Dwayne C. Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown@nasa.gov
Priscilla Vega
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-1357
priscilla.r.vega@jpl.nasa.gov
RELEASE: 11-235
NASA DAWN SPACECRAFT RETURNS CLOSE-UP IMAGE OF ASTEROID VESTA
PASADENA, Calif. -- NASA's Dawn spacecraft has returned the first
close-up image after beginning its orbit around the giant asteroid
Vesta. On Friday, July 15, Dawn became the first probe to enter orbit
around an object in the main asteroid belt between Mars and Jupiter.
The image taken for navigation purposes shows Vesta in greater detail
than ever before. When Vesta captured Dawn into its orbit, there were
approximately 9,900 miles (16,000 kilometers) between the spacecraft
and asteroid. Engineers estimate the orbit capture took place at 10
p.m. PDT.
Vesta is 330 miles (530 kilometers) in diameter and the second most
massive object in the asteroid belt. Ground- and space-based
telescopes have obtained images of Vesta for about two centuries, but
they have not been able to see much detail on its surface.
"We are beginning the study of arguably the oldest extant primordial
surface in the solar system," said Dawn principal investigator
Christopher Russell from the University of California, Los Angeles.
"This region of space has been ignored for far too long. So far, the
images received to date reveal a complex surface that seems to have
preserved some of the earliest events in Vesta's history, as well as
logging the onslaught that Vesta has suffered in the intervening
eons."
Vesta is thought to be the source of a large number of meteorites that
fall to Earth. Vesta and its new NASA neighbor are currently
approximately 117 million miles (188 million kilometers) away from
Earth. The Dawn team will begin gathering science data in August.
Observations will provide unprecedented data to help scientists
understand the earliest chapter of our solar system. The data also
will help pave the way for future human space missions.
After traveling nearly four years and 1.7 billion miles (2.8 billion
kilometers), Dawn also accomplished the largest propulsive
acceleration of any spacecraft, with a change in velocity of more
than 4.2 miles per second (6.7 kilometers per second), due to its ion
engines. The engines expel ions to create thrust and provide higher
spacecraft speeds than any other technology currently available.
"Dawn slipped gently into orbit with the same grace it has displayed
during its years of ion thrusting through interplanetary space," said
Marc Rayman, Dawn chief engineer and mission manager at NASA's Jet
Propulsion Laboratory (JPL) in Pasadena, Calif. "It is fantastically
exciting that we will begin providing humankind its first detailed
views of one of the last unexplored worlds in the inner solar
system."
Although orbit capture is complete, the approach phase will continue
for about three weeks. During approach the Dawn team will continue a
search for possible moons around the asteroid; obtain more images for
navigation; observe Vesta's physical properties; and obtain
calibration data.
In addition, navigators will measure the strength of Vesta's
gravitational tug on the spacecraft to compute the asteroid's mass
with much greater accuracy than has been previously available. That
will allow them to refine the time of orbit insertion.
Dawn will spend one year orbiting Vesta, then travel to a second
destination, the dwarf planet Ceres, arriving in February 2015. The
mission to Vesta and Ceres is managed by JPL 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 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.
To view the image and obtain more information about the Dawn mission,
visit:
To follow the mission on Twitter, visit:
http://www.twitter.com/NASA_Dawn
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