This Day in History: 
Challenger Disaster January 28, 1986 Seventy-three seconds after 
its 11:38 a.m. launch, NASA's 
space shuttle exploded, killing 
all seven crew members. Among the crew was Christa McAuliffe, 
a 37-year-old high school social 
studies teacher from New Hampshire. McAuliffe had won a 
competition that earned 
her a place on the Challenger. Millions witnessed 
the tragedy on live television. In the aftermath, President Ronald Reagan 
appointed a special commission to 
determine what went wrong with Challenger. The investigation determined 
the disaster was caused by 
the failure of an “O-ring” seal 
due to cold weather. It would be two 
years before NASA sent 
astronauts into space again.