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NASA: Some of moon's craters may be electrified

New NASA calculations suggest that solar wind blowing across the moon's surface may electrically charge polar craters.

By SPACE.com Staff / April 29, 2010

This image provided by NASA shows the first image taken of the moon from the Lunar Crater Observation and Sensing Satellite on Oct. 9, 2009. New NASA calculations have found that some of the moon's solar craters may be electrically charged by solar wind.

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Exploring the craters at the moon's north and south poles may be even more challenging than previously thought for future astronauts. New NASA calculations now show that solar wind streaming over the rough lunar surface may electrically charge polar craters on the moon.

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The moon's polar craters are of particular interest to researchers because resources, including water ice, exist at these lunar structures. The moon's orientation to the sun keeps the bottoms of polar craters in permanent shadow, allowing temperatures there to plunge below minus 400 degrees Fahrenheit (minus 240 degrees Celsius), cold enough to store volatile material like water for billions of years.

"However, our research suggests that, in addition to the wicked cold, explorers and robots at the bottoms of polar lunar craters may have to contend with a complex electrical environment as well, which can affect surface chemistry, static discharge, and dust cling," said William Farrell of NASA's Goddard Space Flight Center in Greenbelt, Md., the lead author of the study.

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These new observations contribute to our evolving understanding of the moon, said Gregory Schmidt, deputy director of the NASA Lunar Science Institute at NASA's Ames Research Center in Moffett Field, Calif.

"This important work by Dr. Farrell and his team is further evidence that our view on the moon has changed dramatically in recent years," Schmidt said. "It has a dynamic and fascinating environment that we are only beginning to understand."

Solar wind hits the moon

Solar wind is a thin stream of electrified components of atoms – negatively charged electrons and positively charged ions – that constantly blows from the surface of the sun into space. Since the moon is only slightly tilted compared to the sun, the solar wind flows almost horizontally over the lunar surface at the poles, and along the region of the moon called the terminator, where day transitions to night.

The researchers discovered that in some ways, solar wind behaves like wind on Earth – flowing into deep polar valleys and crater floors. But, unlike wind on Earth, the dual electron-ion composition of the solar wind may create an unusual electric charge on the side of the mountain or crater wall; that is, on the inside of the rim directly below the solar wind flow.

As solar wind flows into craters, it can erode the surface, which affects recently discovered water molecules. Static discharge could disturb sensitive equipment, while the sticky and extremely abrasive lunar dust could wear out spacesuits and may even be hazardous if tracked inside spacecraft and inhaled by astronauts over long periods of time.