Astronauts, and civilians who are permitted to fly in space, understand the risks. But they believe those risks are what is left over after responsible officials do everything they can to insure a safe mission. Such was not the case for this crew, according to the government's investigative findings.

Christa had been through simulator training many times. She knew where she would sit. She knew what would happen before, during, and after liftoff. Her job (as a payload specialist) would come later, when she used her lesson plans to teach children throughout the country. Lesson plans that were later found by the Coast Guard, floating on the ocean.

Families of the crew were watching the launch. So were millions of others, since most television networks were live broadcasting. Children were glued to the screen, just like school children 25 years before who watched the launches of Allen Shepard and John Glenn. No one realized Challenger was doomed before it left the launch pad. Most, including the crew's families, did not know until they saw an unexpected pattern of smoke in the clear blue sky. (Follow the link to view NASA's movies of the explosion, liftoff, and the Challenger crew.)

But the aft field joint of the right Solid Rocket Booster was already in failure mode within seconds of ignition. A gray smoke puff is clearly visible in the area of the joint at T+0.445 seconds. Before STS 51-L left the launch pad (according to the government's investigative report), the grease, joint insulation and rubber O-rings in the joint seal were being burned and eroded by hot propellant gases. Gases that would be free to go elsewhere, and cause more damage, if the O-rings did not seal sometime during the launch sequence.

As Challenger ascended, it encountered tremendous wind shears 32 to 62 seconds after liftoff. They were the worst wind shears any shuttle had ever faced.

Already weakened by the cold weather, the O-rings (which may have been resealing after liftoff) lost all chance to keep from completely eroding.

As the O-rings eroded, the aft field joint came completely out of alignment. A gap had opened through which blow-by gases could come in contact with Challenger's external tank. The potentially fatal failure cycle - known to responsible officials before liftoff - had commenced.

At 58.32 seconds, an unusual plume in the lower part of the right Solid Rocket Booster was recorded by cameras tracking Challenger's liftoff. At 58.772 seconds the first indication of smoke is visible from the right SRB. A fraction of a second later, at 58.778, the "first flickering flame appeared on the right SRB in the area of the aft field joint." By 59.262, the flickering flame had grown into "a continuous, well-defined plume." At 64.660 seconds after liftoff,

...there was an abrupt change in the shape and color of the plume. This indicated that it was mixing with leaking hydrogen from the External Tank...Within 45 milliseconds of the breach of the External Tank, a bright sustained glow developed on the black-tiled underside of the Challenger between it and the External Tank.

Meanwhile, the crew was given the command to give the shuttle more power:

The last response ever audibly heard from Challenger, rebroadcast many times the night of the disaster, was:

People watching the news that night took some small measure of comfort from those last words: "At least they never knew what happened."

Except - those were not the last recorded words recorded by Challenger's crew.