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On the lasting importance of the SpaceX accomplishment.



 
 
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  #11  
Old July 14th 12, 05:30 PM posted to sci.space.policy,sci.space.history,rec.arts.sf.science
Bob Haller
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Posts: 3,197
Default On the lasting importance of the SpaceX accomplishment.



lets not forget that the stations modules have a finite lifetime. you
can replace all sorts of parts on a old car but that doesnt make it
new, and breakdowns on old vehicles are to be expected.


So do B-52s, KC-135s, T-38s and P-3s, all of which are still in active
military service over 50 years after they were delivered.



Brian


if the modules could be returned to earth and completely refurbished
this is true. in the case of military jets only the airframes havent
been changed. all other parts have perodically upgraded or totally
replaced.....

  #12  
Old July 14th 12, 05:58 PM posted to sci.space.policy,sci.space.history,rec.arts.sf.science
Greg Goss
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Posts: 169
Default On the lasting importance of the SpaceX accomplishment.

Thomas Womack wrote:
Fred J. McCall wrote:
I'm sorry, but that displays a degree of insanity that I just find
impossible to believe. Suppose it comes down on Paris or London. How
many people does it kill, what does it destroy, and what does all that
cost once all the liability suits are settled. You're talking almost
a million tons of stuff coming in at reentry velocities.


If the Space Station weighed a million tons then we've already won.

It weighs four hundred tons; a rock that size comes in at
interplanetary velocity most years, mostly burns up, and is noticed
only in internal publications of ballistic-missile defence
organisations. There's an atmosphere in the way; almost everything
burns up almost entirely, and the rest hits no harder than a component
falling off a plane at takeoff.


And your big rocks are pretty solid. I expect that hollow "rocks"
break up a lot earlier in their entry.

--
I used to own a mind like a steel trap.
Perhaps if I'd specified a brass one, it
wouldn't have rusted like this.
  #13  
Old July 14th 12, 06:48 PM posted to sci.space.policy,sci.space.history,rec.arts.sf.science
Brian Thorn[_2_]
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Default On the lasting importance of the SpaceX accomplishment.

On Sat, 14 Jul 2012 09:30:41 -0700 (PDT), bob haller
wrote:



lets not forget that the stations modules have a finite lifetime. you
can replace all sorts of parts on a old car but that doesnt make it
new, and breakdowns on old vehicles are to be expected.


So do B-52s, KC-135s, T-38s and P-3s, all of which are still in active
military service over 50 years after they were delivered.


if the modules could be returned to earth and completely refurbished
this is true.


It is true regardless.

in the case of military jets only the airframes havent
been changed. all other parts have perodically upgraded or totally
replaced.....


The airframes are likewise the only part of ISS modules that can't be
changed. Pretty much everything else can be changed out. It was
designed that way deliberately, Bob.

Brian
  #14  
Old July 14th 12, 07:39 PM posted to sci.space.policy,sci.space.history,rec.arts.sf.science
Bob Haller
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Posts: 3,197
Default On the lasting importance of the SpaceX accomplishment.

......

The airframes are likewise the only part of ISS modules that can't be
changed. Pretty much everything else can be changed out. It was
designed that way deliberately, Bob.

Brian


Dockings of visiting spacecraft, thermal cycles during each orbit of
Earth, reboost maneuvers and crew exercise can affect the space
station's structural health. Without the ability to inspect the shell
of the craft, like airplane engineers would do on Earth, NASA must use
computer models to predict how cracks and deformities propagate in
space.

So theres no way to directly inspect the modules, a not anticipated
issue may appear, similiar to the square window issues in the first
commercial airliner. plus space is a very challenging environment

  #15  
Old July 14th 12, 11:47 PM posted to sci.space.policy,sci.space.history,rec.arts.sf.science
Peter Stickney[_2_]
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Posts: 124
Default On the lasting importance of the SpaceX accomplishment.

