CAPE CANAVERAL, Fla. -- Mission Control's flight controllers held their emotions in check, worked through their procedures the way they were trained and never gave up hope until it was proved that Columbia was lost.

"This was a tragic day for all of us on the flight control team," Columbia's entry flight director LeRoy Cain said Friday. "It was a very sad day for the entire NASA and contractor family."

Cain and his flight controllers expected a normal re-entry and landing and looked forward to seeing their astronaut colleagues return to Earth after a successful marathon science mission.

But when sensors started failing in Columbia's left wing as the shuttle approached the California coast, and then other indications began to hint at a bad day, Cain said he became increasingly concerned but relied on his training to stay in control of the situation.

"We remained focused and we did the things we were trained to do," Cain said. "My primary focus was to try and regain communications and when we did, what would we need to go do first."

As nothing was heard from the crew and no tracking information was received in the flight control room, Cain was informed by someone watching television that there were reports of "multiple pieces" flying over Dallas.