Controllers both at the Cape and in Houston intently monitored Challenger's roaring ascent for a different reason. It is the most critical and most dangerous phase of a space mission. "When you have that much power, you have to respect it," said Flight Director Jay Greene in Houston. "If you get complacent about the launch phase, you don't understand what's going on." In the shuttle, the crew was about to be jammed back into their couches by three times the force of gravity. Their immediate fate was out of their hands.

"Houston, we have roll program," declared Commander Scobee. The flight was only 16 seconds old.

"Roger, roll Challenger," acknowledged Mission Control's Richard Covey in the professional tones of all air controllers. Like a fly clinging to a caterpillar, the shuttle turned gracefully on its back as the tank and the boosters assumed the proper downrange course for entering orbit.

At 35 seconds, Challenger's engines were throttled back to 65% of full power to pass through the zone of high turbulence. Nesbitt announced that the situation was "nominal," as NASA calls it: "Three engines running normally. Three good fuel cells. Three good APUs (auxilliary power units). Velocity 2,257 ft. per second (1,538 m.p.h.). Altitude 4.3 nautical miles. Downrange distance three nautical miles."

"Challenger, go with throttle up," said Covey after 52 seconds of flight. That was not an order; it meant that the engines had automatically reached full power and systems were go. Based on the performance of earlier engines, Challenger actually reached 104% of the older standard. The power-up meant that the shuttle had begun to endure the greatest stress of physical forces in its ascent.

"Roger, go with throttle up," Scobee confirmed. The message came at 70 seconds into Challenger's flight.

NASA's long-range television cameras had been following Challenger's shiny * white rocket plume, recording the graceful roll that had awed the spectators. But then the cameras caught an ominously unfamiliar sight, imperceptible to those below. However different those photographs later looked to viewers of the endless taped replays, NASA analysts said that an orange glow had first flickered just past the center of the orbiter, between the shuttle's belly and the adjacent external tank. This was near the point where the tank is attached to Challenger. Milliseconds later, the fire had flared out and danced upward. Suddenly, there was only a fireball. Piercing shades of orange and yellow and red burst out of a billowing white cloud, engulfing the disintegrating spacecraft.

Snaking wildly out of control, the two boosters emerged from the conflagration, both clearly intact. They veered widely apart, leaving yellow- orange exhaust glows and gleaming white trails behind them. The configuration resembled a giant monster in the sky, its two claws reaching frantically forward.

In Houston, Commentator Nesbitt had kept his eyes on the programmed flight data displayed in front of him, not yet aware of the images of disaster appearing on the TV monitor to his left. He reported what normally would have been the readings from Challenger. "One minute, 15 seconds. Velocity 2,900 feet per second (1,977 m.p.h.). Altitude nine nautical miles. Downrange distance seven nautical miles." To millions watching their own screens, Nesbitt's narration was surreal. They had seen the fireball.

There was a 40-second pause and silence on the screen as viewers stared in baffled horror. Then, his voice still calm, Nesbitt announced, "Flight controllers are looking very carefully at the situation." He added quickly, "Obviously, a major malfunction." His unemotional tone did not change. Communications with the craft had been severed, he continued. "We have no downlink."

On the consoles in front of Nesbitt and the rows of technicians on duty in Houston, a series of S's froze on the monitoring screens. They signaled "static." No data were coming from Challenger. The range safety officer at the cape pressed a button to destroy the two boosters by radio. Although it was first reported that one had been skittering toward coastal population centers, NASA later conceded that both had remained well out to sea. But NASA's range safety officials had to react in seconds. With the destruction of the boosters went the possibility that if retrieved from the water, they & might have provided valuable evidence of what had gone wrong. After another pause of 40 seconds, Nesbitt pronounced the fateful verdict: "We have a report from the flight-dynamics officer that the vehicle has exploded. The flight director confirms that."

"RTLS! RTLS!" yelled former NASA Engineer Jim Mizell, watching from the press stands at the cape. He looked up in vain, and in horror, expecting Challenger to arc away from the unnatural cloudburst and return safely to the landing strip. In the VIP bleachers, only a few experienced viewers immediately sensed the disaster. To the naked eye, the flames were diluted by the distance. Many thought the explosion involved a normal separation of the boosters from the main tank and orbiter. That maneuver was to have occurred at two minutes, seven seconds into the flight.

McAuliffe's mother and father had watched anxiously at the long-awaited lift-off. They appeared more somber than many of the cheering spectators. Ed Corrigan seemed to sense the tragedy first. He reached out to put an arm around his wife. Grace Corrigan's look of puzzlement turned to tears. She cradled her head against her husband's shoulder. Most of the schoolchildren were mystified. But some began sobbing as they saw the reaction of the adults. To those in the stands came a brusque order: "Everybody back on the buses." The lift-off celebration at McAuliffe's high school faded slowly. To Sophomore Marsha Bailey, the TV pyrotechnics looked like "part of the staging" in any space shot. Students began quizzing each other. Then a deep voice in the balcony shouted, "Shut up, everybody, listen!" In the silence, the televised narration of the disaster finally made the outcome all too clear. Three teachers put their arms around each other at the rear of the auditorium as one wept. Classes were canceled and the students dismissed. Principal Charles Foley explained his students' early reaction: "Someone they admired and loved has been taken away. It makes them mad. They have learned that nothing in this life is certain." He ordered the school closed for the following day and set counseling services for any teachers and students who desired it.