LIVE: STS-120 Flight Day 12 - EVA-4 - P6 4B Solar Array Repair

[Chris Bergin]

Flight Day 12:

Articles:
http://www.nasaspaceflight.com/content/?cid=5270 - When it happened.

http://www.nasaspaceflight.com/content/?cid=5271 - Exclusive on the plan as it emerged.

http://www.nasaspaceflight.com/content/?cid=5272 - Exclusive based on the plan as it came into place

http://www.nasaspaceflight.com/content/?cid=5273 - Exclusive on ground testing and timelines after repair.

http://www.nasaspaceflight.com/content/?cid=5274 - Exclusive on NASA Rallying Call, OBSS etc.

L2: Super Hi Res Images of the plan being carried out on the ground. Numerous presentations on Robotics involved, OBSS (with the Nov.2 final evaluation presentation), stage planning, new mission timeline flight plan etc.etc. and more.

Please keep this thread on live updates of what's happening. We have other threads for general questions etc.

I'll modify this first post as we require...

Make no mistake about how big today is.

ISS On Orbit Status Report outline:

EVA-4 Overview: Primary focus of Scott & Wheels’ outside venture will be inspection and repair of the torn P6 Solar Array Wing (SAW). Afterwards, if certain criteria are satisfied (see below), EV1 & EV2 will get out of the way and monitor the deployment of the wing. Subsequent get-ahead tasks include retrieval of two APFRs (Articulating Portable Foot Restraints, #3 & #7) for inspection, if time available and room in Airlock, mating of a PDGF (Power & Data Grapple Fixture) “horseshoe” connector at Node-2, and installation of the Node 2 HR (hand rail) #371 that was deferred from EVA-2. After the regular overnight Campout by the spacewalkers for denitrogenation/pre-breathe, egress is expected around 6:35am EDT tomorrow morning. EVA duration will again be about 6.5 hrs. [Repair Concept: There are two damaged areas on the SAW 4B inboard blanket: a large rip from the hinge between array segments (“bays”) 35 & 36, and a small gap between bays 37 & 38. To stabilize the blanket in those areas, the affected bays will be “stitched” across the respective hinges (35/36 & 37/38) with five jerry-rigged wire clamps similar to dress shirt cufflinks, utilizing existing pin holes for inserting the cufflink anchors and requiring one-side access only. Because of the location of the pin holes, each of the “stitches” fortunately will run along spine-like rigidizing lines, called “stiffeners”. Criteria for going ahead with the subsequent deployment of the 4B Array Mast include:

Snag on 4B right blanket eliminated;
Array electrically safed by hinge wire being cut & end secured;
Five stabilizers installed across hinge (priority from inboard to outboard);
Guide wire cleared from creating additional hazards (grommet snag, FOD, free float); and
Low tension mode during deployment visually confirmed and blanket stability monitored after each one-half bay deploy (i.e., stabilizers remaining in place, blanket deploying symmetrically, no additional snags, etc.).
 
Why 4B Panel Repair is required:

Array is believed to be stable for the near term;
However, it needs to be able to take loads over the long term;
Right now, about 3 feet of the 15-ft long hinge are missing, which is designed to distribute a load of ~70 lbs across it, i.e. there is a load concentration;
Therefore, the blanket could tear further over time;
If the blanket tears too much, the array cannot be stabilized and would have to be jettisoned (loss of ~20 kW of power);
Thus, P6 deployment is the number one priority for the rest of the mission.

**DO NOT BABBLE ON THIS THREAD - Posts will be deleted, along with duplicates etc.**

New timeline, as per L2 (for the entire remainder of the mission there, for FD12 below:)

[Andy_Small]

TV Schedule.  Going to atempt to help with the updates...haven't slept

about 45 mins from crew wake up

[Andy_Small]

First Live shot for this thread:

[Andy_Small]

playing FD-11 highlights now

[Andy_Small]

Edit: About 15 mins from crew wake up

still showing Fd-11 highlights

[Chris Bergin]

Great preview image of the day to come:

[Andy_Small]

And we're getting ready for FD 12

[jcopella]

Finally!  Some decent wake-up muic!!

[Bubbinski]

They're playing the theme from Star Wars!  And here's a closeup of a solar panel just beamed down.

[generic_handle_42]

Good morning Discovery, on what is going to be a very big day in space!

The wakeup song was the Star Wars Theme by John Williams for Scott Parazynski (who is apparently the father of Luke!).

[Andy_Small]

Star WARS Theme  

Fitting

[Andy_Small]

Shannon saying good morning to Scott for his son Luke!

[Chris Bergin]

"Use the force, Luke" - very fitting wake up song! Scott's son is Luke, even more fitting.

[Bubbinski]

"Use the Force, Luke!"  That was very appropriate.  Shannon Lucid doing the capcom duty as usual.

[Andy_Small]

Execute package printing.  Go For PGSC,  Go for Outlook

Morning Cryo Config

[ckiki lwai]

jcopella - 3/11/2007  6:39 AM

Finally!  Some decent wake-up muic!!

Couldn't agree more

In an age of torn solar arrays across the galaxy
troubling NASA for years
Scott Parazanski will take the fight on with the P6
yet another time, but will he succeed?...

[Firehawk153]

"The target area is only two feet wide...."

[Bubbinski]

They just said spacewalk could begin as early as 5 AM Central.

[Andy_Small]

Reporting that Hygiene break is go for step 5

Current map

[Bubbinski]

ISS over Russia, EVA crew in hygiene break.  Steps 1-4 complete, no delay in step 5.  I'll be stepping away to get some quick Z's before getting back up just before the EVA.