挑战者号航天飞机灾难发生于美国东部时间1986年1月28日上午11时39分（世界标准时间16时39分）：在美国佛罗里达州上空刚起飞73秒的挑战者号航天飞机发生解体，机上7名机组人员丧命。解体后的残骸掉落在美国佛罗里达州中部的大西洋沿海处。

挑战者号航天飞机升空后，因右侧固体火箭助推器的O型环密封圈失效，使得原本应该是密封的固体火箭助推器内的高压高热气体泄漏。这批气体影响了毗邻的外储箱，在高温的烧灼下结构失效，同时也让右侧固体火箭助推器尾部脱落分离。最后，高速飞行中的航天飞机在空气阻力的作用下于发射后的第73秒解体，机上7名机组人员无一幸免。挑战者号的残骸则散落在大海中，在之后被远程搜救队打捞了上来。尽管无法确切知悉机组人员的罹难时间，现在已知在航天飞机初步解体时仍有几个幸存者。但无论如何，没有完善逃生措施以及事发所处环境仍使得7名机组人员全数罹难。

The Space Shuttle Challenger disaster occurred on January 28, 1986, when the NASA Space Shuttle orbiter Challenger (OV-099) (mission STS-51-L) broke apart 73 seconds into its flight, leading to the deaths of its seven crew members, which included five NASA astronauts and two Payload Specialists. The spacecraft disintegrated over the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 11:39 EST (16:39 UTC). Disintegration of the vehicle began after an O-ring seal in its right solid rocket booster (SRB) failed at liftoff. The O-ring was not designed to fly under unusually cold conditions as in this launch. Its failure caused a breach in the SRB joint it sealed, allowing pressurized burning gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB aft field joint attachment hardware and external fuel tank. This led to the separation of the right-hand SRB's aft field joint attachment and the structural failure of the external tank. Aerodynamic forces broke up the orbiter.