Spacewalk danger, outside sub-systems; no ISS/shuttle refuge?

We're told, that this spacewalk, is to replace a "failed power component".
So, given the risks of spacewalks, why are any sub-system modules placed
outside? Offhand, it would seem best to maintain and change replaceable
units, from within. If you have circuit boards, you'd build a module so
access would be on the inside of the craft.
The only reason I can see, is fire danger in an oxygen rich field. While
testing circuit boards, I've seen ICs, caps, or resistors, fail and burst
into small flames. If such a card had been outside a spacecraft, there
would have been no flame. I wonder how this is engineered. Or could be.
Build each card-cage/rack into a air-tight/space box. The inner access door
would have an air-tight gasket. There would be a very small pin-hole on the
outer wall, with a slide cover to be used during access. Normally,
after access, the inner air-tight door would be locked. Thus, any air would
be slowly drawn outside. The card-cage would usually be in a vacuum.
For access, the outer cover would slide over the pin-hole, and inner door
opened, to let in some air, so the door could be opened. Any wires to and
from this box, would have to have vacuum proof seals, (or vacuum proof
bulkhead connectors). Normally, the slide cover over the pin-hole, would be
powered, and controlled. If power failed, the inside door air access covers
could be opened by hand.
Once the box had been flooded with air, the inner door could be opened,
and the outside slide cover also moved by hand, to close over the small pin-
hole letting out air.
But then, during the last, (deadly), shuttle flight, at one point I
felt, something was not right. And maybe they should seek out the ISS, and
via airlock, or spacesuit, find refuge. Even if Nasa found that shuttle
could never land, could the ISS have helped? Say, their optics viewed
a shuttle with no left wing? Was there no way, that shuttle could
not find/join the ISS, and transfer the crew? Don't both have airlocks?
Sent up enough shuttle spacesuits? Maybe with some spare oxygen
and food, to carry over to the ISS during an emergency?
Didn't NASA have any hint, something was wrong? If so, they could have
sent out a spacewalk. With the fatal flaw revealed. That the shuttle could
never return to earth. If the crew couldn't survive via the ISS, they were
doomed. If so, why not? Fuel, orbit, time, air, speed, or what? Interlocks
or airlocks? Was it a moot point? If launch video showed insulation damage,
why couldn't there have been a spacewalk to check on this? Send out an
expert, to say either, "Looks OK", or "There are some large holes in the
shuttle's insulation". "Looks OK"; and there could be a chance for landing.
If not, seems the crew could only have looked towards the ISS, for a chance
at life. Frozen O-Rings, or damaged shuttle insulation; I see NASA doing a
gamble on both. They could have paid more attention to warnings about
a shuttle launch at zero temps. And they had info about shuttle insulation
damage. Any hint, why not to explore? Take a few more orbits, and send
out someone to check under the hood? I don't care if that shuttle cost
a billion or more. Just do the most, to keep the crew alive. There were
hints, this last shuttle had problems and was doomed. What if that crew
had other 'options'; to survive in 'space'?
We've got an International Space Station in orbit. Seems any nation that
sends humans into space, should be able to use the ISS, as a 'safety raft'.

Arty Hues wrote in
rver.com:

We're told, that this spacewalk, is to replace a "failed power
component".
So, given the risks of spacewalks, why are any sub-system modules
placed
outside?

To minimize the number of penetrations through the pressure hull (both the
power source and the load are outside, in this case), minimize the number
of connections through hatches (lesson learned from Mir), and minimize
potential crew exposure to ammonia (used to cool external power
components).

The only reason I can see, is fire danger in an oxygen rich field.

ISS atmosphere is 20% oxygen, no more oxygen rich than sea level air, and
no higher fire hazard.

But then, during the last, (deadly), shuttle flight, at one point
I
felt, something was not right. And maybe they should seek out the
ISS, and via airlock, or spacesuit, find refuge. Even if Nasa found
that shuttle could never land, could the ISS have helped? Say, their
optics viewed a shuttle with no left wing? Was there no way, that
shuttle could not find/join the ISS, and transfer the crew?

No. Columbia was in the wrong orbit to reach ISS.

Didn't NASA have any hint, something was wrong?

They had launch video showing the foam impact, but no direct evidence of
wing damage.

If so, they could have
sent out a spacewalk. With the fatal flaw revealed. That the shuttle
could never return to earth. If the crew couldn't survive via the
ISS, they were doomed. If so, why not? Fuel, orbit, time, air,
speed, or what? Interlocks or airlocks?

The ability to remove CO2 from the atmosphere was the limiting factor. Had
STS-107 been powered down starting on flight day 7, they could have held
out 30 days (through February 15). Oxygen would have lasted one more day.

