CWRU |
The new lunar meteorite is shown here cracked open to reveal a pinkish-tan
interior. The cube, used for calibration, is 1 centimeter (a half-inch) on each side.
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Meteorite hunters have found a rock in Antarctica that they’ve traced to the moon – but it's a type of lunar rock that is virtually a geological terra incognita (or should that be luna incognita)? Experts say there’s only one other sample like it in the world.
Of course, there are plenty of moon rocks from the Apollo missions, but scientists say those rocks may actually be the exception in the big picture of lunar composition. So they’re anxious to start analyzing this handball-sized piece of the moon, known as MIL 05035.
Word of the find came today in a report from Case Western Reserve University in Ohio, headquarters for the U.S. Antarctic Search for Meteorites, or ANSMET. The lunar rock was found during ANSMET's outing last December, on an icefield in the Miller Range of the Transantarctic Mountains about three-fifths of a mile (600 meters) from the team's camp (and about 470 miles from the south pole).
The rock hunters found 238 meteorites in all during the six-week field season - a relatively small return, due to heavy snows that limited the team's search area. For that reason, MIL 05035 was a "particularly welcome find," the ANSMET team said.
Because what happens in Antarctica tends to stay in Antarctica, relatively undisturbed, the polar icefields are a good place to look for extraterrestrial rockfalls. The world's most famous Mars meteorite, ALH 84001, was found in Antarctica's Allan Hills region - and sparked a debate over whether the rock held evidence of Martian "nanofossils."
Like ALH 84001, the newfound lunar specimen was brought to classification experts at NASA's Johnson Space Center, as well as at the Smithsonian Institution's National Museum of Natural History.
The meteorite's composition led the experts to conclude that MIL 05035 was of lunar origin. In fact, the rock appeared to have cooled slowly deep within the moon's crust, and then was subjected to extreme shock - perhaps by the impact event that knocked the rock loose from the moon and sent it earthward.
Experts say the rock resembles only one other Antarctic meteorite - Asuka 881757, which was found 18 years ago and represents one of the earliest specimens to be identified as lunar basalt. ANSMET's report emphasizes that MIL 05035 isn't your run-of-the-mill space rock:
"Like the other lunar meteorites, MIL 05035 is a piece of the moon that can be studied in detail in the laboratory, providing new specimens from a part of the lunar surface not sampled by the U.S. Apollo program. Many researchers believe that Apollo visited some of the most unusual and geochemically anomalous regions of the moon, and lunar meteorites, knocked off the surface of the moon by random impacts, give us samples that are more representative of the moon as a whole. The highly shocked nature of MIL 05035 suggests an old age and may provide new constraints on the early intense bombardment of the Earth-moon system, improving our understanding of the history of the Earth's nearest neighbor and aiding NASA's efforts toward a return to the moon."
Scientists around the world are invited to request chips of the new specimen for their own research. For further details about NASA's Antarctic meteorite program, consult the Antarctic Meteorite Newsletter. For more about lunar meteorites in particular, and check out this Web page for more about lunar meteorites in particular. And if you're a rockhound who's thinking it might be fun to hunt for meteorites during the next Antarctic field season, think again ... then check out this FAQ file from ANSMET.
