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![]() Despite extra care, spacewalker loses another bolt BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: September 13, 2006 Canadian astronaut Steve MacLean ran into the same problem today that spacewalker Joe Tanner encountered Tuesday: a lost bolt from a thermal cover on a newly installed solar array truss. Unlike Tanner, MacLean never saw the spring-loaded bolt separate from its retaining clip and float away. One minute it was there, the next it was gone. "OK, on cover eight, a bolt is missing," MacLean radioed. "Bolt alpha. I did not see it go." "OK, Steve, I copy that, bolt 1 alpha is missing," Heidemarie Stefanyshyn-Piper replied from inside the shuttle-station complex. MacLean and Dan Burbank were in the process of removing 12 launch locks on a massive rotary joint that ultimately will move the station's port-side solar arrays to track the sun as the station circles the globe. The solar alpha rotary joint was launched with its main gear locked in place. To remove the launch locks, thermal covers held in place by four spring-loaded bolts have to be moved aside. The covers are reinstalled after the locks are removed. The attachment hardware is designed to stay in place. But during a spacewalk Tuesday, a retaining clip apparently failed, or was knocked off its threads, and the clip and bolt floated away. Tanner was initially worried some of the hardware might have floated inside the SARJ but flight controllers dismissed that concern, saying they were confident the bolt and washer floated away from the station. Based on Tanner's experience, MacLean and Burbank were taking special care not to put any stress on the bolt hardware as they worked through the removal of the remaining 12 launch locks. MacLean even kept an eye out for the bolt that vanished Tuesday. "Heide and Joe, I've been looking all along for that bolt," he radioed at one point. "Haven't seen anything." He was in the process of re-attaching a thermal cover when he noticed one of his bolts had disappeared. "I'm standing by for your words," MacLean radioed after reporting the lost bolt. "Would you like me to remove the cover and take a look inside? The cover is tacked on right now with three bolts." Flight controllers asked him to do just that, adding "we're just specifically concerned about whether the washer is still there." "OK, the cover is removed again, slowly turning it around," MacLean said a few moments later. "And the washer is gone." Looking inside the truss, he reported seeing "nothing at all that looks like a washer." He then re-attached the thermal cover with the three remaining bolts and pressed ahead. Assuming the spacewalk stays on schedule, flight controllers plan to begin activating the SARJ around 11:15 a.m. If no problems are found, a drive motor will begin turning the main gear about an hour later to rotate a new, still-stowed set of solar arrays 180 degrees. That will put the P4 solar array blanket boxes in the proper position for deployment Thursday. As part of its initial checkout, the SARJ will actually rotate the outboard P4 array truss a full 360 degrees before reversing direction and moving back to the 180-degree position. Flight controllers plan to extend the panels a few feet late this evening. On Thursday, the astronauts will complete the job, sending commands that will cause a motorized mast to extend, pulling the folded solar panels from their boxes like venetian blinds. Fully extended, the arrays will stretch 240 feet from tip to tip.
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