Space Station Solar Panel Repair May Extend Shuttle Mission

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ABC News

Space Station Solar Panel Repair May Extend Shuttle Mission

Rip In Solar Array Panel May Have Implications for Future Missions
By GINA SUNSERI

Oct. 30, 2007—

The current space shuttle mission, STS 120, may be extended another couple of days to give flight controllers at the Johnson Space Center time to figure out what, if anything, they can do about the multiple problems with the solar arrays that provide power for the International Space Station.

A solar panel ripped while it was extended after being reinstalled on the space station. The array, part of the P6 truss that was moved from one side of the space station to another, has a two-and-a-half-foot tear in it.

When space shuttle commander Pam Melroy noticed the rip, she immediately aborted the deployment. "It looks like the damage appeared fairly suddenly," Melroy told Mission Control.

Teams are now working to figure out what caused the array to tear, and what should be done to fix it.

If NASA doesn't figure out a way to fix the torn array, it has implications for future missions. Space shuttles, Soyuz capsules and Progress supply ships will not be able to dock at the space station, because the arrays aren't positioned properly.

The mission management team is trying to figure out which problem is the most important priority for the next space walk on Thursday.

The plan now is to have spacewalking astronauts take a thorough look at the solar array rotating joint on the starboard side of the space station. A large ball joint, used to point solar panels on the station, seems to be rubbing up against something, using more power than normal, and vibrating the solar array.

Astronaut Dan Tani found metal shavings inside the joint when he opened it up during a spacewalk on Sunday.

Is this a problem for NASA? Space station program manager Mike Suffredini says yes.

The solar array is operating at 97 percent capacity, but the concern is about future damage if it is not fixed. Flight director Derek Hassman said they were on the way to having a 95 percent good day, until the solar array ripped. Astronauts Scott Parazynski and Doug Wheelock completed a demanding seven-hour spacewalk to finish installing the truss, and inspect another solar array part for damage.
 

Budyzir

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No worries, he'll fix it;

 

d0uche_n0zzle

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Hope they have enough duct tape.
 

Fr. Dougal

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Mission changed... Repairing array now top priority...

=================================

CBS NEWS STS-120 STATUS REPORT: 61
Posted: 5:30 PM, 10/31/07

By William Harwood
CBS News Space Analyst

Changes and additions:

SR-58 (10/31/07): Crew news conference on tap
SR-59 (10/31/07): Sources say NASA expected to delay fourth spacewalk; attempt solar array repair Friday
SR-60 (10/31/07): NASA confirms spacewalk Friday for solar array repair work
SR-61 (10/31/07): Suffredini says array repair now top priority

=================================

5:30 PM, 10/31/07, Update: Suffredini says mangled array now top priority; engineers refine repair options

Repairing a mangled space station solar array is now NASA's top priority because of concern the ripped, partially deployed blanket could pull apart under the stresses and strains of normal operations, possibly forcing a future crew to dump the panels overboard, NASA officials said today.

After studying the issue overnight, "it became clear to me this needed to be our priority as a program," Mike Suffredini, manager of the space station program at the Johnson Space Center in Houston, told reporters today. "I need this array. This array is in a position where the potential exists for further damage if we leave it in this condition. It's very hard to analyze this specific damage in terms of understanding structurally how much force, how much load it can take.

"Given the fact we could potentially damage this array if we leave it in this configuration, and if we damage this array enough, we could potentially not have it available for the life of the program, this then becomes our priority."

Earlier today, NASA managers called off plans for a spacewalk Thursday by Scott Parazynski and Doug Wheelock to inspect a contaminated solar array rotary joint on the right side of the station's main power truss. Instead, Wheelock and Parazynski, a former emergency room physician, will attempt a daring bit of space surgery to effectively sew up the two rips in the P6-4B solar blanket on the far right side of the power truss and possibly cut away a fouled guidewire.

While engineers have not yet finalized the repair plan, the general idea is to put Parazynski on the end of a shuttle heat shield inspection boom attached to the space station's 50-foot-long robot arm. With the space crane based at a work site at the far left end of the power truss, Parazynski could be maneuvered into position near the damage site on the P6-4B array.

Wheelock, meanwhile, likely would be anchored at the base of the damaged array to provide verbal guidance cues to arm operators back inside the Destiny laboratory module.

Engineers are still debating the details of the surgery, but one option would be for Parazynski to insert pre-made tabs that work like cufflinks through holes in the blanket slats that were used to secure the panels during launch. Fold-out latches, like the wings of a cufflink, would prevent a tab from pulling back out of a hole. The other end would be inserted through the corresponding alignment hole in an adjacent slat.

