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Spacewalks Variations



 
 
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  #1  
Old October 31st 07, 04:34 PM posted to sci.space.shuttle
Albert Blauensteiner
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Default Spacewalks Variations

It is not clear to me why not performing EVA-5 ahead of a EVA-4 now
dedicated to repair the solar array blanket.
The both spacewalks are preplanned with different spacewalkers and different
independent tasks. EVA-5 is well planned and important for the upcoming
timline, and the multiple changed EVA-4 could gain an addtional day of
planning.

Albert


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  #2  
Old October 31st 07, 05:18 PM posted to sci.space.shuttle
Brian Gaff
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Default Spacewalks Variations

I think the current thinking is that the array can be fixed, but the longer
its left, the more danger of the damage getting worse. The rotary joint look
and see is not going to get worse if the joint is not moved, and thus can be
delayed. I'm sure much of the rest can be fitted in as and when.

I myself wonder if the obss could be employed toget access to the array
without running the snagging risk implicit in retracting to get at the
damaged section.

I find it hard visualising the array folding and deployed mechanics, but
seems to me, its got to be under some tension to be rigid enough o not
wobble about as its moved in normal use, so whatever they need to use may
need to be quite strong.

Brian

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"Albert Blauensteiner" wrote in message
...
It is not clear to me why not performing EVA-5 ahead of a EVA-4 now
dedicated to repair the solar array blanket.
The both spacewalks are preplanned with different spacewalkers and
different independent tasks. EVA-5 is well planned and important for the
upcoming timline, and the multiple changed EVA-4 could gain an addtional
day of planning.

Albert




  #3  
Old October 31st 07, 07:39 PM posted to sci.space.shuttle
robert casey
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Default Spacewalks Variations

Brian Gaff wrote:


wobble about as its moved in normal use, so whatever they need to use may
need to be quite strong.


And most likely non-conductive, and not mind UV in the sunlight. And be
something a spacesuited astronaut can successfully work with. Maybe
glue s sheet of something over the tear once it's tied down with some
tie-raps? What sort of glue would work in vacuum? Epoxy? And have on
hand up there, or it would have to wait for a supply mission? I'm sure
people on the ground are on it, trying various solutions...
  #4  
Old October 31st 07, 11:56 PM posted to sci.space.shuttle
snidely
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Default Spacewalks Variations

On Oct 31, 12:39 pm, robert casey wrote:
What sort of glue would work in vacuum? Epoxy? And have on
hand up there,


Tile cement -- that being one of the Mission Objectives that may be
omitted this time around due to the joint and tear problems.

/dps

  #5  
Old November 1st 07, 12:02 AM posted to sci.space.shuttle
snidely
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Default Spacewalks Variations

On Oct 31, 10:18 am, "Brian Gaff" wrote:
[...]
I myself wonder if the obss could be employed toget access to the array
without running the snagging risk implicit in retracting to get at the
damaged section.


Sounds like the new pole in the cargo bay:
-- this from AP via Yahoo http://news.yahoo.com/s/ap/20071031/
ap_on_sc/space_shuttle;

quote
The torn section of the wing cannot be reached with the space
station's 58-foot robot arm. So NASA plans to attach the shuttle
inspection boom to the station's robot arm, and put Scott Parazynski
on the boom to free the snagged part of the wing.

It helps that Parazynski is tall - 6-foot-2 - and has long arms. NASA
doesn't want him bumping the wing or touching its sunlight-collecting
blankets. There would be no need to mend the tears
/quote

/dps

  #6  
Old November 1st 07, 01:33 AM posted to sci.space.shuttle
snidely
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Default Spacewalks Variations

On Oct 31, 10:18 am, "Brian Gaff" wrote:
[...]
I find it hard visualising the array folding and deployed mechanics, but
seems to me, its got to be under some tension to be rigid enough o not
wobble about as its moved in normal use, so whatever they need to use may
need to be quite strong.


Here's an attempt at a verbal pictu imagine a stack of punch cards
(playing cards have too wide an aspect ratio -- the "cards" are long
and skinny).

Add hinges to opposite long sides so you have a Z-fold (or fan-fold if
you prefer). The "first" long side gets attached to a curtain rod,
and the "last" long side gets anchored in the box.

I can't tell from http://www.nasa.gov/images/content/
195515main_iss016e007399_hires.jpg if the narrow sides are attached
to the scissors jack or not -- perhaps Jorge or Jim can fill in that
detail.

The scissors jack is parallel to the narrow sides, and pushes the
curtain rod out, and the panels ("punch cards") follow along, pulled
by the hinges.

This is highly over-simpllified, of course, and may contain errors, so
I'll keep an eye out for those people updating the verbal picture.

/dps


  #7  
Old November 1st 07, 10:17 AM posted to sci.space.shuttle
Brian Gaff
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Posts: 2,312
Default Spacewalks Variations

Well, I wrote my bit before I learned that they were indeed going to use the
OBSS, but I feel that as nobody is really sure about the snag that caused
the tear yet, a range of options will be needed to be on hand. Considring
the array seems to have holes in various places, sounds like some form of
strap could be used. Obviously you want the panel to be as near to flat and
as it was as you can to ensure it gets the sun when in the right attitude.
However, the structural loading is what worries me. If you elect to cut a
snagged wire you may make things worse unless you really know the stress
distribution of a fully deployed array in zero g.

Brian

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"snidely" wrote in message
oups.com...
On Oct 31, 10:18 am, "Brian Gaff" wrote:
[...]
I myself wonder if the obss could be employed toget access to the array
without running the snagging risk implicit in retracting to get at the
damaged section.


Sounds like the new pole in the cargo bay:
-- this from AP via Yahoo
http://news.yahoo.com/s/ap/20071031/
ap_on_sc/space_shuttle;

quote
The torn section of the wing cannot be reached with the space
station's 58-foot robot arm. So NASA plans to attach the shuttle
inspection boom to the station's robot arm, and put Scott Parazynski
on the boom to free the snagged part of the wing.

It helps that Parazynski is tall - 6-foot-2 - and has long arms. NASA
doesn't want him bumping the wing or touching its sunlight-collecting
blankets. There would be no need to mend the tears
/quote

/dps



  #8  
Old November 1st 07, 10:53 PM posted to sci.space.shuttle
snidely
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Posts: 1,200
Default Spacewalks Variations

On Nov 1, 3:17 am, "Brian Gaff" wrote:
[...]
However, the structural loading is what worries me. If you elect to cut a
snagged wire you may make things worse unless you really know the stress
distribution of a fully deployed array in zero g.


Well, at the time I clipped that quote, the plan was to only inspect
on this spacewalk and to decide on repairs only after analyzing the
results.

/dps

  #9  
Old November 2nd 07, 07:57 AM posted to sci.space.shuttle
OM[_6_]
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Default Spacewalks Variations

On Thu, 01 Nov 2007 01:33:20 -0000, snidely
wrote:

This is highly over-simpllified, of course, and may contain errors, so
I'll keep an eye out for those people updating the verbal picture.


....No, you just might have explained what went wrong up the chads
:-)

OM
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] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[
  #10  
Old November 3rd 07, 04:35 AM posted to sci.space.shuttle
snidely
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Posts: 1,200
Default Spacewalks Variations

On Nov 2, 12:57 am, OM wrote:

...No, you just might have explained what went wrong up the chads
:-)


vbg

/dps

 




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