SPACE SHUTTLE MISSION STS-90 LAUNCH COUNTDOWN TO BEGIN APRIL 13

NASA will begin the countdown for launch of Space Shuttle Columbia on mission STS-90 on April 13 at 2 a.m. EDT at the T-43 hour mark. The KSC launch team will conduct the countdown from Firing Room 3 of the Launch Control Center.

The countdown includes 41 hours and 19 minutes of built-in hold time leading to a launch time of 2:19 p.m. EDT on April 16. The launch window extends for 2 hours and 30 minutes.

STS-90 is the second Space Shuttle mission this year. This will be the 25th flight of the orbiter Columbia and the 90th flight overall in NASA's Space Shuttle program. STS-90 is currently scheduled to last 16 days, 21 hours, 48 minutes, which includes a one-day mission extension. The option to extend the mission will be addressed during the flight based on available consumables. Columbia is scheduled to land at KSC at 11:07 a.m. on May 3.

Columbia was rolled out of Kennedy Space Center's Orbiter Processing Facility bay 3 on March 16 and then mated with the external tank and solid rocket boosters in the Vehicle Assembly Building. The Shuttle stack was transported to Pad 39B on March 23.

On the STS-90 Neurolab mission, Columbia will carry a seven member crew into orbit to participate as "test subjects" in complex neurological research. Along with the astronauts, mice, crickets, fish, snails and rats will be used in this advanced study of human and animal neurological systems. Neurolab will examine the effects of spaceflight on the brain, spinal cord, peripheral nerves and sensory organs in the human body.

The STS-90 crew consists of: Commander Richard Searfoss, Pilot Scott Altman, Mission Specialists Rick Linnehan, Kay Hire, Dave Williams of Canada, and Payload Specialists Jay Buckey and James Pawelczyk.

The crew is scheduled to arrive at KSC at about 3:30 p.m., Monday, April 13. Their activities at KSC prior to launch will include crew equipment fit checks, medical examinations and opportunities to fly in the Shuttle Training Aircraft.

• Prepare for the start of the STS-90 launch countdown
• Perform the call-to-stations (1:30 a.m.)
• All members of the launch team report to their respective consoles in Firing Room 3 in the Launch Control Center for the start of the countdown
• Countdown begins at the T-43 hour mark (2 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
• Begin stowage of flight crew equipment
• Inspect the orbiter's mid-deck and flight-deck and remove crew module platforms
• Activate and test navigational systems
• Complete preparations for loading of power reactant storage and distribution system

Enter first planned built-in hold at T-27 hours for duration of four hours (6 p.m.)

• Clear launch pad of all non-essential personnel
• Perform test of the vehicle's pyrotechnic initiator controllers
• Open launch pad to personnel supporting PRSD load

Resume countdown (10 p.m.)

• Begin operations to load cryogenic reactants into Columbia's fuel cell storage tanks and extended duration orbiter (EDO) tanks located in the orbiter's payload bay (10 p.m. - 10 a.m.)

Enter eight-hour built-in hold at T-19 hours (6 a.m.)

• Demate orbiter mid-body umbilical unit and retract into fixed service structure
• Resume orbiter and ground support equipment close-outs

Resume countdown (2 p.m.)

• Start final preparations of the Shuttle's three main engines for main propellant tanking and flight
• Neurolab late stow begins
• Close-out the tail service masts on the mobile launcher platform

Enter planned hold at T-11 hours for 25 hours, 59 minutes (10 p.m.)

• Neurolab late stow complete
• Activate the orbiter's flight controls and navigation systems
• Begin startracker functional checks
• Activate orbiter's inertial measurement units
• Install film in numerous cameras on the launch pad
• Activate the orbiter's communications systems
• Flight crew equipment late stow
• Fill pad sound suppression system water tank
• Safety personnel conduct debris walk down
• Move Rotating Service Structure (RSS) to the park position (8 p.m.)
• Perform orbiter ascent switch list in crew cabin
• Start fuel cell flow-through purge

Resume countdown (11:59 p.m.)

• Activate the orbiter's fuel cells
• Configure communications at Mission Control, Houston, for launch
• Clear the blast danger area of all non-essential personnel
• Switch Columbia's purge air to gaseous nitrogen
• Complete inertial measurement unit activation

Enter planned one-hour built-in hold at the T-6 hour mark (4:59 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 (5:59 a.m.)

• Begin loading the external tank with about 500,000 gallons of cryogenic propellants (about 5:30 a.m.)
• Complete filling the external tank with its flight load of liquid hydrogen and liquid oxygen propellants (about 8:30 a.m.)

Enter planned two-hour built-in hold at T-3 hours (8:59 a.m.)

• Perform inertial measurement unit preflight calibration
• 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 (10:59 a.m.)

• Perform open loop test with Eastern Range
• Crew departs Operations and Checkout Building for the pad (about 11:04 a.m.)
• Complete close-out preparations in the white room
• Check cockpit switch configurations
• Flight crew begins entry into the orbiter (about 11:34 a.m.)
• Astronauts perform air-to-ground voice checks with Launch Control and Mission Control
• Close Columbia's crew hatch (about 12:49 p.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 (1:39 p.m.)

• NASA Test Director conducts final launch team briefings
• Complete inertial measurement unit pre-flight alignments

Resume countdown (1:49 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 planned 10-minute hold at T-9 minutes (2:00 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 (2:10 p.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)

  T-TIME    LENGTH OF HOLD               HOLD BEGINS         HOLD ENDS
T-27 hours     4 hours                  6:00 p.m. Mon.     10:00 p.m. Mon.
T-19 hours     8 hours                  6:00 a.m. Tues.     2:00 p.m. Tues.
T-11 hours    25 hours, 59 minutes     10:00 p.m. Tues.    11:59 p.m. Wed.
T-6  hours     1 hour                   4:59 a.m. Thurs.    5:59 a.m. Thurs.
T-3  hours     2 hours                  8:59 a.m. Thurs.   10:59 a.m. Thurs.
T-20 minutes  10 minutes                1:39 p.m. Thurs.    1:49 p.m. Thurs.
T-9  minutes  10 minutes                2:00 p.m. Thurs.    2:10 p.m. Thurs.

         Commander (CDR):  Richard Searfoss
             Pilot (PLT):  Scott Altman
Mission Specialist (MS1):  Rick Linnehan
Mission Specialist (MS2):  Kay Hire
Mission Specialist (MS3):  Dave Williams
Payload Specialist (PS1):  Jay Buckey  
Payload Specialist (PS2):  James Pawelczyk

Thursday, April 16 

  7:00 a.m.  Wake up 
  7:30 a.m.  Breakfast  
* 9:54 a.m.  Crew photo
 10:24 a.m.  Weather briefing (CDR, PLT, MS2)
 10:24 a.m.  Don launch and entry suits (MS1, MS3, PS)
 10:34 a.m.  Don launch and entry suits (CDR, PLT, MS2)
*10:50 a.m.  Suit up photo
*11:04 a.m.  Depart for launch pad 39B
*11:34 a.m.  Arrive at white room and begin ingress
*12:49 p.m.  Close crew hatch
* 2:19 p.m.  Launch

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