Was it a moot point? If
launch video showed insulation damage, why couldn't there have been a
spacewalk to check on this? Send out an expert, to say either, "Looks
OK", or "There are some large holes in the shuttle's insulation".
"Looks OK"; and there could be a chance for landing. If not, seems the
crew could only have looked towards the ISS, for a chance at life.

Again, Columbia could not have reached ISS. If the spacewalk showed fatal
damage, the only two options were for the crew to attempt to improvise a
patch to the wing (which almost certainly would not have worked, given the
difficulties NASA has since encountered developing RCC repair techniques),
or for the crew to power down and try to hold out until Atlantis could be
launched to rescue them (which was perhaps just barely possible, but would
have involved risking a second orbiter and crew to the same problem that
doomed the first).

We've got an International Space Station in orbit. Seems any nation
that
sends humans into space, should be able to use the ISS, as a 'safety
raft'.

There are an infinite number of possible orbital planes in low Earth orbit,
and ISS occupies only one. It is prohibitively expensive, fuel-wise, to
change planes once in orbit. Requiring that all manned spacecraft be able
to abort to ISS is tantamount to demanding that all manned missions be
planned for ISS in the first place. It is thinking such as yours that got
the Hubble servicing mission cancelled. It is thinking such as yours that
would prevent us from ever returning to the Moon, or travelling to Mars.

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

"Jorge R. Frank" wrote in
Again, Columbia could not have reached ISS. If the spacewalk showed fatal
damage, the only two options were for the crew to attempt to improvise a
patch to the wing (which almost certainly would not have worked, given the
difficulties NASA has since encountered developing RCC repair techniques),
or snip

They would have tried something, in any case -- and stuffing the gap with
metal and water (ice) might have allowed the wing to hold together until
they got low enough to bail out (a matter of only a few minutes more), or it
might have created aero instability EARLIER and destroyed the wing in some
other manner. Knowing is always better than not knowing, and going down
swinging is always better than being blind-sided. But it could well have
been a hopeless situation. Hopelessness was guaranteed by the shuttle team's
inability to understand in real time how serious it was. People within the
team will bitterly regret these lost opportunities all their lives.

Jorge R. Frank wrote:

or for the crew to power down and try to hold out until Atlantis could be
launched to rescue them (which was perhaps just barely possible, but would
have involved risking a second orbiter and crew to the same problem that
doomed the first).

We've all read enough about Columbia, but this point always seems to go
unchallenged. Knowledge of a new failure mode doesn't suddenly make it
more likely. However you slice the data the chances of Atlantis suffering
the same problem were very slim, and I'm quite sure that there would have
been no shortage of volunteers willing to bet against it. And whatever
system you're using, every launch and every re-entry carries some risk.

As has been pointed out, the far greater risk to Atlanta would have been
from rushing the job.

Still wouldn't have happened tho.

--
A man can always find a pub.

Mary Pegg wrote in
:

Jorge R. Frank wrote:

or for the crew to power down and try to hold out until Atlantis
could be launched to rescue them (which was perhaps just barely
possible, but would have involved risking a second orbiter and crew
to the same problem that doomed the first).

We've all read enough about Columbia, but this point always seems to
go unchallenged. Knowledge of a new failure mode doesn't suddenly
make it more likely. However you slice the data the chances of
Atlantis suffering the same problem were very slim,

That requires the assumption that all the bipod-ramp foam incidents shared
a common root cause.

Remember, prior to STS-112, the previous incident of bipod-ramp foam
shedding that NASA knew about was on STS-50, over ten years previous. NASA
had thought they'd licked that problem.

Then STS-112 shed bipod ramp foam, then STS-107. Two out of three flights
in quick succession. Without a firm link between the root causes of the
current and previous incidents, NASA had *no* engineering rationale for
saying that the odds of bipod foam shedding would be any *less* than 67%
for a rescue flight.

and I'm quite sure
that there would have been no shortage of volunteers willing to bet
against it.

Agreed there.

And whatever system you're using, every launch and every
re-entry carries some risk.

As has been pointed out, the far greater risk to Atlanta would have
been from rushing the job.

Still wouldn't have happened tho.

Agreed there, too.


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

Without a firm link between the root causes of the
current and previous incidents, NASA had *no* engineering rationale for
saying that the odds of bipod foam shedding would be any *less* than 67%
for a rescue flight.


The fact that foam shedding had become accepted, and the test they used for
damage didnt really apply were sad.

but worse was knowlingly ignoring a unknown happening and deciding it wasnt
dangerous with no solid info.

HAVE A GREAT DAY!

