Space tragedy: When space shuttle Columbia exploded in the sky, killed all astronauts

In one of the most tragic space flights ever, space shuttle Columbia exploded in the sky on its return trip from space. (NASA)

Columbia was destroyed during reentry on Feb. 1, 2003. (NASA)

The reason behind the destruction of the shuttle was shocking.  (NASA)

While the shuttle reached orbit safely on its way up, its return flight was doomed. The shuttle broke apart high above Texas, just 16 minutes from its planned Florida touchdown. (NASA)

NASA managers dismissed the impact during the flight despite the concerns of others, AP reports. (NASA)

NASA managers dismissed the impact during the flight despite the concerns of others, AP reports. (NASA)

 All seven people aboard, including school teacher Christa McAuliffe and India's Kalpana Chawla, were killed. (NASA)

Like NASA’s earlier tragedies, Columbia’s loss was avoidable, said former shuttle commander Bob Cabana, now NASA's associate administrator. (NASA)

Columbia's last crew included commander Rick Husband, pilot Willie McCool, Michael Anderson, Kalpana Chawla, David Brown, Ilan Ramon and Laurel Clark.

NASA marked the 20th anniversary of the space shuttle Columbia tragedy with somber ceremonies and remembrances during its annual tribute to fallen astronauts on January 26. (NASA)