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STS-103 Hubble EVA.jpg
Grunsfeld and Smith replacing gyroscopes on Hubble during the mission's first EVA
NamesSpace Transportation System-96
Mission typeHubble Space Telescope servicing
COSPAR ID1999-069A Edit this at Wikidata
SATCAT no.25996
Mission duration7 days, 23 hours, 11 minutes 34 seconds
Distance travelled5,230,000 kilometres (3,250,000 mi)
Spacecraft properties
SpacecraftSpace Shuttle Discovery
Launch mass112,493 kilograms (248,005 lb)
Landing mass95,768 kilograms (211,132 lb)
Crew size7
EVA duration24 hours, 33 minutes
Start of mission
Launch date20 December 1999 00:50:00 (1999-12-20UTC00:50Z) UTC
Launch siteKennedy LC-39B
End of mission
Landing date28 December 1999 00:01:34 (1999-12-28UTC00:01:35Z) UTC
Landing siteKennedy SLF Runway 33
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude563 kilometres (350 mi)
Apogee altitude609 kilometres (378 mi)
Inclination28.45 degrees
Period96.4 minutes
Capture of Hubble
RMS capture22 December 1999, 00:34 UTC[1]
RMS release25 December 1999, 11:03 UTC[2]
STS-103 Patch.svg STS-103 crew.jpg
Left to right; C. Michael Foale, Claude Nicollier, Scott J. Kelly, Curtis L. Brown Jr., Jean-Francois Clervoy, John M. Grunsfeld and Steven L. Smith
← STS-93
STS-99 →

STS-103 was a Hubble Space Telescope servicing mission by Space Shuttle Discovery. The mission launched from Kennedy Space Center, Florida, on 19 December 1999 and returned on 27 December 1999. It was also the last Shuttle mission of the 1990s, and the only mission to span through Christmas.


Position Astronaut
Commander United States Curtis L. Brown Jr.
Sixth and last spaceflight
Pilot United States Scott J. Kelly
First spaceflight
Mission Specialist 1 United States John M. Grunsfeld
Third spaceflight
Mission Specialist 2 France Jean-François Clervoy, ESA
Third and last spaceflight
Mission Specialist 3 United Kingdom/United States Michael Foale
Fifth spaceflight
Mission Specialist 4 United States Steven L. Smith
Third spaceflight
Mission Specialist 5 Switzerland Claude Nicollier, ESA
Fourth and last spaceflight

Space walks[edit]

  • Smith and Grunsfeld – EVA 1
  • EVA 1 start: 22 December 1999 – 18:54 UTC
  • EVA 1 end: 23 December 1999 – 03:09 UTC
  • Duration: 8 hours, 15 minutes
  • Foale and Nicollier – EVA 2
  • EVA 2 start: 23 December 1999 – 19:06 UTC
  • EVA 2 end: 24 December 1999 – 03:16 UTC
  • Duration: 8 hours, 10 minutes
  • Smith and Grunsfeld – EVA 3
  • EVA 3 start: 24 December 1999 – 19:17 UTC
  • EVA 3 end: 25 December 1999 – 03:25 UTC
  • Duration: 8 hours, 08 minutes

Mission highlights[edit]

STS-103 launch

The primary objective of STS-103 was the Hubble Servicing Mission 3A. STS-103 had four scheduled Extravehicular Activity (EVA) days where four crew members worked 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 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 believed they understood the cause of the failures, although they could not be certain until the gyros were returned from space. Having fewer than three working gyroscopes would have precluded science observations, although the telescope would have remained safely in orbit until a servicing crew arrived.

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). It is the RSUs that the STS-103's astronauts changed. The RSUs each weigh 11.0 kilograms (24.3 lb) and are 12.8 by 10.5 by 8.9 inches (325 by 267 by 226 mm) in size.

In addition to replacing all six gyroscopes on the December flight, the crew replaced a Fine Guidance Sensor (FGS) and the spacecraft's computer. The new computer reduced the burden of flight software maintenance and significantly lowered costs. The new computer was 20 times faster and had six times the memory of the DF-224 computer previously used on Hubble. It weighs 32.0 kilograms (70.5 lb) and is 18.8 by 18 by 13 inches (478 by 457 by 330 mm) in size. The FGS installed was a refurbished unit that was returned from Servicing Mission 2. It weighs 217 kilograms (478 lb) and is 5.5 by 4 by 2 feet (1.68 by 1.22 by 0.61 m) in size.

