NASA Holds 'Day of Remembrance' on 30th Anniversary of Challenger Explosion Seven astronauts died in the explosion.

 -- Thirty years ago today, the nation watched on live television as the Challenger shuttle carrying seven people, including a high school teacher, exploded into a fireball 73 seconds after liftoff.

On an unusually cold January morning, the astronauts' families and other onlookers watched as the Challenger lifted off from Kennedy Space Center at Cape Canaveral, Florida, for what was supposed to be a seven day trip. Shortly after liftoff an orange fireball and smoke could be seen in the sky.

"Obviously a major malfunction," Stephen Nesbitt at mission control said, according to transcripts of the Challenger disaster.

The accident killed everyone on board and remains one of the worst incidents in the history of the space program. NASA later determined that the accident was caused by a seal failure on a rocket booster, which allowed hot gas to ignite a fuel tank.

On board was Christa McAuliffe, a high school teacher who beat out 11,000 other applicants for the chance to be the first "everyday" citizen to go to space. She was joined by Cmdr. Michael J. Smith of the U.S. Navy, Francis R. Scobee who served as mission commander, Lt. Col. Ellison S. Onizuka of the U.S. Air Force, Judith Resnik, Ronald McNair and Gregory Jarvis.

Steve McAuliffe, Christa's widower, told the Associated Press this week that the disaster still feels fresh.

"For us, Challenger will always be an event that occurred just recently. Our thoughts and memories of Christa will always be fresh and comforting," he said. "We are happy to know that Christa's goals have been largely accomplished in that she has inspired generations of classroom teachers and students, and has focused public attention on the critical importance of teachers to our nation's well-being."