STS-103 (96)

Discovery (27)
Pad 39-B (45)
96th Shuttle Mission
27th Flight OV-103
Night Launch (23)
Night Landing (13)
KSC Landing (49)
KSC Night Landing (8)

NOTE: Click Here for Countdown Homepage


Curtis L. Brown (6), Mission Commander
Scott J. Kelly (1), Pilot
Steven L. Smith (3), Mission Specialist
C. Michael Foale (5), Mission Specialist
John M. Grunsfeld (3), Mission Specialist
Claude Nicollier (4), Mission Specialist (ESA)
Jean-Francois Clervoy (3), Mission Specialist (ESA)


OPF -- 06/06/99 (Reference KSC Shuttle Status 6/06/1999)
VAB -- 11/04/99 (Reference KSC Shuttle Status 11/05/1999)
PAD -- 11/13/99 (Reference KSC Shuttle Status 11/09/1999)


Hubble Servicing Mission 3 (SM3A)

Mission Objectives:

Click here for Additional Info on STS-103

The primary objective of STS-103 is the servicing of the Hubble Space Telescope. STS-103 has four scheduled Extravehicular Activity (EVA) days where four crew members will work in pairs on alternating days to renew and refurbish the telescope.

NASA officials decided to move up part of the servicing mission that had been scheduled for June 2000 after three of the telescope's six gyroscopes failed. Three gyroscopes must be working to meet the telescope's very precise pointing requirements, and the telescope's flight rules dictated that NASA consider a "call-up" mission before a fourth gyroscope failed. Four new gyros were installed during the first servicing mission (STS-61) in December of 1993 and all six gyros were working during the second servicing mission (STS-82) in February 1997. Since then, a gyro failed in 1997, another in 1998 and a third in 1999. The Hubble team believes they understand the cause of the failures, although they cannot be certain until the gyros are returned from space. Having fewer than three working gyroscopes would preclude science observations, although the telescope would remain safely in orbit until a servicing crew arrived.

In addition to replacing all six gyroscopes on the December flight, the crew will replace a guidance sensor, the spacecraft's computer and install a voltage/temperature kit for the spacecraft's batteries. A new transmitter, solid state recorder and thermal insulation blankets will also be installed.

Hubble's gyros spin at a constant rate of 19,200 rpm on gas bearings. This wheel is mounted in a sealed cylinder, which floats in a thick fluid. Electricity is carried to the motor by thin wires (approximately the size of a human hair). It is believed that oxygen in the pressurized air used during the assembly process caused the wires to corrode and break. The new gyros were assembled using nitrogen instead of oxygen. Each gyroscope is packaged in a Rate Sensor assembly. The Rate Sensors are packaged in pairs into an assembly called a Rate Sensor Unit (RSU's). It is the RSU's that the STS-103's astronauts will be changing. The RSU's each weigh 24.3 pounds and are 12.8 by 10.5 by 8.9 inches in size.

In addition to replacing all six gyroscopes on the December flight, the crew will replace a Fine Guidance Sensor (FGS) and the spacecraft's computer. The new computer will reduce the burden of flight software maintenance and significantly lower costs. The new computer is 20 times faster and has six times the memory of the current DF-224 computer used on Hubble. It weighs 70.5 pounds and is 18.8 by 18 by 13 inches in size. The FGS being installed is a refurbished unit that was returned from Servicing Mission 2. It weighs 478 pounds and is 5.5 by 4 by 2 feet in size.

A Voltage/temperature Improvement Kit (VIK) will be also be installed to protect spacecraft batteries from overcharging and overheating when the spacecraft goes into safe mode. The VIK modifies the charge cuttoff voltage to a lower level to prevent battery overcharging and associated overheating. The VIK weighs about 3 pounds.

The repair mission will also install a new S-Band Single Access Transmitter (SSAT). Hubble has two identical SSATs onboard and can operate with only one. The SSATs send data from Hubble thru NASA's Tracking Data Relay Satellite System (TDRSS) to the ground. The new transmitter will replace one that failed in 1998. The SSAT weighs 8.5 pounds and is 14 by 8 by 2 and 3/4 inches.

