nadah.

[Mr Gorsky]

PhantomWolf,

I think I learned more about rocks and their formation from that one post than my entire Geology O' Level.

Thanks,

[gwiz]

I'm guessing the Moon is so dry because its gravity is insufficient to hold on to water vapour for any length of time. Water brought by incoming comets is vapourised at impact. It can freeze out on the night side, but vapourises again in daylight. Only the always-shadowed regions in polar craters can hold ice permanently.

[PhantomWolf]

gwiz said:

I'm guessing the Moon is so dry because its gravity is insufficient to hold on to water vapour for any length of time. Water brought by incoming comets is vapourised at impact. It can freeze out on the night side, but vapourises again in daylight. Only the always-shadowed regions in polar craters can hold ice permanently.

There are several reasons. The current belief is that the moon was formed when a planetoid the size of Mars hit the Earth early in its development into a planet. Because of that collision the moon would have been molten and any water would have boiled off. Without an atmosphere any ice that gets heated by the sun would simply sublime and be lost. The idea of the comet's impact I believe, is that chunks of the comet ice would spray across the surface on impact, some falling into the craters where the sun never heats it. because of that it remains in then as ice. Any ice of the comet that vapourised during the impact would have been lost.

[gwiz]

The impact theory of the Moon's origin wasn't developed until after the Apollo missions, so someone trying to fake the rocks wouldn't have known that they had to be waterless...

[drjohn]

Here's a nice page about lunar geology/rocks.