Could/Should Skylab Have Been Saved?

In article ,
says...
"Jeff Findley" wrote:
Unfortunately, the more the administration and NASA cuts pieces off of the
US segment, the more ISS grows dependant on the Russian segment and the more
likely ISS will have Mir like problems as it ages. :-(

Nonsense. Ageing effects occur regardless of who built the module.

Nonsense. Different engineering teams have different philosophies,
values and priorities. This yields different kinds of designs, some of
which age better than others.

MIR was designed for, iirc, a 5 year lifetime. It did that adequately.
The nasty problems showed up later. The American parts of ISS were
designed with a longer lifetime in mind, so they should last longer.
Time will tell, of course.
--
Kevin Willoughby lid

The loss of the American system of checks and balances
is more of a security danger than any terrorist risk.
-- Bruce Schneier

"Kevin Willoughby" wrote in message
...
In article ,
says...
"Jeff Findley" wrote:
Unfortunately, the more the administration and NASA cuts pieces off of
the
US segment, the more ISS grows dependant on the Russian segment and the
more
likely ISS will have Mir like problems as it ages. :-(

Nonsense. Ageing effects occur regardless of who built the module.

Nonsense. Different engineering teams have different philosophies,
values and priorities. This yields different kinds of designs, some of
which age better than others.

MIR was designed for, iirc, a 5 year lifetime. It did that adequately.
The nasty problems showed up later. The American parts of ISS were
designed with a longer lifetime in mind, so they should last longer.
Time will tell, of course.

The US has little experience with the design of manned space station systems
intended to last more than a few years (Skylab having happened in the early
70's and it was only manned for relatively short periods of time compared to
ISS). The Russians, on the other hand, have the experience. Whether or not
they've used that experience to improve their systems when they went from
Mir to ISS is debatable.

One area that's notable is O2 generation. Many of the same problems they
had on Mir with Elektron have been happening on ISS. However, it's been
reported that a new type of regenerative O2 generator is in the works for
ISS, so there may be an improvement in this area.


The US is still working on "infant mortality" sorts of issues, as can be
seen with the US regenerative CO2 removal system, the failed CMG, failing
laptops, and etc. It therefore remains to be seen how US systems will hold
during their "design lifetime".

Jeff
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On Tue, 30 Aug 2005 08:14:35 -0500, Jeff Findley wrote
(in article ):

One area that's notable is O2 generation. Many of the same problems they
had on Mir with Elektron have been happening on ISS. However, it's been
reported that a new type of regenerative O2 generator is in the works for
ISS, so there may be an improvement in this area.

The U.S. OGA for the Space Station Freedom was working just fine for
months on end in tests as early as 1992. It was pulled from the
baseline for a couple of reasons, not the least of which was Russia's
promise that Elektron worked great. Cost and power issues were the
nails in the coffin, however. Yes, it was small enough and yes it
worked fine, but Russia was making so many grand promises in the early
days of ISS in '93 that it was easy to keep slipping a
seemingly-redundant technology to the right on the schedule in the face
of rising costs and difficulty meeting the power budget.

The US is still working on "infant mortality" sorts of issues, as can be
seen with the US regenerative CO2 removal system,

What's happening with the CDRA really seems to be a fluke - stuck check
valves can happen with any system. The thing everyone *expected* to
cause trouble - the super small, super high-RPM main fan, doesn't seem
to be causing problems much at all. It's the lack of routine up/down
Shuttle capacity that's making the CDRA an issue at all. If orbiters
were docking every 90 days as planned, they'd just pull the ORU with
the wonky valve(s) and replace them. No big deal.

the failed CMG, failing
laptops, and etc. It therefore remains to be seen how US systems will hold
during their "design lifetime".

I would definitely NOT include laptops in the "ISS design lifetime"
discussion. Might as well complain the crew's underwear won't last 15
years, too. :-) Bear in mind that the SSF design lifetime was 30 years
and most of the U.S. stuff hasn't changed one iota. The lifetime was
dropped because of the impracticability to qualify and certify the
hardware for such a long time. The only hardware likely to last that
long in practice is the pressure vessels, the plumbing and wiring in
the standoffs and endcones, and the internal sub-structures (racks and
standoffs themselves). Everything else mechanical and electrical is
probably going to go balls-up and some point, just like they do on the
ground.

