Space Center, Houston ? After three days of uncertainty, NASA said Monday a piece of broken wing found last week was from space shuttle Columbia’s left side — where all the problems appear to have begun in the final minutes of the doomed flight.

The fragment includes a 2-foot piece of carbon-composite panel, a dense material that covered the leading edge of the wing, and a 1 1/2-foot piece of the wing itself. Engineers are not yet certain where the piece fits.

It could be extremely important, given that the trouble apparently originated in the left wing during the final minutes before the Feb. 1 flight broke up above Texas, killing all seven astronauts aboard.

Barely a minute after liftoff on Jan. 16, a piece of insulating foam from Columbia’s external fuel tank broke off and slammed into the ship’s left wing. The impact by the flyaway foam — exonerated by NASA during the flight as to having caused any serious damage — remains a central part of the accident investigation. In the final minutes of flight, some sensors in the left wing and in the left wheel well showed unusual spikes in temperature.

After the wing fragment was found last Friday, NASA’s deputy associate administrator for spaceflight, Michael Kostelnik, called it “a significant recovery.”

The condition of the wing fragment wasn’t immediately disclosed. NASA was checking the carbon panel and the silica glass-fiber thermal tiles for evidence of burning, either from the intense heat of re-entry or from something else.

NASA said it also has found the cover of one of the two landing gear compartments, another potentially critical piece because a temperature surge inside the left wheel well was the first sign of trouble. But officials do not yet know whether it is from the right or left side of Columbia.

Another incident highlighted the confusion even among top NASA officials as to what wreckage is being found — and where.

Bill Readdy, NASA’s top spaceflight official, told reporters in Washington that one of the shuttle’s main computers had been found in a Texas field “apparently in fairly good condition.”

He later said he was informed by a Johnson Space Center manager that it was an avionics box, not a general purpose computer.

“When he had a chance to look at it, sorry, wrong, not a general purpose computer,” Readdy said. “That was our hope; maybe we were hoping too much.”

An avionics box monitors and controls most of the systems on the shuttle. There are more than 300 of the boxes in the spacecraft.

NASA Administrator Sean O’Keefe said debris would be taken this week to Kennedy Space Center in Florida, where it will be cataloged and assembled.