The idea is for the connected cufflinks, or something like them, to carry the 70 pounds or so of tension the blanket experiences when the array is fully extended. It is that tension that provides the necessary structural stability and, in this context, the force that could pull the ripped slats apart if nothing was done to strengthen the area.

"There is a lot of work ahead of us on this," Suffredini said. "The team has worked extremely hard. We've got a lot of great ideas. ... We feel pretty good about our chances of getting out for an EVA-4 on Friday. But we haven't actually made a determination that's what we're going to do. We've asked the team to go work this. Later on, late tonight, we're going to look where we're at. If we have the procedures in place and we're comfortable we have a plan that we can implement then we will formally ask the crew to implement that on EVA-4 on Friday."

Covering all the bases, Suffredini said "what I'd like to have if at all possible is another opportunity to go outside if we need it."

"First, we do EVA-4 on Friday and we get as much work as we can get done," he said. "If we're successful, we can call it a mission and let the crew stand down, we'll get the shuttle all configured for return (and) we'll let the shuttle go home. ... If, on the other hand, we don't quite get all our work done (on EVA-4) - and that's a distinct possibility - then we'd like to have the option to pursue an EVA-5 on Sunday."

In that case, Discovery's mission - already extended one day because of now-canceled plans to carry out a rotary joint inspection - would have to be extended an additional day.

"So where we are as a program is, the team is off trying to come up with way to approach the array, to clear the snag and then perhaps install some load-bearing straps, if you will, to take on the load so we can redeploy the array," Suffredini said. "If we can't get all our work done on Friday, we'll sit down with the shuttle team and the ops team and look at whether or not we can gain ourselves a second EVA on Sunday and have the shuttle leave one day later."

Parazynski and Wheelock will carry out the proposed Friday spacewalk, with Parazynski, one of NASA's most experienced spacewalkers, on the end of the 50-foot-long orbiter boom sensor system.

In normal operations, the shuttle's robot arm latches onto a grapple fixture at one end of the boom. The other end carries a laser scanner and camera for use in heat shield inspections, along with a fitting that can accommodate an astronaut foot restraint. The station's arm is not compatible with shuttle grapple fixtures and instead will have to pick it up using a station fixture mounted at the center of the boom. That will extend the station arm's reach by about 25 feet instead of the full 50.

The station arm currently is parked atop the space station's mobile transporter at work site 8 on the far left end of the main solar power boom. If the repair plan is approved, the arm will be moved back to a central worksite Sunday to pick up the OBSS, currently mounted in Discovery's cargo bay. The transporter then would take the station crane and the OBSS back to work site 8 to await Parazynski and Wheelock on Friday.

It is not yet clear who would carry out a second spacewalk Sunday should one be required. But Suffredini made it clear NASA needs to fix the torn blanket and a second spacewalk opportunity would provide time to complete any unfinished work or perhaps correct any additional problems.

"The snag is providing a sort of ripping function on the blanket," Suffredini said. "Right now, we're supposed to be able to distribute 70 pounds of load across a 15-foot hinge and we're missing about three feet of that hinge. Not only are we trying to distribute that load across the remainder of the hinge, but you also have a high stress area right where you see the rip beginning.

"Given that configuration, the fact that we have sort of a forcing function the way it's being ripped up, we believe we're in a condition where we could, over time, tear the blanket further. And if we do enough damage to the blanket we could potentially get in a configuration where we couldn't stabilize the array and if we can't stabilize the array, we'll have to figure out what to do about that and we don't have a lot of options. The most likely option is we'd have to jettison it. So before we get to that position ... we've made it a priority to go repair it. It's stable right now, we've got time to go work this problem."

In yet another major change for mission planners - and the Discovery astronauts - the Mission Management Team today approved a revised landing strategy that would move re-entry next week from before dawn to the afternoon. The change will require the astronauts to adjust their sleep cycles and fly a trajectory that will carry them over the heartland of America, a northwest-to-southeast flight path NASA has avoided since the 2003 Columbia disaster. The change will permit additional landing opportunities.

=================================

Quick-Launch Web Links:

CBS News STS-120 Status Reports:
http://www.cbsnews.com/network/news/space/current.html

CBS News STS-120 Quick-Look Page:
http://www.cbsnews.com/network/news/space/currentglance.html

NASA Shuttle Web: http://spaceflight.nasa.gov/shuttle/index.html
NASA Station Web: http://spaceflight.nasa.gov/station/index.html
Spaceflight Now: http://spaceflightnow.com/index.html

=================================
 

Arch Stanton

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I spent some time with one of the Astronauts, Doug Wheelock. He is the Brother of a friend of mine who is also an Insurance Agent for the Company I represent. Amazing guy that helps out people all the time, takes trips and time to speak at schools etc.

