Dawn Spacecraft

The Dawn Mission is a NASA robotic mission to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. Dawn is NASA's first purely scientific mission to be powered by ion propulsion and is Orbital’s first planetary mission. It was launched on 27 September, 2007 from Cape Canaveral Air Force Station Launch Complex 17 on a Delta II rocket.

Mission Overview

Dawn is a planetary space science mission funded by NASA’s Discovery Program. Orbital is partnered with Principal Investigator Chris Russell of UCLA and the Jet Propulsion Laboratory (JPL). Dawn’s primary scientific objective is advancing 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 will cruise to the main asteroid belt between Mars and Jupiter where it will rendezvous with and orbit Vesta for eight months. While orbiting, the spacecraft will conduct remote sensing observations using a suite of science instruments. The spacecraft will then depart Vesta and travel to Ceres where it will perform the same set of measurements.

Dawn Mission Timeline

* Launch: 27 September, 2007 (previous launch date was 30 June) from Cape Canaveral Air Force Station Launch Complex 17.
* 10.09.07 NASA's Dawn spacecraft successfully completed the first test of its ion propulsion system in early October 2007.
* Mars gravity assist March 2009
* Vesta arrival September 2011
* Vesta departure April 2012
* Ceres arrival February 2015
* End of primary mission July 2015

Spacecraft Specs:

Mass: 1,210 kg (2,668 lb.) at launch, 740 kg (1,631 lb.) dry
Propulsion: Solar-electric propulsion using three gimballed NSTAR ion engines and monopropellant reaction control system.
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
Dimensions: 20 m (65 ft.) tip-to-tip, spacecraft body is 2 m (6 ft.) high from separation plane to instrument deck
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

Instruments

Framing Camera (MPS/DLR) Visible
Infrared Mapping Spectrometer (ASI/INAF)
Gamma Ray and Neutron Detector (LANL)

About Dawn’s Ion Propulsion

The Dawn spacecraft will be NASA's first purely scientific mission powered by solar electric ion propulsion, the world’s most advanced and efficient space propulsion technology. Ion propulsion will provide the additional velocity needed to reach Vesta once the spacecraft separates from its Delta launch vehicle. 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.

Key Mission Partners

- Principal Investigator: Dr. Christopher Russell, UCLA
- Jet Propulsion Laboratory (JPL), Pasadena, CA (Project management, system engineering, ion propulsion subsystem, science operations and spacecraft flight operations)
- Orbital Sciences Corporation, Dulles, VA; Chandler, Arizona
- Max Planck Institute for Solar System Research/German Space Agency
- Italian space agency/National Institute for Astrophysics, Rome, Italy
- Kennedy Space Center, Cape Canaveral, Florida (Launch services via NASA Launch Services Contract)

If the Dawn Mission is successful, it will be the first time a spacecraft will orbit two planetary bodies on a single voyage.

Did you know?

* Dawn will carry a silicon chip containing the names of asteroid, space and other enthusiasts from around the world. People submitted their names for this historic one-way mission by visiting JPL's Dawn Web site in 2006.

* In the mid 1980s a Multiple Asteroid and Comet Fly-By French Soviet Vesta Mission was proposed for 1991. No approved.

Related Space Books

Impact!: The Threat of Comets and Asteroids
by Gerrit L. Verschuur
From Amazon.com, Amazon.co.uk, Amazon.ca

 Dawn Spacecraft Links:

• Dawn Mission Home Page: NASA JPL
• Only Five More Days for Your Name to Rise With the Dawn: NASA. Source of Artist's concept of Dawn spacecraft. Image credit: William K. Hartmann/UCLA