The university-led Deep Impact project to study a comet by crashing a spacecraft into it has hit another premature bump on its collision course.

Prelaunch tests of the mission’s spacecraft’s software were run with settings that improperly recreated the spacecraft’s operations, pushing the Kennedy Space Center launch in Cape Canaveral, Fla., from Dec. 30 to Jan. 8, said university astronomy professor Michael A’Hearn, who heads the Deep Impact project.

Deep Impact is a NASA-funded six-year project to study the comet Tempel I. The $313 million plan is to smash a dense spacecraft into the comet and send its contents spewing out while another spacecraft trains its two sophisticated recording instruments on the comet.

Scientists believe the comet’s innermost contents date back to the solar system’s birth and hope to extrapolate a cosmic history through their analysis.

Earlier mission outlines called for 18 months of flight time from the launch of the composite spacecraft to impact. The Jan. 2, 2004, launch date was scrubbed because assembly was bogged down by problems with the computer system, contamination of the propulsion system and two defects in the platform on the spacecraft where sensitive instruments were to be mounted.

Cutting the flight time from 18 months to six months meant the Deep Impact team could spend an extra year ground testing the spacecraft, where software and hardware issues could be resolved. If the spacecraft were in orbit now as originally planned, only software issues could be resolved.

A’Hearn characterized the latest delay as a “very minor setback.”

“The only impact is a slightly shorter cruise period in which to learn how to actually fly the spacecraft,” he said. “Encounter date and time and to a good approximation most of the encounter geometry are unchanged.”

Fudge time is built into launch dates if “celestial mechanics allows us to do so,” A’Hearn said. Deep Impact’s 30-day launch window opens Dec. 30.

As the spacecraft nears the comet in July, it will separate into two parts: the flyby and the impactor. Tempel I will overtake the relatively small impactor at a speed of about 23,000 mph while the flyby will record the comet’s contents spewing out of the crater created by the collision.

More information about Deep Impact is available online at deepimpact.umd.edu.