Challenger: Poorly designed O-rings on Challenger's solid rocket boosters provided an opening on an exceptionally cold morning for hot rocket exhaust to leak out and ignite the shuttle's liquid fuel tank, sparking a fiery explosion that blew apart the orbiter. All seven crew members--Dick Scobee, Michael Smith, Ellison Onizuka, Judith Resnik, Ron Mcnair, Greg Jarvis and space teacher Christa McAuliffe--died in the firey fall on Jan, 28, 1986. Shuttle components were redesigned and launch procedures were changed.
Columbia: Investigators say a piece of flying foam from the shuttle's fuel tank knocked a hole in the leading edge of Columbia's left wing during the shuttle's ascent, allowing hot gases to enter and destroy the shuttle from within during its re-entry 16 days later, on Feb. 1, 2003. The seven crew members-- Rick Husband, William McCool, Michael Anderson, David Brown, Kalpana Chawla, Laurel Clark, and Isreal's Ilan Ramon-- were all killed. The shuttle fuel tank has been redesigned, and new procedures provide more opportunities for inspection and backup, although there is still no proven method for fixinga columbia-scale gap in the Shuttles Skin
