STS-103 Day 4 Highlights

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On Thursday, December 23, 1999, 10:00 a.m. CST, STS-103 MCC Status Report # 08 reports:

Discovery's seven-member crew began work early today, preparing for a busy day on orbit, including a second spacewalk and a final check of hardware installed on the Hubble Space Telescope during yesterday's spacewalk.

The primary goal of today's spacewalk, to be conducted by Mike Foale and European Space Agency astronaut Claude Nicollier, is to install a new computer to replace the one currently in use by Hubble. The new computer is 20 times faster and has six times the memory of the outdated unit being replaced. Nicollier and Foale also will change out one of Hubble's three Fine Guidance Sensors that are used to precisely point the telescope as it conducts scientific observations. The unit being installed today is a refurbished unit that was removed and returned to Earth by the STS-82 crew during its servicing of the telescope in February 1997. If time permits, the space walkers also may perform some optional "get ahead" tasks. Foale has conducted two previous spacewalks, during the STS-63 mission in February 1995 and again in September 1997 as he and Mir Space Station Commander Anatoly Solovyev conducted a six-hour survey of the Mir. This is Nicollier's first spacewalk.

Today's spacewalk is scheduled to begin at 1:50 p.m., but could begin earlier if the crew members complete their preparations ahead of schedule. During the spacewalk, Foale can be recognized by the broken red stripes on the legs of his EVA suit, and Nicollier by the diagonally broken red stripes on his suit.

Discovery's astronauts also supported a functional test of the voltage temperature improvement kits - referred to as VIKs - installed by Steve Smith and John Grunsfeld during their spacewalk yesterday. To ensure the checkout is complete prior to the start of today's scheduled EVA, the astronauts began the work shortly after crew wake-up. During the 90-minute long checkout, investigators will monitor the performance of the voltage kits as the telescope's batteries are charged.

This morning's wake-up music honored the two space-walking astronauts, Nicollier and Foale. Traditional Swiss music was played for Nicollier and the song "Only When I Sleep" by The Corrs was played for Foale. Discovery remains in excellent condition, in an orbit with a high point of 380 statute miles and a low point of 369 miles.

On Thursday, December 23, 1999, 11:30 p.m. CST, STS-103 MCC Status Report # 09 reports:

The Hubble Space Telescope received a new advanced computer Thursday from space-walking Discovery astronauts Mike Foale and Claude Nicollier. Their 8-hour, 10-minute space walk, the third longest in history, also saw replacement of a 550-pound fine guidance sensor.

Flight controllers said all major activities of the space walk, the second of three on consecutive days of Discovery's space telescope repair and improvement mission, had been accomplished. Controllers reported that power was reaching both of the new pieces of equipment.

"The brains of Hubble have been replaced," said Mission Specialist John Grunsfeld, who worked Thursday in Discovery's cabin with the space-walking crew members outside. About 30 minutes later Hubble began thinking with those new brains. At an evening mission status briefing, John Campbell, Hubble Space Telescope program manager, said the functional checkout of the new computer showed it was functioning well. Checkout of the Fine Guidance Sensor, is continuing.

The length of Thursday's space walk made it the third longest in history, behind only the 8-hour, 15-minute effort on Wednesday by Payload Commander Steve Smith and Grunsfeld and an 8-hour, 29-minute space walk by three Endeavor astronauts on STS-49 on its Intelsat rescue mission in May 1992.

Replacement of one of Hubble's two S-band transmitters is a highlight of Friday's space walk by Smith and Grunsfeld. The transmitter to be replaced had failed. The second transmitter was able to carry the load alone, so no science was lost. The transmitters are considered very reliable, and unlike most of the equipment aboard Hubble, they were not designed to be changed out in orbit. Special tools were developed to enable astronauts to do the job more easily. Installation of a Solid State Recorder to replace a less reliable and less capable 10-year-old recorder is the second major item on the schedule.

Also on the timeline of the space walk, scheduled to begin at 1:50 p.m. CST, is installation of new insulation on equipment bay doors. The spacewalk could, like its two predecessors on STS-103, begin earlier if the crew completes preparations early. Flight controllers are anxious to end this third space walk at 8 p.m. as scheduled.

Discovery remains is in excellent condition, in an orbit with a high point of 380 statute miles and a low point of 364 miles.

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