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Asteroid Probe's Launch Ends Long Wait for Scientists

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.
(Image: © NASA/Tony Gray & Robert Murray)

NASA's Dawnspacecraft 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-yearjourney to two large asteroids is just beginning.

For Dawnprincipal investigator Chris Russell, the liftoff capped a 15-year effort to plunderthe secretsof planetary formation from asteroids Vesta and Ceres. Russell and hismission team watchedDawn rise over its Cape Canaveral Air Force Station in Cape Canaveral, Floridafrom the spacecraft's Launch Control Center.

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

NASA firstapproved Dawn'smission as part of its Discovery program for smaller, more affordable scienceexpeditions in 2001. Russell added that he first envisioned the mission usingits efficient ion drive in 1992.

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

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

"Thespacecraft is safe, it is healthy and there's not a single [major] issueaboard," said Keyur Patel, Dawn project manager at NASA's Jet PropulsionLaboratory in Pasadena, Calif., after the successful launch.

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

Dawn's twoexpansive solar arrays, which measure about 65 feet (about 20 meters) from tipto tip, successfully unfurled after liftoff and its primary science instrumentswere 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, theyadded.

"They'reall just fine tuning," Patel said.

By Fridaymorning, Dawn is expected to have flown beyond the orbit of the moon as it continuesits outbound flight to the asteroid belt that sits between the orbits of Marsand Jupiter.

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

"Everytime we launch a spacecraft, they all have their own personalities," Patelsaid. "And what we're about to discover is what kind of personality Dawnhas; whether it's going to be a well-behaved child, or someone that's slightlynaughty."

 

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