[meteorite-list] Violent Past Detailed By Moon Rocks

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun Apr 30 13:41:14 2006
Message-ID: <200604281940.MAA21117_at_zagami.jpl.nasa.gov>

http://barometer.orst.edu/v

Violent past detailed by moon rocks

OSU discovery might also shed light on the origin of life on Earth

By Mollie Holmes
Oregon State Daily Barometer
April 28, 2006

Recent research on lunar moon rocks indicate that the moon, and
therefore the Earth, were bombarded by meteorites 3.9 billion years ago.

And it might say more about when life began on the planet.

The rocks were originally gathered during the 1970s Apollo space
missions. Those rocks that have not yet been used for research lay in
storage in the Johnson Space Center in Houston, Texas.

Now, some of these rocks have made it to Corvallis.

These melted lunar fragments, were studied at the noble gas
geochronology laboratory at OSU.

A team at OSU led by Robert Duncan, professor and associate dean in the
College of Oceanic and Atmospheric Sciences, used radiometric dating
techniques to determine when the rocks had melted.

The collision of meteorites with the moon cause the moon's surface rock
to partially melt and turn to glass. At this time the rocks release
argon and begin to reaccumulate the argon through potassium decay.

"The formation of the glass from the melting is like starting a clock,"
Duncan said. ???It resets the time for us to determine billions of years
later."

Duncan's team studied about 50 different melted lunar fragments. All but
a few produced ages close to 3.9 billion years. This signals an influx
of meteorite activity.

"The evidence is clear that there was repeated bombardment by
meteorites," Duncan said. It is hard to find this type of proof on the
Earth due to erosion and the movement of plate tectonics.

"By comparison (to the Earth), the moon is dead, has no atmosphere and
provides a record of meteorite bombardment that we can only assume is
similar to that on Earth," Duncan said.

"The moon is like a library of what happened on our planet," continued
Duncan. "It is a record of geological events present on earth.

What is noticeable, however, is that the date of 3.9 billion years
coincides with the date many scientists believe life first began on earth.

"You get this coincidence,??? Duncan said. "Did life begin with
the end of the bombardment, or did it come with the meteorites?"

This information is also very helpful to NASA, which funded the
research. In 2015 NASA plans to return to the moon.

"The more we understand about the material we have about the moon, the
better we can allocate our limited resources," Duncan said. "We can't go
everywhere (on the moon). We need to know what to sample and where to
visit."
Received on Fri 28 Apr 2006 03:40:42 PM PDT