Shuttle Mission STS-108
Orbiter - Endeavour
   December 4, 2001

"T" stands for scheduled liftoff time, "-" stands for minus, "H" stands for hours, "M" stands for minutes and
"S" stands for seconds.

T-20M00S & Counting.....


 

Primary Event Description

Date
Eastern Standard Time
Resume countdown from scheduled hold period.

 December 4, 2001
4:40 P.M.

OMS burn

Other events occurring during this time frame:

Shuttle Main Engines
   
 

During this 10-minute period, activities escalate and the launch team's focus intensifies -- only one hour to go before liftoff! 

è

The orbiter's onboard computers are transitioned to launch configuration.  This includes:

  • Data processing system engineer confirmation that the onboard computers have been transitioned to the Terminal Countdown configuration.

  • Primary Ascent Software is loaded into the orbiter's computers and Endeavour's Commander Dominic Gorie configures the backup Flight System software to a matching profile.

  • Verification that a dump of the orbiter's general purpose computer memory has been completed.

è A purge of the three fuel cells is underway....
è Pilot Mark Kelly is also busy during this period accomplishing the following tasks:
  • Configuring cockpit displays for launch
  • Performing the Main Propulsion System Helium System reconfiguration.  This activity ensures that helium isolation valves necessary for in-flight engine purges function properly and provide an emergency source of pressure for pneumatic shutdown of the engines.
  • Coordinates with Orbiter Test Conductor, Rudy Tench, to ensure proper Reaction Control System propellant tank levels.  This is required as part of checklist activities necessary to verify the appropriate configuration of cross-feed valves between the Orbital Maneuvering System and the Reaction Control System propellant tanks.
è A gaseous nitrogen purge of the Orbiter's aft skirts is completed.  This flow of inert gas ensures that no explosive or flammable gases accumulate in the bottom of the Solid Rocket Boosters prior to launch. 
è All non-essential personnel are cleared from the launch danger area.
è Final verification is received that all emergency aircraft and contingency support personnel are on station.