Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V08/V8_343.TXT

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Date: Wed, 31 Aug 88 01:06:52 PDT
From: Ted Anderson <[e-mail]>
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Subject: SPACE Digest V8 #343

SPACE Digest                                      Volume 8 : Issue 343

Today's Topics:
           Re: How does NASA detect a Hydrogen leak
             Skinsuits for Space
              Sentient Behavior
        Re: SETI: Why don't we hear anything?
           Re: Space Station power supply (was Re:
         RE: skintight suits (worn in space station)
              Re: Skintight space suits
                   Re: SETI
                   WESPACE
----------------------------------------------------------------------

Date:     Thu, 18 Aug 88 23:21:47 EDT
From: Peter Allsop <[e-mail]>
Subject:  Re: How does NASA detect a Hydrogen leak

There are several methods available for finding Hydrogen leaks all of
which depend on "sniffing" the air for gasseous H2.  While I'm not
sure which method NASA uses the most likely is Thermal Conductivity...
they draw a constant velocity gas stream past a heated wire (or film)
and measure the current required to maintain the wire (film) at a set
temperature.  This is a commonly used method for detecting various gasses
(actually, changes in local gas composition) in refineries and
occupational health surveys, hand held units being available. Alternate
methods include fuel cells, Gas Chromatographs, Pt-MOSFETs, and Mass
Spectrometers.  The first 3 of these are available as hand held units,
although the MOSFET stuff is pretty new technology and Platinum
is an ignition source for Hydrogen.

One contributor suggested that NASA uses portable Mass Spectrometers.
While this is possible I think TC is more likely due to cost and weight.
The problem is that a MS requires a *very* good vacuum to work, and down
here on Earth that means pumps.  I have seen some quite nice MS's which
wouldn't fill a briefcase *if* you exclude the vacuum pumps, but add the
pumps and you have a (heavy) pullman bag.  In addition most systems opt
for turbo pumps, which run at very high rev's and hence don't like to be
moved around while running (as in gyroscopes don't like to be moved).

That reminds me of something a friend once pointed out.  The reason that
movement causes head crashes on disk drives is not because you make
the heads flap around, it's because moving a spinning disk causes it
to precess!

                           Peter Allsop

The determined Real Programmer can write FORTRAN programs
     in any language.

------------------------------

Date: 19 Aug 88 05:28:04 GMT
From: [e-mail]  (Joe Beckenbach)
Subject: Skinsuits for Space


    I can put on a pair of tights in about two minutes. I have
lived in a single change of clothing for eight days on the trail.
I can spray-paint an irregular surface satisfactorily.

    1 + 1 + 1 = 4 [synergy!]
    Put on the special underwear, then pull on the supporting tights.
Pull on the turtle-neck, gasketed, long-sleeve leotard. Pull on the
supporting gloves. Spray on the layer to seal up the whole ensemble.
Add the college T-shirt and gi pants, life support pack, helmet, and
tool belt with lifeline, and step out the lock.

    Any good spray-on films suitable for space skinsuit use?
Also, good solvents, preferably two-part to avoid accidental dissolution
of the suit? If it were transparent, perhaps the last thing to do before
stepping out the airlock for an extended shift would be to take a quick
swim.

    Any fellow brainstormers game? [Including polymer chemists!]
--
Joe Beckenbach    [e-mail]    Caltech 1-58, Pasadena CA 91125
Mars Observer Camera Project            Caltech Planetary Sciences Division
Ground Support Equipment Programmer    And God said, let there be a life.... :-)

------------------------------

Date: 19 Aug 88 05:12:23 GMT
From: [e-mail]  (Joe Beckenbach)
Subject: Sentient Behavior

>>The fact is, we *don't know* why they aren't here now, and it's a major
>>puzzle.
>[Chris Munschy:]
>      Actually, the puzzle isn't quite that complex; we as a race have
>proven ourselves to be capable of the most pernicious acts directed against
>ourselves for some fairly modest differences of opinion. Religious
>and racial intolerance are still at the top of the list of "causes" that we
>are willing to kill each other for. As an open question to all of you in
>Netland, how do you think we as a race would react to somebody as wildly
>different as an Extraterrestrial form of life? I feel that if their tech-
>nology allows for inter-stellar or even intergalactic travel, it must
>certainly allow for some form of remote surveying or monitoring of our planet
>and it's people. And given our fairly unimpressive track record, their
>elusive behavior could be due to a desire not to contact us. After all,
>how we treat ourselves is a mirror of how we would treat others. This all
>may sound a little trite, but surely not too far off the mark.

