NASA News   
National Aeronautics and
Space Administration

John F. Kennedy Space Center
Kennedy Space Center, Florida 32899

                                                
 For release:Dec. 13, 1999


KSC RELEASE NO.  151-99

LAUNCH COUNTDOWN FOR STS-103 SET TO BEGIN DECEMBER 14  

        NASA will begin the countdown for launch of Space Shuttle
Discovery on mission STS-103 on Dec. 14 at 1:30 a.m. EST 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 24 hours and 48 minutes of built-in hold
time
leading to a liftoff on Dec. 14. The launch window opens at 9:18 p.m. and
extends for 41 minutes. 

        This is the third and final mission of 1999. Mission STS-103 marks
the 27th flight of orbiter Discovery and the 96th flight overall in Space
Shuttle history. STS-103 is slated to last 9 days, 21 hours. Discovery
returns to KSC's Shuttle Landing Facility at about 6:56 p.m. EST on
Sunday, Dec. 26.

                Mission STS-103 is designed to replace worn parts on the
9-year-old Hubble Space Telescope and to upgrade other systems on the
space observatory.  All of the six gyroscopes that provide Hubble's
pointing capability will be replaced on orbit along with other equipment
like a guidance sensor and main computer.  Four spacewalks are planned to
support this flight. 

        Discovery rolled out of Kennedy Space Center's Orbiter Processing
Facility bay 1 on Nov. 4 and was mated to the external tank and solid
rocket boosters in the Vehicle Assembly Building. As a precaution, Shuttle
managers opted to change-out Discovery's No. 3 main engine in the VAB.  A
small drill bit had broken off in the engine's coolant cavity during
routine processing several months earlier.  On Nov. 13, the fully
assembled Space Shuttle lumbered out of the VAB atop the crawler
transporter en route to Launch Pad 39B. 

                Once at the pad, workers resumed routine processing
activities along with thorough wiring inspections at the orbiter/external
tank umbilical and aft engine compartment.  Wiring repairs were effected
as required.  Replacement of a dented liquid hydrogen recirculation line
in Discovery's engine compartment was also required in addition to
standard processing.
   
        The STS-103 crew consists of: Commander Curt Brown, Pilot Scott
Kelly, Mission Specialists Steve Smith, Michael Foale, John Grunsfeld,
Claude Nicollier (ESA) and Jean-Francois Clervoy (ESA). The crew arrived
at KSC at about 8:20 p.m., Monday, December 6. Their activities at KSC
prior to launch include crew equipment fit checks, medical examinations
and opportunities to fly in the Shuttle Training Aircraft. 

COUNTDOWN MILESTONES
*all times are Eastern
Launch - 2 Days (Tuesday, Dec. 14)

*       Prepare for the start of the STS-103 launch countdown 
*       Perform the call-to-stations (1 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 the T-43 hour mark (1:30 a.m.)
*       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.)
*       Navigation aids activated and tested (2:30 p.m.)
*       Preparation to load power reactant storage and distribution system
	complete (4:30 p.m.)

Enter first planned built-in hold at T-27 hours for duration of four hours
(5:30 p.m.)

*       Clear launch pad of all non-essential personnel
*       Perform test of the vehicle's pyrotechnic initiator controllers
	(6:30 p.m.)
*       Open launch pad to personnel supporting PRSD load

Resume countdown (9:30 p.m.)
 
*       Begin operations to load cryogenic reactants into Discovery's fuel
	cell storage tanks  (9:30 p.m. - 5:30 a.m.) 

Launch - 1 Day (Wednesday, Dec. 15)

Enter four-hour built-in hold at T-19 hours (5:30 a.m.)

*       Demate orbiter mid-body umbilical unit and retract into fixed
	service structure (6 a.m.)
*       Resume orbiter and ground support equipment close-outs

Resume countdown (9:30 a.m.)

*       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.)
*       Close-out the tail service masts on the mobile launcher platform
	(4:30 p.m.)

Enter planned hold at T-11 hours for 12 hours, 58 minutes (5:30 p.m.)

*       Begin startracker functional checks 
*       Activate orbiter's inertial measurement units (7 p.m.)
*       Activate the orbiter's communications systems (8:30 p.m.)
*       Install film in numerous cameras on the launch pad (9:30 p.m.)
*       Flight crew equipment late stow begins (10 p.m.)
*       Fill pad sound suppression system water tank

Launch Day (Thursday, Dec. 16)

*       Safety personnel conduct debris walk down
*       Move Rotating Service Structure (RSS) to the park position (2:30
	a.m.) 
*       Perform orbiter ascent switch list in crew cabin
*       Start fuel cell flow-through purge (5:30 a.m.)

Resume countdown (6:28 a.m.)

*       Activate the orbiter's fuel cells (7:38 a.m.)
*       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.)

Enter planned one-hour built-in hold at the T-6 hour mark (11:28 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 (12:28 p.m.)

*       Begin loading the external tank with about 500,000 gallons of
	cryogenic propellants (about 12:28 p.m.)
*       Complete filling the external tank with its flight load of liquid
	hydrogen and liquid oxygen propellants (about 3:28 p.m.)

Enter planned two-hour built-in hold at T-3 hours (3:28 p.m.)

*       Inertial measurement unit preflight calibration complete (3:48
	p.m.)
*       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.)

*       Launch Director weather briefing (7:48 p.m.)
*       Perform open loop test with Eastern Range
*       Crew departs Operations and Checkout Building for the pad (about
	5:33 p.m.)
*       Complete close-out preparations in the white room
*       Check cockpit switch configurations 
*       Flight crew begins entry into the orbiter (about 6:03 p.m.)
*       Astronauts perform air-to-ground voice checks with Launch Control
	and Mission Control
*       Close Discovery's crew hatch (about 7:18 p.m.)
*       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.)

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

Resume countdown (8:18 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 40-minute hold at T-9 minutes (8:29 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 (9:09 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-0:6.6 seconds)
*       SRB ignition and liftoff (T-0)


SUMMARY OF BUILT-IN HOLDS FOR STS-103

    T-TIME            LENGTH OF HOLD        HOLD BEGINS        HOLD ENDS 
T-27 hours      4 hours 		5:30 p.m. Tues. 9:30 p.m. Tues. 
T-19 hours      4 hours 		5:30 a.m. Wed.  9:30 a.m. Wed.  
T-11 hours      12 hours, 58 minutes    5:30 p.m. Wed.  6:28 a.m. Thurs.
T-6 hours       1 hour     	       11:28 a.m. Thurs.12:28 p.m. Thurs.
T-3 hours       2 hours     		3:28 p.m. Thurs. 5:28 p.m. Thurs.
T-20 minutes    10 minutes  		8:08 p.m. Thurs. 8:18 p.m. Thurs.
T-9 minutes     40 minutes  		8:29 p.m. Thurs. 9:09 p.m. Thurs.


CREW FOR MISSION STS-103

Commander (CDR):        Curt Brown              
Pilot (PLT):    Scott Kelly             
Mission Specialist (MS1):       Steve Smith             
Mission Specialist (MS2):       Jean-Francois Clervoy           
Mission Specialist (MS3):       John Grunsfeld          
Payload Specialist (MS4): 
Payload Specialist (MS5):     Michael Foale Claude Nicollier               
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