Thursday, August 24, 2006

Space Shuttle (STS-115) Countdown Schedule

NASA began the countdown for the launch of Space Shuttle Atlantis on mission STS-115 at noon EDT Thursday, Aug. 24, at the T-43 hour point. The countdown includes 33 hours, 24 minutes of built-in hold time leading to a preferred launch time at about 4:30 p.m. on Sunday, Aug. 27, with a launch window extending about five minutes. Right now, there is a predicted 30% chance of weather violating launch criteria due to the daily thunderstorms encountered this time of year.

Operations related to tracking, range safety, and booster recovery typically use HF radio.

For information about the STS-115 crew and the mission to the International Space Station, visit:

Here is the nominal countdown schedule, subject to change, of course. All times Eastern:

Launch-3 Days (Thursday, Aug. 24)

Prepare for the start of the STS-115 launch countdown
Perform the call to stations (11:30 a.m.)
Countdown begins at the T-43 hour mark (noon)
Begin final vehicle and facility closeouts for launch
Check out backup flight systems
Review flight software stored in mass memory units and display systems

Load backup flight system software into Atlantis' general purpose
Remove flight-deck platforms (8:30 p.m.)
Complete preparation to load power reactant storage and distribution
system (11 p.m.)

Launch-2 Days (Friday, Aug. 25)

Activate and test navigational systems (1 a.m.)
Flight deck preliminary inspections complete (4 a.m.)

Enter first built-in hold at T-27 hours for duration of 4 hours (4

Clear launch pad of all non-essential personnel
Perform test of the vehicle's pyrotechnic initiator controllers

Resume countdown (8 a.m.)

Begin operations to load cryogenic reactants into Atlantis' fuel cell
storage tanks (8 a.m.)

Enter 10-hour built-in hold at T-19 hours (4 p.m.)

Demate orbiter mid-body umbilical unit (4:30 p.m.)
Resume orbiter and ground support equipment closeouts

Launch-1 Day (Saturday, Aug. 26)

Resume countdown (2 a.m.)

Final preparations of the shuttle's three main engines for main
propellant tanking (2 a.m.)
Begin filling pad sound suppression system water tank (4 a.m.)
Pad sound suppression system water tank filling complete (7 a.m.)
Close out the tail service masts on the mobile launcher platform
Begin star tracker functional checks (9:50 a.m.)

Enter planned hold at T-11 hours for 13 hours, 34 minutes (10 a.m.)

Activate orbiter's inertial measurement units
Activate the orbiter's communications systems
Install film in numerous cameras on the launch pad (10:55 a.m.)
Flight crew equipment late stow (3:10 p.m.)
Move Rotating Service Structure to the park position (7 p.m.)
Perform ascent switch list
Fuel cell flow-through purge complete

Resume countdown at T-11 hours (11:34 p.m.)

Launch Day (Sunday, Aug. 27)

Activate the orbiter's fuel cells (12:45 a.m.)
Clear the blast danger area of all non-essential personnel
Switch Atlantis' purge air to gaseous nitrogen (1:20 a.m.)

Enter planned 2-hour built-in hold at the T-6 hour mark (4:34 a.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 (6:34 a.m.)

Chilldown of propellant transfer lines (6:34 a.m.)
Begin loading the external tank with about 500,000 gallons of
cryogenic propellants (about 6:44 a.m.)
Complete filling the external tank with its flight load of liquid
hydrogen and liquid oxygen propellants (about 9:34 a.m.)
Final Inspection Team proceeds to launch pad

Enter planned 3-hour built-in hold at T-3 hours (9:34 a.m.)

Perform inertial measurement unit preflight calibration
Align Merritt Island Launch Area tracking antennas
Perform open loop test with Eastern Range

Resume countdown at T-3 hours (12:34 p.m.)

Crew departs Operations and Checkout Building for the pad (12:40 p.m.)

Complete closeout preparations in the White Room
Check cockpit switch configurations
Flight crew begins entry into the orbiter (about 1:10 p.m.)
Astronauts perform air-to-ground voice checks with Launch and Mission
Begin to close Atlantis' crew hatch (about 2 p.m.)
Begin Eastern Range final network open loop command checks
Perform hatch seal and cabin leak checks
Complete White Room closeout
Closeout crew moves to fallback area
Primary ascent guidance data is transferred to the backup flight

Enter planned 10-minute hold at T-20 minutes (3:14 p.m.)

NASA test director conducts final launch team briefings
Complete inertial measurement unit preflight alignments

Resume countdown at T-20 minutes (3:24 p.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 (3:35 p.m.)

Launch director, Mission Management Team and NASA test director
conduct final polls for "go/no go" to launch

Resume countdown at T-9 minutes (about 4:21 p.m.)

Start automatic ground launch sequencer (T-9 minutes)
Retract orbiter crew access arm (T-7:30)
Start mission recorders (T-6:15)
Start Auxiliary Power Units (T-5)
Arm solid rocket booster and external tank range safety safe and arm
devices (T-5)
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 bi-pod heaters (T-1:52)
Deactivate solid rocket booster joint heaters (T-1)
Orbiter transfers from ground to internal power (T-0:50 seconds)
Ground Launch Sequencer go for auto sequence start (T-0:31 seconds)
Booster gimbal profile (T-0:21 seconds)
Ignition of three space shuttle main engines (T-6.6 seconds)
Booster ignition and liftoff (T-0)

Commander: Brent Jett
Pilot: Chris Ferguson
Payload Commander (MS1): Joe Tanner
Mission Specialist (MS2): Dan Burbank
Mission Specialist (MS3): Heidemarie Stefanyshyn-Piper
Mission Specialist (MS4): Steve MacLean


Sunday, Aug. 27
6:30 a.m. -- Crew wakes up
7 a.m. -- Breakfast
*10:55 a.m. -- Television coverage from crew quarters
Noon -- Weather briefing
*12:10 p.m. -- Don flight suits
*12:40 p.m. -- Depart for launch pad
*1:10 p.m. -- Arrive at White Room and begin ingress
*2:25 p.m.-- Close crew hatch
*4:30 p.m. -- Launch

* Televised events (times may vary slightly)
All times Eastern


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