Article Posted on : - Apr 17, 2010

NEW YORK (PTI): Planetary scientists at NASA have claimed that the lunar polar craters, which are said to contain water ice, may be electrified.

According to their findings, published in the 'Journal of Geophysical Research', as the solar wind flows over natural obstructions on the moon, it may charge polar lunar craters to hundreds of volts.

Polar lunar craters are of interest because of resources which exist there. The moon's orientation to the sun keeps the bottoms of the craters in permanent shadow allowing temperatures there to plunge below minus 400 degrees F, cold enough to store volatile material 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 team leader William Farrell of NASA's Goddard Space Flight Center.

According to the scientists, solar wind inflow into craters can erode the surface that affects recently discovered water molecules. Static discharge could short out sensitive equipment, while the sticky and extremely abrasive lunar dust could wear out spacesuits and may be hazardous if tracked inside spacecraft and inhaled over long periods.

The solar wind is a thin gas of electrically charged components of atoms -- negatively charged electrons and positively charged ions – that is constantly blowing 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 where day transitions to night, called the terminator.

The scientists created computer simulations to discover what happens when the solar wind flows over the rims of polar craters. They discovered that in some ways, the solar wind behaves like wind on Earth – flowing into deep polar valleys and crater floors.

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, they have claimed.

Since electrons are over 1,000 times lighter than ions, the lighter electrons in the solar wind rush into a lunar crater or valley ahead of the heavy ions, creating a negatively charged region inside the crater.

The ions eventually catch up, but rain into the crater at consistently lower concentrations than that of the electrons. This imbalance in the crater makes the inside walls and floor acquire a negative electric charge.

“The electrons build up an electron cloud on this leeward edge of the crater wall and floor, which can create an unusually large negative charge of a hundred Volts relative to the dense solar wind flowing over the top,” said Farrell.

The negative charge along this leeward edge won't build up indefinitely. Eventually, the attraction between the negatively charged region and positive ions in the solar wind will cause some other unusual electric current to flow, the findings have revealed.