Terrifying on Instagram: "On January 28, 1986, millions watched live as the Space Shuttle Challenger launched from Kennedy Space Center in Florida—only to break apart just 73 seconds after liftoff. All seven astronauts on board lost their lives, including Christa McAuliffe, a schoolteacher who had been selected as the first civilian to travel into space. For her students, and for viewers across the country, the moment was heartbreaking. The disaster was traced to a faulty O-ring seal in one of t