Twenty years after the Columbia disaster, a NASA official reflects on lessons learned

Mourners left a makeshift memorial outside NASA's Johnson Space Center in Houston after the Columbia disaster on Feb. 1, 2003. (Brett Coomer/Getty Images)

It's been exactly 20 years since the Space Shuttle Columbia disintegrated as it returned to Earth, killing all seven astronauts on board: commander Rick Husband, pilot Willie McCool, mission specialists Kalpana Chawla, Laurel Clark, Michael Anderson, David Brown and payload specialist Ilan Ramon of Israel.

Their mission — the 28th flight for Columbia, which became NASA's first shuttle to fly in space some two decades earlier — was focused on research on physical, life and space sciences. The crew spent their 16 days in space conducting some 80 experiments before preparing to return to Florida's Kennedy Space Center on the morning of Feb. 1, 2003.