[meteorite-list] NASA Scientists Find Moon, Asteroids Share History

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 25 Mar 2013 16:40:28 -0700 (PDT)
Message-ID: <201303252340.r2PNeSEU001157_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2013-114

NASA Scientists Find Moon, Asteroids Share History
Jet Propulsion Laboratory
March 25, 2013

PASADENA, Calif. - NASA and international researchers have discovered
that Earth's moon has more in common than previously thought with large
asteroids roaming our solar system.

Scientists from NASA's Lunar Science Institute (NLSI) in Moffett Field,
Calif., discovered that the same population of high-speed projectiles
that impacted our lunar neighbor four billion years ago, also hit the
giant asteroid Vesta and perhaps other large asteroids.

The research unveils an unexpected link between Vesta and the moon, and
provides new means for studying the early bombardment history of
terrestrial planets. The findings are published in the March issue of
Nature Geoscience.

"It's always intriguing when interdisciplinary research changes the way
we understand the history of our solar system," said Yvonne Pendleton,
NLSI director. "Although the moon is located far from Vesta, which is in
the main asteroid belt between the orbits of Mars and Jupiter, they seem
to share some of the same bombardment history."

The findings support the theory that the repositioning of gas giant
planets like Jupiter and Saturn from their original orbits to their
current location destabilized portions of the asteroid belt and
triggered a solar system-wide bombardment of asteroids billions of years
ago, called the lunar cataclysm.

The research provides new constraints on the start and duration of the
lunar cataclysm, and demonstrates that the cataclysm was an event that
affected not only the inner solar system planets, but the asteroid belt
as well.

The moon rocks brought back by NASA Apollo astronauts have long been
used to study the bombardment history of the moon. Now the ages derived
from meteorite samples have been used to study the collisional history
of main belt asteroids. In particular, howardite and eucrite meteorites,
which are common species found on Earth, have been used to study
asteroid Vesta, their parent body. With the aid of computer simulations,
researchers determined that meteorites from Vesta recorded high-speed
impacts which are now long gone.

Researchers have linked these two datasets and found that the same
population of projectiles responsible for making craters and basins on
the moon were also hitting Vesta at very high velocities, enough to
leave behind a number of telltale, impact-related ages.

The team's interpretation of the howardites and eucrites was augmented
by recent close-in observations of Vesta's surface by NASA's Dawn
spacecraft. In addition, the team used the latest dynamical models of
early main belt evolution to discover the likely source of these high
velocity impactors. The team determined that the population of
projectiles that hit Vesta had orbits that also enabled some objects to
strike the moon at high speeds.

"It appears that the asteroidal meteorites show signs of the asteroid
belt losing a lot of mass four billion years ago, with the escaped mass
beating up on both the surviving main belt asteroids and the moon at
high speeds" says lead author Simone Marchi, who has a joint appointment
between two of NASA's Lunar Science Institutes, one at the Southwest
Research Institute in Boulder, Colo., and another at the Lunar and
Planetary Institute in Houston. "Our research not only supports the
current theory, but it takes it to the next level of understanding."

The NLSI is headquartered at NASA Ames Research Center, Moffett Field,
Calif. The Dawn mission to Vesta and Ceres is managed by NASA's Jet
Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission
Directorate, Washington. Dawn is a project of the directorate's
Discovery Program, managed by NASA's Marshall Space Flight Center in
Huntsville, Ala.

To learn more about NLSI, visit: http://lunarscience.nasa.gov .

For more information about the Dawn mission, visit: www.nasa.gov/dawn
<http://www.nasa.gov/dawn> .

Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook at jpl.nasa.gov

Karen Jenvey 650-604-4789
Ames Research Center, Moffett Field, Calif.
karen.jenvey at nasa.gov

2013-114
Received on Mon 25 Mar 2013 07:40:28 PM PDT