Michael A'Hearn is about to find out if there are second acts in American astronomy.
The University of Maryland scientist made international news in 2005 when he ran the Deep Impact mission, which slammed an 820-pound projectile into the path of a comet speeding through space at 23,000 mph.
The smash-up became one of the most widely watched unmanned projects in NASA history.
A'Hearn is now overseeing a $41 million NASA mission that recycles the Deep Impact spacecraft - which fired the projectile into the comet - to search for Earth-like planets in our interstellar neighborhood. The two-year project, now yielding its first data, will also produce one of the closest looks yet at another comet and unprecedented images of Earth from space.
"We're trying to build on what we've learned so far," said A'Hearn.
After it made history by blowing a big hole in comet Tempel 1, scientists recalibrated Deep Impact's instruments to help it use Earth's gravity to propel it along on a new, 1.6 billion-mile journey. The spacecraft will spend five months searching for Earth-like planets, survey some Jupiter-sized ones and then fly toward the comet Hartley 2 for a close-up look.
Reconfiguring an existing probe made the mission an easier sell because it's a relative bargain. "You save the cost of designing, constructing and launching a whole new craft," A'Hearn said.
NASA approved the two-year mission, known as EPOXI, in December. The name is an acronym combining the project's initial, six-month leg, the Extrasolar Planet Observation and Characterization, with its follow-up comet rendezvous, the Deep Impact Extended Investigation.
There will be no comet smashup this time. Because of the path of Hartley 2, the spacecraft must approach from the comet's dark side - away from the Earth - which would make it impossible to beam back images of a collision. "We thought about it having the spacecraft crash right into it, and taking imagery of that, but there was no way," A'Hearn said.
But the EPOXI spacecraft will come within 620 miles of the half-mile wide comet in a rendezvous scheduled for Oct. 11, 2010.
Astronomers designed the mission to resolve questions raised by Deep Impact and its collision with comet Tempel 1 on July 4, 2005. What they saw then surprised them: impact craters, smooth glacier-like channels along the comet's surface and twice-a-week outbursts of granular material.
