NASA liftoff: Dawn brightens the early morning

William Atkins
Thursday, 27 September 2007 19:15

Science - Space

The NASA Dawn spacecraft was launched onboard a Delta 2 rocket at 7:34 a.m. EDT on Thursday, September 27, 2007—about twenty-one minutes after the dawning of the day—on a mission to learn about the early history of the solar system from two large asteroids.           

The NASA Jet Propulsion Laboratory announced the liftoff at its website “Liftoff!”, which is part of its coverage of the Dawn mission titled “a journey to the beginning of the solar system”—a reference to a goal of the mission to investigate materials on the two asteroids that first formed during the early times of the solar system. NASA scientists hope to learn more about the formation and early evolution of the solar system. NASA also carried the news of its liftoff at “Dawn’s Next Stop: Vesta”.

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.