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Solar wing tears during deployment BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: October 30, 2007 Two blankets making up one side of the newly installed P6 solar arrays were successfully re-extended today after the 17-ton truss segment was bolted to the far left end of the space station's main power truss. But the astronauts aborted extension of a second set of panels after noticing an apparent guidewire hangup and a jagged tear in one of the two remaining blankets. The second set of blankets was more than halfway extended at that point, but it was not clear how flight controllers might opt to proceed given the obvious tear between two slats in one of the flexible blankets. In television views from the station, it appeared as if several slats might have gotten hung up on a guidewire, increasing tension in that area and ripping a seam. But engineers did not immediately offer an assessment of what might have gone wrong. Or what, if anything, can be done to fix it. Images of the damage are available here and here and here. Astronauts had major problems retracting the P6 arrays during previous shuttle visits in preparation for this week's move from a central mounting point to the truss segment's permanent position on the far left end of the power truss. Grommets on the sides of the blankets hung up on frayed guide wires during the retraction process, requiring spacewalking astronauts to provide a manual assist. Eventually, the blankets were coaxed back into their storage boxes. Station commander Peggy Whitson said the ripped seam between to slats apparently occurred in the same area where a frayed guidewire was noticed during retraction. "And Houston, Alpha on one, just some further information," she called. "When we were deploying it, we noticed there were more dynamics around the bay 11 point where we were expecting there might be that problem with the frayed line. And at that point, we still thought we were OK. But it appears that maybe that was the extra motion we saw. "We didn't abort because we didn't see the tear. Unfortunately, the sun angle was such that it was in a place that we just didn't see it. You know, we paused it later, but by that point in time the problem area was behind the (robot) arm in one view and the sun angle in out other view was such that it covered it up. So, it was a combination of really bad sun angles, but I think we did see it, you know, we saw the extra motion when it probably happened and it probably happened as we were pulling it out of the blanket box." "Hey, no worries Peggy, we had good video, too, and we were keeping our eye on it, so that's just the way it goes," astronaut Kevin Ford replied from Houston. "We appreciate you doing the abort when you did, that was awesome. And we'll just keep working this." To ease tension on the torn blanket, commands were sent to retract the mast a few feet while engineers debated their options and the astronauts took additional photographs to document the array's condition. Given the design of the arrays, NASA managers said they did not expect any problems with the re-deployment and the first set of panels - P6-2B - extended smoothly. "It looks like they're getting the array all the way out," astronaut Clay Anderson radioed spacewalkers Doug Wheelock and Scott Parazynski from inside the shuttle-station complex as the first of the two arrays slowly extended to its full length. "Wow, that's great," Wheelock replied. "Thanks for the update, Clay," Parazynski said. "That's a good day's work right there." Wheelock and Parazynski were in the process of wrapping up a successful seven-hour eight-minute spacewalk when the P6-2B array was pulled from its storage box by an ingenious motor-driven self-assembling mast. The deployment was carried out in stages, first just a few inches, then one mast bay and finally all the way out. Parazynski reported seeing small bits of debris floating out of the blanket boxes during the initial stages of extension. "I can actually see quite a bit of sparkling material glinting in the sun, I guess, probably mylar fragments or something coming out the blanket box," he observed. "Both of the blanket boxes, actually. I don't know if you can see that out of the aft flight deck. But lots of little sparkles there." "We copy, EV-1, and that is expected," someone replied. With the P6-2B array fully extended, the astronauts sent commands to deploy the 4B array at 12:08 p.m. as the space station sailed high above the south Pacific Ocean. "Three, two, one, mark," shuttle commander Pam Melroy radioed as the the second array began extending. About halfway through the deployment, Melroy halted the procedure to improve the crew's camera views. A few minutes later, the drive motor was restarted and the 4B arrays resumed extension. Then, Melroy ordered another abort when the tear became apparent. "Aborting," she called. "Houston, Alpha, on the big loop. We detected some what appears to be a wrap around or some damage and we're zoomed in on it on camera 24 right now." "OK, Pambo, we see it," Ford replied from mission control. "Thanks for the view." "And of course, we aborted," Melroy continued. "And sorry it took us a little while to be sure that we weren't being fooled by the lighting." "Hey, no problem, Pambo, it was a good call on the abort," Ford said. "And we're having a look. ... We'll take anything you have for us to send down what you guys saw or anything while we're talking about it as well. Don't be shy." "On camera 22, the sun angle was such that we couldn't actually see it and so we didn't see it until we were zooming out on camera 24," Whitson said. "We didn't really notice any significant perturbations as it was deploying. But we just saw the tear and stopped." Because of the array's location on the far end of the power truss, the astronauts cannot reach the area of the tear. One option might be to retract the arrays, resolve the hangup and redeploy, but NASA managers and engineers will need to complete a thorough assessment before deciding on any course of action. Today's spacewalk began at 4:45 a.m. and ended at 11:53 a.m., pushing the crew's total EVA time to 19 hours and 55 minutes over three of five planned excursions. Overall, this was the 95th spacewalk devoted to station assembly and maintenance since assembly began in 1998 and the 18th so far this year, pushing the cumulative total to 587 hours and 54 minutes (note: NASA recently added an hour to its total, which is not reflected here; I am researching the discrepancy). Italian astronaut Paolo Nespoli, assisting Parazynski and Wheelock as they doffed their suits and stowed tools, reported the crew was missing a digital camera and flash. "It's probably outside on the tool box on the airlock," he reported. No word yet on whether that camera was used to snap pictures of the left-side solar array rotary joint inspected by Parazynski earlier in the spacewalk. The camera presumably can be retrieved during a spacewalk Thursday to inspect the right-side joint. During a spacewalk Sunday, contamination was discovered in that joint that may indicate a serious problem.
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