On 01 Jul 2004 04:39:18 GMT, "Jorge R. Frank"
wrote:

So, given the risks of spacewalks, why are any sub-system modules
placed outside?

minimize the number of connections through hatches (lesson learned from Mir),

Er, the timing of the Mir collision incident and ISS design completion
seems to preclude this being a "lesson learned". More likely, someone
thought of it ahead of time and was vindicated by the Progress/Mir
collision. That person or team who pushed such a design must have been
feeling pretty pleased with themselves after that. :-)

Brian

There are an infinite number of possible orbital planes in low Earth orbit,
and ISS occupies only one. It is prohibitively expensive, fuel-wise, to
change planes once in orbit. Requiring that all manned spacecraft be able
to abort to ISS is tantamount to demanding that all manned missions be
planned for ISS in the first place. It is thinking such as yours that got
the Hubble servicing mission cancelled. It is thinking such as yours that
would prevent us from ever returning to the Moon, or travelling to Mars.



Yep. I can see the ISS has only one orbital plane. So, what is so wrong,
to require all manned spacecraft be able to abort to the ISS? Demanding
that all mannned missions be planned in some way for ISS? Hubble is
near it's end. And who's planning a return to the moon, or a trip to
Mars?
'Prohibitvely' expensive? Here's who died during STS-107:
Rick D. Husband
William C. McCool
Michael P. Anderson
David M. Brown
Kalpana Chawla
Laurel Blair Salton Clark
Ilan Ramon
Jules F. Mier, Jr.
Charles Krenek

Put as many words you want in front of 'expensive'. I don't care about
the hardware cost. How can you tally, those lives, vs. cost? Send them
up; then give them a lifeboat.

Arty Hues wrote in
rver.com:

There are an infinite number of possible orbital planes in low Earth
orbit, and ISS occupies only one. It is prohibitively expensive,
fuel-wise, to change planes once in orbit. Requiring that all manned
spacecraft be able to abort to ISS is tantamount to demanding that
all manned missions be planned for ISS in the first place. It is
thinking such as yours that got the Hubble servicing mission
cancelled. It is thinking such as yours that would prevent us from
ever returning to the Moon, or travelling to Mars.

Yep. I can see the ISS has only one orbital plane. So, what is so
wrong, to require all manned spacecraft be able to abort to the ISS?
Demanding that all mannned missions be planned in some way for ISS?
Hubble is near it's end. And who's planning a return to the moon, or
a trip to Mars?

In case you've been hiding under a rock since January 14, the United States
is.

'Prohibitvely' expensive? Here's who died during STS-107:
Rick D. Husband
William C. McCool
Michael P. Anderson
David M. Brown
Kalpana Chawla
Laurel Blair Salton Clark
Ilan Ramon
Jules F. Mier, Jr.
Charles Krenek

And what a wonderful legacy you would leave those nine: a timid space
program forever confined to the safe, suffocating embrace of 51.6 degree,
400 km Earth orbits. If that's all that lies ahead, it's not worth it - you
might as well bring Mike Fincke home and leave the Russians to run ISS. I
don't believe that's what those nine would have wanted. In fact, in the
cases of Husband, McCool, and Chawla, I *know* it's not what they would
have wanted.

Put as many words you want in front of 'expensive'. I don't care
about the hardware cost. How can you tally, those lives, vs. cost?

It's easy. Insurance actuaries do so every day, for a living.

Send them up; then give them a lifeboat.

Exploring frontiers inherently means going beyond the point where lifeboats
can help you. It was the case for the age of sea exploration, the
colonization of the New World, the early air age, and now the space age.
And all the ages of exploration before them. Lives were lost, but our lives
are all the richer for their sacrifices. Had Homo sapiens evolved with your
attitude, humanity would still be scratching out a living in Olduvai Gorge,
forever afraid to risk lives to see what lies beyond the next hill.

As a recently departed former president said while eulogizing another lost
space crew, "The future doesn't belong to the faint-hearted; it belongs to
the brave." You can feel free to continue to be meek. I'm told your kind
will eventually inherit the Earth.

The rest of us will inherit the stars, or die trying.

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

On Sat, 3 Jul 2004 3:22:02 -0700, Arty Hues
wrote:

Put as many words you want in front of 'expensive'. I don't care about
the hardware cost. How can you tally, those lives, vs. cost?

This happens all the time. Every ship that is launched. Every
skyscraper erected. Every car off the assembly line. There are ways
that each and every one of them can kill people, and they do kill
people. It is so common that only the most spectacular makes the news.
Did you know 108 US citizens died in elevators from 1992 to 1998? Do
you demand we ban elevators? Install lifeboats on elevators? Only send
elevators to the 'safe' second floor?

No. Nothing is 100% safe because building things 100% safe is
prohibitively expensive, if not impossible. No one would build them if
we demanded they be perfectly safe. Instead, we accept that from time
to time, people will die using them. We try as hard as we can to make
their number as small as possible. But we do not achieve perfection,
and we never will.

"A ship in port is safe. But that is not what ships are for."

Brian