SPACE SHUTTLE MISSION STS-81 LAUNCH COUNTDOWN TO BEGIN JAN. 9

NASA will begin the countdown for launch of Space Shuttle Atlantis on the fifth mission to dock with Russia's space station Mir on Jan. 9 at 7 a.m. at the T-43 hour mark. The KSC launch team will conduct the countdown from Firing Room 1 of the Launch Control Center.

The countdown includes 26 hours and 27 minutes of built-in hold time leading to the opening of the launch window at about 4:27 a.m. (EST) on Jan. 12. The launch window extends for about 7 minutes. The exact time of launch will be determined about 90 minutes before liftoff based on the location of the Mir space station.

In order to accommodate the short window necessary to rendezvous and dock with Mir, some changes have been made to the standard launch countdown. Most significant is the addition of an extra 30 minutes to the normal 10 minute built-in hold at T-9 minutes. Tanking is scheduled to begin at about 7 p.m. Saturday, Jan. 11.

STS-81 is the first Space Shuttle mission of 1997. This will be the 18th flight of the orbiter Atlantis and the 81st flight overall in NASA's Space Shuttle program. Atlantis last flew on the fourth Shuttle/Mir docking flight in September 1996.

Atlantis was rolled out of Kennedy Space Center's Orbiter Processing Facility bay 3 on Dec. 5 and mated with the external tank and solid rocket boosters in the Vehicle Assembly Building. The Shuttle stack was then transported to Pad 39B on Dec. 10. The vehicle was processed for flight without any significant or unexpected techincal difficulities. However, due to problems experienced with Columbia's airlock hatch actuator on the previous Space Shuttle mission, all six of Atlantis' airlock hatch actuators were removed and recertified for flight.

On mission STS-81, Atlantis will carry into orbit a six member crew. Mission Specialist Jerry Linenger will replace John Blaha on the Mir space station. Blaha will return to Earth with the rest of the STS-81 crew. Linenger will remain on Mir until Atlantis again docks with the space station in May.

The STS-81 crew are: Commander Michael Baker, Pilot Brent Jett, and Mission Specialists Jeff Wisoff, John Grunsfeld, Marsha Ivins and Jerry Linenger. All members of the STS-81 crew are veteran Shuttle flyers.

The crew are scheduled to arrive at KSC at about 10 p.m., Jan. 8. Their activities at KSC prior to launch will include equipment fit checks, medical examinations and opportunities to fly in the Shuttle Training Aircraft.

(The countdown will target launch for about 4:27 a.m. on Sunday, Jan. 12. The exact launch time will be adjusted at the T-9 minute hold.)

• Prepare for the start of the STS-81 launch countdown
• Perform the call-to-stations (6:30 a.m. Thursday, Jan. 9)
• 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 (7 a.m.)
• Start preparations for servicing fuel cell storage tanks
• 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 Atlantis' general purpose computers
• Begin stowage of flight crew equipment
• Inspect the orbiter's mid-deck and flight-deck and remove crew module platforms

Enter first planned built-in hold at T-27 hours for duration of four hours (11 p.m.)

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

Resume countdown (3 a.m.)

• Clear launch pad of all personnel
• Begin operations to load cryogenic reactants into Atlantis' fuel cell storage tanks (4:30 - 9:30 a.m.)
• After cryogenic loading operations, re-open the pad

Enter four-hour built-in hold at T-19 hours (11 a.m.)

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

Resume countdown (3 p.m.)

• Start final preparations of the Shuttle's three main engines for main propellant tanking and flight
• Activate the orbiter's flight controls and navigation systems
• Install mission specialists' seats in crew cabin
• Close-out the tail service masts on the mobile launcher platform

Enter planned hold at T-11 hours for 13 hours, 37 minutes (11 p.m.)

• Install film in numerous cameras on the launch pad

• Perform orbiter ascent switch list in crew cabin
• Activate the orbiter's communications systems
• Activate orbiter's inertial measurement units
• Fill pad sound suppression system water tank
• Safety personnel conduct debris walkdown
• Move Rotating Service Structure (RSS) to the park position (10 a.m.)
• Following the RSS move, begin final stowage of mid-deck experiments and flight crew equipment

Resume countdown (12:37 p.m.)

