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Title: An Unprecedented Constraint on Water Content in the Sunlit Lunar Exosphere Seen by Lunar-Based Ultraviolet Telescope of Chang'e-3 Mission
Author: J. Wang, C. Wu, Y. L. Qiu, X. M. Meng, H. B. Cai, L. Cao, J. S. Deng, X. H. Han, J. Y. Wei

The content of OH/H2O molecules in the tenuous exosphere of the Moon is still an open issue at present. We here report an unprecedented upper limit of the content of the OH radicals, which is obtained from the in-situ measurements carried out by the Lunar-based Ultraviolet Telescope, a payload of Chinese Chang'e-3 mission. By analysing the diffuse background in the images taken by the telescope, the column density and surface concentration of the OH radicals are inferred to be <1011 cm-2 and <104 cm-3 (by assuming a hydrostatic equilibrium with a scale height of 100km), respectively, by assuming that the recorded background is fully contributed by their resonance fluorescence emission. The resulted concentration is lower than the previously reported value by about two orders of magnitude, and is close to the prediction of the sputtering model. In addition, the same measurements and method allow us to derive a surface concentration of <102 cm-3 for the neutral magnesium, which is lower than the previously reported upper limit by about two orders of magnitude. These results are the best known of the OH (MgI) content in the lunar exosphere to date.

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Most Moon Water Comes From the Sun, Not Comets
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Most Moon Water Comes From the Sun, Not Comets

OCT 7, 2014 12:33 PM ET // BY IAN O'NEILL

The moons water came from comet and asteroid impacts, right? As it turns out, the question as to where lunar H2O came from is not so straightforward it was actually baked via reactions with the solar wind.

When Apollo astronauts returned lunar surface samples of rock and regolith (fine, pulverized rocky grains), it was assumed they would be bone dry. After all, the moon has no atmosphere any water deposited on the surface from impacts would have been long lost to space.

But in recent analysis of the regolith, scientists were surprised to find quantities of water locked in the lunar material.

There are quantities of ice deposits all over the moons surface; some large deposits exist in polar craters where sunlight never shines on the crater bottoms. And now we know that even the sun-baked surface and sub-surface has a frozen supply.

NEWS: Man in the Moon Created by Mega Volcano

According to new research by astrochemists Alice Stephant and François Robert, of Muséum National dHistoire Naturelle, Paris, the source of the vast majority of the surface water trapped in regolith samples is not from aeons of asteroid and comet impacts two well known sources of cosmic water ice its the sun. Rather, the water found in lunar regolith is created via chemical reactions with the solar wind.

Their findings have been published in the Proceedings of the National Academy of Sciences.

Through isotopic analysis of deuterium/hydrogen and lithium isotope ratios, the researchers were able to determine that the source of the water did not originate from ancient impacts, but from reactions in and on silicate regolith grains. High-energy protons from the solar wind impact these grains, unlocking oxygen atoms, allowing them to bond with abundant hydrogen atoms, kickstarting the formation of hydroxyl, a tracer for water. Hydroxyl is a simple molecule of one oxygen atom and a hydrogen atom, whereas water has two hydrogen atoms bonded to an oxygen atom.

NEWS: Moon Made Water From Solar Wind

Although there is undoubtedly water deposited on the lunar surface via impacts, with this new analysis in mind, they estimate that the solar wind contribution of lunar water accounts for a whopping 85 percent. In some samples, they believe that all the water came from solar wind interactions.

Of course, this analysis only applied to the moons surface, so water sources found below the surface may have a different origin.

It appear that, once again, the moon has shrugged-off conventional wisdom and shown us a cosmic laboratory where water can be baked from dry lunar regolith and solar wind protons as the only other ingredient.

