Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V08/V8_349.TXT

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Date: Mon, 5 Sep 88 01:04:59 PDT
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Subject: SPACE Digest V8 #349

SPACE Digest                                      Volume 8 : Issue 349

Today's Topics:
                   RE: SETI
        Re: SETI: Why don't we hear anything?
         Re: Brian Eno's _Apollo_ soundtrack
         Inverse SETI (Was:  ET phone home?)
           Re: Inverse SETI (Was:  ET phone home?)
           Re: How does NASA detect a Hydrogen leak
        Re: SETI: Why don't we hear anything?
           Re: Inverse SETI (Was:  ET phone home?)
             Re: Life on Jupiter
----------------------------------------------------------------------

Date: 22 Aug 88 17:22:00 GMT
From: apollo![e-mail]  (Peter Nelson)
Subject: RE: SETI


 Shannon Mann posts:
>Being a science fiction reader, and not yet a writer, I will leave full
>treatment to the above authors.  I will say that, there is a much greater
>chance of stumbling upon a probe than the real beings.  Machines can search
>without stopping for things like having children, growing old, eating, etc.

 Well, I agree.  I would love to see us take a long-range view of
 things and launch some true deep-space probes even if it may be
 centuries before we get anything back from them.

 Several questions:

  One risk is we may put a lot of work and money into making a probe
  which may be passed on it's way to Alpha Centauri or Tau Ceti 50 years
  later by a faster probe.   Has anyone done any realistic calculations
  of what the fastest spacecraft we could build with something like
  existing technology?   How much is that figure likely to change a
  few decades down the road?

  At 1,000,000 miles an hour (i.e., pretty damn fast by today's standards)
  it would take about 2900 years for a probe to get to Alpha Centauri.
  The electronics and other systems are not likely to last anywhere near
  that long.  With a lot of rendundancy and careful design and choice of
  material we *might* be able to make a probe last a hundred years.  So
  to get to Alpha Centauri in that time would require going at 4% of the
  speed of light (not counting acceleration/deceleration time).

  How powerful a radio signal would the spacecraft have to send to be
  receivable with today's technology?  Would it be wise to use a much
  weaker signal and assume our descendents will have better receivers?

                                         --Peter Nelson

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

Date: 23 Aug 88 00:22:04 GMT
From: jpl-devvax![e-mail]  (Larry Wall)
Subject: Re: SETI: Why don't we hear anything?

I have no difficulty (logically, not morally) with the assumption that
advanced races will always prevent primitive races from developing.
All this would prove is that we are the first, by some kind of modified
anthropic principle.  In a universe in which we weren't first, we simply
wouldn't exist.  Somebody had to be first here, so it might as well be us.

Culturally we are quite environmentally conscious at the moment, but I think
this may be because we aren't in any kind of frontier expansion at the
moment.  Morals and ethics seem to get looser at the frontier, if you
believe all the Westerns.  Even where people are trying to do the right
thing, mere economic growth tends to usurp ecological niches into which
future sentient beings could fit.  If you travel 50 light years to colonize
another planet, are you going to turn around and go back because there
are some sad-eyed lemurs there when you arrive?  I think not.

This is not to say that we wouldn't "uplift" the sad lemurs or dolphins or
whoever.  But they'd be a part of our expansion, not someone else's.

I don't think you can calculate the probability of our being first.  It
depends too much on what kind of an expansion rate we can attain.  We don't
even know enough to calculate the probability of life itself, really.
We just know it can happen at least once out of n tries, where n is the
number of universes that were "tried".

Larry Wall
[e-mail]

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

Date: 23 Aug 88 00:38:25 GMT
From: [e-mail]  (Mike Smithwick)
Subject: Re: Brian Eno's _Apollo_ soundtrack

In article <[e-mail]> [e-mail] (Bill Carson) writes:
>Having just read the liner notes of Brian Eno's 1983 album, _Apollo_,  it
>mentions that most of this music was composed for a movie/documentary of
>the Apollo space missions.  Directed by Al Reinert,  it is supposed to have
>been compiled from the some 6 million feet of film shot by NASA during this
>fantastic and mystical period of space exploration.
>
>My question is,  does this film exist as a released production?
>And if so,  who could I contact to obtain more information about it?
>--
>Bill Carson ...!{ucbvax,sun}!pixar!brighton

Could you be talking about the film "The Space Movie"? It was done several
years ago, and ended up a real hodge-podge of clips mostly dealing with
Apollo, but including some Skylab. It looks like very little thought
went into what scenes were chosen, or their ordering. (Except for the
Apollo 11 launch sequence which is magnificant!!)

