Forty years ago, on January 28, 1986, millions of people across the United States—including school kids—witnessed a shocking disaster live on TV. The space shuttle Challenger exploded only moments after launch, tragically killing all seven people on board. The crew included Christa McAuliffe, a high school social studies teacher from New Hampshire. She’d been selected to join the mission as part of NASA’s brand-new “Teachers in Space” project.