(CNN) - Wednesday marks the 40th anniversary of the Challenger space shuttle explosion. It was a moment of collective grief on Jan. 28, 1986, when the space shuttle exploded during a live broadcast.

For many in New Hampshire, the memory of the Space Shuttle Challenger disaster is still vivid, those who were in Florida for the launch say they will never forget it.

🚀 On This Day — 28 Jan In 1986, the Challenger shuttle tragically disintegrated shortly after launch, claiming the lives of seven astronauts. This disaster reshaped our views on spaceflight safety and exploration. #NITheCS #ScienceHistory #SpaceExploration pic.twitter.com/slHHwVrf3n

Forty years ago, Americans were shocked when the space shuttle Challenger exploded 73 seconds after it launched on a chilly day in Florida.

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.

It was Jan. 28, 1986 when seven crew members loaded onto the Challenger space shuttle on Florida's Space Coast, with plans to head to space. Instead, the shuttle exploded minutes after launching – killing all seven people on board: Christa McAuliffe,