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UCLA-Led
Project Will Send Spacecraft
to Study the Origins of the Solar System
Dawn Mission to Study Ceres and Vesta, the Largest Asteroids
The Office of Space Science at NASA has approved the "Dawn
Mission," a UCLA-led project that will develop a spacecraft
to orbit and study Ceres and Vesta, the two largest asteroids
(minor planets) in our solar system.
The Dawn Mission marks the first time that a spacecraft
will orbit two planetary bodies on the same mission.
Christopher T. Russell, professor in the Department of Earth
and Space Sciences at UCLA, will direct the Dawn mission.
According to current theories, the differing properties
of Vesta and Ceres are the result of these minor planets being
formed and evolving in different parts of the solar system.
By observing both minor planets with the same set of instruments,
Dawn will provide new answers to questions about the formation
and evolution of the early solar system.
The Dawn mission will launch in May 2006. It will study
Vesta beginning in July 2010, and Ceres beginning in August
2014.
This Web page contains general background material about
the Dawn mission. For the Web site of the Dawn science team,
visit http://www-ssc.igpp.ucla.edu/dawn.
The Dawn Mission is part of NASA's Discovery Program, an
initiative for lower-cost, highly focused, rapid-development
scientific spacecraft. The Discovery Program is managed by
NASA's Jet Propulsion Laboratory, for the Office of Space
Science, Washington, D.C. For more information about the Discovery
Program, visit http://discovery.nasa.gov.
The Discovery Program is part of NASA's initiative for lower-cost,
highly focused, rapid-development scientific spacecraft. The
Discovery Program is managed by NASA's Jet Propulsion Laboratory,
for the Office of Space Science, Washington, D.C.
This Web site contains background material
about the Dawn mission. The sections include:
The
Dawn Mission
The Dawn Mission: Why Ceres
and Vesta?
Ceres
Vesta
Dawn Mission Overview
The Dawn Spacecraft
Dawn: Mission Management
Dawn: Science Team
Ion Propulsion
The Discovery Program
Attempting to Answer
the Fundamental Questions
The Discovery Program Objectives
Asteroids, Discovery
Program and the Dawn Mission: More Information
The Dawn Mission
The goal of the Dawn mission is to understand the conditions
and processes during the earliest history of our solar system.
To accomplish this mission, Dawn will explore the structure
and composition of Ceres and Vesta, two minor planets that
have many contrasting characteristics and have remained intact
since their formation more than 4.6 billion years ago.
The Dawn mission will launch from Cape Canaveral on May
27, 2006. After more than four years of travel, the spacecraft
will rendezvous with Vesta on July 30, 2010. Dawn will then
orbit Vesta for almost a year, studying its basic structure
and composition.
On July 3, 2011, Dawn will leave orbit around Vesta for
a three-year cruise to Ceres. Dawn will rendezvous with Ceres
and begin orbit on August 20, 2014, and conduct studies and
observations until July 26, 2015. After the exploration of
Ceres, and more than nine years of space travel, Dawn may
continue with additional exploration of the asteroid belt.
The Dawn mission is led by UCLA space scientist Christopher
T. Russell. Team members include scientists from the German
Aerospace Center (DLR), The Institute for Space Astrophysics
in Rome, the Jet Propulsion Laboratory, Los Alamos National
Laboratory, University of Hawaii, University of Maryland,
University of Tennessee (Knoxville), Brown University, NASA
Goddard Space Flight Center, University of Arizona and Massachusetts
Institute of Technology.
Orbital Sciences Corporation will construct the spacecraft,
and the Jet Propulsion Laboratory will provide the ion engines
and management of the overall flight system development. The
German Aerospace Center will provide the framing camera, and
the Institute for Space Astrophysics in Rome will provide
the mapping spectrometer.
Educators from New Roads School in Santa Monica, Calif.,
and Mid-continent Research for Education and Learning (McREL),
Aurora, Colo., will develop standards-based learning materials
for people of all ages, helping to bring the mission into
classrooms and homes across the nation.
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The Dawn Mission: Why Ceres and
Vesta?
The Dawn mission focuses on two of the first bodies formed
in our solar system, the minor planets Ceres and Vesta.
Studies of meteorites believed to be from Vesta that were
found on Earth suggest that this body formed from dust in
the solar nebula within 5-15 million years of the time the
solar system evolved about about 4.6 billion years ago. Although
no meteorites from Ceres have yet been found, this body also
formed during the first 10 million years of the solar system's
existence. Today Ceres and Vesta represent two of the few
large protoplanets that have not been heavily damaged by collisions
with other bodies.
Ceres and Vesta feature striking contrasts in composition.
Scientists believe many of these differences stem from the
conditions under which Ceres and Vesta formed, with Ceres
forming wet and Vesta dry. Evidence of water -- frost or vapor
on the surface, and possibly liquid water under the surface
-- still exist on Ceres; this water kept Ceres cool throughout
its evolution. At the same time, Vesta was hot, melted internally
and became volcanic early in its development. As a result
of these two different evolutionary paths, Ceres remains in
its primordial state, while Vesta evolved and changed over
millions of years.
