Rudolphi is NASA's lead manager for directing the debris recovery effort, an operation that involves dozens of federal, state and local government agencies.
"We're about two-third's done, with the intent that in four to six weeks we'll wrap up the field search efforts," Rudolphi said. "Obviously that will be impacted by what we find. If there's a need to go and search broader areas and look at more sights we'll do that."
As of Tuesday, the debris recovery effort has collected about 22,300 pounds of material, which represents about 24 percent of Columbia's dry weight, said Steve Altemus, a shuttle test director at KSC who is managing the debris reconstruction here.
Of those items, about 1,400 have been identified by shuttle engineers and placed in a hangar that is near KSC's shuttle runway where Columbia was just 16 minutes from landing when it was lost Feb. 1 over Texas skies.
The 40,000-square-foot hangar floor is marked with tape to create a giant grid that also traces the outlines of various shuttle parts, such as the top and bottom of a wing.
On more than a handful of occasions a second check of a part's identity has resulted in it being repositioned or taken off the grid altogether.
"It is like putting together a multi-thousand piece 3-D jigsaw puzzle on a 2-D surface," said Gregory Kovacs, an associate professor of electronics at Stanford University who is working on the debris analysis effort for the CAIB in Florida.
Investigators are beginning to study the debris down to the microscopic level in an attempt to identify clues within the structure and chemistry of the material that will help solve the mystery of exactly what happened to Columbia before, during and after its break up.
Shooting foam
Investigators also are counting on the results of tests planned to begin the week of April 6th at the Southwest Research Institute in San Antonio, Texas.
The tests involve shooting one- to two-pound pieces of insulating foam material from the shuttle's external tank at four different materials that are part of the shuttle fleet's thermal protection system, or heat shield, which protects the spaceplanes during the extreme heat of re-entry.
The materials include standard black tiles found on the belly of each orbiter, tiles that line the main landing gear doors, so-called carrier panels that are near the wing's leading edge and a U-shaped, grey reinforced carbon-carbon (RCC) panel that does make up the wing leading edge.
Officials want to see what kind of damage foam moving at some 500 mph can do when it strikes those materials at a certain angle. Results are expected in about a month.
Two launch day cameras on Jan. 16 captured a piece of foam falling from Columbia's external tank and striking the leading edge of the left wing.
Although an analysis during the mission came to the conclusion the shuttle was not at risk from any potential damage from the foam, it's possible the shedding foam contributed to the disaster in some way.
A popular theory is that the foam hit the wing's leading edge, damaging an RCC or carrier panel.
The damaged part either broke loose during the mission -- a mystery object was seen by military radar floating away from the shuttle Jan. 17 -- or was ripped away early during Columbias hypersonic dive through Earths atmosphere.
That resulting breach allowed dangerous heat inside the left wing, which led to sensor wires and the aluminum structure within the wing to melt. That, in turn, led to the loss of Columbia's structural integrity and disaster ensued.
Data dump
Another potential source of information about Columbia's final moments could be stored on a data recorder now at KSC that was recently found in a Texas field after searchers were asked to take a second look for debris in a certain area.
Retrieved in relatively good condition, the recorder was activated for 30 minutes during Columbia's launch and climb to orbit and also was turned on about 30 minutes prior to landing.
Magnetic tape on the take up reel is to be copied at KSC on Thursday and the tapes then shipped by Friday to the Johnson Space Center in Houston, where data analysis is scheduled to begin Monday, said CAIB board member Scott Hubbard.
"The million dollar question, of course, is what's on it?" Hubbard said.
Hubbard said that in "a perfect world" the recorder will have stored 721 various measurements from sensors that were installed all over Columbia to support the ship's early test flights, which began in 1981.
The measurements would supplement those radioed to Mission Control that come from a different set of sensors.
Unfortunately the sensor wiring in the left wing follows the same path as the other sensors that stopped working in the minutes before Columbia's loss, Hubbard said.
So it's possible the amount of useful information could be limited if those wires also were melted by the breach in the wing.
The first key indication of what might be in store could come on Thursday during the copying process. Although engineers won't try to decipher the actual data, they will know if there is a good magnetic signal on the tape to work with.
"If all the data were there that I described of course this would be a gold mine of information that could lead us to a much, much better understand of what happened throughout the vehicle, and particularly on the left wing," Hubbard said.
A new view
Helping officials to better aim their tests, a new analysis was done of the launch video and film to try and clarify exactly where the foam struck Columbia's wing.
Two-dimensional pictures from two different angles were compared and mathematically combined to generate a three-dimensional computer model of the event.
The result: officials are confident the debris struck first one and then a second RCC panel, then carved a path through a carrier panel and several standard black tiles very near, but not quite touching, the left-hand main landing gear door.
"It has taken quite a bit of effort to get to this point," Hubbard said. "We will continue to be challenged to match the test and analysis with the observed events. We will not be able to conclude that we know the initiating event that started this tragedy until our theories match the facts."
The CAIB chairman did say, however, that the board was close to releasing a pair of "interim advisories," which would provide NASA some early guidance on what it needs to fix, either in terms of hardware or its operation.
Two items were close to being released last week both are considered to be "administrative" and "obvious in nature," Gehman said -- but were pulled so additional work could be done to make sure the wording and actions were exactly right.
"They needed a little more polishing and little more research," Gehman said.
The boards final report is still considered several months away from being finished.
The next pair of CAIB public hearings are scheduled for April 7th and 8th in Houston at the Clear Lake Hilton, which is across the street from the Johnson Space Center.
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