NASASpaceFlight.com Forum
NASA Shuttle Specific Sections => Atlantis (Post STS-135, T&R) => Topic started by: jacqmans on 09/12/2006 03:31 am
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Highlight day for the mission and ISS program as a whole. Truss attatchment and solar array deployment :)
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Haven't heard a response from the crew after the wake up call. What gives?
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Nevermind there they are. Configuring for cryocooling. What's the scheduled duration for this EVA today? Good luck Tanner and Piper!
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EVA scheduled for about 6.5 hrs, can go 7 if needed.
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Big day, for more than one reason.
Attached are two overview screenshots of FD4 on the 207 page STS-115 Final Flight Plan on L2.
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P3/4 ready to latch.
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P3/P4 ready to latch.
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First stage of capture complete. SSRMS in limp mode.
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Second and third stages of capture now complete.
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Two of four bolts now complete. One more and the EVA will pick up...the third bolt is being driven now...takes about 8-10 minutes.
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@ astrobrian: the deployement of the solar arrays isn't planned for today. The arrays wil be deployed after EVA 2...
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Airlock depress scheduled for about 15 minutes from now.
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It's about to officially become a part of the ISS :)
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Standing by for bolt #2...(1 and 3 already done)
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Can some one post the close up view of the computer screen shot they are showing on NASA TV.
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The third bolt is now officially confirmed; it looked it happened on the display while it was being showed. PAO says that the SSRMS can now ungrapple and the EVA is go to start.
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slipstream - 12/9/2006 4:44 AM
nitin52 - 12/9/2006 12:39 PM
Can some one post the close up view of the computer screen shot they are showing on NASA TV.
Got one however in low quality
Thanks.
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Ground just gave the crew a go to depress.
Also now a go to ungrapple the P3/P4.
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Ok. Thanks.
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Today's execute package has been posted: http://www.nasa.gov/pdf/157294main_fd04_ex_pkg.pdf
Good morning Atlantis!
Thanks for one more day of superb work on orbit yesterday! Today is construction day and
we will be happily following along! Good luck with powering up Station!
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Airlock depress approaching 5 psi...
Fourth of four bolts on P3/P4 to P1 interface now being driven.
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Airlock depress below 2 psi and sounds like the SSRMS is in motion...
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Fourth bolt of the segment-to-segment attach system now tightened.
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Hatch opening confirmed...I think I heard Heidemarie Stefanyshyn-Piper say "sure looks dark out."
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Looks like they're waiting for sunrise to get out...
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I can't work out what she's saying.
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eeergo - 12/9/2006 5:24 AM
Looks like they're waiting for sunrise to get out...
They're doing EMU and other EVA equipment status checks -- recording suit parameters, etc. -- before they start translating over to the truss.
It's not a fast process; we're getting video now.
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Heidemarie Stefanyshyn-Piper now out of the airlock.
5:17 am Eastern was the official EVA start time (suits to internal power).
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That's right, my fault. :O
Anyway, they're waiting for good lightning :)
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eeergo - 12/9/2006 5:33 AM
That's right, my fault. :O
Anyway, they're waiting for good lightning :)
No worries -- actually, they're not wasting any time -- they've already translated across the spur to S0 and are doing the tether swap...
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How's this truss addition going to affect station's attitude? Obviously the CM is shifting quite a lot, so how are they going to compensate it?
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They've reached the new piece of the station...it's nice to know when sunrise is, because they'll probably want to put down the sun visors on the helmets -- the lighting change is pretty fast.
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Look at them... so cute crawling on the truss :)
Edit: Yeah, helmetcam!
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eeergo - 12/9/2006 5:38 AM
How's this truss addition going to affect station's attitude? Obviously the CM is shifting quite a lot, so how are they going to compensate it?
There was a note in one of the ISS status reports just before the launch campaign started (late August)...have to go look for that, but it might be a good question to throw over to the ISS forum.
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Anyone who is on L2 are welcome to copy some useful pages out of the STS-115: Full EVA overview and images (326 pages, 56 meg) document into here.
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There's a timeline in today's execute package, too...Joe Tanner got a go for beginning the P3 lower tray work...
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eeergo - 12/9/2006 4:38 AM
How's this truss addition going to affect station's attitude? Obviously the CM is shifting quite a lot, so how are they going to compensate it?
CMGs shouldn't have a problem for normal attitude control. Orbit boosts will have to compensate for the mass change until S3/S4.
