STS-103 launch countdown overview
SPACEFIGHT NOW
Posted: Dec. 14, 1999
| Launch Minus-2 days |
Tuesday, December 14 |
- Prepare for the start of the STS-103 launch countdown
- Perform the call-to-stations (1 a.m. EST)
- All members of the launch team report to their respective consoles
in Firing Room 1 in the Launch Control Center for the start of the countdown
- Countdown begins at the T-43 hour mark (1:30 a.m. EST)
- Begin final vehicle and facility close-outs for launch
- Load backup flight system software into Discovery's general purpose
computers
- Inertial measurement unit checks (12 p.m. EST)
- Navigation aids activated and tested (2:30 p.m. EST)
- Preparation to load power reactant storage and distribution system
complete (4:30 p.m. EST)
- Enter first planned built-in hold at T-27 hours for duration of four hours
(5:30 p.m. EST)
- Clear launch pad of all non-essential personnel
- Perform test of the vehicle's pyrotechnic initiator controllers
(6:30 p.m. EST)
- Open launch pad to personnel supporting PRSD load
- Resume countdown (9:30 p.m. EST)
- Begin operations to load cryogenic reactants into Discovery's fuel
cell storage tanks (9:30 p.m. - 5:30 a.m. EST)
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| Launch Minus-1 day |
Wednesday, December 15 |
- Enter four-hour built-in hold at T-19 hours (5:30 a.m. EST)
- Demate orbiter mid-body umbilical unit and retract into fixed
service structure (6 a.m. EST)
- Resume orbiter and ground support equipment close-outs
- Resume countdown (9:30 a.m. EST)
- Start final preparations of the Shuttle's main engines for
propellant tanking and flight
- Begin Mission Specialist seat installation and cable routing
verifications (11:30 a.m. EST)
- Close-out the tail service masts on the mobile launcher platform
(4:30 p.m. EST)
- Enter planned hold at T-11 hours for 12 hours, 58 minutes (5:30 p.m. EST)
- Begin startracker functional checks
- Activate orbiter's inertial measurement units (7 p.m. EST)
- Activate the orbiter's communications systems (8:30 p.m. EST)
- Install film in numerous cameras on the launch pad (9:30 p.m. EST)
- Flight crew equipment late stow begins (10 p.m. EST)
- Fill pad sound suppression system water tank
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| Launch day |
Thursday, December 16 |
- Safety personnel conduct debris walk down
- Move Rotating Service Structure (RSS) to the park position (2:30
a.m. EST)
- Perform orbiter ascent switch list in crew cabin
- Start fuel cell flow-through purge (5:30 a.m. EST)
- Resume countdown (6:28 a.m. EST)
- Activate the orbiter's fuel cells (7:38 a.m. EST)
- Configure communications at Mission Control, Houston, for launch
- Clear the blast danger area of all non-essential personnel
- Switch Discovery's purge air to gaseous nitrogen (8:43 a.m. EST)
- Enter planned one-hour built-in hold at the T-6 hour mark (11:28 a.m. EST)
- Launch team verifies no violations of launch commit criteria prior
to cryogenic loading of the external tank
- Clear pad of all personnel
- Resume countdown (12:28 p.m. EST)
- Begin loading the external tank with about 500,000 gallons of
cryogenic propellants (about 12:28 p.m. EST)
- Complete filling the external tank with its flight load of liquid
hydrogen and liquid oxygen propellants (about 3:28 p.m. EST)
- Enter planned two-hour built-in hold at T-3 hours (3:28 p.m. EST)
- Inertial measurement unit preflight calibration complete (3:48 p.m. EST)
- Align Merritt Island Launch Area (MILA) tracking antennas
- Close-out crew and Final Inspection Team proceed to Launch Pad 39B
- Resume countdown at T-3 hours (5:28 p.m. EST)
- Launch Director weather briefing (7:48 p.m. EST)
- Perform open loop test with Eastern Range
- Crew departs Operations and Checkout Building for the pad (about
5:33 p.m. EST)
- Complete close-out preparations in the white room
- Check cockpit switch configurations
- Flight crew begins entry into the orbiter (about 6:03 p.m. EST)
- Astronauts perform air-to-ground voice checks with Launch Control
and Mission Control
- Close Discovery's crew hatch (about 7:18 p.m. EST)
- Perform hatch seal and cabin leak checks
- Complete white room close-out
- Close-out crew moves to fallback area
- Enter planned 10-minute hold at T-20 minutes (8:08 p.m. EST)
- NASA Test Director conducts final launch team briefings
- Complete inertial measurement unit pre-flight alignments
- Resume countdown (8:18 p.m. EST)
- 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 planned 40-minute hold at T-9 minutes (8:29 p.m. EST)
- Launch Director, Mission Management Team and NASA Test Director
conduct final polls for go/no go to launch
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| Final count |
Thursday, December 16 |
- Resume countdown at T-9 minutes (9:09 p.m. EST)
- 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-0:6.6 seconds)
- SRB ignition and liftoff (T-0)
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Data source: NASA.
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Flight data file
Vehicle: Discovery (OV-103)
Payload: HST Servicing Mission-3A
Launch date: Dec. 17, 1999
Launch window: 0218-0259 GMT (2118-2159 EST on Dec. 16)
Launch site: LC-39B, Kennedy Space Center, Fla.
Landing date: Dec. 26, 1999
Landing time: 2356 GMT (1856 EST)
Landing site: SLF, Kennedy Space Center, Fla.
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