"We always talked about Columbia being the queen of the fleet," Ojeda recalled, acknowledging that often times some wanted to call her a "hangar queen." However, once in space, Columbia's team could boast that the queen had the fewest problems to deal with.

At least until the morning of Feb. 1, when the orbiter disintegrated in the skies above Texas and Louisiana.

"It was much more than a machine," Ojeda said. "The loss of the vehicle means a lot to us."

On Wednesday NASA hosted what officials called the "last advertised walk-through" of the Kennedy Space Center hangar where thousands of pieces of shuttle debris are carefully positioned on the floor.

Like a giant jigsaw puzzle, Ojeda and hundreds of KSC employees worked over the past four months to piece together clues to Columbia's destruction, to come up with an explanation of what happened when it broke up killing the seven-member crew.

But now it's time to move on, pack up the debris and store it for possible future use by researchers interested in making future spacecraft safer, says Mike Leinbach, the NASA launch director overseeing the Columbia reconstruction effort

"The activity in the hangar has wound down," Leinbach said. "This has been a tremendous effort by hundreds of workers here in the hangar."

During a tour of the hangar, Leinbach pointed out the key evidence that led the KSC team to conclude that a breach in the left wing's leading edge allowed hot gas to penetrate the wing's interior and lead to Columbia's total destruction.

"We have concluded here in the hangar, based solely on the debris, what happened to the orbiter," he said.

Those clues were both difficult to decipher and easy to see.

Difficult, because the melted and twisted parts -- many with grass and dirt from the ground still sticking -- look almost nothing like they did before the Jan. 16 launch. Yet easy when it becomes clear with a glance at two areas of the floor that there is much less debris recovered from the left wing than from the right.

That something very bad happened on the left side is apparent.

This working theory is the same one obtained by other sources of data analyzed by the Columbia Accident Investigation Board.

So with that effort now nearly complete -- the final report by the reconstruction team is due June 23 -- Leinbach and his team are cementing plans on where to move the debris and under what guidelines researchers can have access to the material.

Debris recovered from the 1986 Challenger disaster was buried in an abandoned Minuteman missile silo at Cape Canaveral Air Force Station, a move many KSC employees didn't want to repeat with Columbia's remains.

"We want to learn from this debris," Leinbach said. "We owe it to the astronauts who gave their lives in pursuit of study."

Debris not loaned out for study will be packed away and stored at the Canaveral Spaceport, likely either in an empty room within the mammoth VAB or across the Banana River inside NASA's original Mercury Mission Control Center.

Columbia's recovered parts -- 38 percent of the whole vehicle by weight -- will remain on the hangar floor through July and then be crated up and moved to its storage facility beginning in August, Leinbach said.

Although the entire space center said farewell to Columbia during a Feb. 7 memorial service, specific team members like Ojeda, assigned to work on NASA's oldest orbiter and part of the debris recovery teams, were faced with saying good bye again.

Being so familiar with the vehicle, it's been tough to be involved with the debris recovery effort, said Ojeda, who flew out to Texas the evening Columbia was lost.

"It was very hard to sit there and look at these parts and try to identify what they were," he said. "It brought a tear to people's eyes, mine included, to see parts that you had worked on and installed on the orbiter full of mud and laying on the floor."

The experience has been similar for Terri Halverstadt, a 17-year KSC veteran -- now with USA -- who has been working on Columbia since 1990, most recently as a manager helping to coordinate work on the orbiter's rear engine compartment.

"Losing Columbia was emotional because it was something that I got up every morning and went to work on," Halverstadt said.

One of the 870 KSC workers who went to Texas and Louisiana and was involved in the debris recovery effort, Halverstadt spent 10 weeks helping identify and ship the hardware back to Florida.

It was just another way to help say good bye to the "old lady," Halverstadt said. "You know, we always said we would bring our baby home -- and I wanted to be a part of that."

Before the tragedy, Halverstadt would be among the earliest to arrive each day at the Orbiter Processing Facility. The high bay would be quiet, she recalled, with Columbia waiting to be serviced like a member of royalty.

As the day wore on, and more and more workers would appear, the hangar would echo with sounds of shuttle launch preparation.

Now, the processing hangar is empty. When Halverstadt comes to work, the sound barely rises above the voices of the few workers who remain. Many have been dispatched to other duties. And Columbia is gone.

"That's what I first felt," she said, "after I knew that she was gone, was that feeling that she wasn't going to be waiting on us anymore."