Dawn is designed to orbit the protoplanet Vesta and the dwarf planet Ceres -- the two most massive bodies in the main asteroid belt between Mars and Jupiter -- to characterize the conditions and processes that shaped our solar system. By studying these two giant remnants from the epoch of planet formation, Dawn will provide scientists with new knowledge of how the solar system formed and evolved.
Thanks to its ion propulsion system, Dawn is the only spacecraft ever to have the capability to orbit two extraterrestrial destinations.
Feb. 17, 2009: Dawn flies by Mars on its way to the main asteroid belt.
July 15, 2011: Dawn enters orbit around the giant asteroid Vesta, becoming the first probe ever to enter orbit around an object in the main asteroid belt between Mars and Jupiter. Dawn spends 14 months in orbit, fully imaging the surface, taking pictures in stereo, measuring the composition and temperature, determining the interior structure, and searching for moons. It uses its ion propulsion system to spiral down to an altitude of only 130 miles (210 kilometers).
Sept. 4, 2012: Dawn departs Vesta.
Early 2015: Dawn arrives at the dwarf planet Ceres to begin science investigations.
Dawn's science investigations at Vesta result in a number of findings about the protoplanet:
- Vesta is more closely related to the terrestrial planets (including Earth) than to typical asteroids. Like planets, it has a dense core, surrounded by a mantle and a crust.
- Vesta has a crater more than 300 miles in diameter. In the center is a mountain more than twice the height of Mount Everest.
- Vesta has a network of more than 90 chasms -- some with dimensions rivaling those of the Grand Canyon -- that are scars from two giant impacts hundreds of miles away.
- Vesta is the source of more meteorites on Earth than Mars or the moon.
- Gamma ray spectrometer
- Neutron spectrometer
- Visible mapping spectrometer
- Infrared mapping spectrometer
- Gravity measurements (using telecommunications subsystem and Deep Space Network)