Timeline tracks final moments of space shuttle Columbia

From the first hints that things were going wrong aboard the space shuttle Columbia until it disintegrated over Texas, killing its seven astronauts, the timeline was brief but full.

Seven minutes of racing through the atmosphere, tracked by computer monitors and the worried words of controllers. Seven minutes of awed or troubled sightings from the ground. Seven minutes to silence.

8:52 a.m.

The sky is still dark over the Pacific Ocean, but a luminous pink glow shines into the cockpit where Commander Rick Husband is at the controls as Columbia plummets like a shooting star into Earth's atmosphere, creating its own artificial dawn on Feb. 1. The light show also beams through the windshield onto crewmembers a deck below.

No one is talking to the ground now. The last transmission was a few minutes ago, when Mission Control radioed to note a change in the orbiter's attitude.

"Roger that, Houston. ... We bumped the stick," Husband said.

"Not a problem, Rick," said the capsule communicator.

The craft is traveling at 23 times the speed of sound at an altitude of 44 miles. Husband and his six crewmates are about 2,500 miles from the Kennedy Space Center in Florida, where loved ones await their landing.

8:52:17

Computers at NASA Mission Control in Houston detect an abnormal temperature in the inboard wall of the left landing gear compartment or wheel well. It is the first sign something's wrong. NASA engineers had been concerned about this area since insulating foam from the external fuel tank broke off and struck the shuttle on liftoff 16 days earlier, possibly damaging heat shields that insulate Columbia during re-entry.

The shuttle is a minute and a half into the hottest part of its fiery return to Earth. Some parts of it are enveloped in a cloud of gases called plasma, reaching temperatures as high as 3,000 degrees.

8:53:11

Columbia is traveling at Mach 23.16, 43 miles up over the Pacific. Signals begin to indicate deep trouble.

"I just lost four separate temperature transducers (sensors) on the left side of the vehicle," says Jeff Kling, a controller monitoring Columbia's systems in Houston.

"OK," flight director Leroy Cain says. "Is there anything common to them? ... I mean, you're telling me you lost them all at exactly the same time?"

"No, not exactly," Kling says.

"OK, where are those?" Cain asks.

"All four of them are located in the aft part of the left wing ..." Kling says. "And there is no commonality."

Kling's responses suggest this problem is more than just an isolated, faulty sensor.

8:54

Some 2,300 feet up Mount Hamilton, outside San Jose, Calif., Ian Kluft is looking skyward and he's frustrated.

He's with members of the Peninsula Astronomical Society, watching for the shuttle, but a fog bank has rolled in.

Kluft throws his camera into his Dodge pickup and races farther up the mountain when he sees the streak of light. But something's not quite right.

During the other two pre-dawn re-entries he's observed, the shuttle looked like a highway flare. The same reddish-pink light is present, but this time it is followed by a wide, billowy contrail. "Almost smoky," Kluft remarks to another observer.

At the same moment, a few hundred miles to the south, Aldo Spadoni is standing on the balcony of his hillside home in Rancho Palos Verdes, a Los Angeles suburb. His Bushnell Rangemaster 7X35 mm binoculars are trained to the northern sky. Then Columbia appears, a bright yellow-white light.

"Beautiful," he thinks.

Then a second, brighter point of light appears below Columbia's trail. It winks out suddenly. A few seconds later, another, dimmer point of light shoots off from the shuttle.

An aerospace illustrator, Spadoni begins to create his own rendition of what he's witnessed.

8:55

The light pollution from nearby Las Vegas is a challenge, but Vic Panegasser isn't going to miss a chance to get a picture of a shuttle passing so close overhead. He peers northwest, through the lens of his digital camera, its internal timestamp synchronized with an atomic clock.

The shuttle appears, and Panegasser, a warehouse manager, follows it for eight seconds as it heads southeast.

"Got it," he says to himself, then heads inside to watch the landing on TV.

At the Tomlinson home in Las Vegas, civil engineer Kevin Tomlinson and his wife Laura have awakened their daughters early to see the shuttle. They've been waiting in the dark for 10 minutes. Kali, 4, is in her father's arms and 3-year-old Kyra is squirming in her mother's lap.

Suddenly, a white dot with a greenish tail screams across the sky.

"Hurry, stand up!" Kevin shouts. They watch the orbiter's streak, like "the slowest, longest meteor you ever saw," until it fades into the expanding pink of the eastern sky. Then, they go inside thinking nothing is wrong.

The shuttle, meanwhile, has passed over an acoustic array outside Hawthorne, Nev., roughly 250 miles to the northwest, which would will record Columbia's sonic signature. There's something "unusual" about it, though scientists will not confirm that until later comparisons with data from previous shuttle missions.

8:55:49

Columbia and its crew pass from the Earth's shadow into the light of dawn. The shuttle is over the Utah/Arizona border, just east of Zion National Park.

The astronauts' families -- parents, spouses and children -- are waiting near a runway at Kennedy Space Center for Columbia's expected 9:16 a.m. touchdown. At Mission Control, engineers are checking runway wind measurements and making final preparations for what they expected would be the 112th successful landing in the 22-year-old shuttle program.

"Your air to grounds are enabled for the landing count," says Bill Foster, the engineer in charge of ground control.

8:57

Mission Control picks up an unintelligible voice transmission from Columbia.

At the same time, Kling reports a loss of pressure on both left-side landing gear tires. He knows the reading would appear on the cockpit control panel in front of Husband.

"And Columbia, Houston, we see your tire pressure messages and did not copy your last," says astronaut Charlie Hobaugh, Mission Control's capsule communicator.

"Roger," Husband responds. "Buh --"

That final remark is cut off mid-syllable. This is the last voice communication from Columbia, although data transmissions continue for another two minutes.

At that moment, three researchers at Kirtland Air Force Base in New Mexico snap the shutter on a telescopic camera and capture a silhouette of Columbia. The photo shows a bulge around the left wing and a plume from the left side.

8:58

Columbia's automatic pilot is sending a stream of signals to its tail in a desperate attempt to regain control of the wildly pitching craft. The shuttle is 40 miles above Fort Sumner in eastern New Mexico. Its speed has dropped to just under 20 times the speed of sound.

"Flight, INCO, I didn't expect this bad of a hit" on communications, says Laura Hoppe, instrumentation and communications officer.

A few seconds later, guidance, navigation and control officer Mike Sarafin says: "If we have any reason to suspect any sort of controllability issue, I would keep the control cards handy ..."

8:59

Maj. Emco Jellema and Capt. Erik Starmans are hovering in an Apache attack helicopter over Fort Hood in central Texas. They are Dutch air force officers here for training.

Starmans wears a device that focuses a camera and records whatever he sees. He catches sight of a shower of bright, white streaks of light. Jellema sees it too and thinks: This looks like a jet fighter dropping chaff or flares to fool an incoming missile. He knows it's traveling too fast to be a jet fighter.

It must be Columbia. The camera captures images of glowing debris streaking to the east and behind a line of trees.

8:59:30

Columbia's autopilot fires rockets again and again. It's struggling to control the gliding spacecraft, which continues to pull to the left.

8:59:32

As NASA controllers in Houston watch their screens, main sensors on the left side of Columbia's fuselage blink off. Sensors on the brake lines and hydraulic systems quickly follow.

Mission Control records the cascade of system failures as the spacecraft streaks at 18 times the speed of sound 37 miles above Texas.

Then, all signals cease.

Afterward, Mission Control calls out repeatedly: "Columbia, Houston, comm check."

The response is silence.