From the Annals of Space Exploration – In 2003, the Space Shuttle Columbia broke up upon reentry killing all seven astronauts.  It was the second catastrophic failure of the Space Shuttle program following the Challenger which exploded about a minute after liftoff in 1986.  The problem occurred during the launch when a piece of foam insulation broke off from the  external tank and struck insulating tile under the left wing of the Shuttle craft.  NASA was aware of this problem as previous shuttle launches had seen foam shedding damage in various degrees.  Some NASA engineers suspected that the damage to Columbia was serious, but managers limited the investigation arguing that any fix was impossible even if a major problem was confirmed.  The engineers were right and when Columbia re-entered the atmosphere hot gasses penetrated the heat shield causing the Shuttle to ultimately break apart.   A massive search and recovery mission ensued with pieces of Columbia being primarily found over a 28,000 square mile area of Texas and Louisiana.

National Weather Service Radar Image of Columbia breakup upon reentry.