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