Source: PNAS via Phys.org

http://news.discovery.com/space/most-moon-surface-water-comes-from-the-sun-not-comets-141007.htm



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Moon water came from young wet Earth

The notion that all Earth's water was delivered by comets or asteroids has just taken a hit. Chemical analysis of lunar rocks suggests that Earth was born wet, and it held on to its water long enough to donate some to the moon.
Alberto Saal of Brown University in Providence, Rhode Island, and colleagues studied rocks brought back from the Apollo 17 mission in the 1970s. In 2008 they found that crystallised magmas in the rocks do in fact contain water - and not just a little. The minerals hold as much as those in Earth's upper mantle.

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Moon's water may have come from the Sun

Particles from the Sun may be responsible for the presence of water recently detected in lunar soil, a new study has found.
Scientists have been speculating on how minute water reached the Moon ever since its discovery over the past decade by orbiting spacecraft.
There are a number of possibilities ranging from comet or meteor impacts, through to trapped volcanic gases during the Moon's formation four and half billion years ago.

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 NASA Spacecraft Reveals Ice Content in Moon Crater

NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft has returned data that indicate ice may make up as much as 22 percent of the surface material in a crater located on the moon's south pole.
The team of NASA and university scientists using laser light from LRO's laser altimeter examined the floor of Shackleton crater. They found the crater's floor is brighter than those of other nearby craters, which is consistent with the presence of small amounts of ice. This information will help researchers understand crater formation and study other uncharted areas of the moon. The findings are published in Thursday's edition of the journal Nature.

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Title: Water on The Moon, I. Historical Overview
Authors: Arlin Crotts (Columbia University)

By mid-19th century, astronomers strongly suspected that the Moon was largely dry and airless, based on the absence of any observable weather. In 1892, William H. Pickering made a series of careful occultation measurements that allowed him to conclude that the lunar surface's atmospheric pressure was less than 1/4000th of Earth's. Any number of strange ideas arose to contradict this. Respectable scientists realised that significant amounts of water on the Moon's surface would rapidly sublime into the vacuum. Since 2007, however, the field has started another revolution in thought, and we describe this, including some lesser known aspects.

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Title: Water on The Moon, II. Origins & Resources
Authors: Arlin Crotts (Columbia University)

In Part I we recount the history of observation and laboratory measurement culminating with the excavation of water from a permanently shadowed region near the lunar South Pole by the impact of the LCROSS mission in 2009. In this installment we consider what the current data imply about the nature of water and other volatile substances on and in the Moon

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Title: Water on The Moon, III. Volatiles & Activity
Authors: Arlin Crotts (Columbia University)

For centuries some scientists have argued that there is activity on the Moon (or water, as recounted in Parts I & II), while others have thought the Moon is simply a dead, inactive world. The question comes in several forms: is there a detectable atmosphere? Does the surface of the Moon change? What causes interior seismic activity? From a more modern viewpoint, we now know that as much carbon monoxide as water was excavated during the LCROSS impact, as detailed in Part I, and a comparable amount of other volatiles were found. At one time the Moon outgassed prodigious amounts of water and hydrogen in volcanic fire fountains, but released similar amounts of volatile sulphur (or SO2), and presumably large amounts of carbon dioxide or monoxide, if theory is to be believed. So water on the Moon is associated with other gases. We review what is known (and touch on what is unknown) about outgassing of various gases from the Moon.

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UT scientists discover source of lunar water

UT researchers have recently uncovered the probable source of water deposits left on the lunar surface.
Lawrence Taylor, professor in the Department of Earth and Planetary Science, has already achieved great acclaim in the scientific community, proving the existence of abundant water deposits on the Moon. His new findings indicate that some of this water originated from various comets' collision with the moon.

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Origins of lunar water
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Simulation casts doubt on origins of lunar water

The mystery of how the moon got its surface water has just got deeper, following the failure of an attempt to replicate the mechanism that was thought to produce it.
Three separate space missions last year reported detecting a sheen of water only molecules thick over large parts of the moon's surface. Many planetary scientists assumed the water was created when particles from the solar wind hit lunar soils, but this idea has now been thrown into doubt.

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