Christa McAuliffe remembered 40 years after space shuttle Challenger exploded

It's now been 40 years since New Hampshire school teacher Christa McAuliffe died when the space shuttle Challenger exploded.

All seven on board were killed when Challenger broke apart following liftoff on live television on Jan. 28, 1986.

The bitter cold weakened the O-ring seals in Challenger's right solid rocket booster, causing the shuttle to rupture 73 seconds after liftoff. A dysfunctional culture at NASA contributed to that disaster and, 17 years later, shuttle Columbia's.

Kennedy Space Center's deputy director Kelvin Manning said those humble and painful lessons require constant vigilance "now more than ever" with rockets soaring almost every day and the next astronaut moonshot just weeks away.

McAuliffe was selected from thousands of applicants representing every state. Two of her fellow teacher-in-space contenders - both retired now - attended a memorial ceremony last week as the families of the astronauts gathered back at the launch site.

"We were so close together," said Bob Veilleux, a retired astronomy high school teacher from New Hampshire, McAuliffe's home state. McAuliffe was 37 when she was killed.

Bob Foerster, a sixth grade math and science teacher from Indiana who was among the top 10 finalists, said he's grateful that space education blossomed after the accident and that it didn't just leave Challenger's final crew as "martyrs."

"It was a hard reality," Foerster noted at the Space Mirror Memorial at Kennedy's visitor complex.

Twenty-five names are carved into the black mirror-finished granite: the Challenger seven, the seven who perished in the Columbia disaster on Feb. 1, 2003, the three killed in the Apollo 1 fire on Jan. 27, 1967, and all those lost in plane and other on-the-job accidents.