Two grandfathers completed the structural attachment of the newest component of the International Space Station today, mating two large tripod legs of a 13 ½ ton truss to the station’s main laboratory during a 7 hour, 30 minute spacewalk.
Dubbed the “Silver Team” by their colleagues because of their age, 54-year old Jerry Ross and 49-year old Lee Morin of Atlantis’ crew had little trouble extending and bolting the final two struts of the new S-Zero (S0) truss to the Destiny Laboratory, insuring that the centerpiece for the future expansion of the station would be permanently secured to accept additional trusses and solar array towers over the next year. The station will ultimately span some 350 feet from end to end, the length of a football field.
The first two struts of the truss were mated to Destiny on Thursday by the other Atlantis spacewalking team, Steve Smith and Rex Walheim, who will venture back outside Sunday to continue the outfitting of the truss and to reroute electrical power to the station’s 58-foot long robotic arm.
Morin worked at the end of the ISS’ Canadarm 2 throughout the day during his first spacewalk, while Ross, America’s most experienced spacewalker and the most flown space traveler in history, remained tethered to the station to provide “free-floating” support during the eighth spacewalk of his career.
Smith, Walheim and Expedition Four Flight Engineer Dan Bursch helped choreograph the spacewalk from Atlantis’ aft flight deck, while shuttle crew member Ellen Ochoa and station Flight Engineer Carl Walz took turns maneuvering Morin as they operated Canadarm2 from a robotic work station inside Destiny.
Shuttle and station Commanders Mike Bloomfield and Yury Onufrienko and shuttle Pilot Steve Frick provided photographic and television support for the spacewalk, the 36th devoted to ISS assembly over the past 3 ½ years.
After the truss struts were bolted in space, Ross and Morin removed a series of panels and clamps that provided structural support for the truss during its launch in Atlantis’ cargo bay.
The spacewalkers then began work to install a backup device containing an umbilical reel for the Mobile Transporter railcar on the truss that will provide redundancy to a similar device mounted on the truss Thursday. The two sets of umbilicals for the Mobile Transporter, which is designed to move the robotic arm up and down the length of the completed station truss, provide power, data and video capability for the system, which will be tested for the first time in orbit Monday.
Ross tried to remove a restraining bolt on the mechanism which, if required, can cut the umbilical cable should it snag during its operation, but the bolt proved to be a bit balky and did not back out of its socket as planned. Flight controllers decided not to spend additional time troubleshooting the stubborn bolt today after engineers determined that the cable cutter cannot inadvertently fire in its current configuration. The backup umbilical system is operating normally and the stubborn bolt will be dealt with on one of the mission’s two remaining spacewalks. The primary umbilical system installed Thursday is also operating normally.
The spacewalk, which was conducted out of the station’s Quest Airlock, began at 9:09 a.m. Central time and concluded at 4:39 p.m. as Ross and Morin repressurized the outer compartment of the two-chamber module.
Late today, Frick fired Atlantis’ steering jets in a one-hour procedure to slowly reboost the space station by about 2 statute miles. It was the first of three scheduled reboost maneuvers to eventually raise the orbit of the ISS by about 6 statute miles before Atlantis departs the station on Wednesday.
The ten shuttle and station crew members are scheduled to begin their eight-hour sleep period at 7:44 p.m. and will awaken Sunday just before 4 a.m. to begin preparations for the third spacewalk of the flight.
The next STS-110 mission status report will be issued Sunday after crew wake up, or earlier, if events warrant.
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