Details on Dawn

The decision to reinstate the Dawn mission doesn't mean the system isn't working, NASA Associate Administrator Rex Geveden said today. "This is an example of how our system works now," he said.

The cost overruns that helped prompt the initial cancellation add up to about $70 million, bringing the overall cost to $446 million. The cost overruns were already taken into account in the 2007 budget, officials said, before the cancellation and reinstatement. The extra money came from other programs, but they couldn't name a particular project that lost money.

"For R&D missions of this nature, cost overruns are pretty typical," Geveden said. Still, he added, "I take cost overruns deadly seriously, as does the science mission directorate, and that's the reason this mission was under review for cancellation."

Launch from Cape Canaveral is expected in summer 2007, a delay of about a year. Uncertainty about the cost has been reduced, Geveden said, and the spacecraft's schedule has a "typical" level of risk, with two or three months of reserve time, as it finishes assembly and testing.

"What we had here was a very gut-wrenching decision ... we're happy to be going forward," said Colleen Hartman, deputy associate administrator for the Science Mission Directorate.

Scientists and the mission's international partners are no doubt happy about the decision. Dawn is to visit two large bodies in the asteroid belt between Mars and Jupiter -- Vesta in October 2011 and Ceres in August 2015. "It's going to investigate the first bodies formed in the solar system," Hartman said.

See the letter on the reinstatement (a PDF).