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Subject: SPACE Digest V11 #301

SPACE Digest                                     Volume 11 : Issue 301

Today's Topics:
Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things)
       Re: NASA Headline News for 04/20/90 (Forwarded)
              Re: Decompression and 2001
   Re: Large Format CCDs for astronomy (was Re: release of images)
             Digests and status postings
       Re: Drake Equation (was Re: Interstellar travel)
           Voyager/Neptune images request.
              Re: Decompression and 2001
         Re: Interstellar Radio Communications (long)
         Re: Apollo 13, STS-1, Vostok 1 anniversaries
                   Re: SETI
----------------------------------------------------------------------

Date:     Sat, 21 Apr 90 06:18 CST
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject:  Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things)
Original_To:  SPACE

vsi1!hsv3![e-mail]  (Mike Van Pelt) wrote:

>Nope, "Silent Running" goofed, too.  The nuclear explosions, though
>visually very good, made noise -- the "bang" *BEFORE* the flash!  I
>could accept some kind of tenuous shock wave hitting the ship some time
>after the explosion, but *BANG*FLASH* is just stupid.

Well, Mike, I am getting old and the memory is going fast, but I am *pretty*
sure that back in the unlamented Seventies, I saw prints of *Silent Running*
that had it BOTH ways.  There was a version with silent nuclear explosions.
There was a version, I think later, where noises had been dubbed in.

It would take a real scholar of film to track down the truth.  But this is the
way I remember it.

And, yes, the explosion effect was very convincing: a bright sphere that faded
to dimmer and dimmer reds as it expanded.  None of your puffs of smoke and
whirling debris that have been so popular in the post-*Star Wars* era.

They did have other sounds in outer space, though.  It seems that once you pass
the orbit of Saturn, you begin to hear Joan Baez singing.


                        ///        Bill Higgins
   E                   ///
  |8D:O:          occc))))<))      Fermi National Accelerator Laboratory
   E                 ///
                    ///            Bitnet: [e-mail]

Bumper sticker seen on a Soyuz:    SPAN/Hepnet/Physnet: 43011::HIGGINS

 DON'T LAUGH-- IT'S PAID FOR       Internet: [e-mail]

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

Date: 21 Apr 90 16:59:39 GMT
From: mtndew![e-mail]  (Steve Friedl)
Subject: Re: NASA Headline News for 04/20/90 (Forwarded)

Peter Yee reports:
> With the batteries up to "full charge" the
> Shuttle launch team will have up to April 28 to launch before the
> batteries need to be charged again.

Why can't the batteries be trickle-charged from the orbiter directly?

> During the rollout the huge crawler-transporter will rack up
> its 1000th mile.

Maybe time for an oil change? :-)

     Steve

--
Stephen J. Friedl, KA8CMY / Software Consultant / Tustin, CA / 3B2-kind-of-guy
[phone] voice   /   [e-mail]   /   {uunet,attmail}!mtndew!friedl

"The UNIX PC 3B1: 75% of the power of a VAX-11/780" - Technology Resource Ctr

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

Date: Sat, 21 Apr 90 12:12:04 PST
From: [e-mail] (Tim Shimeall)
To: [e-mail], [e-mail]
Subject: Re: Decompression and 2001

It just so happens that SHOWTIME rebroadcast 2001 this morning, and I watched
it especially to see this seen.  The interval between when Dave blew the
pods hatch and when he pulled the switch was VERY short.  He blew into the lock,
bounced off the back wall, and pulled the swich.  It was closer to 3 seconds
than 8.
            Tim
P.S. But he was still too "clean" in the next seen (no nosebleed, etc.)

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

Date: 21 Apr 90 23:13:56 GMT
From: portal!cup.portal.com![e-mail]  (Mark Robert Thorson)
Subject: Re: Large Format CCDs for astronomy (was Re: release of images)

Does anybody every sell these things?  How much do they cost?
Do they have any special requirements, like cooling in liquid
nitrogen?

Are they designed by the semiconductor house, or the observatory?
How long are they exposed to collect an image?

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

Date: 22 Apr 90 01:25:55 GMT
From: portal!cup.portal.com![e-mail]
Subject: Digests and status postings



 I will be adding Usenet to my BBS in the next month or so.  Was wondering
what space items I could subscribe to and pass on to my users.

  Many thanks,  Steve

.................................................................
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.ARPANET and INTERNET domains please use:             |         .
.       portal!j_stephen_hall%cupertino.pcc@suncom    |   ;-)   .
.SYSOP: The 19th Hole [phone] Sarasota, Florida|         .
.       Fido: 1:137/208            Eggnet: 99/9008/208|         .
.................................................................

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

Date: 20 Apr 90 17:45:14 GMT
From: nuchat![e-mail]  (Steve Nuchia)
Subject: Re: Drake Equation (was Re: Interstellar travel)

In article <[e-mail]> [e-mail] (Andrew Pettifer) writes:
>What about all those 50Hz power grids?
>They would cause some beat frequencies, and i'm sure that the phase
>relationships are drifting all the time, which would help to make the signal(?)
>seem more random.

