Orbital is partnered with Principal Investigator Dr. Christopher Russell of UCLA and the Jet Propulsion Laboratory (JPL) for a never-before-attempted interplanetary mission funded by NASA's Discovery Program. The mission, Orbital's first planetary space science program, will culminate in the rendezvous, orbit and study of the two largest known asteroids in our solar system, Vesta and Ceres.
The primary scientific mission of the Dawn program is to advance our understanding of how the solar system was formed by studying the two asteroids located in the "main belt" between Mars and Jupiter. Earth-based studies indicate that the two protoplanets have very different compositions and have remained intact since their formation more than 4.6 billion years ago. The Dawn spacecraft will rendezvous with and orbit Vesta for one year, conducting remote sensing observations using a suite of instruments. It will then leave Vesta and travel to Ceres and make the same types of measurements.
The Dawn spacecraft is NASA's first purely scientific mission powered by ion propulsion, the world's most advanced and efficient space propulsion technology. Ion propulsion is providing the velocity needed to reach Vesta and Ceres, and will also be used during asteroid proximity operations to raise and lower the spacecraft's orbit.
Orbit: Vesta: 200 to 2735 km; Ceres: 700 to 5920 km
Launch Mass: 1218 kg (includes 471 kg of xenon and hydrazine fuel)
Solar Arrays: Single axis articulated, >10 kw EOL @ 1.0 AU
Stabilization: 3-axis, zero momentum
Propulsion: Solar-electric (ion)
Mission Life: 10 years
Status: Launched on September 27, 2007. After travelling approximately 1.75 billion miles in space, a journey which included a flyby of Mars, Dawn has spent the last year orbiting its initial destination, Vesta, at altitudes as close as 200 kilometers (120 miles). Dawn recently fired its ion propulsion engines in order to propel it towards Ceres. After a two-and-one-half year journey, Dawn is expected to arrive at Ceres in 2015.
Quick Facts 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 first 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 to be 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