Stock Photo - 09/03/1999 ___ In the payload bay of the orbiter Discovery, STS_103 Mission Specialists John M. Grunsfeld Ph.D., left, and Claude Nicollier of Switzerland, right, are briefed on part of the equipment they will use on their mission by a worker from Johnson Space Center, center. The mission involves the repair and upgrade of the Hubble Space Telescope. The crew, who are at KSC to take part in a Crew Equipment Interface Test, also includes Commander Curtis L. Brown Jr., Pilot Scott J. Kelly, and Mission Specialists Steven L. Smith, C. Michael Foale Ph.D., and Jean_François Clervoy of France. Nicollier and Clervoy are with the European Space Agency. Mission STS_103 is a call_up due to the need to replace portions of the pointing system, the gyros, which have begun to fail on the Hubble Space Telescope. Although Hubble is operating normally and conducting its scientific observations, only three of its six gyroscopes are working properly. The gyroscopes allow the telescope to point at stars, galaxies and planets. The STS_103 crew will not only replace gyroscopes, it will also replace a Fine Guidance Sensor and an older computer with a new enhanced model, an older data tape recorder with a solid_state digital recorder, a failed spare transmitter with a new one, and degraded insulation on the telescope with new thermal insulation. The crew will also install a Battery Voltage/Temperature Improvement Kit to protect the spacecraft batteries from overcharging and overheating when the telescope goes into a safe mode. The scheduled launch date in October is under review