On Sat, 14 Jul 2012 12:48:44 -0500, Brian Thorn wrote:

On Sat, 14 Jul 2012 09:30:41 -0700 (PDT), bob haller
wrote:



lets not forget that the stations modules have a finite lifetime. you
can replace all sorts of parts on a old car but that doesnt make it
new, and breakdowns on old vehicles are to be expected.

So do B-52s, KC-135s, T-38s and P-3s, all of which are still in active
military service over 50 years after they were delivered.





if the modules could be returned to earth and completely refurbished
this is true.


It is true regardless.

in the case of military jets only the airframes havent been changed. all
other parts have perodically upgraded or totally replaced.....


And once again, Bob, you get it wrong.

All of Above name aircraft have been through a continual process of inspection, IRAN,
overhaul and rebuild for decades. About the only thing still original
on a KC-135R (Especially after Pacer Crag) is the data plate.
B-52s even more so, even though both types have relatively few
hours on them for their ages - all that time spent on alert during
the Cold War.
The T-38s have also been through several complete rebuilds.
The P-3s not so much, but they go through an intense
(almost Space Shuttle) level of mandatory inspection and
special maintenance (Such as fresh-water high pressure washdowns
after each flight - the corrosion from flying over the oceans
for all those years is a tremendous problem.)
It's interesting that you didn't mention other contemporaneous types,
the C-141B (Which got its wings flown off during Desert Shield/Desert
Storm), and the Handley Page Victor (Supporting the Black Buck operations
in the Falklands War did them in)
It's not just the years, it's the mileage.

How does this relate to the ISS? You can't pull a full inspection,
taking apart the structure and performing Non-Destructive Testing
on it. We don't have the knowledge base yet to be able to predict
what the long-term effects of the space environment are going to be.
Any predictions now are guesses, surmise, and prejudice.


The airframes are likewise the only part of ISS modules that can't be
changed. Pretty much everything else can be changed out. It was designed
that way deliberately, Bob.


What everybody seems to miss, or ignore, is that the ISS just being there is a
vital part of long endurance spaceflight. If we can't build structures, power systems,
environmental systems, and all the rest that can't be trusted beyond the next
scheduled resupply flight, than anything like a mission beyond the Moon
is right out. Mir was jack-legged together - the crew spent most of their time
(Especially in the later years) working at not dieing. The Russians, and we,
learned a lot, but not enough. ISS's history shows that we still have a lot to learn.
That's going to be the big takeaway, not the Classic Space Nerd goals of
large semiconductor wafers and Zero-G sex.

--
Pete Stickney
Failure is not an option
It comes bundled with the system
  #16  
Old July 16th 12, 02:26 PM posted to sci.space.policy,sci.space.history,rec.arts.sf.science
Jeff Findley[_2_]
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Posts: 1,388
Default On the lasting importance of the SpaceX accomplishment.

In article ,
says...

Jeff Findley wrote:

In article 42848d20-dd90-48d3-8b3e-
,
says...
well since ares orion wouldnt be operational till after 2020, and by
that time whats left of ISS will be in the pacific.....


This is not a given. Mir stayed in orbit long after its design lifetime
was up. The shuttle bringing up spare parts had a lot to do with this.
Given the multitude of resupply ships both flying to ISS and in
development, I don't see spare parts being much of an issue.


Well, yes, it is a given because once we're done with it we will
deorbit it as we are responsible for anything it might hit if we don't
and it does an uncontrolled reentry.


True, once it's deorbited, it's done. I don't discount the possibility
that the Russians may try to extend the program somehow. They've been
toying with the idea of taking "their" ISS modules and using them as an
initial starting point for a "new" station.

Not out of the question, but if NASA's in charge, I'd wager it's far
more likely to contain ISS derived modules. After all, they might get
the Europeans to build the HAB module, which means NASA wouldn't have to
pay for it.


Oh, don't be silly! You think we don't pay for the stuff others do?
That's like saying we don't have to pay because we're going up on
Russian boosters!


