Mysterious Lunar Swirls

This idea provides an explanation for the light, creamy appearance of swirls. According to some researchers, moondust is darkened by long exposure to solar wind. Maybe the swirls are light because they get less exposure: their magnetic fields deflect solar wind. If so, lunar swirls are merely a shadow of the magnetic forces arching above them.

Courtesy of NASA A magnetic map of Reiner Gamma obtained by NASA's Lunar Prospector spacecraft in the 1990s.

It all sounds neat and tidy, but there's a problem: While two of the lunar swirls are directly opposite an impact basin, one is not: Reiner Gamma. The prototype swirl doesn't fit! "It's a real mystery," acknowledges Lin.

More clues are on the way. NASA is returning to the Moon, eventually with people but first with robot scouts. Leading the way is Lunar Reconnaissance Orbiter (LRO), due to launch in 2008. Among other things, LRO will make detailed 3D maps of the whole Moon using a state-of-the-art camera and a laser. Its view of the swirls should be breathtaking.

Another NASA instrument, the Moon Mineralogy Mapper, is hitching a ride to the Moon onboard India's Chandrayaan-1 spacecraft, also due to launch in 2008. Using an infrared spectrometer, "M-cubed" will survey the lunar terrain and tell us in fantastic detail what minerals are in the ground. The whole Moon will be surveyed--including swirls.

What are swirls made of? Are they truly flat? How does the cream differ from the coffee? Questions to ponder over your next cup of joe...

For more information:

European Space Agency - Reiner Gamma swirl: magnetic effect of a cometary impact?
http://www.esa.int/esaMI/SMART-1/SEM05FNFGLE_0.html

NASA - Lunar Reconnaissance Orbiter
http://lunar.gsfc.nasa.gov/missions/

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