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FWIW, the 24 August status report waves "good-bye" to the XPOP attitude. That's on L2.
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Finally got the cameras repointed...Stefanyshyn-Piper out on P4 (left) and Tanner on the right working on the P3/P1 lower tray hookups.
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Lower tray utility connections complete 51 minutes into EVA.
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There's the CID-7 call from the summary timeline. Next step for Tanner is releasing the aft (4A) beta gimbal assembly (BGA) restraints. Stefanyshyn-Piper is working on the aft solar array blanket box (SABB) restraints.
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Crew just now called that focused TPS inspections not needed...
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No FI required. They surely must believe the Gap Filler (the main one) will fall out during re-entry.
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Stefanyshyn-Piper has finished releasing the aft solar array blanket box (SABB) restraints, now moving to do the same for the forward (2A) SABB.
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They should have the EV-1 and 2 stripes on the top of the gloves too to make it easier to see who's helmet cam we are looking through.
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Nice view.
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Looks like the four-bar linkage is swinging out on the aft wing...
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Tanner has all four linkages on the aft wing latched now.
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The night has fallen... and by the way, the helmetcams seem to have some problem, all we get are stills...
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45 minutes ahead of schedule! wow, that's fast :)
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45 minutes ahead of schedule! wow, that's fast :)
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Just reported ~45minutes ahead of timeline
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I heard 25 mins but the sound quality here isn't very good.
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eeergo - 12/9/2006 6:44 AM
The night has fallen... and by the way, the helmetcams seem to have some problem, all we get are stills...
That could just be orbiter Ku blockage. It's only a problem for us that we're only getting sequence stills from the orbiter...the IV has been referring to the helmet cams in the air-to-ground...
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Oh no! She's holding a galactic plasma gun! :)
Beautiful screwdriver!
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Stefanyshyn-Piper getting ready to swing the forward wing out...
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Looks like we're getting some orbiter TV approaching sunrise...
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SARJ preparation underway... first task: to release a shroud and cover fasteners.
And look at that... P4 is stretching its arms!
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Stefanyshyn-Piper working on manually deploying four-bar linkage...it's moving...
Edit: this one (the forward one) sounds like it's a little harder to deploy...
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Will they test SARJ motion before unfolding the panels?
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chksix - 12/9/2006 7:18 AM
Will they test SARJ motion before unfolding the panels?
Yes.
Sounds like Tanner is being asked to help with the forward four-bar linkage deploy.
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Swung all the way out now, checking the latches...
Edit: ...sounds like it's locked down...
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Great view... and all solar arraw masts are deployed!
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Stefanyshyn-Piper now at the end of the mast canister swinging the blanket boxes out on the forward wing...looks like it's done.
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The ground is ready to start the P3-P1 upper tray work; discussing whether to finish current steps in work on the SARJ.
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Tanner is working on the SARJ drive locking assembly (DLA)...
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Anybody have any further thoughts on that 20-sec blinking object? They had promised not to jettison anything during this EVA but that looks like an obvious explanation -- if we can identify what object, cover, blanket, whatever got loose.
By the way, I think your site clock is fast by a few minutes. I note posts coming up with time tags about 3 minutes ahead of my WWV watch display time.
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JimO - 12/9/2006 1:35 PM
Anybody have any further thoughts on that 20-sec blinking object? They had promised not to jettison anything during this EVA but that looks like an obvious explanation -- if we can identify what object, cover, blanket, whatever got loose.
Maybe a nearby satellite reflecting at that moment the light in the correct direction?
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From the images you posted it looked like lens flare, I take it you think otherwise.
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Really does give you an idea of scale, doesn't it.
How's their timeline? Missed the last note on that (Rob Navis I assume, seen as this is great coverage).
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Tanner is working with the drive lock assemblies while Piper is rigidizing the AJIS struts...
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JimO - 12/9/2006 12:35 PM
By the way, I think your site clock is fast by a few minutes. I note posts coming up with time tags about 3 minutes ahead of my WWV watch display time.
It is Jim - we'll sort it (job for the webwizards).
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Chris Bergin - 12/9/2006 7:51 AM
(Rob Navis I assume, seen as this is great coverage).
That's your buddy Kyle Herring. :)
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Chris Bergin - 12/9/2006 7:53 AM
It is Jim - we'll sort it (job for the webwizards).
Might want to consider increasing the time-sync frequency for your servers...or is that a manual thing?
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"From the images you posted it looked like lens flare, I take it you think otherwise."
