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SPACE Digest                                     Volume 10 : Issue 244

Today's Topics:
          EJASA, November 1989 - Volume 1, Number 4
----------------------------------------------------------------------

Date: 13 Nov 89 15:25:25 GMT
From: wrksys.dec.com![e-mail]  (CUP/ASG, MLO5-2/G1 6A, 223-3283 13-Nov-1989 1025)
Subject: EJASA, November 1989 - Volume 1, Number 4


                         THE ELECTRONIC JOURNAL OF
                 THE ASTRONOMICAL SOCIETY OF THE ATLANTIC

                    Volume 1, Number 4 - November 1989

                       ###########################

                            TABLE OF CONTENTS

                       ###########################

         * ASA Membership Information - Don Barry

         * Does Extraterrestrial Life Exist? - Angie Feazel

         * Suggestions for an Intragalactic Information Exchange System

              - Lars W. Holm

         * A View From Down Under - Michael Carini

                       ###########################

                       ASA MEMBERSHIP INFORMATION

         The Electronic Journal of the Astronomical Society of the Atlantic
    is published monthly by the Astronomical Society of the Atlantic, Inc.
    The ASA is a non-profit organization dedicated to the advancement of
    amateur and professional astronomy and space exploration, and to the
    social and educational needs of its members.

         Membership application is open to all with an interest in
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    Society recording at [phone].

         ASA Officers and Council -

         President - Don Barry
         Vice President - Bill Bagnuolo
         Secretary - Scott Mize
         Treasurer - Alan Fleming
         Board of Advisors - Bill Hartkopf, David Dundee, Anita Kern

         EJASA Editor - Larry Klaes
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         Telephone the Society Info Line at [phone] for the
    latest ASA News and Events.

         ARTICLE SUBMISSIONS -

         Article submissions on astronomy and space exploration to
    the EJASA are most welcome.  Please send your on-line articles to
    Larry Klaes, EJASA Editor, at the following net addresses:
    [e-mail], or ...!decwrl!wrksys.dec.com!klaes,
    or [e-mail], or [e-mail]

         If you cannot send your articles to Larry, please submit them
    to Don Barry, ASA President, at the following net addresses:
    [e-mail], or chara![e-mail], or [e-mail]

         You may also use the above net addresses for EJASA backissue
    requests and ASA membership information.

         Please be certain to include either a net or U.S. Mail address
    where you can be reached, along with a brief background about yourself.

         DISCLAIMER -

         Submissions are welcome for consideration.  Articles submitted,
    unless otherwise stated, become the property of the Astronomical
    Society of the Atlantic, and although they will not be used for
    profit, are subject to editing, abridgment, and other changes.
    This Journal is Copyright (c) 1989 by the Astronomical Society of
    the Atlantic.


                      DOES EXTRATERRESTRIAL LIFE EXIST?

                              by Angie Feazel

        Since the time that humans first developed the ability to walk on
    two legs, we have gazed wistfully at the stars, wondering what they
    were.  We now know that those minute pinpoints of light are actually
    giant glowing balls of gas, but we still look at them and wonder if
    we are the only forms of life in the Universe.  The answer to the
    question, however, requires first the definition of life's properties.
    The characteristics of life are widely varied but are generally assumed
    to be composed of the four basic traits of growth, reproduction,
    reaction to stimuli, and the ability to ingest and process external
    material (WEBSTER'S DICTIONARY).

        This is a very rudimentary definition of life, and does not
    discriminate between the simple amoeba and the very complex human
    being.  While the amoeba may be mildly interesting, the intelligent,
    communicative, complex organism is by far the more interesting of
    the two and the type that we would most wish to find.

        Because of the vast interstellar distances, finding these advanced
    beings, assuming for a moment that they do exist, is an extremely
    difficult task.  For instance, other than physical contact, receiving
    a radio signal or some other form of communication would be the only
    method of proving the existence of such life.  Light travels at
    roughly 300,000 kilometers per second (186,000 miles per second).  In
    order to measure interstellar distances, it is convenient to utilize
    this constant velocity (c) in measuring huge separations in space.  We
    use the light year (ly), which is the distance light travels in one
    year.  In order to illustrate our scale of distance, we may use a
    sample from our own solar system:  Our planet Earth is approximately
    150 million kilometers (93 million miles) from our Sun.  It takes
    eight minutes for the light of the Sun to reach our planet.
    Therefore, it is said that Earth is eight light-minutes from the Sun.

