UTK: Study Confirms Solar Wind as Source for Moon Water

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bystander
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UTK: Study Confirms Solar Wind as Source for Moon Water

Post by bystander » Tue Oct 16, 2012 3:52 am

Study Confirms Solar Wind as Source for Moon Water
University of Tennessee, Knoxville | 2012 Oct 15
Three years ago University of Tennessee, Knoxville, researchers helped to discover water on the surface of the moon. Now, they are piecing together the origin of that water: solar wind.

A new study published in this month’s Nature Geoscience confirms solar wind as a source for water embedded in the lunar surface.

Solar wind is the continuous flow of charged particles from the sun. Scientists have speculated it to be responsible for water on the surface of the moon.

Last year Larry Taylor, distinguished professor in the Department of Earth and Planetary Sciences, confirmed comets as the source for water inside the moon. This year, Yang Liu, research assistant professor, and Taylor have confirmed solar wind as the source for water on the outside—by depositing positively charged hydrogen atoms, or protons, onto its surface, allowing it to combine with the moon’s oxygen to create water.

“When those protons hit the lunar surface with enough force, they break apart oxygen bonds in soil materials to join together and form water,” said Liu. “This does not happen on Earth because our atmosphere and magnetic field protect us from being bombarded by these protons, but the moon lacks this protection.”

The researchers used lunar samples from three Apollo missions, including one brought back by Neil Armstrong, analyzing something called an agglutinate. An agglutinate, which resembles “dirty Swiss cheese,” is a unique product of space weathering in the lunar regolith, the crushed materials on the moon’s surface. The agglutinate was chosen because it consisted of products suspected to contain hydrogen. The researchers used infrared spectroscopy to confirm the presence of hydroxyl (OH). Then they used secondary ion mass spectrometry to obtain the amount of hydroxyl and the origins of the hydrogen.

The researchers discovered that most of the water in the agglutinates came from solar wind. Confirming the solar-wind- induced hydroxyl emphasizes the possibility of finding water on the surface of other similar airless bodies.

“This means water likely exists on Mercury and on the asteroids such as Vesta or Eros further within our solar system,” said Liu. “These planetary bodies have very different environments, but all have potential to produce water. The finding also implies solar-wind contributes to water ice in lunar poles.”

The research also identifies the largest reservoir for water on the lunar surface since regolith, and thus the corresponding hydroxyl is very widespread. This gives the moon the potential to serve as a habitat and gas station in the sky.

“The hydroxyl in such a volumetrically large reservoir is a valuable resource,” said Taylor. “With the cost of $25,000 for taking one pint of water to the moon, water has the potential to be used as rocket fuel as liquid hydrogen or oxygen.”

Solar wind particles likely source of water locked inside lunar soils
University of Michigan | 2012 Oct 15

Direct measurement of hydroxyl in the lunar regolith and the origin of lunar surface water - Yang Liu et al
Moon Made Water From Solar Wind
Discovery News | Irene Klotz | 2012 Oct 15

The Moon’s Water Comes From the Sun
Universe Today | Jason Major | 2012 Oct 15

http://asterisk.apod.com/viewtopic.php?t=20308
APOD: Water Discovered on the Moon (2009 Sep 28)
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neufer
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The dark top of Mercury

Post by neufer » Thu Nov 29, 2012 9:25 pm

bystander wrote:Study Confirms Solar Wind as Source for Moon Water
University of Tennessee, Knoxville | 2012 Oct 15
The researchers discovered that most of the water in the agglutinates came from solar wind. Confirming the solar-wind- induced hydroxyl emphasizes the possibility of finding water on the surface of other similar airless bodies. “This means water likely exists on Mercury and on the asteroids such as Vesta or Eros further within our solar system,” said Liu. “These planetary bodies have very different environments, but all have potential to produce water. The finding also implies solar-wind contributes to water ice in lunar poles.”

The research also identifies the largest reservoir for water on the lunar surface since regolith, and thus the corresponding hydroxyl is very widespread. This gives the moon the potential to serve as a habitat and gas station in the sky. “The hydroxyl in such a volumetrically large reservoir is a valuable resource,” said Taylor. “With the cost of $25,000 for taking one pint of water to the moon, water has the potential to be used as rocket fuel as liquid hydrogen or oxygen.”
http://www.nytimes.com/2012/11/30/science/space/mercury-home-to-ice-messenger-spacecraft-findings-suggest.html wrote: On Closest Planet to the Sun, NASA Finds Lots of Ice
By KENNETH CHANG, N.Y. Times, November 29, 2012

<<Mercury is as cold as ice. Indeed, Mercury, the closest planet to the Sun, possesses a lot of ice — 100 billion to 1 trillion tons — scientists working with NASA’s Messenger spacecraft reported on Thursday. Sean C. Solomon, the principal investigator for Messenger, said there was enough ice there to encase Washington, D.C., in a frozen block two and a half miles deep.

That is a counterintuitive discovery for a place that also ranks among the hottest in the solar system. At noon at the equator on Mercury, the temperature can hit 800 degrees Fahrenheit (or about 400 degrees Celsius). But near Mercury’s poles, deep within craters where the Sun never shines, temperatures dip to as cold as minus 370 Fahrenheit (minus-220 Celsius). “In these planetary bodies, there are hidden places, as it were, that can have interesting things going on,” said David J. Lawrence, a senior scientist at the Johns Hopkins University Applied Physics Laboratory working on the Messenger mission.

The findings appear in a set of three papers published Thursday on the Web site of the journal Science. The ice could be an intriguing science target for a future robotic lander or even a resource for astronauts in the far future. Planetary scientists had strong hints of the ice a couple of decades ago when telescopes bounced radio waves off Mercury and the reflections were surprisingly bright. But some researchers suggested the craters could be lined with silicate compounds or sulfur, which might also be highly reflective.

The Messenger spacecraft, which swung into orbit around Mercury in March 2011 and has completed its primary mission, took a closer look by counting particles known as neutrons that are flying off the planet. High-energy cosmic rays break apart atoms, and the debris includes neutrons. But when a speeding neutron hits a hydrogen atom, which is almost the same weight, it comes to almost a complete stop, just like in billiards when the cue ball transfers its momentum to another ball. Water molecules contain two hydrogen atoms, and thus when Messenger passed over ice-rich areas, the number of neutrons dropped. The same technique was used to detect frozen water below the surface on Mars and within similar craters on the Moon. The neutron number would not have dropped if the bright surfaces were made of sulfur or silicates. “Water ice is the only candidate we’ve got that fits all those observations,” said Dr. Solomon, who is also director of Columbia’s Lamont-Doherty Earth Observatory.

The ice is almost pure water, which indicates that it arrived within the last few tens of millions of years, possibly from a comet that smacked into Mercury. Dr. Solomon said several young craters on the surface of Mercury could be candidates for such an impact. Not all of the icy regions were bright. In slightly warmer regions, where temperatures exceed minus 280 Fahrenheit (minus-170 Celsius), the ice was covered by a dark layer about half a foot thick. The scientists believe in these places the water ice vaporized, leaving behind other materials that had been trapped, including carbon-based molecules known as organics. That could be similar to how water and the building blocks of life reached Earth billions of years ago.

The water could also be an intriguing resource for people. Between the scorched equator and the frozen poles, temperatures on Mercury can be temperate, especially a few feet below the surface, where the soil insulates against the temperature swings between day and night — an ideal location to build a colony. “People joke about it, but it’s not so crazy, really,” said David A. Paige, a professor of geology at U.C.L.A. who calculated the crater temperatures.>>
Art Neuendorffer