Washington Post Staff Writer
Tuesday, February 4, 2003
NASA investigators yesterday offered a new interpretation of the sudden heating the shuttle Columbia experienced on its left wing and side as it descended toward its destruction, speculating the fatal damage began elsewhere on the spaceship.
They have been studying the possibility that the shuttle's insulating tiles had been damaged as early as the first minutes of the flight when a piece of foam insulation appeared to break off from the shuttle's massive external tank and strike the underside of the left wing near the wheel well, where instruments recorded unusual warming just prior to the disaster.
At a late-day briefing in Houston, shuttle program manager Ron Dittemore said it is also possible the spaceship was breached someplace other than the wheel well, where the temperature increases were first registered. He said engineers were baffled as to how the modest temperature increases observed in the left wheel well and fuselage "end up with an event that lost the vehicle."
The evidence, he said, leaves engineers thinking "there's some other missing link that we don't have yet that's contributing to this temperature increase."
That missing link is the subject of a massive, round-the-clock search through telemetry readouts and other records as well as through farms, fields and lakes -- an effort that promises to go on for weeks or months.
Late yesterday, authorities found the tip of the shuttle's nose cone in a thickly forested area, which they secured. "We were just elated that we were able to recover that," said Sabine County Sheriff Tom Maddox, who added that the cone was "in pretty good condition."
NASA yesterday set up a second base of operations at Carswell Air Force Base near Fort Worth to collect the thousands of fragments of debris, in addition to one already established at the Barksdale Air Force Base in Louisiana.
Engineers have been directed to consider the giant external tank as a possible root cause of the accident, Dittemore said. But they will also continue to investigate a range of possible alternative causes, from inspection procedures to wiring and computer controls.
As they declared a day of mourning today for the seven fallen astronauts, NASA's shuttle managers settled in for a top-to-bottom review of their flight designs and practices. In light of new data, NASA yesterday appealed for the public farther back along the shuttle's flight path, beginning in California, to look for debris. "We are extremely interested in any debris upstream of the primary impact area," Dittemore said. Pieces have been found as far west as Fort Worth.
Officials hoped to find a single crucial piece that would reveal how the disaster began, but conceded that the odds were against it. The shuttle crossed California at 220,000 feet or so, descending rapidly and braking from 20 to 18 times the speed of sound. It was traveling 12,500 mph when it was lost.
"Let's say we did shed a tile or two," Dittemore said. "A tile maybe six by six inches. Where are they? That's a tough problem."
The tiles are individually coded, so engineers could readily tell what part of the shuttle they came from.
Amateur observers with telescopes have reported seeing possible debris coming off the shuttle over California, but officials cautioned that this could have been an illusion caused by the shroud of hot gas that surrounds the shuttle as it reenters the atmosphere.
"We have received a large amount of information from the public . . . and are methodically following up to see whether they were fooled by a phenomenon that is natural or whether they actually saw something," Dittemore said. "We are searching for any key parameter that might unlock the mystery to this tragedy."
In an effort to extract every last bit of information from the ill-fated flight, engineers also planned to travel to a facility in White Sands, N.M., where data flow directly from the shuttle and then are relayed to Johnson Space Center in Houston, site of mission control.
NASA officials seemed intent on avoiding the pattern of defensiveness and secrecy that compounded the fallout from the 1986 Challenger disaster. They have set up a regular schedule of lengthy briefings that have impressed even some longtime detractors. "This is a change in the NASA culture that should be encouraged," said James Oberg, a former NASA engineer and frequent critic of the agency.
"This will be probably the most open accident investigation on this scale that people have experienced," Michael Kostelnik, deputy associate administrator for the space station and shuttle, said at a morning briefing from NASA headquarters in Washington.
Dittemore said repeatedly he was taking full responsibility for the accident. "I'm the accountable individual," he said at one point yesterday. Many top NASA officials were sharply criticized for sidestepping responsibility after the 1986 Challenger accident.
Kostelnik yesterday encouraged anyone with information or documents to inform NASA's in-house anonymous reporting system, the inspector general or top officials.
At the Johnson Space Center briefing, Dittemore said new data showed that unusual heating had begun a minute earlier than previously known, at 8:52 a.m. Eastern time Saturday as the shuttle passed over California. A minute later, the measurements in a left-side brake line and other equipment showed a steeper increase than was known on Sunday -- a 30- to 40-degree rise over five minutes. Two minutes later, another left brake line temperature showed a heat spike.
But, he said, with an outside temperature of at least 2,000 degrees, such small increases do not point to a major breach -- and a flood of heat -- at that site. The temperature increases might be a reflection of a penetration elsewhere. That amount of change in itself "does not represent a structural problem."
At 8:59 a.m., in the shuttle's final moment over West Texas, he said, the new data showed that the shuttle's computer-driven controls were "losing ground" as they fought to counteract increasing drag on the spaceplane's left side and the shuttle moved farther and farther out of correct orientation. "It was not long after that that we lost all data and communication with the crew," Dittemore said.
Engineers discovered that two of four jets on the right-hand side fired for 11/2 seconds, he said, "trying to help the aileron and elevon surfaces counteract what we believe is increasing drag."
NASA yesterday also released its engineers' initial analyses of the damage that might have been done to the shuttle's protective tiles when a piece of foam apparently broke free from its external tank during launch on Jan. 16.
The analyses, which were worked out while the shuttle was in orbit, included one hypothetical worst-case scenario involving a piece of foam 20 by 16 by 6 inches and weighing 2.67 pounds hitting the underside of a shuttle wing. That analysis estimated there could be "tiles missing over an area of about 7 in. by 30 in." It also predicted that even though there might be "localized heating, with some effect on the basic structure in that area, you would not have damage sufficient to cause a catastrophic event" or even affect the vehicle's flight capabilities, Dittemore said. The engineers' conclusion was that the scenario posed "no safety of flight issue."
This and other such estimates, based on videos and other information, were deemed routine during the shuttle's flight, but became a prime focus of media attention yesterday.
Officials acknowledged that there might be something inherently wrong with the analyses and said they had started a thorough review. "We are completely redoing the analysis from scratch," Dittemore said. "We want to know if we made any erroneous assumptions . . . if we made any mistakes."
Asked if anyone had objected to the original damage estimate, Dittemore said he would think it "unusual that we had 100 percent of 17,000 people who work in this program to have no reservations. That would not happen on the easiest problems." But if anyone did have objections, he said, "they were not brought to my attention" at the time. Some objections were brought to his attention after the accident, he said.
In another exercise, NASA has asked engineers to assume that some problem with the external tank was the root cause of the loss of Columbia and work out an analysis of the cascading results. "That is a fairly drastic assumption," Dittemore said. "It is sobering. We have asked the techs and contractors to make that assumption."
Engineers are also reviewing all modifications,including tile work, made to Columbia when it was being refurbished recently in Palmdale, Calif.
Asked why certain documents had been impounded, such as a research report on how a foam impact could affect the tile, Dittemore said, "Generally, we've impounded information we believe will be helpful. We have more things impounded today than we really need . . . because we're really overreacting to make sure we don't lose any evidence . . . that might be an important contribution. Over time, you're going to see us back away" from this state of affairs.