Testing Moonrocks

StarDate: July 23, 2009

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The 12 astronauts who walked on the Moon gathered more than 840 pounds of lunar rocks and soil. Those samples have helped scientists decipher the Moon's birth, its history, and its structure. And they're still teaching us lessons about the Moon today.

In January, for example, researchers at MIT reported that the young Moon had a molten core, which generated a weak magnetic field. Their work was based on a rock from the last Apollo mission.

The Apollo samples have been preserved in a lab at the Johnson Space Center in Houston. Several hundred pounds remain. As new techniques and tests are invented, that allows scientists to take a fresh look at the samples.

The MIT team, for example, used a device that probed the magnetism at many points inside a small fragment of a rock that's 4.2 billion years old. The device is far more powerful than anything that was available at the time of the Apollo missions.

The magnetism of most of the Apollo rocks was "reset" by impacts on the lunar surface. But this rock maintained the magnetism of the Moon itself.

The findings suggest that when the Moon was just 300 million years old, its core was molten. As the Moon turned on its axis, the core and the surrounding rock rotated at different rates, creating a magnetic field -- the same process that powers Earth's magnetic field today.

Researchers will continue to probe the Apollo rocks for decades to come -- unlocking new secrets about the Moon.

Script by Damond Benningfield, Copyright 2009

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