Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V11_4/V11_427.ZIP/V11_427

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Date: Sat, 19 May 90 02:22:33 -0400 (EDT)
Subject: SPACE Digest V11 #427

SPACE Digest                                     Volume 11 : Issue 427

Today's Topics:
             Re: Shuttle Designs
           Hubble Space Telescope Update - 05/18/90
            Re: Terraforming Venus
              Strain Wave Gearing on HST
               HST Solar Panels
              Re:Glass stops IR?
               Re: O2 pressure
              Re: The Vatican Connection
               Re: Endangered squirrels
              Re:Glass stops IR?
----------------------------------------------------------------------

Date: Fri, 18 May 90 14:05:44 CDT
From: [e-mail]
Subject: Re: Shuttle Designs

> From: agate!agate![e-mail]  (William Baxter)

> In article <[e-mail]> [e-mail] (Dave Smith) writes:
>
> >William Baxter writes:
> >>Had the promises been based on the detailed design which you [mccall] claim
> >>existed, it is unlikely that they would have been so wildly inaccurate.
>
> >Why would this be so?  His claim is that the original design, which would
> >have been much more costly in terms of development, would have fulfilled
> >these promises.
>
> Yes, this is his claim.  Where do you suppose this 'original design' has
> gone?  Is the problem with the shuttle simply that Congress didn't give
> NASA enough money to do it right?  In similar circumstances today should
> we give them whatever they ask for?

This seems to be the favorite straw man for use with anyone who
disagrees with Mr. Baxter or Mr. Bowery.  The interesting thing is
that they are the only ones who have suggested that anyone thinks it
would be a solution.

Where do you suppose the design for the Saturn V has gone, Mr.
Baxter?  We no longer have that, and it was flying hardware at one
time!  Why would you expect that studies and such that never got
built would still be around anywhere except perhaps in someone's
personal papers?

No one (other than you) has said that the *only* problem with the
Shuttle is the way the budgetary evolution happened, nor has anyone
(other than you) said that we should do that now with the Space
Station.

I continue to be amazed at the oversimplified view of the world you
put forth in order to support your own political agenda.  Can't you
discuss these things without all the ranting, raving, and personal
sniping?

> The Space Station is now in a stage of development similar to that of
> the shuttle at the time of its alleged 'original design.' What can we
> do to avoid similarly disappointing results?

What are *YOU* proposing we should do?  All I've seen so far from
you is simplified political rhetoric that's damned short on logical
reasoning or facts.


==============================================================================
| Fred McCall  ([e-mail]) | "Insisting on perfect safety is for  |
| Advanced Systems Division           |  people who don't have the balls to  |
| Defense Systems & Electronics Group |  live in the real world."            |
| Texas Instruments, Inc.             |                     -- Mary Shafer   |
+-------------------------------------+--------------------------------------+
|  I speak for me.  I don't speak for others, and they don't speak for me.   |
==============================================================================

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

Date: 18 May 90 21:46:31 GMT
From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Hubble Space Telescope Update - 05/18/90


                   Hubble Space Telescope Update
                           May 18, 1990

     Ground operators commanded the Hubble Space Telescope
through its pointing control and mirror focusing paces today,
a repeat of a series of commands that will lead up to the
first optical images from the telescope, called "First Light,"
probably this weekend.

     Goddard Operators began a 36.5-hour re-run of Bootstrap Phase A,
Part One, at 10 p.m. EDT Thursday night.  As of 8 a.m., EDT Friday, two
data takes were successfully completed, each with nine successes
in nine attempts to locate and lock onto line-of-sight, or target,
stars.  Based on the data from scans performed during the first
data take, operators adjusted the secondary mirror focus to 1.4 arc
seconds.  Further refinement of the focus will be done as other
command loads are uplinked to the telescope.

     Engineers are continuing to gather and analyze data on three
issues: a slight roll in one axis of the telescope, small
vibrations in the telescope when it passes between night and day,
and slight telescope attitude drift.
       _   _____    _
      | | |  __ \  | |       Ron Baalke           |  [e-mail]
      | | | |__) | | |       Jet Propulsion Lab   |  [e-mail]
   ___| | |  ___/  | |___    M/S 301-355          |
  |_____| |_|      |_____|   Pasadena, CA 91109   |

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

Date: 18 May 90 03:34:49 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: Terraforming Venus

One of the problems with terraforming Venus is that most of the obvious
methods leave the surface rather toxic.  Among other things there is all
this sulfur and carbon in the atmosphere, presently as H2SO4 and CO2,
but even if you find some way to recombine it, it stays around.