Now that I've looked at the images again, I suspect a lens effect too. Does its brightness vary with that of other apparitions along that optical line where the other flares also align?
Maybe it'll show up on the 'space UFO' websites shortly. ;)
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Well, I'm leaving for a while, my girlfriend is getting angry ;) Great spacewalk, hope I'm back in a few hours!
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Is that schedule on the left screen available on L2? I havn't been able to locate it...
Edit:
My error I think since that is the ISS controlroom.
Not even sure if it's a schedule ;)
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Did the PAO say that they are 90 mins ahead of schedule?! They must have expected big problems when planning for this EVA. That's a good thing that they don't have any of those problems.
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That left front screen IIRC, is a combination of cautions and warnings, items in work, and work scheduled.
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JimO - 12/9/2006 6:57 AM
"From the images you posted it looked like lens flare, I take it you think otherwise."
Now that I've looked at the images again, I suspect a lens effect too. Does its brightness vary with that of other apparitions along that optical line where the other flares also align?
Maybe it'll show up on the 'space UFO' websites shortly. ;)
It'll of been an optical illousion on the lens, via flare, which are the mainstay of UFO sites
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MKremer - 12/9/2006 2:11 PM
That left front screen IIRC, is a combination of cautions and warnings, items in work, and work scheduled.
Thanks!
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Re mystery flare -- I really doubt it's a 'nearby satellite', they would have much greater angular rates in the FOV. If it's real, it's something off the ISS. Let me check with other sources -- including radar tracking. What was the clock time of that scene again?
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re message 67202, slipstream's initial post, about 4:55 AM EDT...
The light flares when the solar reflection flares, and it subsides when the solar reflection in the right of the FOV also subsides.
The 20-23 second period could merely reflect (pun intended) a slow flexing motion of the reflecting surface, or a slow cycle of the camera's AGC -- auto gain control.
It will take a lot to convince me that this is not a camera artifact.
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Good comment just now from Heidemarie about how realistic the Pool training is except "No Divers and No bubbles"...
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Welcome to tool time on the ISS :)
Seems like the rather cool drill is being a bit of a pain..
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Craftsman...NOT the Official Tools of NASA...The Official Tools of NASCAR
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Anyone knows the get-ahead tasks for this EVA?
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Time to relax and enjoy the view :-)
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What do they mean by 'analog downlink' ? The picture looks highly digital to me.
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Installing the thermal cover...
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4 hrs and 16 min into the EVA...
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They'd legally have to go for a 15 minute tea break in the UK now :)
Great storyboard on the mission here.
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Are they going to interupt this with a press conference at 3pm, 10am East?
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Felix - 12/9/2006 9:12 AM
Anyone knows the get-ahead tasks for this EVA?
Seems like they're handling this in real time...
Added just now (Pulled from EVA2)
Cover and Launch Locks (1 apiece Page FS 7-45)
DEPLOY SARJ BRACES (Page FS 7-50)
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4 and a half hours EVA elapsed time... and yet 2 hours to go!
They've got a good mess with the cover numbers :)
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Joe dropped a bolt and washer (for the MLI) it's gone now... Suprised this doesn't happen more often... Do they have spares?
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One cover removed by Piper, and one launch lock by Tanner... and the poor little bolt/washer is lost in space!
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It sounded to me like they lost a bolt in the structure.
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Consequences?
Mark
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nathan.moeller - 12/9/2006 4:29 PM
It sounded to me like they lost a bolt in the structure.
It was from one launch lock, so there shouldn't be more consequences than other bit of orbital debris out there...
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eeergo - 12/9/2006 9:35 AM
nathan.moeller - 12/9/2006 4:29 PM
It sounded to me like they lost a bolt in the structure.
It was from one launch lock, so there shouldn't be more consequences than other bit of orbital debris out there...
That would be my guess as long as no one comes back and says it could affect the truss in any way. SFN comfirms it was a lost bolt, spring and washer from the launch lock.
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An object of that size should be trackable by ground radar. Presumably they will monitor it to ensure it won't recontact the stack at some point later. I have a faint memory of something being lost on a spacewalk before and it being tracked.
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kneecaps - 12/9/2006 9:40 AM
An object of that size should be trackable by ground radar. Presumably they will monitor it to ensure it won't recontact the stack at some point later. I have a faint memory of something being lost on a spacewalk before and it being tracked.
Yeah it was Piers Sellers favorite spatula during tile repair technique testing on the final spacewalk for STS-121 ;) I imagine it'll just stay down in the truss structure.
