CAPE CANAVERAL, Fla. Sep 27, 2007
NASA's Dawn spacecraft rocketed away today toward an unprecedented double encounter in the asteroid belt.

Scientists hope the mission sheds light on the early solar system by exploring the two largest bodies in the belt between Mars and Jupiter: an asteroid named Vesta and a dwarf planet the size of Texas named Ceres.

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.