Someday we'll be able to fix Venus if we really want to, I suppose, but
one hopes by then we'll realize the pointlessness of it.  What do we
gain by doubling our living space?  We've proved we can fill it in
a century or two.  We have to learn to manage Earth property, and if
we can do that, it's plenty big enough.

But for off-Earth living in general, we must ask what a planet like
Venus brings to the party anyway.  The technology required to live there
matches or exceeds in complexity the challenges of living in space
itself.  All that a planet really supplies is an atmosphere and a
resource pile.  The atmosphere may serve as a radiation shield but it
may also make life much more difficult than vacuum would, as in Venus'
case.  The resources are terrific if you can get at them, but must be
weighed against their counterparts in smaller or nonexistent gravity
wells, e.g. the Moon or the asteroids.  Also, as we are discovering on
Earth, intensive resource extraction can interfere with habitability.

--
When I was [in Canada] I found their jokes like their   * Tom Neff
roads -- not very long and not very good, leading to a  * [e-mail]
little tin point of a spire which has been remorselessly
obvious for miles without seeming to get any nearer. -- Samuel Butler.

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

Date: 18 May 90 12:41:00 EDT
From: "Steven Welby" <[e-mail]>
Subject: Strain Wave Gearing on HST
To: "space+" <[e-mail]>

    I've been led to understand that the Hubble Space telescope
makes use of a large number (>80?) of high efficiency self contained
strain wave gear drives (maybe better known under their trademark name
Harmonic Drive).  Does anyone khow anything about these units? (ie.
actual number, application etc.)  I also understand that this type of
gearing was also employed previously as part of the gearing on the
"lunar rover" (moon buggy?) vehicle.  Any info would be appreciated.

                   Steve Welby
                   US Army Laboratory Command
                   Harry Diamond Laboratories
                   [e-mail]

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

Date: 17 May 90 20:06:28 GMT
From: hpda!hpcupt1!hprnd![e-mail]  (Wesley Cole)
Subject: HST Solar Panels

Maybe a reader out there who knows something about the solar panels used on
modern spacecraft could answer a few questions for me.  I've been reading
with great interest the reports about the Hubble Space Telescope.  It sounds
as though the ground controllers were quite concerned that it's solar panels
were promptly deployed by the shutttle crew since it's battery power was
quite limited.

How different are space craft solar panels from panels that can be purchased
commercially?  I'm thinking about solar panels made by Arco that are about
4-5 sq ft producing ~50W.  I'm sure that NASA panels must be space flight
certified (very resistant to vibration, heat, etc) but do they use the
same process to convert sunlight to electricity at the same efficiency as
earth bound panels?

Do solar panels on spacecraft somehow track the sun to maximize their energy
output?  I assume you wouldn't want them to be in the shade.  How does this
effect the HST's operation?  When they point the telescope at a particular
object do they have to move the solar panels at the same time to keep them
perpendicular to the sun light?  If so, then I feel even more respect for the
designers of this wonderful instrument.  What about when the HST passes into
the shadow of the earth?  Do all obsevations have to cease due to the sudden
power reduction or is it in an orbit that prevents this ever happening?
(I assume batteries wouldn't be sufficient during this period.)  Lastly, how
long do solar panels last in space?  With no corrosion or moving parts (except
for tracking systems?) and barring a catastrophic meteor impact, it seems as
though they would last many decades.

Thanks for the help.

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

Date: 18 May 90 12:45:37 GMT
From: zaphod.mps.ohio-state.edu!samsung!umich!newsserv!osl380a![e-mail]  (Ken Ellis)
Subject: Re:Glass stops IR?

The glass won't transmit the IR radiation (radiative transfer of energy) but
is a very poor way to stop heat loss by convection. The vacuum between the
layers of glass in a thermos bottle prevents convection and provides it with
its insulating properties.

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

Date: Thu, 17 May 90 18:56:50 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: O2 pressure


>From: usc!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!stiatl![e-mail]  (Tim Porter)

>>2, he's got a very good chance of getting "the bends", as nitrogen in
>>solution in his body comes out as bubbles.  The only way to prevent this
>>is to spend quite a while breathing pure oxygen (typically via a mask)
>>            ^^^^^^^^^^^^^
>Does this mean that any time it becomes necessary to don a spacesuit and
>step out of the shuttle, an astronaut must first spend "quite a while"
>pre-breathing?  Sort of makes the idea of an emergency space-walk fairly
>difficult, doesn't it?  Or are there other reasons why an emergency space-
>walk would be unfeasable?