        Radio signals are an invisible form of electromagnetic radiation
    similar to light, so they travel at the same speed as visible light.
    If we were to beam a radio signal at the nearest star other than our
    Sun - the Alpha Centauri trinary system - it would take 4.3 years for
    that signal to reach it.  If there were life at the star, it would
    take an additional 4.3 years for our signal to be answered, provided
    that this life were intelligent, communicative, and possessed of the
    curiosity to receive and reply to our inquiry.

        The issue to be investigated here is the probability that advanced
    beings do exist elsewhere in the Universe.  To that end, scientists
    have spent much deliberation in defining and estimating factors
    necessary for extraterrestrial life to develop and be found.  For
    example, in 1961, a noted astronomer named Frank Drake proposed a very
    important algebraic equation.  This equation, though we use numerical
    values, is not strictly mathematical.  It is a method of structuring
    our thinking and approach to the question of the existence of
    extraterrestrial life. (Furenlid)

        In order to understand the Drake equation, we must make some
    definitions.  We denote the total number of instances of detectable
    planetary life by the variable N.  First, we assume that N is the
    product of factors, which increasingly narrow the number of stars and
    planets which could prove habitable.  Since we know that life has
    developed at least once in the Universe (on Earth), we may assume that
    none of these factors is zero.  Second, we must base our estimates on
    what we know.  Our solar system is the only example we have of life
    emerging anywhere; therefore, our estimates must be educated guesswork.

        Each factor of the equation represents a condition which is
    necessary for the emergence of life.  By beginning with a relatively
    large number (R* - See below), we may whittle away at it by using
    current astronomical data and assumptions to arrive at N, the
    predicted number of intelligent civilizations.

        The equation as stated by Drake is written as follows:

        N = R* fp ne fl fi fc L

        where:

        R* = The number of stars in the Milky Way Galaxy.

        fp = The fraction of these stars with planets.

        ne = The fraction of these planets suitable for life.

        fl = The fraction of suitable planets which develop life.

        fi = The fraction of life-bearing planets developing intelligence.

        fc = The fraction of intelligently-inhabited planets who have formed
             civilization and harnessed radio or other means to communicate.

         L = The lifetime of such a communicative civilization in a ratio
             to the age of its star.

        The only number of which we can be reasonably certain is the value
    for R*, the number of stars in our galaxy, the Milky Way.  Our galaxy
    resembles a pinwheel with a giant central bulge.  It is about one
    hundred thousand ly from side to side and ranges from 900 ly to 3000
    ly thick.  We are located approximately thirty thousand ly from the
    central nucleus.  Our galaxy contains too many stars to physically
    count, and many are not visible because they lie on the other side of
    the galaxy and are obscured by the interstellar gas and dust of the
    central bulge.  Even though we cannot observe these stars directly, we
    can calculate the mass of the galaxy and infer the number of stars by
    observing our own solar neighborhood and extrapolating (Furenlid).  If
    we do this, we discover that there are several hundred billion stars
    in the galaxy (McDonough, 71-76).  This may sound like a very large
    number of potentially habitable places, but the figures get
    significantly smaller once we begin multiplying by the other factors
    necessary for communicative life.

        If we plot the temperatures of stars against their luminosities on
    a graph, we get what is known as the Hertzsprung-Russell (HR) Diagram.
    The letters O B A F G K M along the bottom correspond to temperature
    and the numbers along the left correspond to luminosity or brightness.
    Our Sun is a G2 type star on the "Main Sequence", which means that it
    is neither very hot nor very cool.  Because we must assume that our
    solar system is typical, we will include only G stars as potentially
    life-bearing.  Therefore, we may take our initial number R to be 125
    billion. (Furenlid)

        As a star collapses from a cloud of gas and dust, a quality called
    angular momentum causes formation of a central condensation surrounded
    by a thin disk of matter.  At this point it seems the system then
    either evolves into a planetary system or a binary/multiple star
    (Ridpath, 19-20); but how might we detect a planet?  Each planet
    exerts a certain amount of pull on the Sun.  That pull from a planet
    as comparatively small as Earth around some other star would be
    unobservable.  By measuring the deviation of a star from its presumed
    normal course, some investigators say they have discovered the
    existence of Jupiter-or-larger-sized companions around several of the
    nearest stars (Talcott, 18; Sagan and Drake, 80).  If these stars had
    Earth-sized worlds, then those planets would be undetectable.

