Which component failed during the Challenger’s January 1986 launch, causing it to explode?

Which component failed during the Challenger’s January 1986 launch, causing it to explode?

The component that failed during the Challenger’s January 1986 launch, causing it to explode, was an O-ring seal in the right Solid Rocket Booster (SRB). This critical rubber component, designed to create a seal between segments of the booster, lost its elasticity due to unusually cold temperatures on the launch day.

On January 28, 1986, the temperature at Cape Canaveral was unseasonably low, hovering near freezing. Engineers from Morton Thiokol, the contractor for the SRBs, had actually voiced concerns about the O-rings’ performance in cold weather prior to the launch, even recommending a delay. However, these warnings were ultimately overruled by NASA management. The cold stiffened the O-rings, preventing them from properly sealing the joint when the rocket motor ignited.

Source:

https://www.youtube.com/watch?v=OfgS_MkMApE

https://www.threads.com/@heavyweightwriting/post/DLqMoptTPX6