WASHINGTON - NASA officials said yesterday that they have identified a 2-foot-long piece of wreckage from the space shuttle Columbia as a piece of the left wing - where evidence suggests the doomed craft's troubles began.
The officials also said they recovered computer equipment Sunday that they hope might contain data about the shuttle's last seconds.
There were conflicting accounts last night from NASA officials on the details of what the space agency had recovered.
Investigators have been eager to piece together as much of the wing as possible, in hopes of determining whether a breach of its heat-protective tiles or front edge played a major role in the accident that killed seven astronauts.
But NASA officials also said yesterday that the wing was found near Lufkin, Texas, 200 miles east of where they said Friday that it had landed.
If the second location is accurate, the discovery of the wing could prove less significant than investigators had first hoped.
Fragments found far west of the main wreckage would be among the first pieces of the shuttle to break up, and thus could contain important clues about what went wrong.
NASA officials said yesterday that they did not yet know where on the wing the fragment came from or whether it showed evidence of "burn-through," the damage done by super-heated gases as the orbiter re-entered Earth's atmosphere.
Under several theories of what went wrong, those gases penetrated the heat-shielding cladding around the wing and destroyed it from the inside.
The breach of the protective layer might have occurred when debris hit the wing during the shuttle's liftoff Jan. 16.
But yesterday, for the first time, a senior executive of Boeing Corp. defended the work his engineers had done while Columbia was in orbit, concluding that the debris had not caused mission-threatening damage.
Michael I. Mott, Boeing's vice president and general manager of NASA systems, said in a telephone interview that the company had conducted a "very disciplined" analysis by "some of the top engineering talent on the planet."
"To imply that the most rigorous and complete analysis was not brought to bear on this I find absurd," Mott said, adding that Boeing has reviewed the work in both reports since Columbia's destruction Feb. 1.
"We thought the analysis was thorough then, and we think the analysis is thorough now," he said.
The object recovered Sunday was described by William F. Readdy, the associate administrator for space flight, as "one of the general purpose computers that may allow us to get some more data about what happened to the Columbia."
It was in the avionics bay of the shuttle, he said, not far from where the crew sits in the orbiter.
Readdy said the computer appeared "in good shape" and was being rushed to a Lockheed-Martin laboratory in upstate New York - a laboratory that once belonged to IBM when it developed the shuttle's computers - in an effort to drain whatever data remain in the system.
He said the computers were powered by batteries designed to preserve data for two weeks.
But in another sign of the confusion enveloping the agency as it sorts through more than 12,000 pieces of wreckage, Alan D. Buis, a spokesman for NASA in Houston, said last night that the object found Sunday is computer-related, but not one of the five identical general purpose computers that control all of the space shuttle's functions.
The memory system of those computers is the grand prize, assuming that they kept collecting information even after contact between the doomed shuttle and Houston was lost at 8:59 a.m.
Space station concerns
NASA officials also said they were beginning to discuss with Russia what Sean O'Keefe, the agency's administrator, described as "a range of options" for keeping the International Space Station running, in the absence of shuttle flights to bring supplies and to improve the structure.
Three astronauts are currently aboard.
The station, he said, had enough fuel to last a year and food through June. "The real pacing item will be water," he told reporters at NASA headquarters yesterday.
In Moscow yesterday, the chief spokesman for the Russian Aviation and Space Agency, Sergei A. Gorbunov, said that NASA has asked for scheduling and cost estimates in case additional Russian flights to the station are needed.
"Our experts have agreed with their American counterparts that at least four Progress [flights] have to be made," he said, referring to one of the Russian craft.
"But for us it's quite a tense program in terms of money."
There is widespread speculation that Russia might be paid by NASA to fill in the gaps while the shuttle fleet is grounded.
O'Keefe faces the first congressional hearing on the shuttle disaster and its implications tomorrow, where he is the sole witness.
Yesterday, he seemed to back away from NASA's habit last week of revealing details of both the wreckage discovered and potentially important photographic and video evidence of the shuttle's last, desperate moments. He and other officials did not volunteer news of the possible computer discovery - it was mentioned in passing by officials as they left the room.
O'Keefe has made no secret of his unhappiness with the widespread discussion of theories about what happened to the shuttle - and continued questions about whether NASA engineers were sufficiently careful in their analysis of risks to the shuttle after it was hit by debris on launch.