In 2003 NASA’s Columbia broke up during reentry, killing all seven astronauts on board. The disaster occurred just minutes before it was to land at the Kennedy Space Center in Florida. Reentry is perhaps the most dangerous phase of a space mission. Spacecraft re-enter Earth’s atmosphere traveling at some 25,000 miles (40,000 km) per hour and face high G-forces and intense heat of about 5,000 ℉ (2,760 ℃). Another complication is a temporary loss of radio communication. For up to several minutes, a plasma sheath—generated by the intense friction—will block radio waves.
The cause of the Columbia disaster was a piece of insulating foam that broke loose from the shuttle’s external propellant tank and struck the leading edge of the left wing soon after liftoff, damaging protective tiles. During Columbia’s atmospheric reentry, hot gases penetrated the damaged tile section and melted major structural elements of the wing, which eventually collapsed.
In addition, several fatal incidents occurred with the Soviet Soyuz program. In 1967 test pilot Vladimir Komarov was killed when the descent module’s parachute failed to unfurl after reentry, and the module crashed—the first human death during a spaceflight. In 1971 three cosmonauts aboard the Soviet spacecraft Soyuz 11 died when their descent module accidentally depressurized while returning to Earth.