June 19, 1995

KSC Release No. 55-95

SPACE SHUTTLE MISSION STS-71 LAUNCH COUNTDOWN TO BEGIN JUNE 20

     NASA will begin the countdown for the 100th U.S. human space
launch on Tuesday, June 20 at 9:30 a.m. The countdown for the
launch of Space Shuttle Atlantis on mission STS-71 is scheduled
to begin that day 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 36 hours and 39 minutes of built-in
hold time leading to the opening of the launch window at about
5:08.37 p.m. (EDT) on June 23. The launch window extends for only
seven 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 seven minute window
necessary to rendezvous and dock with Mir, several changes have
been made to the standard launch countdown. Most significant is
the addition of an extra 30 minutes added to the normal 10 minute
built-in hold at T-9 minutes. Also, tanking is scheduled to begin
about 30 minutes earlier than usually.

     The launch of Atlantis will mark the beginning of the first
mission to dock with Russia's space station Mir. A rendezvous
with the space station occurred earlier this year on mission STS-63.

     STS-71 is the third mission scheduled for 1995. This will be
the 15th flight of the Shuttle Atlantis and the 69th flight
overall in NASA's Space Shuttle program.

     Launch of Atlantis in June will mark a historic milestone in
U.S. spaceflight endeavors as the 100th U.S. human space launch,
dating back to Alan B. Shepard's first historic 15-minute sub-
orbital flight 34 years ago.

     Atlantis was rolled out of Orbiter Processing Facility bay 2
on April 20 and mated with the external tank and solid rocket
boosters in the Vehicle Assembly Building. The Shuttle stack was
then transported to Pad 39A on April 26. Atlantis last flew in
November 1994.

     Atlantis will carry into orbit a seven member crew
consisting of five U.S. astronauts and two Russian Cosmonauts,
which are designated the Mir 19 crew. The two Mir crewmen will
remain on the Russian Space Station changing places with the Mir
18 crew who will return to Earth aboard Atlantis. The Mir 18
crew, which includes astronaut Norm Thagard, have been aboard Mir
since March 16.

     The STS-71 crew are: Commander Robert (Hoot) Gibson, Pilot
Charles Precourt, and Mission Specialists Ellen Baker, Greg
Harbaugh and Bonnie Dunbar and Mir 19 crew cosmonauts Anatoly
Solovyev and Nikolai Budarin. Members of the Mir 18 crew are:
astronaut Norm Thagard and cosmonauts Vladimir Dezhurov and
Gennady Strekalov.

     The STS-71 crew are scheduled to arrive at KSC at about 4:30
p.m. Tuesday, June 20. 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 5:09 p.m. The exact launch
time will be adjusted at the T-9 minute hold.)


                      COUNTDOWN MILESTONES

*all times are Eastern

               Launch - 3 Days (Tuesday, June 20)

Prepare for the start of the STS-71 launch countdown
Perform the call-to-stations at the T-43 hour mark (9 a.m.)
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 9:30 a.m.
Start preparations for servicing fuel cell storage tanks
Begin final vehicle and facility close-outs for launch

              Launch - 2 Days (Wednesday, June 21)

Enter first planned built-in hold at T-27 hours for duration of
  four hours (1:30 a.m.)
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
Perform test of the vehicle's pyrotechnic initiator
  controllers

Resume countdown (5:30 a.m.)

Clear launch pad of all personnel
Begin the 5 hour operation to load cryogenic reactants into
  Atlantis' fuel cell storage tanks

Enter eight-hour built-in hold at T-19 hours (1:30 p.m.)

After cryogenic loading operations, re-open the pad
Resume orbiter and ground support equipment close-outs
Demate orbiter mid-body umbilical unit and retract into
  fixed service structure

Resume countdown (9:30 p.m.)

Start final preparations of the Shuttle's three main engines
  for main propellant tanking and flight

                Launch - 1 Day (Thursday, June 22)
                                
Activate 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 19 hours, 49 minutes (5:30 a.m.)

Perform orbiter ascent switch list in crew cabin
Install film in numerous cameras on the launch pad
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
  at about 8:30 p.m.
Following the RSS move, begin final stowage of mid-deck
  experiments and flight crew equipment

                  Launch Day (Friday, June 23)

Resume countdown (1:19 a.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 (6:19 a.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 7:45 a.m.)

Resume countdown (8:19 a.m.)

Perform inertial measurement unit preflight calibration
Align Merritt Island Launch Area (MILA) tracking antennas
Complete filling the external tank with its flight load of
  liquid hydrogen and liquid oxygen propellants (about 10:45 a.m.)
Perform open loop test with Eastern Range
Conduct gimbal profile checks of orbital maneuvering system
  engines

Enter two-hour hold at T-3 hours (11:19 a.m.)

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

Resume countdown at T-3 hours (1:19 p.m.)

Crew departs Operations and Checkout Building for the pad
  (about 1:24 p.m.)
Complete close-out preparations in the white room
Check cockpit switch configurations
Flight crew begins entry into the orbiter (about 1:54 p.m.)
Astronauts perform air-to-ground voice checks with Launch
  Control and Mission Control
Close Atlantis' crew hatch
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 (3:59 p.m.)

NASA Test Director conducts final launch team briefings

Resume countdown (4:09 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 40-minute hold at T-9 minutes (4:20 p.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.)

Launch Director, Mission Management Team and NASA Test
  Director conduct final polls for go/no go to launch

Resume countdown at T-9 minutes (5 p.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 MPS 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-71

 T-TIME         LENGTH OF HOLD         HOLD BEGINS        HOLD ENDS
T-27 hours       4 hours              1:30 a.m. Wed.     5:30 a.m. Wed. 
                                             
T-19 hours       8 hours              1:30 p.m. Wed.     9:30 p.m. Wed. 
                                             
T-11 hours      19 hours,49 minutes   5:30 a.m. Thurs.   1:19 a.m. Fri.                                 

T-6 hours        2 hours              6:19 a.m. Fri.     8:19 a.m. Fri.
                                   
T-3 hours        2 hours             11:19 a.m. Fri.     1:19 p.m. Fri.
                                   
T-20            10 minutes            3:59 p.m. Fri.     4:09 p.m. Fri.
                                    
T-9 minutes     40 minutes            4:20 p.m. Fri.     5:00 p.m. Fri.
                                  


                     CREW FOR MISSION STS-71

Commander (CDR): Robert "Hoot" Gibson
Pilot (PLT): Charles Precourt
Mission Specialist (MS3): Ellen Baker
Mission Specialist (MS1): Greg Harbaugh
Mission Specialist (MS2): Bonnie Dunbar
Mir 19 Commander: Anatoly Solovyev (MS4 - Ascent only)
Mir 19 Flight engineer: Nikolai Budarin (MS5 - Ascent only)
Mir 18 Commander: Vladimir Dezhurov (Entry only)
Mir 18 Flight engineer: Gennady Strekalov (Entry only)
Mir 18 Cosmonaut-Researcher: Norm Thagard (Entry only)


          SUMMARY OF STS-71 LAUNCH DAY CREW ACTIVITIES

Friday, June 23

 5:09 a.m.      Wake up
 5:45 a.m.      Breakfast
11:30 a.m.      Dinner and crew photo
12:14 p.m.      Weather briefing (CDR, PLT, MS2)
12:14 p.m.      Don flight equipment (MS1, MS3, MS4, MS5)
12:24 p.m.      Don flight equipment (CDR, PLT, MS2)
12:54 p.m.      Depart for launch pad 39A
 1:24 p.m.      Arrive at white room and begin ingress
 3:09 p.m.      Close crew hatch
 5:09 p.m.      Launch