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nathan.moeller - 12/9/2006 9:47 AM
kneecaps - 12/9/2006 9:40 AM
An object of that size should be trackable by ground radar. Presumably they will monitor it to ensure it won't recontact the stack at some point later. I have a faint memory of something being lost on a spacewalk before and it being tracked.
Yeah it was Piers Sellers favorite spatula during tile repair technique testing on the final spacewalk for STS-121 ;) I imagine it'll just stay down in the truss structure.
Joe said he was pretty sure it skittered over the cover and went overboard. He looked over and around quite a bit there and in the direction it went and couldn't see it.
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Images of the array base with our spacewalking friends kind of puts it in perspective how big this truss structure is. Quite stunning! It's going to be absolutely beautiful once they get those wings deployed. Are there 16 launch locks that have to be removed from the SARJ?
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MKremer - 12/9/2006 9:58 AM
nathan.moeller - 12/9/2006 9:47 AM
kneecaps - 12/9/2006 9:40 AM
An object of that size should be trackable by ground radar. Presumably they will monitor it to ensure it won't recontact the stack at some point later. I have a faint memory of something being lost on a spacewalk before and it being tracked.
Yeah it was Piers Sellers favorite spatula during tile repair technique testing on the final spacewalk for STS-121 ;) I imagine it'll just stay down in the truss structure.
Joe said he was pretty sure it skittered over the cover and went overboard. He looked over and around quite a bit there and in the direction it went and couldn't see it.
Guess it's a pretty good thing that these things get moving and stay moving in one direction away from the station then huh? Funny thinking that it'll find it's way back to Earth eventually in the form of a charred piece of metal.
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Well, they're already verifying they have everything inside the retrieval bag... so the spacewalk is about to end :(
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Hopefully they won't lose anymore lock thermal cover bolts tomorrow.
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"This could be the world's ugliest bag... it doesn't need to be pretty"
Tanner
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Correct me if I'm wrong but it seems the SARJ won't be able to allow the arrays to move 360 degrees until 12A.1 retracts the port array on P/6 or the P/4 arrays will come in contact with it. Am I seeing that wrong or did I miss some information completely?
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You're right nathan, they need to retract that P6 wing to allow full rotation of the SARJ - I guess they could test it a little though.
I'm wondering whether the lost bolt (if still inboard) could interfere with the working of the SARJ....
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nathan.moeller - 12/9/2006 5:16 PM
Correct me if I'm wrong but it seems the SARJ won't be able to allow the arrays to move 360 degrees until 12A.1 retracts the port array on P/6 or the P/4 arrays will come in contact with it. Am I seeing that wrong or did I miss some information completely?
Correct. Also until 12A.1 P4 will only have survival power as it won't generate any energy.
This one of the major objectives of 12A.1, to recofigure the station from it's early interim cooling and power generation, to the permanent configuration which uses power from P4 and cooling from S1/P1 trusses.
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:) Apparently a 6 hour EVA means you don't have to cook. Brent getting dinner for Joe and Heide
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Joe and Heide is now back at Quest.
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Solar panels don't have to be exactly facing the sun to still be able to generating power. On Earth they generate power even when it's cloudy.
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triddirt - 12/9/2006 4:24 PM
:) Apparently a 6 hour EVA means you don't have to cook. Brent getting dinner for Joe and Heide
Heh. Good work today.....some of the calls going up were really complex, as the mission is supposed to be.
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DaveS - 12/9/2006 10:23 AM
nathan.moeller - 12/9/2006 5:16 PM
Correct me if I'm wrong but it seems the SARJ won't be able to allow the arrays to move 360 degrees until 12A.1 retracts the port array on P/6 or the P/4 arrays will come in contact with it. Am I seeing that wrong or did I miss some information completely?
Correct. Also until 12A.1 P4 will only have survival power as it won't generate any energy.
This one of the major objectives of 12A.1, to recofigure the station from it's early interim cooling and power generation, to the permanent configuration which uses power from P4 and cooling from S1/P1 trusses.
Yeah that's what I was beginning to think would happen. I guess they've got it configured to move around a little bit to make sure it works and add some power. I guess that's why 12A.1 is designated a "power reconfig" huh? Haha. Yeah I knew they didn't have to face the sun directly to provide power. And in any case, P/6 is enough to power the station on its own for a good while longer. So these arrays won't make much difference until they start getting more modules hanging off the front of the station. Thanks for the answers!
