CAPE CANAVERAL AIR FORCE STATION, Fla. — This moment, 13:47:08 on Jan. 12, 2005, was 10 years in the making. With less than 60 seconds left in the countdown, university associate professor of astronomy Lucy McFadden was giddy with excitement, biting her bottom lip in anticipation.

A dry erase board and an idea

Michael Belton was frustrated.

It was 1995 and he had just returned from a meeting on the Rosetta mission, whose spacecraft is currently en route to rendezvous with the Comet 67P/Churyumov-Gerasimenko in 2014. The mission will land a spacecraft on a comet, but won’t give scientists a look at the comet’s pristine interior, which they think holds a geologic snapshot of the solar system’s birth.Belton, Belton, then an astronomer with the Kitt Peak National Observatory in Tuscon, Ariz., sought a more direct approach to comet study.

He paid a visit to Jay Melosh, a University of Arizona professor of planetary science and expert on impacts and cratering in his office across the street from the observatory.

“What would happen if we hit a comet with a 500-kilogram spacecraft?” Belton asked.

Melosh worked out the math on a dry-erase board in his single-window office: The impact would punch a crater several stories deep, the size of a football stadium into the comet.

Belton was pleased. Deep Impact was born.

Passing the torch

Belton was at the helm of the brazen plan, assembling a team of scientists, engineers and space experts, including university astronomy professor Michael A’Hearn. The plan was to launch a two-part spacecraft into the path of a comet. With 24 hours to impact, it would separate into an impactor and flyby, which would record the resulting impact and relay information back to Earth.

But the success of the mission’s most critical stage — impact — was in doubt. Could they hit a moving target of indeterminate shape millions of miles from Earth in just the right spot to create the desired effect with an unguided impactor?

NASA rejected the proposal.

In March 1997, Belton’s wife of 36 years died, and he passed the lead position for the project on to A’Hearn.

Over budget, behind schedule

A’Hearn retooled the proposal, calling for a “smart” impactor that could autonomously guide itself into the sunlit side of its target, comet Tempel I. Computer models showed a 99.9 percent chance of success.

NASA approved the mission with a budget of $279 million.

By 2002, the project was over budget and behind schedule, and the agency feared the project’s budget would exceed the $350 million cost cap, prompting a NASA termination review from October 2002 to March 2003.

The project could continue with an additional $14.4 million, though “NASA challenged us to give back money at the end,” A’Hearn said in April 2003, though the cost has continued to balloon up to $313 million.

The initial January 2004 launch date was scrubbed, cutting out a one-year Earth orbit designed for testing the spacecraft’s target algorithms. Celestial mechanics limited future launch opportunities to a launch window that originally straddled December 2004 and January 2005.

The launch date was postponed multiple times, from Jan. 2 to Jan. 8 and finally to Jan. 12.

Launch day

With less than 24 hours to go before launch, only Mother Nature and Father Time stood between the $65 million Boeing Delta II rocket carrying the spacecraft and outer space.

The National Weather Service issued a dense fog advisory for the morning of Jan. 11 and it rained intermittently in the afternoon, though Air Force weather officer Joel Tumbiolo said at a press conference there was a “90 percent” chance of good weather.

The project’s launch window was open until Jan. 28, though Tumbiolo said weather conditions were expected to worsen because a cold front was pushing its way into the area.

A crowd of about 40 journalists and Deep Impact team members milled about impatiently at the press site. With less than two hours to launch, flags whipped in the moderate wind and a nearby radar station failed, jeopardizing the launch. Air Force weather balloons revealed the winds were within tolerable limits.

“It either goes up, or goes tomorrow,” said Jim Hester, a contractor who worked on the rocket.

At 1:25 p.m., a message chattered over the public address stating that the radar was back online. With 8 minutes to launch, NASA spokesman Mike Rein emerged from an observation shack: “Green.” The launch was on.

Lucy McFadden, a member of the science team, chatted excitedly “You guys hungry? … I’ve got an apple, but I’m too excited to eat it.”

Liftoff

The expendable rocket took off on time, eight seconds after 1:47 p.m. from Cape Canaveral Air Force Station, while members of the Deep Impact team and media stood in awe at a press site 1.4 miles away.

When the countdown reached zero, an anticlimactic puff of smoke spat from the base of the rocket, accompanied by a low thundering rumble. In seconds, the puff of smoke grew into a massive ground-level cloud enveloping the rocket itself and the rumble grew into a deafening roar. Only the rapid clicks and whirs of cameras were audible before the rocket’s roar climaxed in a wave of white noise.

“I wasn’t thinking anything” during the launch, McFadden said. “I was screaming — screaming! I could feel the tears coming. It was just unbelievable… I’m still shaking.”

The rocket, lifting off slowly at first, rose out of the white cloud with smoke in its wake. A shaft of what appeared to be black light streaked from the rocket’s path to the ground — the rocket’s shadow.

High in the sky, the ring of smaller rockets peeled off the main rocket’s base, creating several smoke trails before disappearing out of sight.

In space, the rocket deployed the automobile-sized mission spacecraft, which began its six-month journey into the path of comet Tempel I, despite a minor hiccup that temporarily shut down all of its nonessential systems.

Deep Impact team members resolved the problem, and brought the spacecraft out of its “safe mode.”

Belton, now 70 years old, said watching the launch was “tremendous” and “exhilarating,” but bittersweet, like seeing a child move out.

On July 4, Tempel I will crash into the impactor at a relative speed of 23,000 miles per hour, destroying it, while the flyby records the event and relays data from the impactor back to Earth.

More information on Deep Impact is available at http://deepimpact.jpl.nasa.gov.