A voltage/temperature improvement kit (VIK) was also installed to protect spacecraft batteries from overcharging and overheating when the spacecraft goes into safe mode. The VIK modifies the charge cutoff voltage to a lower level to prevent battery overcharging and associated overheating. The VIK weighs about 1.4 kilograms (3.1 lb).

The Mars flag

The repair mission also installed 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 through NASA's Tracking Data Relay Satellite System (TDRSS) to the ground. The new transmitter replaced one that failed in 1998. The SSAT weighs 3.9 kilograms (8.6 lb) and is 14 by 8 by 2+34 inches (356 by 203 by 70 mm).

A spare solid state recorder was also installed to allow efficient handling of high-volume data. Prior to the second servicing mission, Hubble used three 1970s-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 was replaced by a second solid state recorder. The new recorder could hold approximately 10 times as much data as the old unit (12 gigabytes instead of 1.2 gigabytes). The recorder weighs 11.3 kilograms (25 lb) and is 12 by 9 by 7 inches in size.

Finally, the EVA crew replaced the telescope's outer insulation that had 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) 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 also carried hundreds of thousands of student signatures as part of the Student Signatures in Space (S3) program. The unique project provided 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.

On STS-103, Discovery reached the highest orbit ever flown in the program's history, at the apogee of 609 kilometers (378 mi) above Earth. It was the Discovery's last solo spaceflight. All later missions by Discovery were International Space Station missions.

Astronaut John Grunsfeld, who was one of the mission specialists on this mission, brought a "Planet Mars Flag" aboard Discovery.

Attempt Planned Result Turnaround Reason Decision point Weather go (%) Notes
1 6 Dec 1999, 2:37:00 am Scrubbed Technical Additional wiring inspection
2 16 Dec 1999, 9:18:00 pm Scrubbed 10 days, 18 hours, 41 minutes Technical Concern about fuel line welds[3]
3 17 Dec 1999, 8:47:00 pm Scrubbed 0 days, 23 hours, 29 minutes Weather 20%
4 18 Dec 1999, 8:21:00 pm Scrubbed 0 days, 23 hours, 34 minutes Weather
5 19 Dec 1999, 7:50:00 pm Success 0 days, 23 hours, 29 minutes - 60%

Wake-up calls[edit]

NASA began a tradition of playing music to astronauts during the Gemini program, which was first used to wake up a flight crew during Apollo 15.[4] Each track is specially chosen, often by their families, and usually has a special meaning to an individual member of the crew, or is applicable to their daily activities.[4][5]

Flight day Song Artist/composer
Day 2 "Takin' Care of Business" Bachman–Turner Overdrive
Day 3 "Rendezvous" Bruce Springsteen
Day 4 "Hucklebuck" Beau Jocque and the Zydeco Hi-Rollers
Day 6 "Magic Carpet Ride" Steppenwolf
Day 7 "I'll Be Home for Christmas" Bing Crosby
Day 8 "We're So Good Together" Reba McEntire
Day 9 "The Cup of Life" Ricky Martin

See also[edit]


  1. ^ NASA (21 December 1999). "STS-103, Mission Control Center Status Report #05". Johnson Space Center Mission Status Reports. Houston, TX. Archived from the original on 28 January 2021. Retrieved 28 January 2021.
  2. ^ NASA (26 December 1999). "STS-103, Mission Control Center Status Report #14". Johnson Space Center Mission Status Reports. Houston, TX. Archived from the original on 28 January 2021. Retrieved 28 January 2021.
  3. ^ Harwood, William (15 December 1999). "External tank weld issue appears resolved" (TXT). CBS News. Archived from the original on 4 March 2016. Retrieved 30 August 2009.
  4. ^ a b Fries, Colin (25 June 2007). "Chronology of Wakeup Calls" (PDF). NASA. Archived from the original (PDF) on 5 June 2010. Retrieved 13 August 2007.
  5. ^ NASA (11 May 2009). "STS-103 Wakeup Calls". NASA. Archived from the original on 29 February 2000. Retrieved 31 July 2009.

External links[edit]