[meteorite-list] Giant Asteroid's Troughs Suggest Stunted Planet

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 26 Sep 2012 17:03:21 -0700 (PDT)
Message-ID: <201209270003.q8R03LPR012011_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2012-304

Giant Asteroid's Troughs Suggest Stunted Planet
Jet Propulsion Laboratory
September 26, 2012

Enormous troughs that wrap around the giant asteroid Vesta may actually
be dropped blocks of terrain bounded by fault lines, suggesting a
geologic complexity beyond that of most asteroids. Since the discovery
of the troughs last year in data from NASA's Dawn spacecraft, scientists
have been working to determine the story behind these unusual features.
The research reinforces the claim that Vesta has a core, mantle and
crust, a structure normally reserved for larger bodies, such as planets
and large moons.

An extensive system of troughs encircles Vesta's equatorial region. The
biggest of those troughs, named Divalia Fossa, surpasses the size of the
Grand Canyon. It spans 289 miles (465 kilometers) in length, 13.6 miles
(22 kilometers) in width and 3 miles (5 kilometers) in depth. The
complexity of the troughs' morphology can't be explained by small
collisions. New measurements from Dawn indicate that a large collision
could have created the asteroid's troughs, said Debra Buczkowski, a Dawn
participating scientist based at the Johns Hopkins University Applied
Physics Laboratory in Laurel, Md., who is the lead author of a new paper
in Geophysical Research Letters, a journal of the American Geophysical
Union. The crustal layer at the surface appeared to stretch to the
breaking point and large portions of the crust dropped down along two
faults on either side of the downward-moving block, leaving the giant
troughs we see today.

The scale of the fracturing would only have been possible if the
asteroid is differentiated - meaning that it has a core, mantle and
crust. "By saying it's differentiated," said Buczkowski, "we're
basically saying Vesta was a little planet trying to happen."

For more information on the paper, see
http://www.agu.org/news/press/pr_archives/2012/2012-42.shtml .

Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jia-rui.c.cook at jpl.nasa.gov
Sean Treacy 202-777-7516
American Geophysical Union, Washington
streacy at agu.org

2012-304
Received on Wed 26 Sep 2012 08:03:21 PM PDT