How did Kalpana Chawla die?

Kalpana Chawla was one of the seven astronauts that died on February 1, 2003 when the space shuttle Columbia broke up upon re-entry. During the launch, a piece of foam insulation fell off the external tank and damaged the heat shielding on the left wing, causing it to eventually fail.

When the space shuttle re-entered the atmosphere, the heat buildup along the leading edge of the left wing became too much for the damaged heat tiles to absorb. The intense heat melted the structural supports inside the wing, causing it to buckle and disintegrate. The orbiter broke up over Texas, and everyone aboard was killed.