Orbital Dawn User Manual
LEO
Planetary
Exploration
Dawn
Investigating the "Dawn" of Our Solar System
FACTS AT A GLANCE
Mission Description
Dawn is a planetary space science mission funded by NASA’s Discovery Program for which Orbital is
partnered with Principal Investigator Chris Russell of UCLA and the Jet Propulsion Laboratory (JPL).
Dawn’s primary scientic objective is to advance our understanding of the origin and evolution of
the solar system by studying two of the largest asteroids, Vesta and Ceres, which appear to have
remained intact since their formation 4.6 billion years ago. Earth-based studies indicate that these two
protoplanets have very different and complementary compositions which may provide clues to the
conditions and processes of planetary formation.
Powered by solar electric ion propulsion, the Dawn spacecraft has traveled to the main asteroid
belt between Mars and Jupiter. In July 2011 Dawn arrived at Vesta and spent a year orbiting the
asteroid conducting remote sensing observations using a suite of science instruments. The spacecraft
departed Vesta in August 2012 and is currently en-route to Ceres where it will perform the same set of
measurements.
About Dawn's Ion Propulsion
The Dawn spacecraft is NASA's rst purely scientic mission powered by solar electric ion propulsion,
the world’s most advanced and efcient space propulsion technology. Ion propulsion is providing
the velocity needed for its journey to Vesta. Ion propulsion will also be used during asteroid proximity
operations to raise and lower the orbit altitude. Dawn’s ion propulsion system is based on the
technology successfully demonstrated by Deep Space 1.
Vesta, the brightest asteroid, is named
for the ancient Roman goddess of the
hearth and is the only asteroid visible
with the naked eye.
Ceres, the largest asteroid and the rst
to be discovered, revolves around the
Sun once every 4.6 terrestrial years and
has a diameter estimated at about 960
km (575 miles).
The ion propulsion system employed
by Dawn and pioneered on NASA's
Deep Space 1 mission represents
the culmination of over 50 years of
development of electric engine systems
in space begun by Dr. Wernher von
Braun.
Mission:
NASA Discovery program
Customer:
UCLA, Jet Propulsion Laboratory
Dawn prior to launch
Dawn
Specications
Spacecraft
Mass: 1,210 kg (2,668 lb.) at launch, 740 kg (1,631 lb.) dry
Dimensions: 20 m (65 ft) tip-to-tip, spacecraft body is 2 m (6 ft)
high from separation plane to instrument deck
Power: Gallium Arsenide triple junction solar arrays, 10 kW
at Earth and 1.4 kW at Ceres
Communications: Deep Space Network – compatible with science
downlink rates of 41-128 kbps
Propulsion: Solar-electric propulsion using three gimbaled
NSTAR ion engines and monopropellant reaction
control system
Orbit Altitude: At target asteroids: As high as 4,500 km and as low
as 25 km
Mission Life: 10 years
Reliability: Redundant and cross-strapped spacecraft bus
electronics
Heritage: GALEX, SORCE, Deep Space 1, STAR
™
Bus
Status: Fully operational
Launch
Launch Vehicle: Delta II 7925H
Site: Kennedy Space Center
Date: September 27, 2007
Instruments
Two Framing Cameras (MPS/DLR)
Visible and Infrared Mapping Spectrometer (ASI/INAF)
Gamma Ray and Neutron Detector (LANL)
Diagram of Dawn Spacecraft
Key Mission Partners
UCLA, Jet Propulsion Laboratory
Principal Investigator: Dr. Christopher Russell; project
management, system engineering, ion propulsion
subsystem, science operations and spacecraft ight
operations
Orbital Sciences Corporation
Spacecraft design, integration and test, ight software,
and launch operations
Max Planck Institute for Solar System Research/
German space agency (MPS/DLR)
Katlenburg-Lindau, Germany
Italian space agency/National Institute for Astrophysics (ASI/INAF)
Rome, Italy
Kennedy Space Center
Launch services via NASA Launch Services Contract
Dawn Mission "Firsts"
• The Dawn spacecraft is the rst to orbit two planetary
bodies during a single mission.
• Dawn is the rst mission to study two of the largest
asteroids in the main belt.
• Dawn is NASA's rst purely scientic mission to be
powered by ion propulsion.
• Dawn is Orbital’s rst planetary mission. The spacecraft
design draws on the company’s extensive ight-proven
heritage.
X
Low Gain
Antenna
Solar Array
High Gain
Antenna
Z
RCS
Thrusters
Y
IPS
Thrusters
Orbital Sciences Corporation
45101 Warp Drive
©2014 Orbital Sciences Corporation FS006_02_2998
•
Dulles, Virginia 20166
Framing
Cameras
VIR
Low Gain
Antenna
Star
Trackers
Gamma Ray/Neutron
•
www.orbital.com
Spectrometer
Radiator Panel
with Louvers
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