CAPE CANAVERAL, Fla. -- The space shuttle Challenger exploded into a huge fireball moments after liftoff yesterday morning, killing all seven crew members, including Christa McAuliffe, the New Hampshire high school teacher who was to be the country's first private citizen to orbit the Earth.
As Challenger rose spectacularly off its launch pad into clear blue skies at 11:38 a.m., all appeared normal, and a crowd that included McAuliffe's husband, two children and parents roared its approval.
Then, 75 seconds into the flight, as Challenger achieved full engine power for the thrust that would carry it into orbit, the spacecraft inexplicably exploded.
It was the country's worst space disaster, stunning the nation at a time when the shuttle program -- and McAuliffe -- had succeeded in captivating the American public.
At first, thousands of spectators in VIP stands and press boxes assumed that the brilliant burst was the separation of the shuttle from its rocket boosters. But seconds later, a Mission Control official announced over loudspeakers: "We have a report that the vehicle has exploded."
As shocked onlookers stared in horror at the plumes of smoke that streaked the sky high above the Atlantic, NASA teams began rescue operations in hopes that some of the astronauts might be found at sea. But late yesterday afternoon, the space agency announced that all the crew members had died in the explosion.
A Coast Guard spokesman said late last night that searchers at the crash site 18 miles offshore had recovered small pieces of debris.
"There has been some debris recovered but it has not been identified," said the spokesman, Chief Petty Officer Bob Baeten. "The wreckage was described as being several small chunks, but I don't know the exact size or where it was found."
He said that none of the bodies has been recovered, and that the search would resume at daybreak this morning.
In addition to McAuliffe, 37, the Challenger crew members killed in yesterday's explosion were mission commander Francis R. Scobee, 46; pilot Michael J. Smith, 40; Judith Resnik, 36; Ronald E. McNair, 35; Ellison S. Onizuka, 39; and Gregory B. Jarvis, 41.
At an outdoor press conference at the Kennedy Space Center overlooking the launch site, Jesse Moore, the director of the shuttle program, said the agency had no explanation for the explosion. In the distance, a flag flew at half staff, but a clock continued to tick off milliseconds as if the shuttle were still in flight.
"Flight controllers polled said they did not see anything unusual," Moore said.
Asked about a taped replay of the flight that appeared to show a leak in one of the shuttle's two fuel tanks, Moore said, "We will not speculate on the specific cause of the explosion based on that footage over this national tragedy."
Moore said that an interim NASA committee had been formed to begin investigating the explosion and that shuttle operations would be suspended ''until we get a handle on what our problems are."
For a country accustomed to space flight and the routine launchings that have characterized the shuttle program, the explosion of the shuttle and deaths of the seven astronauts came as a national shock.
In Washington, President Reagan postponed his State of the Union speech, scheduled for delivery before Congress last night, and instead made a brief address to the nation from the Oval Office on the loss of the shuttle and its crew.
"We mourn seven heros," Reagan said.
The president, who learned of the explosion during a late-morning meeting with senior advisers, reaffirmed the government's commitment to space flight and the shuttle program. "The future doesn't belong to the faint-hearted," Reagan said. "It belongs to the brave." He added: "Nothing ends here. Our hopes and journeys continue."
Members of both houses of Congress said yesterday that they also expected committees with jurisdiction over the space program to investigate the explosion.
The disaster marked the first time in the American manned space program that astronauts had been killed in flight. It occurred a day after the 19th anniversary of the deaths of Air Force Lt. Col. Virgil I. (Gus) Grissom, Lt. Col Edward H. White and Navy Lt. Cmdr. Robert B. Chaffee, killed when a fire broke out in their capsule atop a Saturn rocket being tested for the first manned Apollo flight.
Throughout the afternoon yesterday, the television networks, as they have during other national tragedies, linked the nation to the disaster, repeatedly replaying Challenger's brief flight and the horrifying footage of the explosion.
According to a transcript of the conversations between Mission Control and the shuttle released late last night, flight controllers told the shuttle about one minute after launch, "Challenger, go, with throttle up."
The shuttle replied: "Roger, go, with throttle up."
Seventy-five seconds into the flight, at the time of the explosion, a NASA spokesman said: "One minute, 15 seconds, velocity 2,900 feet per second, altitude nine nautical miles, down-range distance seven nautical miles.
