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Ice Confirmed at the Moon's Poles:
In the darkest and coldest parts of its polar regions, a team of scientists has directly observed definitive evidence of water ice on the Moon's surface. These ice deposits are patchily distributed and could possibly be ancient. At the southern pole, most of the ice is concentrated at lunar craters, while the northern pole's ice is more widely, but sparsely spread.
A team of scientists, led by Shuai Li of the University of Hawaii and Brown University and including Richard Elphic from NASA's Ames Research Center in California's Silicon Valley, used data from NASA's Moon Mineralogy Mapper (M3) instrument to identify three specific signatures that definitively prove there is water ice at the surface of the Moon.
M3, aboard the Chandrayaan-1 spacecraft, launched in 2008 by the Indian Space Research Organization, was uniquely equipped to confirm the presence of solid ice on the Moon. It collected data that not only picked up the reflective properties we'd expect from ice, but was able to directly measure the distinctive way its molecules absorb infrared light, so it can differentiate between liquid water or vapor and solid ice.
Most of the newfound water ice lies in the shadows of craters near the poles, where the warmest temperatures never reach above minus 250 degrees Fahrenheit. Because of the very small tilt of the Moon's rotation axis, sunlight never reaches these regions.
Also at The Guardian and CNET.
Direct evidence of surface exposed water ice in the lunar polar regions (open, DOI: 10.1073/pnas.1802345115) (DX)
(Score: 3, Insightful) by RS3 on Tuesday August 21 2018, @01:42PM (5 children)
I wonder when and how much water was on the moon at its peak?
Where did the water go, out into space, or did some / much fall back to Earth?
Losing the water mass would change moon's orbit, but I don't remember orbital physics enough- with more mass, would it have been closer to Earth, but moving much faster?
Did Earth have much greater ocean tidal motion when Moon had more mass?
If so, could that have been a significant factor in Earth's geological processes?
(Score: 4, Interesting) by All Your Lawn Are Belong To Us on Tuesday August 21 2018, @02:01PM
Interesting questions. I've read previously that the Moon does still in fact have an atmosphere, but it consists of very few molecules spaced very far apart from each other - the Apollo landings each produced about twice the total Lunar atmosphere in gases. Anyway, the current gases do bleed off to space somewhat if I remember right. My wild-ass guess is that a significant portion of the water converted to gases (if not steam than back to H and O), and bled out when heated, which is why the ice that's left is in the shadows. As you noted the Moon does orbit the earth (why we get our phases). More mass = more attraction = closer = faster is what I remember, like you. How much so is a different question, and also if you favor the most common theory that the Moon split out from the Earth the timings of that might be relevant (maybe it slowed the departure phase but the Moon was steadily departing anyway - no real idea). It would be interesting to know if the Earth ever actually passes through the Moon's track (around Last Quarter / Waning I'd think). Or if we repass the track close enough (if we do meteor showers reguarly I'd think the track comes back around, but I'm just an amateur observer. Would the atom(s)/molecule(s) rejoin the atmosphere or be repelled by the belts....
And I wouldn't be surprised at all if micrometeorite bombardment might still liberate a few molecules occasionally in the cold zones, too.
Is there an astrophysicist in the house? :)
This sig for rent.
(Score: 3, Informative) by takyon on Tuesday August 21 2018, @02:05PM (3 children)
Moon May Have Been Habitable 3.5 Billion Years Ago [soylentnews.org]
The Moon [wikipedia.org] was closer to Earth billions of years ago, and it was rotating faster before it became tidally locked.
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(Score: 3, Interesting) by bzipitidoo on Tuesday August 21 2018, @04:00PM (2 children)
Yes. The current thinking on how the Moon came to be is that early in the solar system's history, when the planets were forming and collisions were frequent, another planet collided and merged with Earth, knocking enough matter off to form the Moon, and giving the Earth a terrific rate of spin. In that scenario, the Moon forms close to Earth. Tides were 1000 feet high, and Earth's day was only 6 hours long. Over the billions of years since, the Earth's rotational energy has been slowly transferred to the Moon's orbit around Earth, causing the Moon to move further form Earth, and slowing the Earth's spin.
If no external interruptions occur, this energy transfer will continue until Earth is tidally locked to the Moon, at which point there will be no more tides, a day will be a month long, but a month will be rather longer than it is currently. I have read it will take about 15 billion years for the Earth and Moon to reach this equilibrium. However, the Sun is expected to exhaust its fuel well before then, in about 5 billion years, and swell into a red giant that might reach the Earth's orbit, in which case both Earth and Moon could fall into the Sun. Also possible that in the process of expanding into a red giant, the Sun will push the planets into higher orbits, and so Earth might not fall into the Sun after all.
The Moon does not have anywhere close to enough gravity to hold onto lighter elements against the constant erosive force of the solar wind. Gaseous matter released by any chemical reaction or heating will be very quickly lost. Of the terrestrial planets, only Earth has the combination of enough gravity (barely) and distance from the Sun to hang onto the lightest element, hydrogen. Earth can't hold much hydrogen, not when it significantly increases the planet's diameter, thus positioning the hydrogen high enough that the solar wind can strip it away.
So yeah, the water on the Moon can only be a small portion of what must have cycled through billions of years ago. Makes perfect sense that remnant surface water would be at the poles, the only places that never get any sunlight. There's no external source in the inner solar system that would add more than trace amounts of water, not for billions of years has there been lots of watery comets zipping about. Lot of interesting questions, like, how much water did there have to be to leave the remnants we see today? How did it get there, as rain in a gaseous atmosphere, or were the poles low elevations that ended up as ocean bottoms, or something else?
(Score: 2) by takyon on Tuesday August 21 2018, @04:26PM
Only a tiny fraction of Earth's mass is water, due to its starting proximity to the Sun. Whereas other objects in the solar system (most past the snow line [nature.com]) can be as much as 50%+ water. Looks like both the Earth and Moon got their water delivered by comets. The Moon may have had a comparatively dense atmosphere and surface water for a while. Which implies that rain is possible.
There could be sources of water trapped underground, and ice in permanently shadowed parts of craters that aren't near the poles.
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(Score: 2) by RS3 on Tuesday August 21 2018, @05:08PM
Yes, but remember Earth's gravity is not enough to hold an atmosphere. The Van Allen belts https://www.space.com/33948-van-allen-radiation-belts.html [space.com] deflect much of the solar wind, protecting our thin shell of an atmosphere. It's theorized that Mars might once have had a good atmosphere, but due to cooling of the planet's core, the belts it may have had would have dissipated and Mars lost most of its atmosphere.
(Score: 3, Funny) by Runaway1956 on Tuesday August 21 2018, @05:05PM
https://www.ice.gov/ [ice.gov]
So, now we're paying for ICE to post officers to the lunar poles, because of illegal aliens? Are there any limits to this insanity?
https://www.youtube.com/watch?v=1-bjPqMMLN4 [youtube.com]
Abortion is the number one killed of children in the United States.
(Score: 2) by arslan on Tuesday August 21 2018, @10:46PM (1 child)
So would a moon base near the poles be useful as we can then harness the water and reduce some of the regular supply train needed?
(Score: 2) by takyon on Wednesday August 22 2018, @12:44AM
Absolutely.
https://en.wikipedia.org/wiki/Colonization_of_the_Moon [wikipedia.org]
AFAIK there are no manned missions planned at this time [wikipedia.org]. So all details are up in the air.
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(Score: 0) by Anonymous Coward on Tuesday August 21 2018, @11:43PM
It is very cold on the moon, so when the astronauts left the landing module to take a leak their pee froze on the ground.