The Russians are a huge exception because there is currently no other
way for the US to get crew. In other cases, we tend to barter for
hardware and/or services. Direct cash payments to other countries are
generally frowned upon.

Buying modules from Bigelow means paying for them. That's not
completely out of the question, I think it's unlikely to happen without
Bigelow "proving" their inflatables are safe for human occupancy.


The original idea for the Bigelow inflatable's came from the
government; Lowell Wood at LLNL, to be precise.


True, but others still see inflatables as a new, as yet to be trusted,
technology.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker
  #18  
Old July 16th 12, 02:47 PM posted to sci.space.policy,sci.space.history,rec.arts.sf.science
Jeff Findley[_2_]
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Posts: 1,388
Default On the lasting importance of the SpaceX accomplishment.

In article 32fbdc15-236e-4bbe-a95a-
, says...

.....

The airframes are likewise the only part of ISS modules that can't be
changed. Pretty much everything else can be changed out. It was
designed that way deliberately, Bob.

Brian


Dockings of visiting spacecraft, thermal cycles during each orbit of
Earth, reboost maneuvers and crew exercise can affect the space
station's structural health.


So now you're an expert in structural fatigue? This could be an issue,
but considering the loads experienced by the modules during launch, I'd
think it would take quite a long time for such small loads to cause the
sort of fatigue you're talking about. Please remember that ISS is in
orbit and is experiencing microgravity conditions. This is compared to
the 3 or so g's (plus a lot of vibrations) experienced by those same
modules during launch.

Without the ability to inspect the shell
of the craft, like airplane engineers would do on Earth, NASA must use
computer models to predict how cracks and deformities propagate in
space.


You're speculating here. You have not done the analysis. Cite?

So theres no way to directly inspect the modules, a not anticipated
issue may appear, similiar to the square window issues in the first
commercial airliner. plus space is a very challenging environment


So where are the square holes in the structures on ISS? Besides, space
(specifically microgravity) is *not* a challenging environment for
structures. *Launch* (especially aboard the space shuttle) is a
challenging environment for a structure which otherwise will experience
microgravity conditions.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker
  #19  
Old July 16th 12, 02:52 PM posted to sci.space.policy,sci.space.history,rec.arts.sf.science
Jeff Findley[_2_]
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Posts: 1,388
Default On the lasting importance of the SpaceX accomplishment.

In article ,
says...

How does this relate to the ISS? You can't pull a full inspection,
taking apart the structure and performing Non-Destructive Testing
on it. We don't have the knowledge base yet to be able to predict
what the long-term effects of the space environment are going to be.
Any predictions now are guesses, surmise, and prejudice.


The materials results from LDEF gave us a pretty good baseline.
Besides, "the space environment" largely consists of microgravity and
either vacuum or sea level air pressure (depending on which side of the
pressure vessel you're talking about).

The airframes are likewise the only part of ISS modules that can't be
changed. Pretty much everything else can be changed out. It was designed
that way deliberately, Bob.


What everybody seems to miss, or ignore, is that the ISS just being there is a
vital part of long endurance spaceflight. If we can't build structures, power systems,
environmental systems, and all the rest that can't be trusted beyond the next
scheduled resupply flight, than anything like a mission beyond the Moon
is right out. Mir was jack-legged together - the crew spent most of their time
(Especially in the later years) working at not dieing. The Russians, and we,
learned a lot, but not enough. ISS's history shows that we still have a lot to learn.


I beg to differ. I think we've learned enough to go beyond LEO for long
missions. Humans have been "doing" long duration spaceflight in LEO
since the 70's. We're coming up on about four decades of long duration
flights. If we're not "ready" to leave LEO by now, then we're gutless
cowards.

Money (the high cost of spaceflight) is what's holding us back, not
technical, engineering, or medical issues. We know how to deal with the
technical, engineering, and medical issues.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker
 




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