STS-121 Launch Date Decision

Despite Objections, NASA Decides to Launch the Space Shuttle on July First, SpaceRef

“Griffin was rather clear about what would happen if there was a larger problem. “If we have another major incident with the launch of the shuttle I would not want to continue with the program.” Griffin added later “If we lost another vehicle I will tell you right now that I would be moving to shut the program down. I am sorry if that sounds too blunt for some but that’s where I am.”

Shuttle launch date set despite safety objections, Spaceflight Now

“NASA Administrator Mike Griffin, overruling objections from the agency’s chief engineer and safety office, cleared the shuttle Discovery for launch July 1 on a mission to service and resupply the international space station.”