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dutch courage - 12/9/2006 10:36 AM
Solar panels don't have to be exactly facing the sun to still be able to generating power. On Earth they generate power even when it's cloudy.
P4 won't be electrically connected to the station power grid until the 12A.1 mission, however.
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MKremer - 12/9/2006 5:45 PM
dutch courage - 12/9/2006 10:36 AM
Solar panels don't have to be exactly facing the sun to still be able to generating power. On Earth they generate power even when it's cloudy.
P4 won't be electrically connected to the station power grid until the 12A.1 mission, however.
I think they are going to rotate that SARJ to check it before deploying the solar blankets...
And untill 12A.1 it will just maintain power for itself (as MKremer said)
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EVA End: 6 hours and 26 minutes.
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And EVA-1 has officialy finished! Good work, Tanner and Piper, awesome job!
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DaveS - 12/9/2006 11:23 AM
Correct. Also until 12A.1 P4 will only have survival power as it won't generate any energy.
What I thought I heard was that the 2A and 4A wings on P4 would only power P3/P4 until the power distribution was reconfigured on the next flight...but that's plenty of margin for just that set of electronics...
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Beautiful view of the solar array mast on NASA TV.
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HKS - 12/9/2006 10:48 AM
I think they are going to rotate that SARJ to check it before deploying the solar blankets...
Yes, after tomorrow's EVA (and assuming there's no problem to prevent it), they'll test the SARJ joint. P4 has to be rotated back to its neutral position before they unfold the arrays, and that needs to be done first because P6 is in the way.
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"Guess it's a pretty good thing that these things get moving and stay moving in one direction away from the station then huh? "
But they don't, necessarily -- that's the scary part. I wrote up an explanation over at msnbc.com about the only 'safe' way to throw something overboard from a spacecraft. The link might still be good: http://www.msnbc.msn.com/id/11102068/
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If something like a nut or a washer drifts away (as opposed to being heaved), isn't its ballistic coefficient going to be low enough that it will appear to continually move away from the station, forward and down?
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JimO - 12/9/2006 5:34 PM
"Guess it's a pretty good thing that these things get moving and stay moving in one direction away from the station then huh? "
But they don't, necessarily -- that's the scary part. I wrote up an explanation over at msnbc.com about the only 'safe' way to throw something overboard from a spacecraft. The link might still be good: http://www.msnbc.msn.com/id/11102068/
Link is good - great read.
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Chris Bergin - 12/9/2006 12:03 PM
JimO - 12/9/2006 5:34 PM
"Guess it's a pretty good thing that these things get moving and stay moving in one direction away from the station then huh? "
But they don't, necessarily -- that's the scary part. I wrote up an explanation over at msnbc.com about the only 'safe' way to throw something overboard from a spacecraft. The link might still be good: http://www.msnbc.msn.com/id/11102068/
Link is good - great read.
Seconded. That's an awesome article. It's just like Heinlein said--if you want to slow down, speed up, and if you want to speed up, slow down.
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yinzer - 12/9/2006 10:44 AM
If something like a nut or a washer drifts away (as opposed to being heaved), isn't its ballistic coefficient going to be low enough that it will appear to continually move away from the station, forward and down?
The "drift" description implies that the separation velocity of the orbits was low, so effectively the orbital parameters are the same, and will recross twice each orbit. Look for the nut or washer to reappear! The saving grace might be the drag, especially for a washer, which would indeed tend to take it down (and hence forward).
...and welcome to the board, stroker.
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There's a media conference at the top of the hour, in case no one has mentioned. Good to see you around here Jim, how's Jay Barbee these days?
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yinzer - 12/9/2006 11:44 AM
If something like a nut or a washer drifts away (as opposed to being heaved), isn't its ballistic coefficient going to be low enough that it will appear to continually move away from the station, forward and down?
Not especially - it would be about the same as, say, undocking one of the Soyuz or Progress ships and immediately allowing it to free-drift. Its 'new' orbit would bring it back around near the station again.
The only hope with small parts and pieces that drift off is that their lighter mass allows quicker atmospheric friction decay, or that they can be tracked fairly quickly so just one small thruster "burp" is all that's needed to avoid it from then on.
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If I'm not mistaken the screw/spring/washer shouldn't be able to come lose from the thermal protection.
So Tanner is not to blame for that added space junk.
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mission briefing...
