Spaceflight Now STS-109

STS-109 Countdown Timeline
Updated: February 23, 2002

All times are Eastern Standard Time

Minus-3 Days
Monday, Feb. 25
- Columbia's astronauts arrive at Kennedy Space Center (1 a.m.)
- Perform the call-to-stations (9:30 a.m.)
- STS-109 launch countdown begins at the T-43 hour mark (10 a.m.)
- Begin final vehicle and facility close-outs for launch
- Check out back-up flight systems
- Review flight software stored in mass memory units and display systems
- Load backup flight system software into Columbia's general purpose computers
- Remove mid-deck and flight-deck platforms (6 p.m.)
- Activate and test navigational systems (11 p.m.)
Minus-2 Days
Tuesday, Feb. 26
-Complete preparation to load power reactant storage and distribution system (1 a.m.)
- Flight deck preliminary inspections complete (2 a.m.)
- Enter first built-in hold at T-27 hours for duration of 4 hours (2 a.m.)
- Clear launch pad of all non-essential personnel
- Perform test of the vehicle's pyrotechnic initiator controllers (3 a.m.)
- Resume countdown (6 a.m.)
- Begin operations to load cryogenic reactants into Columbia's fuel cell storage tanks (6 a.m. - 2 p.m.)
- Enter 4-hour built-in hold at T-19 hours (2 p.m.)
- Begin filling pad sound suppression system water tank (2 p.m.)
- Demate orbiter mid-body umbilical unit (2:30 p.m.)
- Resume orbiter and ground support equipment close-outs
- Resume countdown (6 p.m.)
- Final preparations of the Shuttle's three main engines for main propellant tanking and flight (6 p.m.)
- Pad sound suppression system water tank filling complete (7 p.m.)
- Close out the tail service masts on the mobile launcher platform
Minus-1 Day
Wednesday, Feb. 27
- Enter planned hold at T-11 hours for 12 hours, 58 minutes (2 a.m.)
- Begin star tracker functional checks (3 a.m.)
- Activate orbiter's inertial measurement units
- Activate the orbiter's communications systems
- Install film in numerous cameras on the launch pad (4:50 a.m.)
- Flight crew equipment late stow (7:20 a.m.)
- Move Rotating Service Structure (RSS) to the park position (11 a.m.)
- Perform ascent switch list
- Fuel cell flow-through purge complete
- Resume countdown at T-11 hours (2:58 p.m.)
- Activate the orbiter's fuel cells (4:08 p.m.)
- Clear the blast danger area of all non-essential personnel
- Switch Columbia's purge air to gaseous nitrogen (4:43 p.m.)
- Enter planned 2-hour built-in hold at the T-6 hour mark (7:58 p.m.)
- Launch team verifies no violations of launch commit criteria prior to cryogenic loading of the external tank
- Clear pad of all personnel
- Resume countdown (9:58 p.m.)
- Chilldown of propellant transfer lines (9:28 p.m.)
- Begin loading the external tank with about 500,000 gallons of cryogenic propellants (about 9:58 p.m.)
Launch Day Thursday, Feb. 28
- Complete filling the external tank with its flight load of liquid hydrogen and liquid oxygen propellants (about 12:58 a.m.)
- Final Inspection Team proceed to launch pad
- Enter planned 2-hour built-in hold at T-3 hours (12:58 a.m.)
- Perform inertial measurement unit preflight calibration
- Align Merritt Island Launch Area (MILA) tracking antennas
- Perform open loop test with Eastern Range
- Resume countdown at T-3 hours (2:58 a.m.)
- Crew departs Operations and Checkout Building for the pad (3:04 a.m.)
- Complete close-out preparations in the white room
- Check cockpit switch configurations
- Flight crew begins entry into the orbiter (about 3:34 a.m.)
- Astronauts perform air-to-ground voice checks with Launch and Mission Control
- Close Columbia's crew hatch (about 4:48 a.m.)
- Begin Eastern Range final network open loop command checks
- Perform hatch seal and cabin leak checks
- Complete white room close-out
- Close-out crew moves to fallback area
- Primary ascent guidance data is transferred to the backup flight system
- Enter planned 10-minute hold at T-20 minutes (5:38 a.m.)
- NASA Test Director conducts final launch team briefings
- Complete inertial measurement unit preflight alignments
- Resume countdown at T-20 minutes (5:48 a.m.)
- Transition the orbiter's onboard computers to launch configuration
- Start fuel cell thermal conditioning
- Close orbiter cabin vent valves
- Transition backup flight system to launch configuration
- Enter estimated 40-minute hold at T-9 minutes (5:59 a.m.)
- Launch Director, Mission Management Team and NASA Test Director conduct final polls for go/no go to launch
Final Count Thursday, Feb. 28
- Resume countdown at T-9 minutes (about 6:39 a.m.)
- Start automatic ground launch sequencer (T-9:00 minutes)
- Retract orbiter crew access arm (T-7:30)
- Start mission recorders (T-6:15)
- Start Auxiliary Power Units (T-5:00)
- Arm SRB and ET range safety safe and arm devices (T-5:00)
- Start liquid oxygen drainback (T-4:55)
- Start orbiter aerosurface profile test (T-3:55)
- Start main engine gimbal profile test (T-3:30)
- Pressurize liquid oxygen tank (T-2:55)
- Begin retraction of the gaseous oxygen vent arm (T-2:55)
- Fuel cells to internal reactants (T-2:35)
- Pressurize liquid hydrogen tank (T-1:57)
- Deactivate SRB joint heaters (T-1:00)
- Orbiter transfers from ground to internal power (T-0:50 seconds)
- Ground Launch Sequencer go for auto sequence start (T-0:31 seconds)
- SRB gimbal profile (T-0:21 seconds)
- Ignition of three Space Shuttle main engines (T-6.6 seconds)
- SRB ignition and liftoff (T-0)