It has a lonnnnnggg, droning, rhythmic soundtrack, interesting at spots,
and very repetitive at others. Virtually no talking at all, just music
and a little air-to-ground. I don't remember if it was Eno who wrote the
music, I was told it was supposed to have been the same guy who did
The Exorcist soundtrack (was that Eno?).

It's interesting viewing, I would recommend trying to get a tape of it
for a space-party or some such thing. (I got a copy off of an LA
cable system.)


--
               *** mike (starship janitor) smithwick ***
"You can fool some of the people all of the time, or all of the people
 some of the time, but you can't fool Mom".
[disclaimer : nope, I don't work for NASA, I take full blame for my ideas]

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

Date: 22 Aug 88 13:27:00 CDT
From: "Pat Reiff" <[e-mail]>
Subject: Inverse SETI (Was:  ET phone home?)
To: "space" <[e-mail]>
Cc: eos
Reply-To: "Pat Reiff" <[e-mail]>

With regards to the observation of earthlings from just the carrier
of the TV transmission:

  I read an interesting article in *Science* (I believe) several years ago,
and the author pointed out several interesting things that could be
inferred by a nearby (~20 Lightyears) observer, listening only to our TV
carriers:
1.  They could tell the earth's rotation speed, since the carriers are
beamed parallel to the local horizon, giving a daily modulation of the
signal.
2.  Since this "day" would be the synodic day relative to the observer, it
would basically be our sidereal day (24 hours less 4 minutes). Since many
TV transmitters are turned off at night (solar day), the observer could
tell the "beat frequency" between the solar day and the sideral day, and
thus tell how long our year is.
3.  Knowing our year, and with a guess of our sun's mass (easy since at
that distance they can see its color and from the HR diagram estimate its
mass), they can tell how far we are from the sun and thus our mean
temperature, etc.
4.  From the daily modulation of the signal, they could tell the
concentration of population centers on the continents, and perhaps infer
the existence of oceans or uninhabited regions.

My apologies to the writer for forgetting his name - it was a good piece.


------
From the First Space Physics Department (celebrating its 25th anniversary):
                                                    :
     Patricia H. Reiff                              :  Not only are my
     Department of Space Physics and Astronomy      :  opinions solely my
     Rice University, Houston, TX 77251-1892        :  own, I reserve the
     internet:  [e-mail]     :  right to change my
     SPAN:      RICE::REIFF                         :  mind occasionally!
     telemail:  [preiff/edunet] mail/usa            :
------
------

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

Date: 23 Aug 88 04:31:11 GMT
From: agate!soup.ssl.berkeley.edu![e-mail]  (George Kaplan)
Subject: Re: Inverse SETI (Was:  ET phone home?)

In article <[e-mail]> "Pat Reiff" <[e-mail]> writes:
    [on what nearby ET observers could infer from our TV signals]
>1.  They could tell the earth's rotation speed, since the carriers are
>beamed parallel to the local horizon, giving a daily modulation of the
>signal.
>2.  Since this "day" would be the synodic day relative to the observer, it
>would basically be our sidereal day (24 hours less 4 minutes). Since many
>TV transmitters are turned off at night (solar day), the observer could
>tell the "beat frequency" between the solar day and the sideral day, and
>thus tell how long our year is.

Wouldn't it be simpler just to use the Doppler shift due to the Earth's
orbital velocity to determine the length of our year?  (Assuming there
is enough structure to the Earth's radio spectrum to determine a
Doppler shift).

It seems to me that using the measured "beat frequency" requires a
major assumption about the cause of the second frequency (ie.
broadcasters shutting down at night).  If the extraterrestrial
observers' TV stations customarily transmit continuously, for example,
this may not be an obvious conclusion.