"Flight controllers here looking very carefully at the situation. Obviously a major malfunction. . . . We have a report from the flight dynamics' officer that the vehicle has exploded. The flight director confirms that."
For NASA, the explosion was a disastrous setback in the shuttle program, and raised immediate questions about whether the space agency could hold to its ambitious schedule to launch 13 flights on its three remaining orbiters this year.
The program was expected to receive a major boost from the flight of Challenger because of McAuliffe, the social studies teacher from Concord, N.H., who was picked to be the first private citizen in space.
McAuliffe was to have given two lessons on the Challenger mission to millions of students Friday from the shuttle, and her odyssey from the classroom to the shuttle had been followed closely by schoolchildren across the country.
At Concord High School yesterday, 1,200 students and 140 faculty, many with party hats and noise makers, eagerly awaited the launch on television. Gathered in the high school's auditorium, in the cafeteria, and in classrooms, they cheered loudly as Challenger lifted off after two minor delays.
"Awesome," said several students as they watched the 110-ton spacecraft slowly clear the pad and climb toward orbit.
When the shuttle exploded, many students burst into tears. Teachers escorted the students back to their homerooms and principal Charles Foley asked reporters to leave the building.
NASA's first public explanation on the explosion did not come until five hours after the disaster, and it provided few details. Videotape replays of the launch, however, led to speculation about what may have caused the explosion.
The tape appeared to show that within a minute of liftoff, a leak developed near the bottom of one of the two solid-fuel tanks that together contain 3.8 million pounds of propellant. Within seconds, another, larger leak seemed to appear in the same tank. Then the fiery explosion destroyed the shuttle.
Because the shuttle and the second fuel tank appeared unharmed until the explosion of the first tank, some observers speculated that the same leak had caused the entire explosion.
One of the two fuel tanks had been scraped last Saturday night in an incident that NASA dismissed then as insignificant. In that incident, according to a report issued by the space agency last night, a bolt protruding
from a scaffolding platform scaped an area that connected the tank to the orbiter.
However, the report said that because the bolt protruded only one inch and penetrated a two-inch layer of foam insulation, "The scratch was determined to be of no consequence."
According to Moore, "Some repair work was done on one of the external tanks. We looked at that on Saturday. It was not even in the same area on the tank . . ."
Shortly after the explosion, a parachute was spotted in the area. NASA officials at first said a paramedic had been dropped into the ocean near the site where debris was believed to be falling. Last night, however, an Air Force spokesman, Sgt. Charlie Miller, said he believed that the parachute had come from one of the shuttle's reusable fuel tanks, which is designed to detach from the orbiter two minutes after liftoff.
Challanger had no ejection seats. One other shuttle, Columbia, had two ejection seats, but they were removed last year because NASA believed they could not be used effectively.
NASA also believed the seats were too heavy to provide one for each of the seven astronauts and "were not needed because of the reliability and safety program of the shuttle," a NASA spokesman said.
Moments after the explosion, an Air Force search-and-rescue team that has been on alert as part of normal flight procedures headed toward the crash site 18 miles offshore. Debris from the explosion fell over a wide area, keeping searchers away from the scene for more than an hour.
A squad of 13 aircraft and seven ships carrying more than 1,000 military personnel searched for signs of life yesterday afternoon.
"There weren't any," said Miller.
The aircraft went home at sunset, but ships equipped with special search
lights were scheduled to patrol the seas all night. At daybreak today, the entire search team will resume operations.
Unlike airliners, the shuttle carries no "black box," a device on which flight data is recorded. The information is crucial to unraveling the cause of an air crash.
However, the shuttle does employ telemetry, a system that relays back to the ground, second by second, the status of every electronic and mechanical system on board, as well as data from sensors that monitor the vital functions of the astronauts.
NASA officials said they were confident they will uncover details of Challenger's flight when they examine the information. That examination is an exhaustive process and is not expected to be completed for several days.
There were also a variety of NASA cameras following the rocket's flight, NASA spokesmen said. All of the videotaped images shown repeatedly on television were recorded from a single camera, but other views of the accident should be available among the information impounded yesterday by NASA for detailed study.