The 10 Hz beat would be interesting.  The phase relationship
probably doesn't change very much, since most grids are phase-locked
to a coordinated time base.  The time bases are stable enough that
a simple AC line-synchronous mechanical clock is more accurate than
most quartz crystal time bases (ie, watches).  As long as they don't
lose power.

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

Date: 18 Apr 90 20:21:53 GMT
From: usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Rick Ellis)
Subject: Voyager/Neptune images request.

In a message of <Apr 10 12:39>, [e-mail] writes:

 > I am interrested in obtaining the images from the Voyager Neptune
 > flyby from last summer.

I have a modest collection here available for downloading.  They are all in
.GIF format.



--
Rick Ellis
...!{dhw68k,zardoz,lawnet,conexch}!ofa123!rick                             [e-mail]
714 544-0934 2400/1200/300

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

Date: 21 Apr 90 06:41:06 GMT
From: nuchat![e-mail]  (Steve Nuchia)
Subject: Re: Decompression and 2001

In article <[e-mail]> [e-mail] (Andrew Bennett) writes:
>I have read (from multiple sources) that an individual should be able to
>survive about 30 sec. in a vacuum (give or take, depending on the individual).
>Your ear drums would probably rupture, you'd get a bloody nose and you'd have

If you happen to have a pressure gauge lying about, try this experiment:
put the open end in your mouth and arrange to view the dial.  See if
you can blow 14.7 PSI.  See how long you can hold it.  See how it makes
you feel.  This is what the pressure differential effects of going
from a 1ATM "shirt-sleeve" environment to hard vacuum would do to
you if you held your breath.  It would probably _not_ rupture the
eardrums unless the decompression was very rapid, or the eustachean
tubes were blocked.

The partial pressure effects -- bends, localized boiling, and rapid
drying of delicate tissue -- are a different matter on which my speculations
would not be particularly valuable.

In SCUBA, you lose one atmosphere of pressure for every thirty
feet, a distance you can cover rather rapidly in a panic ascent.
A good SCUBA class drills one simple but important rule into you:
"blow bubbles".  You exhale continuously any time you aren't
inhaling.  If your air passages are open enough to make a stream
of bubbles you probably won't embolize.  Air embolism, passage of air
into the bloodstream through pressure trauma in the lungs, is
a killer.  Unless I _knew_ better, if I suddenly found myself
in Dave's situation I'd start blowing bubbles.

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

Date: 21 Apr 90 17:46:14 GMT
From: calvin.spp.cornell.edu![e-mail]  (John Sahr)
Subject: Re: Interstellar Radio Communications (long)

76 lines total --- you may wish to hit 'n' now.

More thoughts on a: why we don't hear anything, and b: why no one may be
hearing us, and c: a possible explanation to Fermi's "paradox."

Humans have been radiating a fair amount of electromagnetic power for
the last 50 years or so.  As our electronics art has improved, we have
begun to rely more and more on "tricky" schemes to efficiently use
bandwidth and power.

For example, AM radio is a mode that carries around its own local
oscillator, in the sense that the carrier frequency component has a
substantial fraction of the transmitter power.  It also has two
technically redundant sidebands.  Because better, stable oscillators
can be built, and tricky filter or mixing circuits can pass 2.4 khz at
several MHz operating frequency, single sideband (no carrier, one
sideband) has become a popular mode for some kinds of radio
communication.

Another relatively new idea is to use "spread spectrum" techniques to
aid interference reduction (and perhaps to impede detection).  This is
roughly related to code-domain multiplexing techniques as well.

Even in radar waveforms, which may have repetition times of a few
milliseconds, the actual transmitted wave may not be a simple pulse.
Incoherent scatter radars use fairly elaborate techniques of frequency
hopping, "random" pulse spacing, and "pseudo-random" codes to improve
their operation, while increasing the bandwidth and complexity of the
signal.  I don't know much about military radars, but I can imagine
several reasons for using complex waveforms there as well.

The point is, there are advantages to using modulation techniques
which make our radio emissions look more and more noiselike, which is
one way of expressing a fundamental result of Claude Shannon's work.

The abundant radio power we emit, while growing larger in absolute
size, is also growing in complexity.  Our own signals may not seem
particularly interesting, because they look like everything else.
Clearly this is not literally the case, but on the average, I suspect
that our "energy per radiated bit" is decreasing, even if our total
radiated power is increasing.  That the "energy per bit" is decreasing
makes the detection of Earth-origin signals harder, and is ultimately
more relevant than the total power we radiate.

Basically, my postulate is this: A civilization "discovers" radio, and
spends fifty years learing how to occupy the spectrum and make high
power transmitters.  As their electronic prowess increases, so does
their net irradiated power, but the "energy per bit" drops
dramatically, so that two hundred years after the discovery of radio,
the civilization is transmitting signals that are largely
indistinguishable from noise, rendering them rather invisible against
the background of stars.  Thus, rather than having "enlightened"
civilizations continuously radiating signs of their presence, they may
in fact only emit a two hundred year thick shell of "detectibility."

