Asteroid Probe's Launch Ends Long Wait for Scientists
NASA's Dawn asteroid probe launches on a three billion mile (4.9 billion-kilometer) mission to the asteroids Vesta and Ceres atop a Delta 2 rocket on Sept. 27, 2007 at Cape Canaveral Air Force Station in Cape Canaveral, Fla.
Credit: NASA/Tony Gray & Robert Murray

NASA's Dawn spacecraft is in fine health after rocketing into space just after sunrise today, ending a long wait for mission scientists even as the probe's own eight-year journey to two large asteroids is just beginning.

For Dawn principal investigator Chris Russell, the liftoff capped a 15-year effort to plunder the secrets of planetary formation from asteroids Vesta and Ceres. Russell and his mission team watched Dawn rise over its Cape Canaveral Air Force Station in Cape Canaveral, Florida from the spacecraft's Launch Control Center.

"They were very taken by today's launch," said Russell, of the University of California, Los Angeles, of his colleagues in launch control after liftoff. "In fact, my wife cried when she saw it."

NASA first approved Dawn's mission as part of its Discovery program for smaller, more affordable science expeditions in 2001. Russell added that he first envisioned the mission using its efficient ion drive in 1992.

Since then, the mission has survived solar array dings, weather delays, rocket booster and launch tracking issues, as well as cancellation in March 2006. The space agency set the mission's current cost at about $357.5 million, not counting the cost of Dawn's Delta 2 rocket.

Dawn is now headed for a February 2009 swing past Mars before reaching its first space rock target, the bright and rocky asteroid Vesta, in August 2011. The probe's novel Xenon ion propulsion system is expected to guide it into orbit around Vesta for almost a year, then send it off toward the icy dwarf planet Ceres -- the largest space rock in the asteroid belt -- for a February 2015 rendezvous.

"The spacecraft is safe, it is healthy and there's not a single [major] issue aboard," said Keyur Patel, Dawn project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif., after the successful launch.

He credited Dawn's experienced mission team with tackling the last-minute hurdle of a wayward ship that encroached within the launch range perimeter. The snag delayed the probe's liftoff by about 14 minutes, after which the ship moved clear of the launch range in time for a 7:34 a.m. EDT (1134 GMT) space shot.

Dawn's two expansive solar arrays, which measure about 65 feet (about 20 meters) from tip to tip, successfully unfurled after liftoff and its primary science instruments were found to be in good health, mission managers said. A few minor issues, such as a one amp difference in the current produced by the two solar arrays, have popped up, but none are considered serious enough to pose a problem, they added.

"They're all just fine tuning," Patel said.

By Friday morning, Dawn is expected to have flown beyond the orbit of the moon as it continues its outbound flight to the asteroid belt that sits between the orbits of Mars and Jupiter.

Mission managers plan to test its three ion engines within about five days. A series of instrument checks of Dawn's optical camera, mapping spectrometer and gamma ray and neutron detector will also be performed, though the tools won't be fully calibrated until after the Mars flyby, Patel said.

"Every time we launch a spacecraft, they all have their own personalities," Patel said. "And what we're about to discover is what kind of personality Dawn has; whether it's going to be a well-behaved child, or someone that's slightly naughty."