New station truss installed during spacewalk
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: August 11, 2007
Astronaut Rick Mastracchio and Canadian flier Dave Williams floated back into the space station's Quest airlock, closed the hatch and began repressurizing the module at 6:45 p.m. to wrap up a successful six-hour 17-minute spacewalk. The astronauts accomplished all of their objectives, attaching a new solar array truss segment and latching down a folding radiator on another solar array segment to clear the way for relocation later this year.
This was the 89th spacewalk devoted to station assembly and maintenance since construction began in 1998 - the 12th so far this year - pushing cumulative station EVA time to 551 hours and one minute by 50 U.S. astronauts, 15 Russians, three Canadians and four fliers from Japan, Germany, France and Sweden. If all goes well, Mastracchio and Williams will stage a second spacewalk Monday; station astronaut Clay Anderson will join Mastracchio for a third EVA Wednesday; and Anderson and Williams will stage a fourth spacewalk Friday.
While today's spacewalk was underway, the primary command-and-control computer in the U.S. Destiny lab module unexpectedly shut down. There are three computers in the set and the backup immediately assumed the duties of the primary computer and a third machine that had been on standby was activated and configured for backup duty.
Mission control commentator Kyle Herring said late today engineers were still troubleshooting the problem, but the two operational computers remain healthy and in control of critical station functions.
"Just to update folks on the status of the station computers, there's no change to the earlier comments relative to the health of the command-and-control computers on the station," Herring said around 6:30 p.m. "At about (3:52 p.m.), the primary command-and-control computer shut down, the automatic sequence showed the backup basically taking over the primary computer's functions and then the third computer, which remains in standby, that computer was brought out of standby and took over as the backup and that configuration remains the same.
"There are three command-and-control computers located in the Destiny laboratory and the station flight control team, as time permits in and around the other activity ... will continue to look at why that computer went off line earlier this afternoon. But at this point, there are no issues with any of the systems on board the station."
The spacewalkers successfully bolted a 5,000-pound spacer segment to the right end of the international space station's solar power truss today to accomplish the primary objective of the crew's first spacewalk.
The boxy truss segment was moved into position by shuttle pilot Charles Hobaugh, operating the space station's robot arm. Guided by the spacewalkers, Hobaugh positioned the S5 truss segment so that coarse alignment pins slipped into the proper holes to line up the bolts necessary to lock it in place on the end of the S4 solar array truss segment. Mastracchio and Williams then drove the bolts home to complete the installation, just under two hours into the planned six-and-a-half-hour spacewalk.
With S5 in place, the astronauts moved a robot arm grapple fixture to keel of the segment and made cable connections between S5 and the S4 solar arrays that will carry power and data from S6 when the new outboard arrays are attached next year.
After final cleanup work, the spacewalkers moved to the top of the station's central Z1 truss to monitor the retraction of a cooling radiator and to lock it down. The radiator was on the P6 solar array segment, mounted atop Z1 to provide power during the initial stages of station assembly. The two P6 arrays were stowed during shuttle flights in December and June and if all goes well, the segment will be moved to the left end of the main power truss in October and the arrays re-extended.