Jeff

--
"Fame may be fleeting but obscurity is forever." ~Anonymous
"I believe as little as possible and know as much as I can."
~Todd Stuart Phillips
www.angryherb.net

"Herb Schaltegger" wrote in
message .com...
On Tue, 30 Aug 2005 08:14:35 -0500, Jeff Findley wrote
(in article ):
The US is still working on "infant mortality" sorts of issues, as can be
seen with the US regenerative CO2 removal system,

What's happening with the CDRA really seems to be a fluke - stuck check
valves can happen with any system. The thing everyone *expected* to
cause trouble - the super small, super high-RPM main fan, doesn't seem
to be causing problems much at all. It's the lack of routine up/down
Shuttle capacity that's making the CDRA an issue at all. If orbiters
were docking every 90 days as planned, they'd just pull the ORU with
the wonky valve(s) and replace them. No big deal.

I agree that it should be no big deal, as long as it really is a problem
with this particular check valve. That's why I called it an "infant
mortality" sort of issue. It cropps up early on, is fixed, and should not
reappear during the remaining life of the unit.

the failed CMG, failing
laptops, and etc. It therefore remains to be seen how US systems will
hold
during their "design lifetime".

I would definitely NOT include laptops in the "ISS design lifetime"
discussion. Might as well complain the crew's underwear won't last 15
years, too. :-) Bear in mind that the SSF design lifetime was 30 years
and most of the U.S. stuff hasn't changed one iota. The lifetime was
dropped because of the impracticability to qualify and certify the
hardware for such a long time. The only hardware likely to last that
long in practice is the pressure vessels, the plumbing and wiring in
the standoffs and endcones, and the internal sub-structures (racks and
standoffs themselves). Everything else mechanical and electrical is
probably going to go balls-up and some point, just like they do on the
ground.

Except that you need those laptops to provide the "user interface" of the
ISS systems to the astronauts. Don't some of them perform command and
control sorts of things? I recall reading many status reports where things
like hard drives failed so many times the ISS crew ended up pulling
components from other laptops in order to keep the more important ones
running. Has a cause been found for the rash of hard drive failures? I
certainly don't see that kind of hard drive failure rate at home or at work,
so what's killing them on ISS?

That's not quite the same as underwear, since going commando won't interfere
with the crew's ability to monitor and control ISS. ;-)

Finally, I always worry about the issue of things not working as expected in
zero gravity. Something may work just fine in the lab, living up to its
predicted lifetime, but fail prematurely in zero gravity.

Jeff
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Remove icky phrase from email address to get a valid address.

Jeff Findley wrote:
The US has little experience with the design of manned space station systems
intended to last more than a few years

I think this experience was acquired during the 1990s and early 2000s
with the development of the ISS. There are many aspects of the US
segment which are by far superior to the russian segment. (think CBM,
think micrometeroid shield etc). A lot of the US segment has benefitted
from the US experience on Mir. (CBMs, MPLM to return racks who are no
longer needed, velcro and handrails (and footrails) in good locations
inside the station etc etc etc.


ISS). The Russians, on the other hand, have the experience. Whether or not
they've used that experience to improve their systems when they went from
Mir to ISS is debatable.

When you combine some time pressure to deliver early, with lack of
funds, it is probably quite fair to speculate that Zvezda has very very
similar systems to Mir. One system which is different is the computer
systems where ESA made an important contribution (and this would include
the interfaces to the US segment).


One area that's notable is O2 generation. Many of the same problems they
had on Mir with Elektron have been happening on ISS.

Because Mir did not have any cargo return capacity, the russians were
never able to perform an autopsy on Elektron on mir. The failed ISS
Elektron has now been returned in the Shuttle/MPLM and the russians will
be able to get a better idea of what went wrong. And hopefully the
shuttle will still be flyingif the new O2 generator starts to fail so it
could be returned for analysis.


The US is still working on "infant mortality" sorts of issues, as can be
seen with the US regenerative CO2 removal system, the failed CMG, failing
laptops, and etc.


CDRA has an untold story. I wish NASA discuss it openly. Do they have
any plans to fix this ?

