Unusual meteorite found in Kansas

From: http://edition.cnn.com/2006/TECH/space/10/16/meteorite.kansas.ap/index.html

October 16, 2006

Workers from the Houston Museum of Natural Science lift a meteorite they dug up in a field near Greensburg, Kansas, on Monday.

GREENSBURG, Kansas (AP) -- Scientists located a rare meteorite in a wheat field thanks to new ground penetrating radar technology that someday might be used on Mars.

The dig in Kansas Monday was likely the most documented excavation yet of a meteorite find, with researchers painstakingly using brushes and hand tools in order to preserve evidence of the impact trail and to date the event of the meteorite strike. Soil samples were also bagged and tagged, and organic material preserved for dating purposes.

Even before they had the meteorite out of the ground, the scientific experts at the site were able to debunk prevailing wisdom that the spectacular meteorite fall of Brenham, Kansas, occurred 20,000 years ago. Its location in the Pleistocene epoch soil layer puts that date closer to 10,000 years ago.

"We know it is recent," said Carolyn Sumners, director of Astronomy at the Houston Museum of Natural Science, as she surveyed progress on the dig. "Native Americans could have seen it."

The scientific expedition of the meteorite strewn field in western Kansas was put together by the Houston Museum of Natural Science and led by meteorite hunters Steve Arnold and Philip Mani. Johnson Space Center's Lunar and Planetary Institute, the Rice Space Institute at Rice University and George Observatory in Houston also sent researchers.

Fewer than 1 percent of the meteorites discovered on earth are pallasite meteorites, known for their crystals embedded in iron, Mani said.

Sophisticated metal detectors at the site initially detected what had been thought to be the largest pallasite meteorite ever discovered. But ground penetrating radar showed that object to be a steel cable.

But with about a dozen potential targets on the site, the team still uncovered a sizeable pallasite buried four feet (1.2-meter) under the ground and located a quarter of a mile (0.4 kilometers) from where Arnold and Mani found the world's largest pallasite meteorite a year ago.

The newest find weighs 154 pounds (70 kilograms).

The Brenham field was discovered in 1882. Scientists have since traced pieces of the shower as far away as Indian mounds in Ohio, indicating the meteorites were traded as pieces of jewelry and ceremonial artifacts. The site was largely forgotten in recent decades until Arnold and Mani leased eight square miles (20 square kilometers) of it and began looking deep below the surface.

More than 15,000 pounds (6,800 kilograms) of meteorites have been recovered from the Brenham fall, with about a third of them found by the two men in the past year, Mani said. About three dozen meteorites have been pulled from the field by their Brenham Meteorite Co.