    And assuming that any other species which is sapient is driven by
the same or similar motivations, such as self-preservation, self-interest,
and diversity of opinion, I would not blame then one bit for standing off.
I personally have no inclination yet to go rushing to the Iran-Iraq border
to help oversee the truce efforts, but then I [think I] have the wisdom to
know that I haven't seen enough of the world to do this without acquitting
myself passably.
    The global perspective is VERY hard to develop; few people have
the requisite skills and aptitudes to bring themselves about their own
positions for a considerable amount of time, and THINK / use WISDOM.
This seems to be the result of many factors, most of which I could mention
individually and getting royally flamed for. And since competence in the
thinking / wisdom / decision process cannot be guaranteed, I believe that
Homo sapiens and other space-able species will manage to muddle by,
very much like we have managed to do so far here on Terra: history and
wisdom are either examined and ignored, shit happens, and more history
results. Civilizations breathe, live, and occasionally die. Life continues.

    Lest I be accused of preaching to the converted, let me pre-emt it:
this is the one forum of the few I have had extensive experience on which
I see concern above the normal "me first" myopia. I guess that's because
I don't take any of the talk.* newsgroups. :-) :-)
--
Joe Beckenbach    [e-mail]    Caltech 1-58, Pasadena CA 91125
Mars Observer Camera Project            Caltech Planetary Sciences Division
Ground Support Equipment Programmer    And God said, let there be a life.... :-)

------------------------------

Date: 19 Aug 88 06:34:40 GMT
From: oliveb!tymix!antares![e-mail]  (phil nelson)
Subject: Re: SETI: Why don't we hear anything?

In article <[e-mail]> [e-mail] (Mike Van Pelt) writes:
>In article <[e-mail]> [e-mail] (Peter Kinsella) writes:
>>In article <[e-mail]>, [e-mail] (Mike Van Pelt) writes:
>>> [description of the "berserker hypothesis"
>
>Understand, my arguments here are of a "devil's advocate" nature.
>I do not think that this is the answer to the silence problem.
>(Maybe I'm being overly optimistic...)
>
..stuff deleted

>>If we assume that the galaxy is as expansive as most people claim.
>
>This supports the Berserker Hypothesis.  If the galaxy (or universe
>if we allow for intergalactic travel) is so big, it almost doesn't
>matter how fantastically improbable the Berserker Hypothesis is.  It
>only has to happen ONCE in fifteen billion years of the history of
>the entire galaxy/universe.  If anyone, anywhere, anytime, built
>self-replicating robots programmed to seek out and destroy all life
>(Saberhagen's version) or even all technological civilizations
>(Benford's version), they could fill the galaxy in on the order of
>a million or two years.  That what makes it so scary.
>
...more stuff deleted

I hope you will pardon me any errors of etiquette, this is my first
posting to this group, though I have been reading with interest for some time.

 I think that the problem of creating these "self-replicating robots" may
be more difficult than we imagine, perhaps too difficult even for our
hypothetical "advanced" xenophobes.

 These "robots", to be effective in their mission, might require so many of
the characteristics of living creatures that the problem of creating them is
essentially the problem of creating life. That, in my opinion, is a very
difficult problem.

 But, maybe it is possible, in that case;

 Among other lifelike qualities this race of robots might require is the
ability to adapt to new conditions. Assuming for a moment that these robots
can be (and are) created, isn't it likely that they would either evolve into
something more benevolent or (perhaps more likely) devolve into something
much less terrible?

hopefully,
--
{ames|pyramid}oliveb!tymix!antares!pnelson  | Contains one or more of the
OnTyme: QSATS.P/Nelson  POTS: [phone] | following: Pleas for help, Free
Disclaimer: Not officially representing     | advice, Opinion, Misc. rambling.
McDonnell Douglas Corporation policy.       |    * Use at your own risk *

------------------------------

Date: 18 Aug 88 15:02:00 GMT
From: a.cs.uiuc.edu!m.cs.uiuc.edu![e-mail]
Subject: Re: Space Station power supply (was Re:


>my opinion:
>The best reason for 220 VAC at 20 KHz is that it provides the contractors
>with the opportunity to engineer custom parts at great profit.  It seems
>unlikely that the savings in size by 20 KHz power are worth the trouble.

