[meteorite-list] UCLA Professor Christopher Russell Leads NASA's Dawn Mission

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 26 Jun 2007 14:57:50 -0700 (PDT)
Message-ID: <200706262157.OAA05619_at_zagami.jpl.nasa.gov>

http://newsroom.ucla.edu/page.asp?RelNum=8052

Date: June 26, 2007
Contact: Stuart Wolpert ( swolpert at support.ucla.edu )
Phone: 310-206-0511

UCLA Professor Christopher Russell Leads NASA's Dawn Mission, a Journey
Through Space and Time, Scheduled for July 7 Launch

Christopher T. Russell, UCLA professor of geophysics and space physics,
has spent 15 years working on NASA's Dawn mission to the doughnut-shaped
asteroid belt between Mars and Jupiter. As the scheduled July 7 launch
from Cape Canaveral nears, Russell is ready, and so is Dawn.

"The spacecraft will spend much less time in space than we put in
preparing for the mission," said Russell, the mission's principal
investigator. "I want to get this spacecraft up in space, where it
belongs. I'm really confident about the spacecraft. We've been testing
and retesting."

Dawn will conduct a detailed study of the structure and composition of
two of the first bodies formed in our solar system: the "dwarf planet"
Ceres and the massive asteroid Vesta. The mission's goals include
determining the shape, size, composition, internal structure, and the
tectonic and thermal evolution of Vesta and Ceres. Dawn, which will be
the first spacecraft to orbit two planetary bodies on the same mission,
is expected to reveal the conditions under which these objects formed.
Comparing their different evolutionary paths will provide evidence about
the role of size and water in planetary evolution.

Dawn is scheduled to fly past Mars by April 2009, and after more than
four years of travel, the spacecraft will rendezvous with Vesta in 2011.
The spacecraft will orbit Vesta for approximately nine months, studying
its structure and composition. In 2012, Dawn will leave for a three-year
cruise to Ceres. Dawn will rendezvous with Ceres and begin orbit in
2015, conducting studies and observations for at least five months.

"I think of Dawn as two journeys," said Russell, who proposed the
mission to NASA. "One is a journey into space. This is analogous to what
ancient explorers did, who knew there was unexplored territory and
wanted to discover what was there. We're going to explore a region for
the first time to find out what the conditions are today.

"Dawn is also a journey back in time. Ceres and Vesta have been altered
much less than other bodies. The Earth is changing all the time; the
Earth hides its history, but we believe that Ceres and Vesta, formed
more than 4.6 billion years ago, have preserved their early record.
They're revealing information that was frozen into their ancient
surfaces. By looking at the surface and how it was modified by the
bombardment of meteoroids, we will get an idea of what the early
conditions of Ceres and Vesta were and how they changed. So Dawn is a
history trip too. We're going back in time to the early solar system."

Ceres could harbor life.

"Evidence indicates it has substantial water or ice beneath its rocky
crust," Russell said. "Our instruments on board will be able to
determine whether there is water."

Dawn's instruments include a gamma ray and neutron spectrometer that can
detect the hydrogen from water.

Evidence of whether water still exists on Ceres could come from frost or
vapor on the surface, and possibly liquid water under the surface. The
water kept Ceres cool throughout its evolution. In contrast, Vesta was
hot, melted internally and became volcanic early in its development.
Ceres remains closer to its primordial state, while Vesta evolved
further over the first few millions of years of its existence, Russell said.

Ceres, named for the Roman goddess of agriculture, revolves around the
sun every 4.6 terrestrial years and has an average diameter of
approximately 600 miles. A roughly round object, Ceres orbits the sun in
the asteroid belt between Mars and Jupiter, approximately 258 million
miles from Earth. Ceres is much larger than Vesta - more than two times
further across, with a volume eight or nine times greater - but is less
dense, as the material in it is lighter.

