NASA Selects 'Dawn' Discovery Mission for 2006 Launch
21 Dec 2001
(Source: University of Arizona)
From Lori Stiles, UA News Services, 520-621-1877
NASA today announced that "Dawn" will be one of the two new Discovery missions slated for launch in 2006.
The ion-propulsion powered mission will make a nine-year journey to orbit Vesta and Ceres, the two most massive asteroids known. The asteroids, located in the main asteroid belt between Mars and Jupiter, have recorded what the early solar system was like when the terrestrial planets formed.
"This is terrific," said University of Arizona astronomer Mark V. Sykes, a scientist on the Dawn mission. "We've been proposing advanced propulsion technology missions for many years now, and it's great to have an opportunity to actually fly one."
The Dawn mission is led by Christopher T. Russell of the University of California - Los Angeles. The project is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Orbital Sciences Corp., Dulles, Va., will develop the spacecraft.
NASA selected the missions from 26 proposals made in early 2001. The missions must stay within the Discovery Program's development-cost cap of about $299 million.
"Dawn will study the conditions and processes of planet formation during the earliest epoch of our solar system by orbiting and studying Ceres and Vesta," Sykes said. Dawn builds on decades of asteroid and meteorite studies, he added.
"Ceres is more than a quarter the diameter of the moon, is water-rich, and has retained its primitive composition and condition. Vesta, on the other hand, was dry, heated to the point of melting, and preserves a record of its subsequent differentiation.
"Almost all asteroids that we observe today are the fragments of larger asteroids like Vesta and Ceres that were destroyed by ancient catastrophic collisions. By studying Vesta and Ceres, we gain a much greater understanding of how these modern fragments were once put together," Sykes said.
Actually, scientists already have pieces of one of the asteroids within reach - as meteorites that landed on Earth.
"Cratering collisions have knocked off pieces of Vesta, which have been recovered as meteorites. They provide us with detailed information on geochemical processes that have occurred within specific sites on Vesta from the time of its formation at the beginning of the solar system," Sykes said.
"Going to Vesta will give us the big picture within which these hand-sized pieces fit. It will be like going from studying bits of hair, nail, and bone to seeing and studying the entire animal up close for the first time," he added.
Sykes, an associate astronomer at Steward Observatory, specializes in the study of asteroids, comets and interplanetary dust. He is the Chair of the Division for Planetary Sciences of the American Astronomical Society.
Dawn will carry a framing camera and mapping spectrometer provided by the German Aerospace Center, DLR, Institute of Sensor Technology and Planetary Exploration in Berlin; a laser altimeter experiment provided by the NASA Goddard Space Flight Center in conjunction with the Massachusetts Institute of Technology; a gamma ray/neutron spectrometer from the Department of Energy's Los Alamos National Laboratory; and a magnetometer provided by UCLA.
Ion engines will power the spacecraft to the asteroid belt, where it first orbits Vesta in an ever-tightening circle and then spirals outward and heads to its rendezvous with Ceres. The spacecraft will orbit as high as 800 kilometers (500 miles) to as low as 100 kilometers (about 62 miles) above the surface of the asteroids. Flybys of more than a dozen other asteroids along the way are planned.
NASA also selected the Kepler mission for 2006 launch. Kepler, a spaceborne telescope, will search for Earth-like planets around stars beyond the solar system.
"Kepler and Dawn are exactly the kind of missions NASA should be launching, missions that tackle some of the most important questions in science yet do it for a very modest cost," said Edward Weiler, associate administrator for space science at NASA Headquarters in Washington. "It's an indicator of how far we've come in our capability to explore space when missions with such ambitious goals are proposed for the Discovery Program of lower-cost missions rather than as major projects costing ten times as much."
Information about Dawn and images are available on the Internet at: