35 YEARS LATER: On this day in 1986, the Space Shuttle Challenger exploded after liftoff, killing all seven astronauts on board. The Challenger broke apart at 11:39 a.m., falling into the Atlantic Ocean. Investigators would later discover the disaster was caused by the failure of an “O ring” seal in one of the two solid-fuel rockets. As a result of the horrific accident, NASA did not send astronauts into space for more than two years as it redesigned a number of space shuttle features for improv

The NASA space shuttle Challenger exploded 40 years ago, on January 28, 1986, just 73 seconds after liftoff. The disaster claimed the lives of all seven astronauts aboard, including Christa McAuliffe, a teacher from New Hampshire who would have been the first civilian in space. “The crew of the space shuttle Challenger honored us by the manner in which they lived their lives,” President Regan said in an address to the nation that night. “We will never forget them, nor the last time we saw them,