Solar Storms Could Sandblast the Moon

[n2doc]

ScienceDaily (Dec. 7, 2011) — Solar storms and associated Coronal Mass Ejections (CMEs) can significantly erode the lunar surface according to a new set of computer simulations by NASA scientists. In addition to removing a surprisingly large amount of material from the lunar surface, this could be a major method of atmospheric loss for planets like Mars that are unprotected by a global magnetic field.

The research is being led by Rosemary Killen at NASA's Goddard Space Flight Center, Greenbelt, Md., as part of the Dynamic Response of the Environment At the Moon (DREAM) team within the NASA Lunar Science Institute.

CMEs are basically an intense gust of the normal solar wind, a diffuse stream of electrically conductive gas called plasma that's blown outward from the surface of the Sun into space. A strong CME may contain around a billion tons of plasma moving at up to a million miles per hour in a cloud many times the size of Earth.

The moon has just the barest wisp of an atmosphere, technically called an exosphere because it is so tenuous, which leaves it vulnerable to CME effects. The plasma from CMEs impacts the lunar surface, and atoms from the surface are ejected in a process called "sputtering."

"We found that when this massive cloud of plasma strikes the moon, it acts like a sandblaster and easily removes volatile material from the surface," said William Farrell, DREAM team lead at NASA Goddard. "The model predicts 100 to 200 tons of lunar material -- the equivalent of 10 dump truck loads -- could be stripped off the lunar surface during the typical 2-day passage of a CME."

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http://www.sciencedaily.com/releases/2011/12/111207000851.htm

[Ilsa]

1. I rec'ed this because it contradicts a fundie argument

that the moon is only 6000 years old because it doesn't have much depth of fine sand and dirt on the surface. They had argued that geologically, if the moon is billions of years old, it would have deep layers of silty dirt, but only has a few inches.

[n2doc]

2. Dirt is generated by weathering of rocks

Which generally requires wind and water. On the moon you have the solar wind, radiation, and meteor strikes.

[TheMadMonk]

4. Micrometeorite weathering. Early conceptions of the moon had a lot...

...of sharp jagged features. When we finally got there, we found that pretty much everything was rounded off.

As for why the surface isn't covered by metres upon metres of dust, a few inches of dust will serve just as well as several killometres of atmostphere, to prevent deeper penetration. And bigger impacts will serve to keep up a good supply of bigger chunks for astronauts to manually dodge on landing.

There really is nothing unsurprising about solid moon, regolith, a bit of dust and a scattering or rocks and boulders (bottom to top). What is surprising, is that even really deep thinkers, managed to completely forget the role of liquid water freezing in spalling off big chunks of rock as temperatures swing between extremes. They just assumed -200 to +200 = lots and lots of fracturing.

[Javaman]

3. Suppose a CME did hit the moon, what would become of the

particulate matter? would it encircle the earth? Or go off into space?

[TheMadMonk]

5. Some will be given enough "oomph" to leave the Earth-Moon system.

Most will fall back to the moon or sink into Earth's deeper gravity well.