Challenger had a TDRSS satellite in its cargo bay and we were tracking live telemetry from the satellite as the shuttle lifted off. My buddy was on the TDRSS support team and was distraught after the explosion fearing that perhaps something had happened to the liquid hydrazine in the satellite's fuel tank. Everybody even remotely responsible for something on the many systems and subsystems in the shuttle and its cargo was what-iffing to figure out what just happened and why. It was a dark day for all of us--on top of the greater tragedy of the loss of the crew.