[GioFX]

0010 GMT (7:10 p.m. EST Thurs.)

T-minus 90 minutes and counting. Countdown clocks continue to tick down to T-minus 20 minutes where the next hold is planned. Countdown activities remain on track for liftoff at 9:35:48 p.m.

At this point in the count, the ground launch sequencer software that will control the final nine minutes of the countdown has been initialized. Also, the solid rocket boosters' gas generator heaters in the hydraulic power units are turned on, the aft skirt gaseous nitrogen purge is starting and the rate gyro assemblies (RGAs) are being activated. The RGAs are used by the orbiter's navigation system to determine rates of motion of the boosters during the first stage of flight.