CAPE CANAVERAL, Fla. (AP) – NASA took aim at the heart of the asteroid belt Thursday, launching a spacecraft on a nearly decade-long journey that will include two never-before-attempted close encounters.

The scientific probe Dawn is on a 3 billion-mile course that will have it meeting up with an asteroid named Vesta in 2011 and a dwarf planet called Ceres in 2015. They are the biggest members of the crowded asteroid belt between Mars and Jupiter, and scientists hope that by studying them up close, some of the secrets of the early solar system will be revealed.

Dawn’s sunrise liftoff was especially emotional for Christopher Russell, the mission’s lead scientist from the University of California at Los Angeles. He waited 15 years to see Dawn rise, and during that time endured two funding-related project cancellations and two years of postponements.

Russell monitored everything from inside Launch Control and was half-expecting yet another delay. His wife, watching from outside, cried.

“This was an intense relief,” Russell said, adding that he was “very, very happy at what happened today.” He considered it vindicating, given all he’d been through.

Dawn’s mission is the world’s first attempt to journey to a celestial body and orbit it, then travel to another and circle it as well. Ion-propulsion engines, once confined to science fiction, are making it possible.

“To me, this feels like the first real interplanetary spaceship,” said Marc Rayman, chief engineer. “This is the first time we’ve really had the capability to go someplace, stop, take a detailed look, spend our time there and then leave.”

Scientists chose Vesta and Ceres not only because of their size but because they are so different from one another.

Asteroid Vesta, about the length of Arizona with a huge crater at its south pole, is dry and rocky and appears to have a surface of frozen lava. It’s where many of the meteorites found on Earth came from. Texas-sized Ceres, upgraded from asteroid to dwarf planet just last year, is nearly spherical, icy and may have frost-covered poles. Both formed around the same time some 41/2 billion years ago.

Spacecraft have flown by asteroids before – albeit much smaller – and even orbited and landed on them, and more asteroid missions are on the horizon. But none has attempted to orbit two on the same mission

“I think many people think of asteroids as kind of little chips of rock. But the places that Dawn is going to really are more like worlds,” said Rayman, who is based at Jet Propulsion Laboratory in Pasadena, Calif.

Dawn has cameras, an infrared spectrometer and a gamma ray and neutron detector to probe the surfaces of Vesta and Ceres from orbit. It also has solar wings to generate power as it ventures farther from the sun.

Most importantly, Dawn has three ion engines that will provide a gentle yet increasingly accelerating thrust. Electrons will bombard Dawn’s modest supply of xenon gas, and the resulting ions will shoot out into space, nudging the spacecraft along.

Even “Star Wars” had only twin ion engines with its T.I.E. Fighters, Rayman noted earlier in the week. “Dawn does the ‘Star Wars’ T.I.E. Fighters one better,” he said.

The mission costs $357 million, excluding the undisclosed price of the rocket.

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On the Net:

Jet Propulsion Laboratory: http://dawn.jpl.nasa.gov/

AP-ES-09-27-07 1558EDT

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