A spare solid state recorder will also be installed to allow efficient handling of high-volume data. Prior to the second servicing mission, Hubble used three 1970's style reel-to-reel tape recorders. During the second servicing mission one of these mechanical recorders was replaced with a digital solid state recorder. During this mission a second mechanical recorder will be replaced by a second Solid State Recorder. The new recorder can hold approximately 10 times as much data as the old unit (12 gigabytes instead of 1.2 gigabytes). The recorder weighs 25 pounds and is 12 by 9 by 7 inches in size.

Finally, the EVA crew will replace the telescopes outer insulation that has degraded. The insulation is necessary to control the internal temperature on the Hubble. The New Outer Blanket Layer (NOBL) and Shell/Shield Replacement Fabric (SSRF) will help protect Hubble from the harsh environment of space. It protects the telescope from the severe and rapid temperature changes it experiences during each 90 minute orbit as it moves from sunlight to darkness.

STS-103 will also carry hundreds of thousands of student signatures as part of the Student Signatures in Space (S3) program. The unique project provides elementary schools (selected on a rotating basis) with special posters to be autographed by students, then scanned onto disks and carried aboard a NASA Space Shuttle mission.


Launched December 19, 1999 7:50:00.069 p.m. EST

Discovery launched on time at the beginning of the 42 minute window from Launch Pad 39B on mission STS-103, the third Hubble Space Telescope servicing mission.

At 6:10 pm, the go was given to the closeout crew to close out the white room at Launch Pad 39-B.

On December 19, 1999, shuttle managers decided to proceed with the STS-103 launch countdown and loading Discovery's external tank. The tanking activity began at 10:30 a.m. today and took 3 hours to complete.

Due to the prediction of poor weather on Saturday, the the mission management team decided to preserve a launch option for Sunday and rescheduled Discovery's launch from December 18 at 8:47 p.m. to December 19 at 7:50pm EST. (Reference KSC Shuttle Status 12/18/1999)

External tank cyrogenic loading was started at 11:29 a.m. EST. By T-minus 3 hours 21 minutes and counting the LH2 tank (2:35 pm EST) was full and in stable replenish mode with 385,265 gallons of LH2. Tanking operations were complete at 3:00pm EST. The Liquid Oxygen (LOX) tank was finishing with its load of 143,350 gal of LOX. The weather forcast is currently 80% chance of unfavorable weather. The crew had breakfast in the O&C crew quarters and suited up at 4:41 pm EST and departed for the launch pad. By 6:10pm EST all crew members were seated in the orbiter and voice checks began. By 6:48pm the hatch was closed and locked for flight. At 7:45pm EST the countdown clock came out of the planned hold at the T-minus 20 minute mark. The launch countdown proceeded to the T-minus 9 minute mark and held due to weather constraints. At 8:52pm EST the launch director scrubbed the launch due to violations of weather launch commit criteria.

The launch was scheduled for Thursday, December 16, 1999 but was delayed 24 hours to check quality control inspection paperwork. On Tuesday, December 15, 1999, during a routine manufacturing inspection of gaseous pressurization lines, a weld made with an improper welding rod was detected. Due to a concern that such an improper weld may have been used, welds and paperwork on STS-103's external tank were reviewed and cleared. The same manufacturer also performed welds on the 17 inch propellant feed lines and struts in the AFT engine compartment when Discovery was constructed. The 24 hour delay was called to give the shuttle team time to review the manufacturing inspection records for those lines as well. (Reference STS-103 Press Conference 12/16/99)
On Tuesday, December 14, 1999, The launch countdown for STS-103 began on schedule today at 1:30 a.m. Yesterday, workers completed aft compartment close-outs and Discovery's aft confidence test concluded last night. Current weather forecasts call for scattered to broken clouds at 3,000 feet and scattered clouds at 25,000 feet; visibility of 7 miles; winds from the north at 12 peaking to 20 knots; temperature at 52 degrees F; relative humidity at 69 percent; and no chance of showers. Weather officials indicate an 80 percent chance of favorable weather conditions for launch attempts on Thursday or Friday. By Saturday, the forecast declines to a 70 percent chance of favorable weather. (Reference KSC Shuttle Status 12/14/1999)

