For many, no single word evokes as much pain.
A quarter-century later, images of the exploding space shuttle still signify all that can go wrong with technology and the sharpest minds. The accident on Jan. 28, 1986 — a scant 73 seconds into flight, nine miles above the Atlantic for all to see — remains NASA's most visible failure.
It was the world's first high-tech catastrophe to unfold on live TV. Adding to the anguish was the young audience: School children everywhere tuned in that morning to watch the launch of the first schoolteacher and ordinary citizen bound for space, Christa McAuliffe.
She never made it.
McAuliffe and six others on board perished as the cameras rolled, victims of stiff O-ring seals and feeble bureaucratic decisions.
It was, as one grief and trauma expert recalls, "the beginning of the age when the whole world knew what happened as it happened."
"That was kind of our pilot study for all the rest to come, I think. It was so ghastly," said Sally Karioth, a professor in Florida State University's school of nursing.
The crew compartment shot out of the fireball, intact, and continued upward another three miles before plummeting. The free fall lasted more than two minutes. There was no parachute to slow the descent, no escape system whatsoever; NASA had skipped all that in shuttle development. Space travel was considered so ordinary, in fact, that the Challenger seven wore little more than blue coveralls and skimpy motorcycle-type helmets for takeoff.
In a horrific flash, the most diverse space crew ever — including one black, one Japanese-American and two women, one of them a Jew — was gone. The name of NASA's second oldest shuttle was forever locked in a where-were-you moment.