>     Patricia H. Reiff                              :  Not only are my
>     Department of Space Physics and Astronomy      :  opinions solely my
>     Rice University, Houston, TX 77251-1892        :  own, I reserve the
>     internet:  [e-mail]     :  right to change my
>     SPAN:      RICE::REIFF                         :  mind occasionally!
>     telemail:  [preiff/edunet] mail/usa            :

---------------------------------------------------------------
Standard disclaimers apply
---------------------------------------------------------------
    George C. Kaplan
    Space Sciences Lab
    University of California
    Berkeley  CA,  94720

    [e-mail]

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

Date: 22 Aug 88 18:18:16 GMT
From: mnetor!utzoo![e-mail]  (Henry Spencer)
Subject: Re: How does NASA detect a Hydrogen leak

In article <8808190326.AA12350@watdcsu> [e-mail] (Peter Allsop) writes:
>... the most likely is Thermal Conductivity...
>One contributor suggested that NASA uses portable Mass Spectrometers.
>While this is possible I think TC is more likely...

I think AW&ST has explicitly mentioned portable mass spectrometers as
NASA's hydrogen-hunting technology, but I could be wrong (I don't save my
back issues, so I can't easily check).  My understanding is that TC isn't
sensitive enough to trace amounts to be really good for leak-hunting, but
it's not a technology I keep up with, so my information may be obsolete.
--
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry [e-mail]

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

Date: 22 Aug 88 18:35:00 GMT
From: mnetor!utzoo![e-mail]  (Henry Spencer)
Subject: Re: SETI: Why don't we hear anything?

In article <[e-mail]> [e-mail] (phil nelson) writes:
> 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.

If so, the difficulties must be in an area we can't foresee today.  People
have looked at building self-replicating robots.  The conclusion has been
that we can't do it today, but it doesn't look that far off.  There don't
seem to be any fundamental barriers.  Given that we haven't done it yet,
it's always possible to speculate that there is some bogeyman lurking
hidden somewhere, but I for one am reluctant to accept this without some
more specific suggestion of where the obstacle lies.

> 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?

Well, it's not clear why they would require the ability to evolve -- their
job is pretty well-defined and their environment is not a particularly
variable one.  The ability to evolve might be useful, especially in the
long term, but it would not seem essential.

And assuming that evolution is provided for, why would they evolve in the
direction of benevolence?  It seems to me that evolution the other way
is much more likely:  unless one postulates a mutation so radical that
it converts the machines into friends, it is in the machines' interests
to be the most efficient enemies possible, to prevent the development of
a race capable of destroying them.

In the long run, "time and chance happen to us all", but for a well-crafted
self-replicating machine, "the long run" might be a very long time indeed.
--
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry [e-mail]

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

Date: 23 Aug 88 08:12:29 GMT
From: [e-mail]  (Samudra E. Haque)
Subject: Re: Inverse SETI (Was:  ET phone home?)

regarding aliens receiving our television carrier signals
and inferring all sorts of nasty opinions about us.

It was mentioned that the aliens (Big Green WoMen?) could
receive TV carriers at a distance of 100 LY.

They would have to have tremendously good recievers for that feat.

Also, once they received such a "carrier" signal from the
electromagnetic spectrum, what would they do with it? They coudn't
possibly know the modulation parameters (i.e., bandwidth, modulation
techniques <am, fm, fsk, pcm, etc. etc.> or even chrominance and
luminance coding mechanisms <pal, secam, ntsc> in that TV signal once
they get it - if at all they do.

What I'm trying to get it that  SETI don't stand a chance of getting
ANY useful information from our radio/tv carriers - unless they take
some really good guesses. Maybe they'd just think that we're some
random noise generating solar system with systematic characteristics.

********************************************************************************
**Who knows, all the pulsar and quasar radio signals that we pick up all
**over the place may actually be the equivalent TV stations of the
**galaxy.
********************************************************************************
All you'd have to do is to design a power source that could
modulate the orbital parameters of a large body - say the size of a M
or N class sun. Couple of chained fusion reactors could do it.


--
Samudra E. Haque
Computer Science Laboratories, Computer Science Department
University of Minnesota, Minneapolis, MN 55455.
(1)-(612)-625-0876 || [e-mail] || [e-mail]

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

Date: 23 Aug 88 10:42:34 GMT
From: jumbo![e-mail]  (Jorge Stolfi)
Subject: Re: Life on Jupiter

>   [Someone:] Jupiter cannot be left out [from the list of planets
>   that may harbor life].  At some altitudes, the atmosphere is
>   much the same as Earth's.