By Monday, December 13, 1999, workers at Launch Pad 39B had completed inspections and leak checks on Shuttle Discovery's replaced liquid hydrogen recirculation line that was replaced over the weekend. Engine compartment close-outs started Sunday and are expected to conclude later today. Launch managers at KSC plan to begin the 43-hour countdown Tuesday at 1:30 a.m. EST. Weather forecasts indicate an 80 percent chance of favorable weather conditions for Thursday's launch attempt at 9:18 p.m. (Reference KSC Shuttle Status 12/13/1999)

On Wednesday, December 8, 1999, Shuttle managers have decided to delay the start of the STS-103 launch countdown by at least 24 hours while engineers evaluate a dented main propulsion system hydrogen line found during closeout inspections of Discovery's engine compartment. A final decision on whether or not the line must be replaced is expected tomorrow. If the line requires replacement, it is anticipated that the work would postpone launch by a minimum of several days. The four-inch diameter line carries liquid hydrogen fuel for the Space Shuttle main engines. (Reference KSC Shuttle Status 12/08/1999)

On Monday, December 6, 1999, the crew of STS-103 arrived at KSC in preparation for launch.

On Wednesday, December 1, 1999, Space Shuttle managers today completed a review of Shuttle Discovery's readiness for flight on mission STS-103. They maintained a launch date of Dec. 9 for Discovery, although a further review of work remaining to close-out Discovery for flight will be held later this week. The launch date may be adjusted slightly pending the status of remaining work that is reported at that time. At the launch pad, workers completed replacement of Discovery's mass memory unit No. 1. Close-out work on the recently repaired orbiter/external tank umbilical wiring harness continues as engineers conduct validation tests on that system. Tonight, workers are slated to begin Shuttle ordnance installation and replacement of a leaky quick disconnect on auxiliary power unit No. 2 is planned for later this week. Routine orbiter aft compartment close-outs continue along with wiring inspections. (Reference KSC Shuttle Status 12/01/1999)

On Sunday, November 15, 1999, The seven-member flight crew arrived at KSC and will participate in Terminal Countdown Demonstration Test (TCDT) activities through Wednesday. The launch day dress rehearsal concludes Wednesday at 11 a.m. with a simulated main engine cutoff. Shuttle managers will convene the STS-103 Flight Readiness Review on Friday, Nov. 19 to discuss the overall readiness of all Space Shuttle systems for flight. (Reference KSC Shuttle Status 11/15/1999)

On Saturday, November 13, 1999, Space Shuttle Discovery rolled out to Launch Pad 39B. First motion began at 7:27 a.m and the Shuttle was hard down at the pad by 2:17 p.m. Discovery had been scheduled to begin its transfer to the pad at 2 a.m., but inspections of minor external tank foam damage delayed the departure. (Reference KSC Shuttle Status 11/15/1999)

On Tuesday, November 9, 1999, Workers have already removed the damaged range safety cable and replacement efforts begin later today. Engineers plan to retest the range safety system Wednesday and close-out the work area Thursday. The damaged range safety cable relays a redundant emergency destruction signal between the solid rocket boosters (SRB) in the unlikely event of a contingency. The cable being replaced runs from the right-hand SRB forward attach point, through the external tank and connects to the left-hand booster. The cable was damaged during close-out operations causing yesterday's test failure. Since the orbiter will remain in the VAB for cable replacement, Shuttle managers have decided to replace Discovery's main engine No. 3 in the VAB as well. Engine replacement efforts are in work and will conclude Thursday. Engine close-outs and verifications will be performed at the pad. (Reference KSC Shuttle Status 11/09/1999)

