This tests the switch over procedures. T - 9 Minutes. The last built-in hold of the countdown. When the count does pick up at T-9 minutes and counting, it will be under the control of the Ground Launch Sequencer, a major mainframe computer that controls the final countdown. Each console has displays and gauges showing each department's responsibility during the launch.
Safety is foremost in everyone's mind.
These are their friends up there strapped into that spacecraft. The guys at T-20 were the bosses, who wanted their bosses to hear them over NASA Select to show how important they are. He's the most unpredictable guy on the consoles. Normally, when SRO is happy, everyone is happy. Weather is the only other console that can hold a countdown short at T-5 minutes, and still expect to launch today.