CAPE CANAVERAL - With the last truckload of Columbia wreckage delivered, the accident investigation board looked over the broken and charred remains of the space shuttle Saturday, paying especially close attention to what little is left of the left wing.
A hole along the wing's leading edge doomed the spaceship during its dive through the atmosphere 31/2 months ago.
"We saw the things today which we believe are compelling pieces of evidence that tell us how the heat got into the vehicle and where the flaw started," said the chief investigator, retired Navy Adm. Harold Gehman Jr.
Gehman said he and other board members felt it was their duty to see the wreckage one last time as a group, before winding up their investigation and writing their final report. He hopes to have the report completed by the end of July.
"There are a number of pieces of debris out here which are extraordinarily significant that contribute directly to our investigation, and we wanted to see if, as a jury, we came to the same conclusion that our experts have," said Gehman, standing in a Kennedy Space Center hangar filled with shuttle wreckage.
Gehman said he sees no reason why NASA cannot resume shuttle flights, although he would not estimate when.
"The board has not come across any showstoppers that, in our minds, would prevent the shuttle from returning to flight," he said. "Now, how high is the stack of return-to-flight items going to be when we get finished, I can't tell you right now. But right now, it looks to me like it's manageable."
Gehman and five others on the 13-member board observed up close the spray of molten aluminum and small drops of melted metal on certain wing parts, and the knifelike edges of the wing panel remnants near the spot where the deadly heat penetrated. The board suspects the hole was created by a chunk of foam insulation that broke off the fuel tank at liftoff and slammed into that very part of the wing.
NASA's reconstruction team has put back together, as best it could, the leading edge of the left wing, using 3-D plexiglass molds and scraps of salvaged carbon panels. Tiles from the underside of the wing are displayed on a long wooden table, like a giant, burned jigsaw puzzle missing many of its pieces. Other shuttle parts are stacked on metal racks or flat wooden crates, or in plastic bins.
"The work that was done here turned out to be more significant than we thought it would have been at the beginning," Gehman said.
More than 84,000 pieces of Columbia have been recovered and transported to the space center from Texas and Louisiana. The total weight - nearly 85,000 pounds - represents 38 percent of the shuttle. NASA had expected to collect no more than 20 percent, said launch director Mike Leinbach, who's heading the space agency's reconstruction team.
"This has shocked a lot of people we got this much back," Leinbach said.