>   [Paul F.  Dietz:] Vertical circulation in Jupiter's atmosphere
>   carries any given parcel downward to great depth [hence high
>   temperatures and pressures] every few days or so.  It is
>   unlikely that life could have originated or could survive
>   there.

I would not bet on it either, but...

Imagine a small particle floating in Jupiter's atmosphere,
on the ascending side of a convection cell, at an altitude where
liquid Water condenses out.  Imagine that the particle consists of
a Cheese core surrounded by a Glue solution. (Please substitute your
favorite substances for Water, Cheese, and Glue, and your favorite
gas giant for Jupiter.)

If the particle is too light, it will be lifted to cooler altitudes,
where it will gain more Water by condensation and become heavier.
Conversely, if the particle is too heavy, it will sink, get hotter,
lose some Water by evaporation, and become lighter.
Conceivably, this mechanism might lead to equilibrium: a particle whose
dry weight falls in some relatively broad range will be able to hover
indefinitely at a more or less constant altitude.

Of course, this assumes the circulation pattern is reasonably stable.
Modest changes in the speed of rising air can  be compensated for
by the same mechanism: a stronger/weaker updraft will only shift the
equilibrium point to higher/lower altitudes.  Lateral drift may be
a problem, but if the equilibrium altitude lies somewhat below the
center of the convection cell, I believe that the horizontal component
of the air flow will tend to push the particle towards the center
of the rising column.

Particles that are VERY big or VERY small will eventually fall or be
carried down to the very hot levels where the Cheese and Glue are
vaporized.  Presumably, as these vapors are carried up by the
convecting atmosphere they will condense again into particles of random
sizes, which will go through the same cycle.  So, even if particles of
the right size to stay up are rare to begin with, they will be
naturally selected for, and with time their numbers may grow by many
orders of magnitude.  The result would be a relatively stable cloud of
relatively uniform particles, hanging somewhere along the lower part of
every rising air column.

I may be wrong, but I belive this is the same mechanism that creates
the sharply defined, flat-bottomed cumulus clouds here on Earth.
In our turbulent atmosphere, the convection cells change constantly,
and therefore our cumulus clouds have lifetimes measured in hours.
In contrast, Jupiter's large-scale convection patterns last for hundreds
of years (Thousands?  Millions?  Billions?).  Unless the convection
cells are too turbulent on a small scale, it may be possible for a
sizable population of Wet Sticky Cheese particles to survive
indefinitely as cumulus-like clouds in the rising zones.

Assuming such such particles exist, they may survive long enough for
life to have spontaneously evolved on them.  Natural selection would
favor particles whose composition provides better altitude feedback, so
certain "weird" droplets that _a priori_ would seem highly improbable
may actually become quite common.  Furthermore, any particle able to
"reproduce" --- i.e., able to somehow promote the formation of similar
particles --- would eventually dominate its cloud.

Even if the Wet Sticky Cheese particles survive only for a few thousand
years, we shouldn't rule out the possibility of life evolving on them.
We still haven't got the foggiest idea of how long it took to go from
Earth's primordial soup to something that could pass for life; and
even if we did, there is no reason to believe that the answer would
be in any way relevant to Jupiter's chemistry and physics.

Even is such particles do not last long enough to support the
evolution of life, they may still provide a suitable habitat
for organisms that evolved elsewhere.  For example,
microscopic lifeforms evolved on Europa could have been lifted by
meteorite impacts,  rained onto Jupiter, and found themselves a new home in
Jupiter's Cheese clouds.

I would not bet more than a nickel on this theory; I am presenting it
mostly as an example of the kind of things that are easy to overlook in
this subject.  My point is that Life may have more aces up its sleeve
than we can imagine, and we shouldn't be too quick to dismiss planets
as "too hostile" for life or evolution.

In my opinion, the tropical region of the Moon is the only solid place
off the Earth where there is persuasive scientific evidence for the
lack of life.  Everywhere else the question is still wide open.

                Jorge Stolfi @ DEC Systems Research Center
                [e-mail], ...!decwrl!stolfi

PS.
>   [Paul:] At high pressure and temperature, hydrogen reacts
>   exothermically with organic compounds to form methane, ammonia
>   and water.

Shouldn't this be "ENDOthermically"? (Just asking)

DISCLAIMER: The above opinions are not the sort of stuff my employer,
my teachers, my friends, or my mother would like to be associated with.

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

End of SPACE Digest V8 #349
*******************