The mission is special in two aspects. It is the first mission that will attempt to orbit two natural planetary bodies after leaving Earth. Ceres and Vesta, also called protoplanets, are located within the main asteroid belt that is situated between the orbits of the planets Mars and Jupiter. Ceres is also classified as a dwarf planet, just like the former planet Pluto.

Dawn also contains a unique engine called an ion engine that uses electrical and magnetic fields to move the spacecraft forward. The engine uses beams of electrically charged atoms (ions), actually using the element Xenon, for propulsion at very highs speeds.

Specifically, Dawn contains three Xenon electrostatic ion thrusters that will fire at different times in order to allow Dawn to orbit and explore these bodies. Dawn uses high voltage electrodes to accelerate the Xenon ions with electrostatic forces—thus providing a highly efficient but low acceleration thrust for its journey to the main asteroid belt.

More information about the ion drive engine is found in the iTWire article “NASA’s Dawn mission to asteroids powered with high-tech ion drive”.

Dawn will take about four years to traverse approximately 1.8 billion miles (2.9 billion kilometers) for its first stop over at the asteroid Vesta. Its mission is scheduled to end in 2015.



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