The decision making underlying the Challenger space shuttle disaster is a classic example of groupthink because

no one really knew if the shuttle was okay to launch.

some people knew the shuttle was not okay to launch, but they did not speak up and thereby risk disrupting group cohesion.

some people spoke up and said the shuttle should not launch, but they were shunned by the rest of the group.

the group was torn apart by disagreement over whether or not the shuttle should launch.