On Friday, November 5, 1999, Orbiter Discovery has been mated to the external tank and solid rocket boosters stack in VAB high bay 1. Electrical and mechanical connections will conclude late Friday and the orbiter/external tank umbilical mate occurs Saturday. Over the weekend, workers will begin preparations for the engine No. 3 replacement work scheduled to happen at the launch pad. Managers currently plan to transfer Discovery out to Launch Pad 39B Tuesday, Nov. 9 beginning at about 2 a.m. Payload managers plan to transfer the Hubble Servicing Mission cargo to the launch pad Monday, Nov. 8 with installation into the orbiter slated for Nov. 12. KSC managers are developing the remainder of Discovery's prelaunch processing schedule and expect to brief Shuttle program managers at a meeting Monday morning. Program managers are likely to set a new target launch date for STS-103 after the meeting. (Reference KSC Shuttle Status 11/05/1999)

On Friday, October 29, 1999 Shuttle managers will resume discussions on Monday at 1 p.m. to determine Discovery's readiness to leave the Orbiter Process Facility. The orbiter's planned transfer to the Vehicle Assembly Building will now occur no earlier than Monday evening. The postponement accommodates unplanned work to repair a temperature sensor on Discovery's No. 2 nitrogen tank, in the orbiter's midbody. Retests of Discovery's repaired and protected wiring are ongoing and will continue through the vertical processing flow. Several standard prelaunch tests will accommodate necessary functional and redundancy checks of the wiring. Once the orbiter, external tank and booster mating operations are complete, Space Shuttle Discovery will roll out to Launch Pad 39B. Rollout to the pad is currently slated for Sunday, Nov. 7. (Reference KSC Shuttle Status 10/29/1999)

On Thursday, October 7, 1999, with wiring inspections and repairs of Discovery and Endeavour nearing completion and similar work beginning on Atlantis, Shuttle program managers set new planning target launch dates for the next three Space Shuttle missions. (Reference KSC Shuttle Status 10/7/1999)

On Thursday, September 30, 1999, Inspections of the wiring onboard orbiter Discovery are about 95 percent complete, and Shuttle managers expect all remaining wire inspections to conclude next week. During retests of Discovery's recently replaced right-hand orbiter maneuvering system (OMS) engine pod, technicians noted an oxidizer isolation valve that did not cycle properly. Subsequent valve inspections revealed minor corrosion of a manifold No. 5 oxidizer valve, and managers have decided to replace that valve before the STS-103 flight. As a precaution, technicians will conduct thorough inspections of all manifold No. 5 oxidizer and fuel valves located in both OMS pods and the orbiter's forward reaction control system. Inspection of these six valves will be performed in parallel with ongoing orbiter processing and is not expected to further impact the schedule. (Reference KSC Shuttle Status 9/301999)

On Thursday, August 12, 1999 Technicians completed testing of Discovery's power reaction and storage distribution system. Shuttle main engine securing efforts and payload premate testing continue. Later this week, workers will install the orbiter's waste collection system and install the external airlock hatch. (Reference KSC Shuttle Status 8/12/1999)


Altitude: 317nm
Inclination: 28.45
Orbits: 119
Duration: 7 days, 23 hours, 11 minutes 34 seconds
Distance: 3.25 million miles


ET :
MLP : 2


December 27, 1999 KSC 7:01:34 pm EST. Runway 33.
Main Wheel Touchdown (MET 7 Days 23 H 10 M 47 S) (7:00:47)
Nose Wheel Touchdown (MET 7 Days 23 H 10 M 58 S) (7:00:58)
Wheels Stop (MET 7 Days 23 H 11 M 34 S) (7:01:34)

At 5:20pm EST, Discovery was given a go for the deorbit burn. Sonic booms heard at 26 miles from runway with Discovery at 26,000ft. The first landing opportunity at KSC at 5:18pm EST was waived off due to high crosswinds at the Shuttle Landing Facility. The 3rd landing opportunity on 12/27/99 for KSC would have been at 8:43pm EST.

Mission Highlights:

STS-103 Flight Day 1 Highlights:
STS-103 Flight Day 2 Highlights:
STS-103 Flight Day 3 Highlights:
STS-103 Flight Day 4 Highlights:
STS-103 Flight Day 4 Highlights:
STS-103 Flight Day 5 Highlights:
STS-103 Flight Day 6 Highlights:
STS-103 Flight Day 7 Highlights:
STS-103 Flight Day 8 Highlights:

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Last Updated Friday June 29 11:37:08 EDT 2001
Jim Dumoulin (