[meteorite-list] NASA's Dawn Spacecraft Begins Science Orbits of Vesta

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 1 Aug 2011 09:41:34 -0700 (PDT)
Message-ID: <201108011641.p71GfYtY019445_at_zagami.jpl.nasa.gov>

August 01, 2011

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

Priscilla Vega
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-1357
priscilla.r.vega at jpl.nasa.gov


RELEASE: 11-254

NASA'S DAWN SPACECRAFT BEGINS SCIENCE ORBITS OF VESTA

WASHINGTON -- NASA's Dawn spacecraft, the first ever to orbit an
object in the main asteroid belt, is spiraling toward its first of
four intensive science orbits. That initial orbit of the rocky world
Vesta begins Aug. 11, at an altitude of nearly 1,700 miles (2,700
kilometers) and will provide in-depth analysis of the asteroid. Vesta
is the brightest object in the asteroid belt as seen from Earth and
is thought to be the source of a large number of meteorites that fall
to Earth.

The Dawn team unveiled the first full-frame image of Vesta taken on
July 24:

http://go.nasa.gov/ohdkyh

This image was taken at a distance of 3,200 miles (5,200 kilometers).
Images from Dawn's framing camera, taken for navigation purposes and
as preparation for scientific observations, are revealing the first
surface details of the giant asteroid. These images go all the way
around Vesta, since the giant asteroid turns on its axis once every
five hours and 20 minutes.

"Now that we are in orbit around one of the last unexplored worlds in
the inner solar system, we can see that it's a unique and fascinating
place," said Marc Rayman, Dawn's chief engineer and mission manager
at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

After traveling nearly four years and 1.7 billion miles (2.8 billion
kilometers), Dawn has been captured by Vesta's gravity, and there
currently are 1,800 miles (2,900 kilometers) between the asteroid and
the spacecraft. The giant asteroid and its new neighbor are
approximately 114 million miles (184 million kilometers) away from
Earth.

"We have been calling Vesta the smallest terrestrial planet," said
Chris Russell, Dawn's principal investigator at the UCLA. "The latest
imagery provides much justification for our expectations. They show
that a variety of processes were once at work on the surface of Vesta
and provide extensive evidence for Vesta's planetary aspirations."

Engineers still are working to determine the exact time that Dawn
entered Vesta's orbit, but the team has reported an approximate orbit
insertion time of 9:47 p.m. PDT on July 15 (12:47 a.m. EDT on July
16).

In addition to the framing camera, Dawn's instruments include the
gamma ray and neutron detector and the visible and infrared mapping
spectrometer. The gamma ray and neutron detector uses 21 sensors with
a very wide field of view to measure the energy of subatomic
particles emitted by the elements in the upper yard (meter) of the
asteroid's surface. The visible and infrared mapping spectrometer
will measure the surface mineralogy of both Vesta and Dawn's next
target, the dwarf planet Ceres. The spectrometer is a modification of
a similar one flying on the European Space Agency's Rosetta and Venus
Express missions.

Dawn also will make another set of scientific measurements at Vesta
and Ceres using the spacecraft's radio transmitter in tandem with
sensitive antennas on Earth. Scientists will monitor signals from
Dawn and later Ceres to detect subtle variations in the objects'
gravity fields. These variations will provide clues about the
interior structure of these bodies by studying the mass distributed
in each gravity field.

"The new observations of Vesta are an inspirational reminder of the
wonders unveiled through ongoing exploration of our solar system,"
said Jim Green, planetary division director at NASA Headquarters in
Washington.

Dawn launched in September 2007. Following a year at Vesta, the
spacecraft will depart in July 2012 for Ceres, where it will arrive
in 2015. Dawn's mission to Vesta and Ceres is managed by JPL for
NASA's Science Mission Directorate in Washington. Dawn is a project
of the directorate's Discovery Program, managed by NASA's Marshall
Space Flight Center in Huntsville, Ala.

UCLA is responsible for overall Dawn mission science. Orbital Sciences
Corp. in 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 international partners on the mission team.

For more information about Dawn, visit:

http://www.nasa.gov/dawn
        
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Received on Mon 01 Aug 2011 12:41:34 PM PDT