Shuttle Showed Sensor Failures Moving Inboard From Wing

Timeline To Disaster

All Times: Central Standard Time

NASA's version of minute-by-minute events during the last moments of the Space Shuttle Columbia:

0753: (Over California) Four heat sensors monitoring the flight controls on the left wing fail. Sensor junction box located in left wheel well. Temperature monitors on strut actuator, elsewhere in wheel well show heat increasing 25-30F in a span of five minutes.

0754: (Over Eastern California, Western Nevada) Left bondline temperature sensor shows significant temperature rise -- 60F in five minutes. Right bondline temperature gauge shows only minor increase in temperature of 15 degrees. No temperature increase noted in payload bay on either side.

0758: (Over New Mexico) Flight Control System (FCS) compensates for left roll, indicating an increase in drag on the left wing. Left gear and hydraulic line temperature sensors fail. Pressure sensor monitoring tires in left main gear fail.

0759: (Over West Texas) FCS again adjusts roll trim, indicating increasing drag on the left side of the spacecraft. Final voice transmission between Mission Control and Challenger is interrupted by loss of signal.

Sunday's NASA Briefing

"We're beginning to make progress" Shuttle Program Manager Ron Dittemore told reporters Sunday, as the investigation into why the Columbia came apart during re-entry began to focus on the space plane's left wheel well. That's approximately where a piece of insulating foam from the external tank smacked the orbiter, turning into a cloud of dust during lift-off on January 16th.

"It's very interesting," said Dittemore, "(Saturday), we told you that we lost instrumentation readings on the trailing edge of the left wing. The wires for those sensors junction in the wheel well."

"It's looking more and more like a thermal event," said Dittemore, "more than a structural event. But I caution you, it's still early in the investigation."

A NASA-led investigation board arrived at Barksdale AFB, Shreveport (LA) to take over local and federal search efforts. Law enforcement officials in East Texas reported thousands of debris sites strewn across an area five thousand square miles wide.

Dittemore said Sunday NASA engineers were trying to retrieve as much as 32 seconds of data recorded after the shuttle breakup from computers at Mission Control in Houston. That information, he said, could yeild vital clues into the cause of the shuttle disaster.

NASA investigators had also spoken with astronomer Anthony Beasley an Australian working at an observatory north of Los Angeles. Beasely told ABC's Peter Jennings on Saturday that he saw pieces of what appeared to be thermal tile break off and trail the orbitor as it streaked toward its landing at the Kennedy Space Center in Florida.

"After the first few flashes I thought to myself that I knew the shuttle lost tiles as it re-entered and quite possibly that was what was going on," Beasley said on ABC. "I think that after the particularly bright event I started to wonder whether or not things were happening how they should."

Dittemore said Beasley's statement was being reviewed at the Johnson Space Center and significant times were being correlated to see if a loss of tiles might have indeed caused the shuttle to disintegrate.

"Yesterday was... the hardest day of my life."

Flight Crew Operations Director Bob Cabana was still obviously choked up at the news conference, one day after he had to gather the crew's families together and break to them the tragic news. "yesterdfay was probably the hardest day of my life," Cabana said. "To have to sit down with the families of close friends and tell their wives, children and parents their loved one isn't coming home.... I don't know if you ever had to do that. I hope you never do."

Cabana said astronauts have been assigned to each of the seven Columbia crewmembers' families as "Casualty Assistance Officers," seeing after the families' needs in every possible way.

NASA officials wouldn't detail reports that human remains had been found among the bits of shuttle debris. Cabana did confirm that remains had been found. "We're honoring our fellow crewmates," he said. "We're taking good care of them."

FMI: www.nasa.gov