Thinking of him and hoping for success.
 

d0uche_n0zzle

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Notice how everything falls apart when they put a woman in charge.
 

THE FEZ MAN

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Notice how everything falls apart when they put a woman in charge.
lol


its a shame that they cant just tape it back together, but duct tape sucks..... i hope they fix it, nasa needs to pull a few out of there ass to rebuild some of there credibility
 

GoCamels

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Careful what you read from the mainstream media...they can go Panicky Pete faster than Sandy Kane could go down on Phil Specter. Harwood's stuff at CBS News has always been very reliable...but its' the ABC and CNN and other's stories that seem to do nothing but say "THEY'RE DOOMED!!!"

Better info/less fluff and panic at http://www.nasaspaceflight.com...

NASA change EVA-4 for array repair, via ambitious plan
By Chris Bergin, 10/31/2007 9:05:52 AM
NASA are working a plan to conduct the repair of the two rips in the P6 4B Solar Array on a 24 hour delayed EVA-4.
The plan is still being worked, though it will involve a spacewalker being sent to the damaged area on the end of the Space Station Remote Manipulator System (SSRMS) and the OBSS (Orbiter Boom Sensor System) arm. Major evaluations are taking place on how long the OBSS' sensor package can survive during the operation.

P6 4B Repairs:

Flight Day 8's deployment of SAW 4B, consisting of two photovoltaic blankets, each made up of 31 individual segments (bays), was aborted at 12:25pm when one of the bays showed a tear at its corner. Another smaller tear can be observed in hi res images of the damage.

While the array is providing good power, structural integrity is the key factor for carrying out a repair.

The plan is to work on a method of repairing the array ahead of EVA-4. Delaying EVA-4 and cancelling EVA-5 will allow NASA to work on a procedure. This proceedure - which is still at the planning stage - may take engineers a while to figure out, and could delay EVA-4 to Saturday.

As far as how the array suffered the tear during deployment, this is still being evaluated. However, it appears one of the guidewires snagged in a grommet.

'We believe one of the three guidewires snagged on one of the grommets, which started tearing out the hinge,' said ISS program manager Mike Suffredini. 'We retracted one bay to relieve some of the stress.'

If EVA-4 fails to repair the array, the program holds the option of added another docked day to STS-120, allowing for another spacewalk to try and find a solution.

'If EVA-4 is not successful, which is a possibility, we would like to have the option to pursue EVA-5 on Sunday. We would have to delay departure of Discovery by another day,' added Suffredini.

'This is our priority as a program. We need this array. It could gain further damage if we leave it in this configuration.'

The main area of conversation at the MMT relates to the trade-offs that would be required to allow a spacewalker to ride up to the damaged area, on top of the SSRMS and OBSS.

The plan to use the SSRMS and OBSS in tandem (as seen in the image associated with this article) has now been confirmed.

While the challenge of having a spacewalker on the end of both booms is obvious, the plan has been deemed as having no expected structural issues for the two arms.

However, the main focus relates to potential damage to the OBSS' sensor package, which would compromise the full capability of Late Inspections of Discovery's Thermal Protection System (TPS) after undocking.

The OBSS sensor package is at risk of suffering a failure during the EVA repair, due to its 'thermal clock', which ranges from two hours for most instruments, to five hours for LDRI if warmed up and covered with a large ORU bag ahead of the EVA.

At present, the OBSS is expected to survive, due to the high beta angle, which will allow the sensor package to stay 'warm enough' during the operation.

Should damage occur to the OBSS, Late Inspections would be conducted only via the Discovery's RMS, which has slightly higher risk numbers, especially after - and still under consideration - the 'large' MMOD strike that was picked up by the WLE (Wing Leading Edge) sensors on Tuesday.

The 2.74 GRMS indication is classed as a 'significant hit' on the port (left) panel 1. The indication was triple the maximum ever observed, noted NASA information. However, should there be MMOD damage on the panel, this would at least be spotted without the need of the OBSS' sensors.

Regardless, NASA are working on contingencies for the OBSS, including the removal of certain sensors, to be left in an unpressurized airlock during the EVA, and the potential swapping around of cameras.

'If the Sensor Package 1 Pan Tilt Unit is not operational after the Solar Array Repair task, the PTU could possibly be swapped out for an Orbiter Payload Bay Camera PTU,' noted one MMT presentation.

'There are 2 other flight LCS units available to the Program currently in flow for other flights.

'The next need date for this particular unit would be mid Feb 2008 for STS-125. However, if the LCS fails due to thermal overstress, there are spare parts available for repair or for an additional unit build.'

With the changes to the mission timeline, the inspection of the starboard SARJ (Solar Alpha Rotary Joint) has been deleted from STS-120.
 
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