Moon rock found in Antarctic

September 15, 2006|By Frank D. Roylance | Frank D. Roylance,Sun Reporter

Scientists scooping meteorites from the Antarctic ice happened on what has proven to be a rare chunk of the moon, they announced Wednesday.

The meteorite was found 466 miles from the South Pole, but only 650 yards from where members of the U.S. Antarctic Search for Meteorites program were camped in the Miller Range of the Trans-antarctic Mountains.

It joins about 90 other known lunar meteorites or fragments, most collected in Antarctica or North Africa, where dry, barren conditions tend to preserve and reveal them.

Dubbed MIL 05035, the 5-ounce rock is just bigger than a golf ball, its surface made glossy black by a fiery entry into the Earth's atmosphere. Inside, its coarse, pinkish-tan grains are composed of ancient basalt and feldspar converted to glass by a violent shock.

"It's clearly had a rough life," said geologist Ralph P. Harvey of Case Western Reserve University in Cleveland. Its large crystals suggest it formed early in the moon's history and cooled slowly under a thick blanket of younger rocks. "The only other rock like that we've seen was one the Japanese Antarctic meteorite program found back in 1988."

The evidence of shock, he said, should teach geologists about a period of intense meteor bombardment of the inner solar system 3.8 billion to 3.9 billion years ago. The cause of that storm, which came and went, remains a mystery. "We don't have a really good explanation for it," he said.

Expeditions to search for meteorites in Antarctica are mounted each year during the southern summer, funded by NASA, the National Science Foundation and the Smithsonian Institution. MIL 05035 was found in December.

The rocks - most from interplanetary space but a few blasted off the moon and Mars - are easy to spot on white ice fields where the sky is the only source of rocks. Ice movements and evaporation also tend to concentrate eons of meteorite falls in particular locations. Last year's expedition recovered 238.

Samples of MIL 05035 - some as small as a hundredth of a gram - will be shared worldwide. Scientists will attempt to determine the material's age, as well as when a meteoroid strike blew it off the moon, and how long it floated in space before falling to Earth.

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Frank D. Roylance

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