The CMG, I reserve judgement. They are going to do a post mortem on it.
In terms of the other CMG problems, they are partly due to having som
much of the electronics outdoors (such as the fancy power switches).
NASA had expected a certain MTBF on the gizmos that are outdoors. It was
not expected to be a problem because at assembly complete, the arm would
be equipped with the hand device that is supposedly capable of pulling
circuit boards out of a box and putting a new one in. Until this is
shipped, only EVAs can fix this, and without shuttle, the Quest airlock
is not usable in the long term because only the shuttle can refill its
tanks. (and that is when the EVA suits are declared usable).

In terms of failed laptops, I think the same happens on the russian
segment too. That is no surprise.

Herb Schaltegger wrote:
The U.S. OGA for the Space Station Freedom was working just fine for
months on end in tests as early as 1992.


Where was it tested for "months on end" in 1992 ? Was it tested on Mir ?

If it was tested on the ground with 1g, then those tests are not valid.
Elektron probably worked fine too in 1 g.

"Jeff Findley" wrote in message
...
That's not quite the same as underwear, since going commando won't
interfere
with the crew's ability to monitor and control ISS. ;-)

That depends on what controls are located around the lower torso

"John Doe" wrote in message ...
Jeff Findley wrote:
One area that's notable is O2 generation. Many of the same problems
they
had on Mir with Elektron have been happening on ISS.

Because Mir did not have any cargo return capacity, the russians were
never able to perform an autopsy on Elektron on mir. The failed ISS
Elektron has now been returned in the Shuttle/MPLM and the russians will
be able to get a better idea of what went wrong. And hopefully the
shuttle will still be flyingif the new O2 generator starts to fail so it
could be returned for analysis.

Actually, the US returned an Elektron to Russia using the shuttle on STS-86:

http://en.wikipedia.org/wiki/STS-86
http://spaceflight.nasa.gov/history/...-h-f-sts86.htm

This mission was flown in 1997, so this was perhaps too late to impact the
Elektron units destined for ISS.

The US is still working on "infant mortality" sorts of issues, as can be
seen with the US regenerative CO2 removal system, the failed CMG,
failing
laptops, and etc.

CDRA has an untold story. I wish NASA discuss it openly. Do they have
any plans to fix this ?

The CMG, I reserve judgement. They are going to do a post mortem on it.
In terms of the other CMG problems, they are partly due to having som
much of the electronics outdoors (such as the fancy power switches).
NASA had expected a certain MTBF on the gizmos that are outdoors. It was
not expected to be a problem because at assembly complete, the arm would
be equipped with the hand device that is supposedly capable of pulling
circuit boards out of a box and putting a new one in. Until this is
shipped, only EVAs can fix this, and without shuttle, the Quest airlock
is not usable in the long term because only the shuttle can refill its
tanks. (and that is when the EVA suits are declared usable).

In terms of failed laptops, I think the same happens on the russian
segment too. That is no surprise.

But the constant failing of laptops does seem to show that they cannot be
relied upon to run for long periods of time without parts failing. Luckily,
they are laptops, so swapping them, and some of their components like hard
drives, isn't so bad. But it does contribute to the overall maintenance
load the crew must endure to keep the station functioning.

Jeff
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Remove icky phrase from email address to get a valid address.

Jeff Findley wrote:
Actually, the US returned an Elektron to Russia using the shuttle on STS-86:

Interesting.

This mission was flown in 1997, so this was perhaps too late to impact the
Elektron units destined for ISS.

That would have given them 2 years of work before the ISS Elektron was
sent up. (remember it was sent separately in a Progress, not launched
with Zvezda). And even if they didn't have time to change it, they
should have had good idea of what was wrong with it. Perhaps they did
fix the problem that happened on Mir, but something else cropped up.


But the constant failing of laptops does seem to show that they cannot be
relied upon to run for long periods of time without parts failing.

But this could be viewed as an experiment: use off the shelf commercial
products (much cheaper) and see how they perform.


But it does contribute to the overall maintenance
load the crew must endure to keep the station functioning.

The use of Windows is probably a much bigger issue in terms of wasting
crewmember's time to fix windows problems. But yes, having unreliable
equipment is a hindrance.

In article ,
The US has little experience with the design of manned space station systems
intended to last more than a few years

True, but there are people in the US who have built (unmanned)
spacecraft that fly for years and years, sometimes decades, without any
maintenance. That talent could be tapped for new (manned) spacecraft.
--
Kevin Willoughby lid

The loss of the American system of checks and balances
is more of a security danger than any terrorist risk.
-- Bruce Schneier