STS -103 (English Space Transportation System) is the designation for a flight mission of the U.S. Space Shuttle Discovery ( OV -103 ) from NASA. The launch took place on 20 December 1999. It was the 96th Space Shuttle mission and the 27th flight of the Space Shuttle Discovery.


  • Curtis Brown ( 6 spaceflight ), Commander
  • Scott Kelly ( first space flight), Pilot
  • Steven Smith ( third space flight), Mission Specialist
  • Michael Foale ( fifth space flight), Mission Specialist
  • John Grunsfeld ( third space flight), Mission Specialist
  • Claude Nicollier (4th space flight), Mission Specialist (ESA / Switzerland )
  • Jean -François Clervoy ( third space flight), Mission Specialist (ESA / France)

Mission Description

The main task of the Discovery crew was repairing major onboard systems of the Hubble Space Telescope. Some of them had failed in the past, others were replaced prophylactically.

On the second day of flying the capture of satellites succeeded in the first attempt. During the approach phase, the outboard Mont Euere itself had already prepared for their debut, which was completed on December 22 still (Smith and basic field for 8 hours and 15 minutes). In this case, all six gyroscopes have been substituted, which are necessary for the accurate alignment of 11.5 ton telescope. In mid- November, the fourth gyroscope failed, the telescope was put into a sleep mode. The second important task of the first phase-out was the replacement of six charging devices on the ten -year-old batteries. These control devices monitor the charging process and ensure that the batteries do not get overcharged or overheated.

At the second exit on December 23 (8 hours and 10 minutes) Foale and Nicollier changed from the onboard computer of the telescope. The aged 386 ( 387er with coprocessor ) was replaced by a twenty-fold faster 486. In addition, a 280 kg heavier guide sensor has been replaced. With him, the orientation of the satellite in space is measured with high accuracy. The satellite has a total of three such sensors.

At the center of the third exit maneuver of replacement of the S-band transmitter, the data collected are transmitted to a satellite relay understood. Since these transmitters were not provided for an exchange in zero gravity, the work designed more complicated. Thanks to the special tool brought the substitution, however, succeeded as planned. One of the three data memories, a tape device has been replaced by an electronic memory. This has ten times the capacity of twelve GB. Finally, the thermal insulation was changed to the access doors. In this way, temperature problems in the inside of the satellite should be avoided.

Since all proposed works have been completed, the Hubble telescope could be released from the cargo bay of Discovery on Christmas Day. The ground control announced the full functionality of the satellite, which resumed its normal operation after two weeks.

The Discovery landed after nearly eight days flying on the shuttle runway at Kennedy Space Center.


During the flight, John Mace Grunsfeld led a Mars flag with it, which was for the first time in space.