This would allow some very old civilizations to be quite near to us,
without being spotted by us, and also without any specific attempts to
hide from us.  Suppose that at 50 ly there is a 10,000 year old "radio
capable" civilization.  Their "shell of detectibility" will have long
passed us, while ours will be just reaching them.

Pure speculation; food for argument, that's all.
--
John Sahr,                   | Electrical Engineering - Space Plasma Physics
[e-mail] | Cornell University,         Ithaca, NY  14853

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

Date: 20 Apr 90 17:59:53 GMT
From: nuchat![e-mail]  (Steve Nuchia)
Subject: Re: Apollo 13, STS-1, Vostok 1 anniversaries

In article <[e-mail]> [e-mail] (Roger Noe) writes:
>spacecraft.  I think it was Grissom, the mission commander, who had pulled
>himself up and out of his side seat toward the hatch in an attempt to
>undo the bolts.  Before he got very far he passed out because there was

There wasn't any way for them to get out.  The fire rapidly raised
the interior pressure, and the door mechanism was designed to be
monkey-proof with a positive pressure differential.  Grissom had
opened the bleed valve but the fire was producing extra gas volume
much faster than it could be bled off.

This is according to a conversation I had with one of the people
who investigated the fire.  The cause was eventually determined
to be a glycol leak, which catalyzed on a metalic surface (silver?)
releasing hydrogen, if I'm remebering the conversation properly.
The gentleman has since left JSC for Boeing.

>day in the history of space exploration than when Haise (I think) radioed,
>"Houston, we've got a problem."

According to this week's "roundup" (summary to follow when I get done
with my circuits test) it was Swigert, and the exact quote was

Swigert: "Okay, Houston, we've had a problem here."

If the reporter didn't blow it this has to be a candidate for
the all-time best-known misquotes list.

Capcom Jack Lousma:  "This is Houston.  Say again please."

Lovell: "Houston, we've had a problem.  We've had a main B bus undervolt."

The article continues...

  "And then, with the remorseless certainty of interconnected,
highly complicated plumbing that has just had a wrench thrown
into it, the CSM began to die."

--
Steve Nuchia          South Coast Computing Services      [phone]
"The study of the art of motorcycle maintenance is really a miniature study
of the art of rationality itself.  Working on a motorcycle, working well,
caring, is to become part of a process, to achieve an inner peace of mind.
The motorcycle is primarily a mental phenomenon."  -- Robert M. Pirsig

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

Date: 21 Apr 90 06:28:52 GMT
From: nuchat![e-mail]  (Steve Nuchia)
Subject: Re: SETI

In article <[e-mail]> [e-mail] (Eric Pepke) writes:
>It's not entirely that grim.  We can determine some things for sure about
>anybody who receives those signals.  We know that they have figure out
>radio.  If they hadn't, they wouldn't be listening.  There are a whole lot

Maybe they are really big, or really small, and can see at those wavelengths.
Maybe they build radiotelescopes like we build optical ones.  Aren't
maybes fun?

>Now, there are a number of possible extreme theoretical objections to
>this, if you really want to reach.  Perhaps the BEMs do not understand the
>concept of integers.  However, even if they naturally think in continua

If you understand radio, you understand integers.  Harmonics are
just too basic a pheonomenon to miss.  The significance of primes
might take a little longer, but if they are looking at the signal
in the time domain they will eventually suspect it is of sentient
origin.  Fibonacci numbers are about the most non-obvious number
sequence to occur naturally here, chances are they won't have
any biology or geology that generates more than, say, a dozen primes.

Geometry is probably a better place to look, nature isn't particularly
fond of right angles but anyone doing hard-matter engineering will
recognize Pythagoryan triples, and probably the face-orders of the
regular solids.  Could try the atomic number/atomic weight pairs
for the stable isotopes.

>Finally, perhaps C.M. Kornbluth was right, and at some point the machines
>they built would acquire self-sustaining capability and the beings would
>evolve into happy little technologically advanced morons, forgetting even
>the basic principles that once they needed to survive.  This one is a
>little bit harder to laugh off.

Like, what planets do we know of where that's happening right now?

Sigh.


Comment on carbon/silicon life:  Don't forget that other temperature
and pressure regimes are possible.  We know staggeringly little
about really high pressures, and less than we'd like about very
low temperatures.  Exotic combinations?  Forget it.  Just about
anything could happen out there, but if it did we'd have a heck
of a time finding anything in common on which to base a meaningful
relationship.


One new theme to emerge in science in the last few decades is
that self-organizing systems aren't as unusual as we thought.
The fact that all four of our gas giants have bands and great
spots is a good example.  (I think -- Neptune does, anyway.)

At one of my clients' offices there is a small poster, apparently
once part of a magazine ad.  It is a picture looking across a
mountain valley from the top of a very high, very rocky slope,
looking over the handlebars of a motorcycle.  The caption:
    "Never rule anything out."

Words to live by.

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

End of SPACE Digest V11 #301
*******************