It has been nearly three decades since the space shuttle orbiter Challenger exploded just 73 seconds after lifting off from Cape Canaveral, Florida, on January 28, 1986. More than 12 years have passed since the February day in 2003, when another space shuttle, Columbia, disintegrated upon re-entry into Earth’s atmosphere. This summer, pieces of the wreckage as well as personal effects of the 14 astronauts killed aboard the two doomed shuttles are on display for the first time, as part of a new permanent memorial at NASA’s Kennedy Space Center.

When the space shuttle Challenger lifted off on its 10th mission on January 28, 1986, its crew of seven included New Hampshire schoolteacher Christa McAuliffe, winner of a national competition designed to highlight the importance of teachers and foster students’ interest in space and other high-tech careers. Countless schoolchildren were among the TV viewers watching in horror as the space shuttle exploded into pieces when a booster engine failed just 73 seconds after liftoff from Cape Canaveral. In the aftermath of this tragedy, the National Aeronautics and Space Administration (NASA) conducted an intensive investigation to determine what had gone wrong, and to make the shuttle program safer for its astronauts. The 118 tons of wreckage, salvaged from the Atlantic Ocean, was then buried in a pair of abandoned missile silos some 90 feet below ground, far from the public eye.

The tragedy that claimed the space shuttle Columbia on February 1, 2003, occurred just minutes before a planned landing at Cape Canaveral’s Kennedy Space Center after a 16-day mission. Columbia, which had made the shuttle program’s first flight in 1981, was reentering Earth’s atmosphere at the end of its 28th mission when it disintegrated into pieces, raining debris over eastern Texas. A subsequent investigation determined that a piece of insulating foam had broken loose and struck the shuttle’s left wing during launch. During reentry, hot gases penetrated the damaged section and melted parts of the wing, which eventually collapsed.