• Continue installation of time critical flight crew equipment
• Perform pre-ingress switch list
• Start fuel cell flow-through purge
• 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 Atlantis' purge air to gaseous nitrogen

Enter planned two-hour built-in hold at the T-6 hour mark (5:37 p.m.)

• Launch team verifies no violations of launch commit criteria prior to cryogenic loading of the external tank
• Clear pad of all personnel
• Begin loading the external tank with about 500,000 gallons of cryogenic propellants (about 7 p.m.)

Resume countdown (7:37 p.m.)

• Complete filling the external tank with its flight load of liquid hydrogen and liquid oxygen propellants (about 10 p.m.)
• Perform inertial measurement unit preflight calibration
• Align Merritt Island Launch Area (MILA) tracking antennas
• Perform open loop test with Eastern Range
• Conduct gimbal profile checks of orbital maneuvering system engines

Enter two-hour hold at T-3 hours (10:37 p.m.)

• Close-out crew and Final Inspection Team proceeds to Launch Pad 39B

Resume countdown at T-3 hours (12:37 a.m.)

• Crew departs Operations and Checkout Building for the pad (about 12:42 a.m.)
• Complete close-out preparations in the white room
• Check cockpit switch configurations
• Flight crew begins entry into the orbiter (about 1:22 a.m.)
• Astronauts perform air-to-ground voice checks with Launch Control and Mission Control
• Close Atlantis' crew hatch (about 2:37 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 (3:17 a.m.)

• NASA Test Director conducts final launch team briefings

Resume countdown (3:27 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 40-minute hold at T-9 minutes (3:38 a.m.)

(This is the last planned built-in hold. Other hold options are available if necessary. During this hold, the exact launch time will be determined based on the exact location of the Mir space station. The hold time could vary by as much as a minute or two.)

• 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 4:18 a.m.)

• Start automatic ground launch sequencer (T-9:00 minutes)
• Retract orbiter crew access arm (T-7:30)
• Start mission recorders (T-5:30)
• 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)

SUMMARY OF BUILT-IN HOLDS FOR STS-81

 T-TIME            LENGTH OF HOLD          HOLD BEGINS        HOLD ENDS
T-27 hours            4 hours            11:00 p.m. Thurs.   3:00 a.m. Fri.
T-19 hours            4 hours            11:00 a.m. Fri.     3:00 p.m. Fri.
T-11 hours           13 hours, 37 min.   11:00 p.m. Fri.    12:37 p.m. Sat.
T-6  hours            2 hours             5:37 p.m. Sat.     7:37 p.m. Sat.
T-3  hours            2 hours            10:37 p.m. Sat.    12:37 a.m. Sun.
T-20 minutes         10 minutes           3:17 a.m. Sun.     3:27 a.m. Sun.
T-9  minutes   about 40 minutes           3:38 a.m. Sun.     4:18 a.m. Sun.

CREW FOR MISSION STS-81

         Commander (CDR):   Michael Baker
             Pilot (PLT):   Brent Jett
Mission Specialist (MS1):   Jeff Wisoff
Mission Specialist (MS2):   John Grunsfeld
Mission Specialist (MS3):   Marsha Ivins
Mission Specialist (MS4):   Jerry Linenger (up)
Mission Specialist (MS4):   John Blaha (down)

SUMMARY OF STS-81 LAUNCH DAY CREW ACTIVITIES

Saturday, Jan. 11

   5:30 p.m.    Wake up
   6:00 p.m.    Breakfast
* 11:27 p.m.    Lunch and crew photo
  11:57 p.m.    Weather briefing (CDR, PLT, MS2)

Sunday, Jan. 12

  12:12 a.m.    Don launch and entry suits (MS1, MS3, MS4)
  12:22 a.m.    Don launch and entry suits (CDR, PLT, MS2)
* 12:30 a.m.    Crew suiting photo
* 12:42 a.m.    Depart for launch pad 39B
*  1:22 a.m.    Arrive at white room and begin ingress
*  2:37 a.m.    Close crew hatch
*  4:27 a.m.    Launch

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