Discovery's astronauts will try to repair a torn solar wing blanket during an spacewalk that will take place at the International Space Station on Friday or Saturday. Inspections of a critical rotary joint on another set of station solar wings is being put off as a result.
The details are still sketchy. In a radio call from NASA's Mission Control Center, NASA astronaut Tony Antonelli told Discovery commander Pam Melroy that managers were ordering up "solar array wing stuff."
The repair work is tentatively planned for Friday, but if more time is needed, the spacewalking work will be pushed back to Saturday, Antonelli said.
"We're going to change the plan for the next couple of days....The contents of which will be solar array wing stuff. You'll hear more about it...We'll leave Flight Day 11 as a placeholder for now, and if we don't get ready, then we'll try Flight Day 12.
"Okay, Houston. Peggy and I copy all," Melroy replied.
The exact nature of the repair work is still being worked by engineers. But this much is likely: spacewalkers likely will make their way to blanket boxes at the near end of the solar wing.
The array then would be retracted enough for the spacewalkers to work on the torn and rippled part of the blanket. It's not exactly clear how the actual repairs would be effected.
The work likely would be done by mission specialist Scott Parazynski, the lead spacewalker on the Discovery crew, and mission specialist Douglas Wheelock. The two astronauts had been scheduled to perform inspections on separate solar wings on Thursday.
Parazynski told reporters today that the two are ready to try whatever repair plan specialists on the ground develop.
"I certainly don't have all the data on board yet. We've taken hundreds of photographs from our windows and from the station assets and folks in Houston are poring over the data trying to figure out exactly what might have happened. My initial take on it was maybe a guidewire that had been frayed earlier might have been the culprit. However, it looks to our eye via binoculars and photos that that guidewire may be intact," Parazynski said.
"It really depends on what the root cause is. We have trained quite a bit (on the ground) and there are numerous contingencies we could effect on the solar array wing. Not sure if they're applicable to this situation, however. One of those might be clip the guidewire, if that might be of help. But we'll see."
Parazynski said he and Wheelock could reach the bottom of the solar wing blankets with an assist from the station's 57.5-foot robot arm.
Italian astronaut Paolo Nespoil "suggested we just climb up the mast and give it a good shake, but that might a little too aggressive,": he joked.
"We actually have pretty good work site access from the bottom. We have what's called a WIF adapter -- a work(site) extender, excuse me -- that allows us to physically place our foot restraint a little bit higher on the P6 structure. So we can reach about eight to 10 feet, I think, and get up about to about the level of the blanket box, and make so repairs at the fairly low," he said.
"So if there were a need to effect a repair out where the damage occured we'd have to retract that array and do the repair close into the lower blanket box. The SSRMS isn't long enough to get us where prior crews have been to do those kinds of repairs."
The solar wings were delivered to the station in December 2000 and its arrays were retracted so the structure could be moved to the far left end of the station's centyral truss. Shuttle crews last December and in June had encountered significant difficulties during the retractions.
The solar arrays are one of four massive American sets of solar wings that are designed to stretch 240 feet from tip to tip. The torn blanket is producing 97 percent of anticipated power, but the damage significantly reduces its structural integrity and could get worse during spacecraft dockings at the station. NASA consequently wants to patch up the torn blanket, shore up the strength of its mast and fully unfurl the blanket.
More details to come.
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