If it's a really serious emergency, I would presume that the prebreathing
time could be reduced by a certain amount, keeping the risk within specified
limits. Anyone know the official NASA policy?
---
>From: rivendell.Ucdavis.EDU![e-mail]  (Steve Nichols)
>Subject: Re: space news from April 2 AW&ST

>In regards to a poster who thought that breathing pure oxygen could be lethal:
>Breathing pure oxygen at sea level pressures for more than short periods will
>result in damage to lung tissues because the tissues get oxidised, therefore
>irritated, so that an inflamatory reaction results.  This does not happen in
>normal air because oxygen is only about 20% of the air we breath.  Therefore
>the partial pressure of oxygen at sea level is about (14 psi * 0.2) or about
>2.8 psi.  This is about the same oxygen partial pressure as is in the EVA suits
>used by the shuttle.  Therefore the shuttle astronaut in an EVA suit is getting
>about the same amount of oxygen as he would at sea level on earth, but without
>all the other gases that are in our atmosphere, mostly nitrogen.  Anyway, the
>oxygen pressure in a shuttle EVA suit is well below the toxic level.

Agreed, but during prebreathing the astronaut is exposed to 14 psi of O2. Since
more time may be spent prebreathing than in EVA, the question becomes "what are
the risks of overexposure to O2 during the prebreathing cycle?"
               John Roberts
               [e-mail]

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

From: [e-mail]
Date: Fri, 18 May 90 18:02:59 EST
Subject: Re: The Vatican Connection
Source-Info:  From (or Sender) name not authenticated.



     In SPACE Digest V11 #422 Mr. Erik K. Sorgatz made various comments
against the Catholic Church.  He said that the Church was completely
opposed to space exploration, without citing any documents.  If the
Church is opposed to space exploration then why is it going to build a
telescope?  If the Church and science cannot finance space research
simultaneously (this does not necessarily mean jointly, although the
University of Arizona project seems to suggest some cooperation) then
why do the various scientific organizations that are involved in the
Arizona project continue to be involved?

     As a point of reality, members of the Roman Catholic Church do not
even come close to a majority of the world's population - and "practicing"
Catholics make up an even smaller fraction.  With this in mind it cannot
be said that the Church continues to keep mankind in scientific darkness.

     Granted the Church has had a terrible history - but does that mean it
is impossible for the Church to do some good now or in the future?  As far
as suggesting that science has not tarnished itself with unethical acts we
can take a look at a few historical examples of misdeeds in science.
Most people know of the medical experiments conducted in the concentration
camps of World War II.  Some people would say that some useful knowledge
might have come from it, but few would say that the experiments were
ethical.  Nuclear weapons did provide useful gains in physics, but this
knowledge did not necessarily mandate that bombs bshould be used on cities.
Obviously political conditions are a factor but in the end scientists must
accept some responsibility for their work.  Scientists can be corrupt, just
as anybody else can (including the Church).  The ends do not justify the
means.

     But if you don't want the Church to be involved in astronomy just
write letters to Congress. Just be sure to send a check to an organization
that builds telescopes so that we'll have the same number of telescopes,
just in case.

     As far as accusing me of being anti-scientific, well, I'm graduating
in June with Bachelor of Science degrees in chemistry and geology - along
with over 15 months of full-time co-op work as a chemist.  And BTW, just
because I am a Catholic doesn't mean that I agree with everything the
Church says.

                                        David R. Brierley

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

Date: 18 May 90 18:38:25 GMT
From: philmtl!philabs!briar![e-mail]  (Robert Casey)
Subject: Re: Endangered squirrels

I see squirrels (grey ones) all around in surburban NYC.  They don't seem to
mind the presence of homo sapiens.  Are the red ones on this mountian very
different from the grey squirrels I see lots of?  I would guess, as long as
you don't knock down too many trees, that the squirrels wouldn't be much
bothered.

But I'm no squirrel expert.

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

Date: 18 May 90 12:47:30 GMT
From: swrinde!zaphod.mps.ohio-state.edu!samsung!umich!newsserv!osl380a![e-mail]  (Ken Ellis)
Subject: Re:Glass stops IR?

The glass won't transmit the IR radiation (radiative transfer of energy) but
is a very poor way to stop heat loss by convection. The vacuum between the
layers of glass in a thermos bottle prevents convection and provides it with
its insulating properties.

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

End of SPACE Digest V11 #427
*******************