Vesta, the brightest asteroid, is named for the ancient Roman goddess of
the hearth. Approximately 220 million miles from Earth, it appears to be
essentially solid rock, with a density similar to Mars. It orbits the
sun every 3.6 terrestrial years, has an oval, pumpkin-like shape, and
has an average diameter of approximately 320 miles. Vesta's basaltic
dust layer reflects its crustal composition, and its dry surface
includes a huge crater near its southern pole.

Studies of meteorites believed to be from Vesta that were found on Earth
suggest that this body formed from galactic dust during the solar
system's first 3 to 10 million years. Although no meteorites from Ceres
have been found, it is believed this body also formed during the first
10 million years of the solar system's existence, Russell said.

Dawn is expected to bring high-resolution images of previously unseen
worlds to the public, including, perhaps, mountains, canyons, craters
and ancient lava flows. In addition to the images, Dawn will generate
data that will help scientists identify geologic minerals and will take
measurements of gamma rays and neutrons. The gamma-ray measurements will
reveal which elements are in the minerals. The data are expected to
arrive a scant 30 minutes after the spacecraft obtains them.

Dawn, which will orbit as close as 125 miles from Ceres and Vesta, is
the first purely scientific mission designed to be powered by an
advanced NASA technology known as ion propulsion. Unlike chemical rocket
engines, ion engines accelerate their fuel nearly continuously, giving
each ion a tremendous burst of speed. The fuel used by an ion engine is
xenon, a gas also used in photo-flash units, which is more than four
times heavier than air. This results in a xenon atom with a positive
charge - a xenon ion. The xenon ions shoot out the back of the engine at
a speed of 78,000 miles per hour.

At full throttle, the ion engine consumes 2,300 watts of electrical
power and produces 1/50th of a pound of thrust - about the same pressure
as a sheet of paper resting on the palm of a hand, and far less thrust
than is produced by even small chemical rockets. This engine, for a
given amount of fuel, can gradually increase a spacecraft's velocity 10
times more than can a conventional rocket powered by liquid or solid fuel.

UCLA is in charge of Dawn's science and public outreach. Russell leads
the science team, brings together the mission's partners, manages the
budget and participates in all major decisions. Russell and his
colleagues will make science decisions and develop the operations plans
through the science center at UCLA's Institute of Geophysics and
Planetary Physics. His science team has the lead role for analyzing and
interpreting the data from Dawn. UCLA graduate students and postdoctoral
scholars will work on the mission, including helping to analyze the data
from Dawn.

Dawn is part of NASA's Discovery Program, in which scientists find
innovative ways to unlock the mysteries of our solar system by answering
some of humanity's oldest questions. The Discovery Program is managed by
NASA's Marshall Space Flight Center for the Science Mission Directorate.

"Why do we explore the solar system?" asked Russell, who has published
more than 1,000 scientific papers. "Why did Lewis and Clark go across
the U.S. at the start of the 19th century? We're not going to expand the
human race off this planet for a long time, but discovering our origins
and how the solar system evolved is valuable in itself. Mankind has
always expanded horizons. Exploration is a human imperative."

Team members include scientists from the Jet Propulsion Laboratory, the
NASA Goddard Space Flight Center, the U.S. Department of Energy's Los
Alamos National Laboratory, the Massachusetts Institute of Technology
and other institutions. Orbital Sciences Corp. is building the
spacecraft, and JPL is providing the ion engines.

"I'm putting my entire being into doing this mission; it's
all-consuming, but fun," said Russell of the 80-hour weeks he has been
working.

For more information, visit Dawn's Web site at http://dawn.jpl.nasa.gov .

UCLA is California's largest university, with an enrollment of nearly
37,000 undergraduate and graduate students. The UCLA College of Letters
and Science and the university's 11 professional schools feature
renowned faculty and offer more than 300 degree programs and majors.
UCLA is a national and international leader in the breadth and quality
of its academic, research, health care, cultural, continuing education
and athletic programs. Four alumni and five faculty have been awarded
the Nobel Prize.

-UCLA-

SW300
Received on Tue 26 Jun 2007 05:57:50 PM PDT