As investigators began the long task of piecing the shattered shuttle back together in Florida, NASA released a recording of the final conversation between Mission Control and the crew of Columbia.

The release of the tapes was just one development Wednesday, as the investigation picked up steam 11 days after the breakup of Columbia upon re-entry to earth's atmosphere.

Shuttle’s last communication made public

Conversations from the tape provide a chilling record of the dawning realization that disaster struck the shuttle mission on the morning of Feb. 1.

There were no hints of trouble before the final six or seven minutes of flight. It was then that Jeff Kling, the shuttle's maintenance officer at Mission Control in Houston, reported the first problem.

Noting a sudden and unexplained loss of sensor data, Kling reported, "I've just lost four separate temperature transducers on the left side of the vehicle."

Mission Control flight director Leroy Cain asked if the sensors shared any commonalities, probing the possibility of specific technical faults. Kling replied with bad news. The sensors located in the aft left wing had failed one after the other. The suggestion was one of a general, rather than specific technical failure.

The chatter continued, establishing the other landing parameters as nominal. Aside from increased drag on the left side ground control offers assurances that everything is "ordinary." Moments later Kling suddenly interjects, reporting the loss of tire pressure in both left tires.

Capsule communicator Charlie Hobaugh hails the shuttle, "And Columbia, Houston, we see your tire pressure message and we did not copy your last."

Flight Commander Rick Husband's reply is the final communication from Columbia. "Roger... buh..." Husband was cut off, mid-word, one minute before 8AM CST.

Having anticipated a periodic loss of communication, Houston tried to re-establish contact with Columbia. As hails went unanswered the ground controllers were suddenly faced with a barrage of problems. Small collisions were reported on the shuttle's tail. Signals from the nose and right landing gear were lost. Then more sensors disappear and drag continued to increase on the shuttle's left wing.

Mission Control did not know that debris was already raining down on east Texas and Louisiana.

Following a long pause Cain orders, "Lock the doors." It is the first sign ground control realized something had gone terribly wrong.

More debris recovered

In Texas, crews are still searching for space shuttle debris, and on Wednesday NASA reported that in Texas "significant amounts" of human remains believed to be Columbia crew had been found.

In other developments:

• Members of NASA's investigative panel, led by retired Navy Adm. Harold Gehman Jr., and two tractor-trailers full of shuttle remnants rolled into Kennedy Space Center in Florida Wednesday. Investigators will use a huge hangar at Cape Canaveral to lay out the pieces in search of clues. Among the debris unloaded were wing segments, spherical fuel tanks and a landing gear.
• Internal memos released by NASA Wednesday show at least one engineer was concerned about the risk of  "catasptrophic" failure aboard Columbia. Describing a worst case scenario, the safety engineer warned that damage near the wheel well could lead to a tire exploding during the shuttle's descent.
• NASA head Sean O'Keefe was in Washington to appear before a joint House-Senate panel Wednesday. Lawmakers questioned the impartiality of the NASA chartered 'Gehman' investigation board. O'Keefe assured the board's independence, dismissing calls for White House oversight.
• NASA shuttle and space station programs head Michael Kostelnik told the joint hearing that discussions about the future of the International Space Station Alpha are under way. Kostelnik sad that a decision will be made soon whether to bring the ISS crew back on a Russian Soyuz flight in April.
• Florida officials launched an online vote to determine whether the shuttle will appear on commemorative state quarters. Shuttle Columbia is not depicted, but two of the five designs pay tribute to Florida’s status as home of NASA's shuttle fleet.