Rocket starts ground-breaking mission
Dawn is the world’s first attempt to orbit two celestial bodies in succession.
Ion-propulsion engines 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 4,800 million-kilometre trip began with lift-off at Cape Canaveral in Florida shortly after dawn. The Delta II rocket thundered through a clear blue sky and headed southeast.
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 and even orbited and landed on them. 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 20 metres from tip to tip, to generate power.
Most importantly, Dawn has three ion engines that will provide a gentle yet increasingly accelerating thrust.
