[meteorite-list] NASA's Dawn Prepares for Trek Toward Dwarf Planet Ceres

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 30 Aug 2012 09:36:48 -0700 (PDT)
Message-ID: <201208301636.q7UGamE9017823_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2012-271

NASA's Dawn Prepares for Trek Toward Dwarf Planet
Jet Propulsion Laboratory
August 30, 2012

PASADENA, Calif. - NASA's Dawn spacecraft is on track to become the
first probe to orbit and study two distant solar system destinations, to
help scientists answer questions about the formation of our solar
system. The spacecraft is scheduled to leave the giant asteroid Vesta on
Sept. 4 PDT (Sept. 5 EDT) to start its two-and-a-half-year journey to
the dwarf planet Ceres.

Dawn began its 3-billion-mile (5-billion kilometer) odyssey to explore
the two most massive objects in the main asteroid belt in 2007. Dawn
arrived at Vesta in July 2011 and will reach Ceres in early 2015. Dawn's
targets represent two icons of the asteroid belt that have been witness
to much of our solar system's history.

To make its escape from Vesta, the spacecraft will spiral away as gently
as it arrived, using a special, hyper-efficient system called ion
propulsion. Dawn's ion propulsion system uses electricity to ionize
xenon to generate thrust. The 12-inch-wide ion thrusters provide less
power than conventional engines, but can maintain thrust for months at a
time.

"Thrust is engaged, and we are now climbing away from Vesta atop a
blue-green pillar of xenon ions," said Marc Rayman, Dawn's chief
engineer and mission director, at NASA's Jet Propulsion Laboratory,
Pasadena, Calif. "We are feeling somewhat wistful about concluding a
fantastically productive and exciting exploration of Vesta, but now have
our sights set on dwarf planet Ceres.

Dawn's orbit provided close-up views of Vesta, revealing unprecedented
detail about the giant asteroid. The mission revealed that Vesta
completely melted in the past, forming a layered body with an iron core.
The spacecraft also revealed the scarring from titanic collisions Vesta
suffered in its southern hemisphere, surviving not one but two colossal
impacts in the last two billion years. Without Dawn, scientists would
not have known about the dramatic troughs sculpted around Vesta, which
are ripples from the two south polar impacts.

"We went to Vesta to fill in the blanks of our knowledge about the early
history of our solar system," said Christopher Russell, Dawn's principal
investigator, based at the University of California Los Angeles (UCLA).
"Dawn has filled in those pages, and more, revealing to us how special
Vesta is as a survivor from the earliest days of the solar system. We
can now say with certainty that Vesta resembles a small planet more
closely than a typical asteroid."

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

UCLA is responsible for the overall Dawn mission science. Orbital
Sciences Corp. of Dulles, Va., designed and built the spacecraft. The
German Aerospace Center, the Max Planck Institute for Solar System
Research, the Italian Space Agency and the Italian National
Astrophysical Institute are part of the mission's team. The California
Institute of Technology in Pasadena manages JPL for NASA.

For information about the Dawn mission, visit: http://www.nasa.gov/dawn
and http://dawn.jpl.nasa.gov .

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

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown at nasa.gov

2012-271
Received on Thu 30 Aug 2012 12:36:48 PM PDT


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