40 years after Challenger: Lingering guilt and lessons learned

The space shuttle Challenger lifts off from Kennedy Space Center in Florida on Jan. 28, 1986, in a cloud of smoke with a crew of seven aboard. The shuttle exploded shortly after this photo.

Forty years after the Challenger disaster, NPR explores the engineers' last-minute efforts to stop the launch, their decades of guilt and the vital lessons that remain critical for NASA today.

(Image credit: Thom Baur)