Because these bodies lie near the plane of the Earth's orbit,
they can both be studied with a single mission. The Dawn mission
will help us understand the evolution of the interior structure
and thermal history of Ceres and Vesta -- information that
provides keys to the secrets of the creation of our solar
system.
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Dawn Mission: The Minor Planets
- Ceres
Ceres, the largest asteroid in our solar system, is a roughly
round object about 600 miles in diameter. It orbits the sun
in the asteroid belt between Mars and Jupiter approximately
258 million miles from Earth.
The year 2001 marks the 200th anniversary of the discovery
of Ceres by Giuseppe Piazzi in 1801 with a small telescope
atop the royal palace in Palermo. At first Piazzi believed
he had found the missing planet expected to be in the region
we now call the asteroid belt. However this minor planet turned
out to be very small indeed, only one-quarter of the diameter
of the Earth's moon.
Ceres was the first asteroid to be discovered in our solar
system. Additional observations by Piazzi were cut short due
to illness. Carl Friedrich Gauss, at the age of 24, was able
to solve a system of 17 linear equations to allow Ceres to
be rediscovered, a remarkable feat for this time. Within one
year of its initial discovery, both H. Olbers and Franz von
Zach were also able to re-identify Ceres.
Ceres was named after the Roman goddess of agriculture.
It circles the sun in 4.6 terrestrial years.
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Dawn Mission: The Minor Planets
- Vesta
Vesta is the brightest asteroid in our solar system, and
is the only one visible with the unaided eye; its oval, pumpkin-like
shape has an average diameter of about 320 miles. Vesta is
the second most massive minor planet. Found on March 29, 1807,
by Heinrich Wilhelm Matthäus Olbers, it was the fourth
minor planet to be discovered.
Named for the ancient Roman goddess of the hearth, Vesta
is approximately 220 million miles from Earth. It circles
the sun in 3.6 terrestrial years.
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Dawn Mission Overview
May 27, 2006:
- Launch from Cape Canaveral on a Delta 7925H rocket
July 30, 2010 - July 3, 2011:
- Rendezvous with Vesta (nine month study)
- Orbit at 420 and 80 miles
July 3, 2011 - August 20, 2014:
- Cruise to Ceres
August 20, 2014 - July 26, 2015:
- Rendezvous with Ceres (nine-month study)
- Orbit at 530 and 80 miles
July 26, 2015:
- Observation of Ceres concludes
- Possible continuing exploration in the asteroid belt
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The Dawn Spacecraft
With a two-stage, nine-year journey to study the minor planets
Ceres and Vesta, Dawn will become the first spacecraft to
orbit two planetary bodies during the same mission.
To accomplish its mission to study the physical structure
and evolution of asteroids Ceres and Vesta, Dawn would carry:
A framing camera provided by the German Aerospace Center (DLR),
Institute of Space Sensor Technology and Planetary Exploration
A mapping spectrometer provided by the Institute for Space
Astrophysics in Rome
A laser altimeter provided by the NASA Goddard Space Flight
Center
A gamma ray spectrometer from the Department of Energy's Los
Alamos National Laboratory
A magnetometer provided by UCLA
The Dawn spacecraft will be built using construction methods
and components that have been used successfully in many other
satellites, including Deep Space 1, Orbview, the Topex-Poseidon
ocean topography mission and the Far Ultraviolet Spectrum
Explorer. The Dawn spacecraft will also be the first fully
scientific space mission to use ion propulsion to power the
spacecraft's journey.
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Dawn: Mission
Management
UCLA:
Science lead -- Science operations, data products, archiving
and analysis
German Aerospace Center (DLR),
Institute of Space Sensor Technology and Planetary Exploration:
Framing camera and mapping spectrometer: Integration, testing,
sequencing and analysis
Jet Propulsion Laboratory (JPL):
Project management, systems engineering, mission assurance,
payload, SEP, navigation, mission operations, level zero data
Orbital Science Corporation:
Spacecraft design and construction
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Dawn: Science
Team
A. Coradini Institute for Space Astrophysics (IAS), Rome
W. C. Feldman Los Alamos National Laboratory (LANL)
R. Jaumann Institute of Space Sensor Technology and Planetary
Exploration,
German Aerospace Center (DLR)
A. S. Konopliv Jet Propulsion Laboratory (JPL)
T. B. McCord University of Hawaii
L. A. McFadden University of Maryland
H. Y. McSween University of Tennessee, Knoxville
S. Mottola DLR
G. Neukum DLR
C. M. Pieters Brown University
C. A. Raymond JPL
C. T. Russell UCLA (project director)
D. E. Smith NASA Goddard Space Flight Center
M. V. Sykes University of Arizona
B. Williams JPL
M. T. Zuber Massachusetts Institute of Technology
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Ion Propulsion
The Dawn spacecraft would be the first purely scientific
mission to be powered by ion propulsion, an advanced technology
now being used by NASA's Deep Space 1 mission.
