NASA's space shuttle Challenger completed 10 missions before it broke apart during a launch in 1986, killing seven astronauts.

On Jan. 28, 1986, the Space Shuttle Challenger exploded 73 seconds after takeoff. All seven crew members on board were killed. The disaster was one of the most significant events in NASA history, watched live by millions of people around the world.

Former astronaut and professor Terry Hart is opening up 40 years later about the friends and colleagues he lost on board the space shuttle Challenger explosion.

Today marks the 40th anniversary of the Challenger explosion. One of the crew members called South Carolina home.

Steve Hawley, who flew five Space Shuttle missions, and Krista Schaffer, a first-grade teacher at Christa McAuliffe Elementary in Lenexa reflect on the 40th anniversary of the Challenger disaster.

To demonstrate this tragic oversight, Feynman dropped a sample of the O-ring rubber in a glass of ice water. The rubber grew rigid in the glass, proving Feynman’s point. “I believe that has some significance for our problem,” he said at a February 1986 hearing of the Challenger commission.

Forty years after the Challenger disaster, its legacy fuels STEM education, inspiring new generations. The milestone calls for reflection and renewed aspirations.