The long-delayed Dawn space probe may finally get off Earth soon (Space.com, AFP, AP). NASA is moving towards a 27th September launch for Dawn, which will visit the rocks Vesta and Ceres in the asteroid belt (press release). After launch the probe will unfurl solar panels 65 feet wide, tip to tip, fire up one of its three ion engines and accelerate away from Earth very slowly (more from NASA). After many delays and threats of cancellation Dawn is finally looking likely to get off the ground (see Nature – subscription required).

Results from Vesta and Ceres may shed light on the process of planetary formation – hence the name Dawn: it is designed to study objects dating from the inception of the Solar System,. These are the two biggest objects in the asteroid belt and details of the differences between them could provide key insights. “In my view, we’re going to be visiting some of the last unexplored worlds in the inner solar system,” said chief engineer Marc Rayman. The Christian Science Monitor goes into detail on Vesta and Ceres, and why they are so important, despite being ‘tiny, planet wannabes’.

If Dawn is successful this will be the first time that a space craft has orbited two bodies in the solar system (excluding the Earth and the Moon). This has been made possible due to the ion engines, which accelerate xenon ions to super-high speeds and spit them out to provide thrust (Dawn info pdf). NASA says at maximum thrust each engine produces “about the amount of force involved in holding a single piece of notebook paper in your hand” and at at maximum throttle it would take Dawn four days to reach 60 miles per hour. Anyone thinking any jalopy can do better should be warned though – after a year Dawn will hit 5,500 miles an hour having burned through only 15 gallons of fuel, according to Reuters.

Image: Artist concept of Dawn / William K. Hartmann courtesy of UCLA