The principle behind the ion engines is much the same as
the phenomenon you experience when you pull hot socks out
of the clothes dryer on a cold winter day. The socks push
away from each other because they are electrostatically charged,
and like charges repel. The challenge in electric space propulsion
is to charge a fluid so its atoms can be expelled in one direction,
and thus propel the spacecraft in the other direction.
Unlike chemical rocket engines, ion engines accelerate 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, that is more than 4 times heavier than
air.
When the ion engine is running, electrons are emitted from
a hollow tube called a cathode. These electrons enter a magnet-ringed
chamber, where they strike the xenon atoms. The impact of
an electron on a xenon atom knocks away one of xenon's 54
electrons. This results in a xenon atom with a positive charge
-- a xenon ion.
At the rear of the chamber, a pair of metal grids is charged
positively and negatively. The force of this electric charge
exerts a strong electrostatic pull on the xenon ions. The
xenon ions shoot out the back of the engine at a speed of
68,000 mph.
At full throttle, the ion engine consumes 2,500 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. That is far less thrust than is produced
by even small chemical rockets. But an ion engine can run
for months or even years, and despite the almost imperceptible
thrust, 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.
The ion propulsion system on NASA's Deep Space 1 spacecraft
won Discover Magazine's Award for Technological Innovation.
For more information about NASA developments in ion propulsion,
visit NASA's site http:nasa.gov
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The Discovery
Program
NASA's Discovery program offers the scientific community
opportunities to accomplish frequent scientific investigations
using innovative and efficient management approaches. It seeks
to keep performance high and expenses low by using new technologies
and strict cost caps. Proposals require careful tradeoffs
between science and cost to produce investigations with the
highest possible science value for the price.
Discovery solicits mission proposals that are assembled
by a team from industry, small businesses, government laboratories
and universities. The goal is to launch these smaller missions
every 12-24 months at a cost of less than $299 million.
The Discovery Program is managed at NASA's Jet Propulsion
Laboratory, a division of the California Institute of Technology,
Pasadena, for the Office of Space Science, Washington, D.C.
More information on the Discovery Program is available at
http://discovery.nasa.gov.
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Attempting
to Answer the Fundamental Questions
The Space Science Enterprise Strategic Plan published by
NASA in November 1997 addresses the concept of cosmic origins,
evolution and destiny -- how the universe began, how life
on Earth originated and what fate awaits our planet and our
species. All that we do in space science is part of a quest
to understand our cosmic origins and destiny, and how these
are linked by cycles of evolution. In response, the space
science community has formulated the following fundamental
questions that lie at the core of gaining this understanding:
How did the universe, galaxies, stars and planets evolve?
How can our exploration of the universe and our solar system
revolutionize our understanding of physics, chemistry and
biology?
Does life in any form exist elsewhere than on planet Earth?
Are there Earth-like planets beyond our solar system?
How can we use knowledge of the Sun, Earth and other planetary
bodies to improve the quality of life on Earth? What cutting
edge technologies must we develop to conduct our research
in the most productive, economical and timely manner?
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The Discovery
Program Objectives
The Discovery Program's prime objective is to enhance our
understanding of the solar system by providing answers to
these fundamental questions. Discovery missions explore the
planets, their moons and other small bodies within the solar
system, either by traveling to them or by remote examination.
Discovery also studies planetary systems beyond our solar
system.
Discovery also offers a Mission of Opportunity program which
allows investigators to participate in a non-NASA mission,
typically sponsored by non-U.S. governments, other U.S. government
agencies or private sector organizations. This participation
could include providing a complete science instrument, hardware
components of a science instrument or expertise in critical
areas of the mission.
Eight Discovery Missions have been chosen to date, including
the Near Earth Asteroid Rendezvous, the Mars Pathfinder Mission,
the Lunar Prospector, the Stardust spacecraft, the Genesis
spacecraft, the Comet Nucleus Tour, the MESSENGER mission
and the Deep Impact Mission.
More information about the Discovery program and its missions
is available at http://discovery.nasa.gov.
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Asteroids,
Discovery Program and the Dawn Mission: More Information
Dawn Mission -- online media information:
http://www.college.ucla.edu/dawn
Dawn Mission -- technical background:
http://www-ssc.igpp.ucla.edu/dawn
Interviews with Dawn team members:
UCLA: Harlan Lebo, (310) 206-0510
UCLA: Stuart Wolpert, (310) 206-0511
JPL contact:
D.C. Agle, (818) 393-9011
Information about the Discovery Program and the NASA Office
of Space Science:
NASA: Don Savage, (202) 358-1727
Asteroids -- An Introduction:
http://www.solarviews.com/eng/asteroid.htm
Ceres:
See the paper "Bode's Law and the Discovery of Ceres"
by Michael Hoskin, at
http://www.astropa.unipa.it/versione_inglese/Hystory/BODE'S_LAW.htm
Vesta:
http://www.solarviews.com/eng/vesta.htm
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accountability report