"Dawn" of a new asteroid-bound spacecraft

I forgot all about this mission, and it is only making headlines (again) now less than a day before launch.

NASA is about to embark on an unprecedented asteroid-belt mission with a spacecraft aptly named Dawn. The Dawn spacecraft will travel 3 billion miles to explore the asteroid belt between Mars and Jupiter.

The 3 billion-mile, eight-year journey to probe the earliest stages of the solar system will begin with liftoff, planned for around lunchtime Irish Time on Thursday Sept 27th. Rain is forecast for Florida, site pf the launch, however, and could force a delay. Scientists have been waiting for Dawn to rise since July, when the mission was put off because of the more pressing need to launch NASA's latest Mars lander, the Phoenix. Once Phoenix rocketed away in August, that cleared the way for Dawn.

Dawn will travel to the two biggest bodies in the asteroid belt between Mars and Jupiter -- rocky Vesta and icy Ceres from the planet-forming period of the solar system. Ceres is so big -- as wide as Texas -- that it's been reclassified a dwarf planet. The spacecraft will spend a year orbiting Vesta, about the length of Arizona, from 2011 to 2012, then fly to Ceres and circle there in 2015. Dawn's three science instruments - a camera, infrared spectrometer, and gamma ray and neutron detector - will explore Vesta and Ceres from varying altitudes.

Because Vesta and Ceres are so different, researchers want to compare their evolutionary paths. No one has ever attempted before to send a spacecraft to two celestial bodies and orbit both of them. It's possible now because of the revolutionary ion engines that will propel Dawn through the cosmos.

Dawn is equipped with three ion-propulsion thrusters. Xenon gas will be bombarded with electrons, and the resulting ions will be accelerated out into space, gently shoving the spacecraft forward at increasingly higher speeds. NASA tested an ion engine aboard its Deep Space 1 craft, which was launched in 1998. Ion engines have been used on only about five dozen spacecraft, mostly commercial satellites.

Dawn also has two massive solar wings, nearly 65 feet from tip to tip, to generate power as it ventures farther from the sun. Ceres is about three times farther from the sun than Earth.

NASA put the cost of the mission at $357 million, but said that does not include the Delta II rocket. Officials refused Tuesday to provide the cost of the rocket, saying that was proprietary information.

DAWN SPACECRAFT SUCCESSFULLY LAUNCHED

CAPE CANAVERAL, Fla. - NASA's Dawn spacecraft began its 1.7 billion
mile journey through the inner solar system to study a pair of
asteroids Thursday at 7:34 a.m. EDT.

The Delta 2 rocket, fitted with nine strap-on solid-fuel boosters,
safely climbed away from the Florida coastline and launch complex 17B
at the Cape Canaveral Air Force Station. "We have our time machine up
and flying," said Dawn Principal Investigator Christopher Russell of
the University of California, Los Angeles.

Dawn is scheduled to begin its exploration of Vesta in 2011 and Ceres
in 2015. The two icons of the asteroid belt are located in orbit
between Mars and Jupiter and have been witness to so much of our
solar system's history.

By using the same set of instruments at two separate destinations,
scientists can more accurately formulate comparisons and contrasts.
Dawn's science instrument suite will measure shape, surface
topography and tectonic history, elemental and mineral composition as
well as seek out water-bearing minerals.

A critical milestone for the spacecraft comes in is acquiring its
signal. The launch team expects that to occur in approximately 2-3
hours.

For the latest information about Dawn and its mission, visit:

www.nasa.gov/dawn


-end-

4 years to go before its first encounter... at the asteroid belt. Seems like a long time, but it is pioneering an ion drive.