Mission Specialists John M. Grunsfeld are briefed on part of the equipment they will use.

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