NASA rocket blasts off

An unmanned NASA rocket scientists hope will shed light on the early solar system by exploring an asteroid and a dwarf planet lifted off successfully today.

Dawn 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 the trip 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.”

The 3 billion -mile trip began with a lift-off at Cape Canaveral in Florida shortly after dawn. The Delta II rocket thundered through a clear blue sky and headed south east above the thick clouds over the horizon.

Dawn will not reach Vesta, its first stop, until 2011, and Ceres, its second and last stop, until 2015.

Vesta and Ceres are the two largest bodies in the asteroid belt between Mars and Jupiter.

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.

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 that measure nearly 65 feet from tip to tip, 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.