Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

It’s Cold and Wet at the Moon’s South Pole

22.10.2010
Frozen water just inches below the moon’s surface has been confirmed by an international team of scientists including University of Arizona professor William Boynton.

Based on data the group obtained with an instrument aboard the Lunar Reconnaissance Orbiter, or LRO, NASA chose the impact site for the LCROSS probe, which slammed into the moon's surface last year in October in an attempt to kick up dust that could be analyzed for the presence of water ice.

The group's findings were obtained separately from the impact experiment and are published in the Oct. 22 issue of Science, which highlights results from the LRO/LCROSS mission in six scientific papers.

"We found significant amounts of water around the north and south poles, in places where previously we were only tentatively thinking of it," said William Boynton, professor in the UA's department of planetary sciences and the UA's Lunar and Planetary Lab.

In addition to confirming water and its distribution in unprecedented detail, the data included an unexpected finding.

"To our surprise, some of the permanently shadowed regions had no water, but some of the areas that receive sunlight occasionally did have water," Boynton said.

In other words, water was found not only where it is supposed to be, but also where it is not supposed to be.

Previously, scientists were convinced water ice could only persist in so-called Permanently Shadowed Regions, or PSRs, places on the moon's surface the sun never reaches. Unlike Earth, whose tilted axis ensures that any spot on the surface receives at least some sunlight at some point during the planet's yearlong journey around the sun, the moon's axis is hardly tilted at all. As a result, some places on the lunar surface are never exposed to sunlight.

"In some of the craters that are close to the north or south pole and have very steep walls, no direct sunlight ever reaches the bottom of the crater," Boynton said.

"At down to -370 degrees Fahrenheit, those PSRs are colder than Pluto, even at noon," added Karl Harshman, a software engineer with the Lunar and Planetary Lab.

But according to the measurements the group obtained using the Lunar Exploration Neutron Detector, or LEND, aboard the LRO spacecraft orbiting the moon, there is water even in areas that are exposed to the sun's warming rays every once in a while. Conversely, some of the PSRs turned out to be completely dry.

The data also helped to obtain a more detailed picture of water distribution on the moon.

"The data we obtained in the first three months of the mission helped LCROSS select the impact site," said Gerard Droege, a data analyst in Boynton's group who created the visual representations of the data. "It gave mission control just enough time to tweak the trajectory, and everybody then said, OK, we're going for Cabeus."

"Previous instruments could only tell us that the whole area around the poles is enriched, now our knowledge is much more spatially refined," Boynton said.

To trace the abundance of water on the moon, the scientists took advantage of cosmic particles constantly bombarding every object in space. Since the moon lacks a protective atmosphere, the particles strike the surface close to the speed of light. When they collide with the atomic nuclei in the dusty soil they knock particles off these atoms, mostly protons and neutrons, some of which escape into space. If one of these particles hits a hydrogen atom, which is most likely part of a water molecule, it slows down dramatically, leaving fewer particles fast enough to escape to space.

By measuring differences in the flow of neutrons coming from the moon's surface, the researchers were able to infer the amount of water present in the soil: Areas emitting low neutron radiation indicated water capturing and retaining most of the neutrons, while areas reflecting high neutron radiation identified themselves as dry.

In the PSRs near the impact site in the Cabeus crater near the Moon's south pole, the soil was found to contain up to four percent water.

"The water might be like some form of ice mixed in with the soil, possibly similar to the slightly damp, frozen soil found in Alaska," Boynton said. "We think that in the PSRs, water ice might be present on the surface, but the fact we found it in the partially sunlit areas, too, means the upper three inches or so must be dry dirt, otherwise the sunlight would cause the water to evaporate."

Possible origins of the water on the moon include impacts of icy comets or hydrogen deposited from solar wind, the authors noted.

The study was led by Igor Mitrofanov at the Institute for Space Research of the Russian Academy of Science in Moscow, the agency that supplied the LEND instrument used in this study. LRO is managed by NASA's Goddard Space Flight Center in Greenbelt, Md.

Media Contact:
William Boynton, Lunar and Planetary Lab, The University of Arizona: wboynton@lpl.arizona.edu, 520-621-6941
Daniel Stolte, University Communications:
stolte@email.arizona.edu, 520-626-4402

Daniel Stolte | University of Arizona
Further information:
http://www.lpl.arizona.edu/~karl/
http://www.arizona.edu

More articles from Physics and Astronomy:

nachricht SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>