The above is untrue. Parts for 20KHZ power supplies are hardly custom
parts. Chopping supplies at the above approximate frequency are about the
only kind used any more, in the computer world. With the higher frequency,
physical size is reduced and you can put in a lunch bucket what would
require a bushel basket at 60HZ.

------------------------------

Date: Fri, 19 Aug 88 10:17:17 CDT
From: [e-mail]
To: [e-mail], [e-mail]
Subject: RE: skintight suits (worn in space station)

> * Dale Amon speculates that the inhabitants of a space station might want
>   to wear skintight suits all the time as a safety precaution. However,
>   when the suit is worn with ambient atmospheric pressure, the ambient
>   pressure and the elastic pressure of the suit are *added*. Assuming
>   something can be done to alleviate breathing difficulties, the problem
>   remains that the the pressure exerted on the extremities is comparable
>   to the systolic blood pressure. Since this is the technique used in a
>   blood pressure test to cut off the flow of blood to a limb entirely,
>   I consider it very likely that the suit worn indoors would significantly
>   interfere with the normal functioning of the circulatory system. This
>   might or might not be a problem for a person "suiting up" to go outside,
>   but I doubt that it would be a good idea for these suits to be worn all
>   the time indoors. (What is the "tightness" of the Soviet indoor suits?)

Wait a minute, if the effect is additive the wearer is subjected to
two atmospheres.  Isn't this the same horrible pressure that a
earthbound diver would experience under 33 feet of water?

Doesn't sound too deadly to me.. if it is not concentrated over
one spot (like a blood pressure cuff does).

    Mike Linnig,
    Texas Instruments

------------------------------

Date: Fri, 19 Aug 88 09:28:55 PST
From: Peter Scott <[e-mail]>
Subject: Re: Skintight space suits
X-Vms-Mail-To: EXOS%"[e-mail]"

>John Roberts <[e-mail]>:

>* Kevin Ryan summarizes an article by Jerry Pournelle, based on NASA Report
>  CR-1892, describing tests of the suit. It is stated that the pressure is
>  maintained at 170mm Hg for the central part of the body (matching the
>  pressure of the breathing air), dropping to 100-120mm at the extremities,
>  the difference being maintained by a gasket. This could be interpreted to
>  mean that gas is normally present between the extremities and the fabric
>  of the suit at this pressure, but I interpret it to mean that this is the
>  pressure exerted by the fabric against the skin, with vacuum outside the
>  skin. There is a considerable difference between the implications of
>  these two interpretations. The fabric can support the skin overall, but
>  not on a microscopic basis. At the microscopic level, the skin, rather than
>  being a continuous sheet of dead tissue, is full of pores, and the pores
>  contain important living, wet cells exposed to the outside pressure. At
>  body temperature, the partial pressure of water is ~50mm, meaning that if
>  the ambient pressure falls below this point, rapid boiling of water at and
>  for a short distance below the surface will begin. It seems highly unlikely
>  that these living cells could be directly exposed to vacuum without a
>  considerable number being killed.

I was the original poster asking for references, so when I got the information
I went and looked at the article on microfiche.  I don't recall all of the
details necessary to answer your questions, so suggest you read the article
for yourself.  I do remember that they found that a spandex-derivative fabric
with mesh holes of 0.5mm**2 was what they used, in several layers.  Sweat
evaporation was considered an asset since the suit did not need a cooling
system as a result of this.

>* Henry Spencer states that the suit has been tested and it works. The
>  problem lies in the interpretation of the word "works". The loosest
>  interpretation is that "the test subject, exposed to these conditions
>  for an unspecified period of time, did not split open and gush blood,
>  and survived the experiment without any observed permanent damage".
>  I would like to know about the results of long-term exposure, which I
>  suspect would at least cause the skin to become dry and brittle, and
>  might kill the hair follicles, oil and sweat glands. It would be very
>  inconvenient to use the suit six hours a day for three weeks and then
>  have your skin fall off.

As far as I recall, the tests were for at least twenty minutes at an equivalent
altitude of 80,000 feet (that's pretty thin), and the subjects showed no
ill-effects whatsoever.  The authors concluded that there were no
fundamental design issues to be resolved, that the only remaining problems
were, in their words, purely mechanical.  I now agree with the original
posting, i.e., why isn't this thing being developed further?

Peter Scott ([e-mail])

------------------------------

Date: 19 Aug 88 17:10:48 GMT
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