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Wow that's an amazing article. I'm afraid I can't wrap my head around all that. Unbelievable how orbital mechanics work. Very cool! Great day for spacewalking. Truss looks beautiful sitting out there. Can't wait for the array deployment!
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was this the post-MMT-briefing already?
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POST-MMT BRIEFING rescheduled to 3:45 pm CDT / 4:45 EDT
Again with John Shannon and Kirk Shireman.
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Briefing starting.
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MKremer - 12/9/2006 10:47 AM
yinzer - 12/9/2006 11:44 AM
If something like a nut or a washer drifts away (as opposed to being heaved), isn't its ballistic coefficient going to be low enough that it will appear to continually move away from the station, forward and down?
Not especially - it would be about the same as, say, undocking one of the Soyuz or Progress ships and immediately allowing it to free-drift. Its 'new' orbit would bring it back around near the station again.
The only hope with small parts and pieces that drift off is that their lighter mass allows quicker atmospheric friction decay, or that they can be tracked fairly quickly so just one small thruster "burp" is all that's needed to avoid it from then on.
I'm unconvinced.
There's the behavior coming from the initial separation impulse, which is determined by the Clohessy-Wiltshire equations and gives the receding-climbing-closing-diving loops described in the Oberg article. If the separation impulse is directly up or down, the thing will come back half an orbit later and hit the space station with exactly the same velocity with which it left.
There's also the behavior due to differential atmospheric drag; this will make the more draggy object move continually forward and down relative to the less draggy object. Assuming an aluminum nut 2 cm in diameter and 1 cm tall, and using the ISS data from here (http://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html), it looks like the nut will be about 10 times more draggy than the ISS.
Given that ISS loses between 50 and 200 m of altitude per day, the nut (the densest of the 3 things) should lose altitude at nearly a kilometer per day. I'd think this would totally dominate the relative motion, and after even a couple of hours the thing should be out of the vicinity of the ISS never to return.
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Atlantis is officially cleared for re-entry. All inspections by the ground teams were completed in half the estimated time of 5 days. Shannon says that Discovery will be in great shape for a night launch in December and that they feel very good about launching at night again due to the lighting from the boosters and the available inspection techniques.
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yinzer said -
I'm unconvinced.
There's the behavior coming from the initial separation impulse, which is determined by the Clohessy-Wiltshire equations and gives the receding-climbing-closing-diving loops described in the Oberg article. If the separation impulse is directly up or down, the thing will come back half an orbit later and hit the space station with exactly the same velocity with which it left.
There's also the behavior due to differential atmospheric drag; this will make the more draggy object move continually forward and down relative to the less draggy object. Assuming an aluminum nut 2 cm in diameter and 1 cm tall, and using the ISS data from here, it looks like the nut will be about 10 times more draggy than the ISS.
I 'm not quibbling with your figures (or your reasoning), but how about a SS bolt 3cm long by 0.5cm (with a 1cm flange), departing zenith (or within 10° forward) @ 20cm/sec?
Being somewhat ignorant about mass -vs- cross section -vs- atmospheric drag, would a more-massive object be susceptable to the same or less atmospheric drag forces than a less-massive object of the same size/shape?
Not to say I'm very worried about it - I would think even if it were even possible to get near the station within 1 or 2 orbits, the most it could do would be to bounce off, which would cause it to lose energy and enter a lower, faster orbit and decay to re-entry. (assuming it didn't bounce off a sensitive/easily damaged area)
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That bolt has a ballistic coefficient about 50% higher than the aluminum nut, but it will still decelerate much faster than the ISS. 20 cm/sec will boost it into an orbit with a mean altitude 300 m higher, and receding 100 km per orbit. Assuming that the altitude loss due to drag figure of 500 m / day is reasonable, this orbit will have decayed to completely within the ISS orbit long before it the ISS catches back up to it.
If Jorge sees this, he can verify or correct my math.
As for collision, well, 20 cm/sec is about what you'd get if you dropped something from a foot up on Earth. Vast areas of the ISS will be completely immune to this, but there might be areas that could be damaged. Chips out of windows or lodging in a moving part would be my main concerns, albeit not big ones.
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OK, thx, sort of what I assumed, if all the details are correct for that kind of piece escaping during an EVA.
It stands to reason the longer the ISS is there and unfinished, the more 'stuff' has a chance of going off on its own during EVAs (of which they may or may not have figured to happen over the years), and the more potential danger the ISS is in during its planned construction.
After Core Complete it's pretty much a wash, assuming a somewhat higher orbit, and less obvious opportunities for debris generation.