        If it is given that any single star would tend to form planets,
    and that approximately seventy-five percent of the stars visible
    from Earth are multiples, then we must reduce that 125 million by
    three-fourths, which gives us our estimate:  fp = 0.25 (Furenlid).

        Our definition of life leaves much to imagination.  As Thomas
    McDonough states, "On Earth, our experience with chemistry has been
    highly biased.  We were born on a lukewarm, watery planet with an
    oxygen atmosphere and carbon-based life...." (102).  His observation
    is the one most likely to influence our value for ne.

        First, temperature would seem to be a major factor in the search
    for a suitable habitat.  A very convenient window for our estimates
    would be between the freezing and boiling points of water.  If the
    temperature were too cold, the molecular bonding processes would be
    too sluggish to give rise to life.  Likewise, if the temperature were
    too hot, molecules complex enough to begin life would break apart.
    Our Earthly temperature is warm enough to allow chemical interactions
    to take place yet cool enough to prevent any compounds from breaking up.

        We must also assume that some sort of liquid must be present to
    give those molecules a medium in which to bond.  Hal Clement suggests
    that the components of that liquid should be relatively abundant.
    Hydrogen and helium compose ninety-eight percent of the mass in the
    Universe.  As helium does not combine with other elements, hydrogen
    is the most likely basic candidate.  There are many elements which
    combine well with hydrogen, but the four which seem to be the most
    reasonable are carbon, nitrogen, oxygen and fluorine (Clement).  The
    compounds formed are methane, ammonia, water, and hydrogen fluoride.
    Although these compounds are gaseous under normal, terrestrial
    circumstances, they could be liquid if the temperature were low enough
    or if the pressure were high enough.  Any one of them could be the
    fundamental building blocks for an extraterrestrial form of life.

        Thirdly, there must be some sort of force present in order to keep
    gasses in liquid form.  Atmospheric pressure serves this purpose.  The
    gasses above the surface of a planet exert a certain amount of force
    upon all things beneath them, thus keeping liquid in its place.
    Atmospheric gases also protect the surface of a planet from potentially
    damaging rays of its sun.  Our Sun emits ultraviolet rays which would
    kill every unprotected living organism.  The ozone layer in Earth's
    atmosphere efficiently absorbs the majority of these killing rays.

        Though there are between one and three planets in our solar system
    to have developed at least two of these characteristics, only one
    planet developed all three.  Moderate temperatures, abundant liquid,
    and a complex atmosphere are observed on the only planet which has
    spawned life.  This is roughly ten percent of the planets in the solar
    system, so we will take our value for ne to be 0.1.

        Frank Drake states that "there seems to be near unanimity of
    opinion that fl is very nearly 1" (325).  As stated earlier, fl is the
    number of habitable planets where life evolves (Drake, 324).  We know
    that life began very early on Earth, probably within the first billion
    years.  The rapidity with which it developed on our Earth suggests that
    life must be common (Furenlid).  Scientists can even create the basic
    building blocks of life, such as amino acids, under conditions mimicking
    those believed to have been present on prehistoric Earth (Drake, 325;
    Shklovski and Sagan, 230).  These laboratory experiments illustrate
    the first step in a series of steps which "had to be completed before
    complex life could evolve...."  These steps are:

        1 - The formation of small organic molecules from Earth's
            original materials.

        2 - The combination of these small molecules into the long
            chains necessary for living organisms.

        3 - The formation of isolated, reproducing systems from these
            long molecules.

        4 - The formation of cells and multicellular organisms.

        5 - The evolution of the different species of plants and animals.
            (Rood and Trefil, 62)

        The first three are exclusively physical and chemical.  Four and
    five deal with biological processes because they deal with living
    organisms.

        Amino acids apparently do nothing but form long chains, but some
    of these chains act as "enzymes" - they modify the way other chains
    are made.  Once a sufficiently sophisticated system of amino acids and
    enzymes have formed, they begin metabolic-like reactions.  They can
    take in and process external material, thus facilitating their growth
    and subsequent reproduction.  The enzymes act as glue to cause
    molecules to bind together and grow (Rood and Trefil, 70-73).

        Step four begins the process of natural selection.  When mutations
    occur in developing cells, the cells pass the new trait onto succeeding
    generations, provided the first cell survived the mutation.  In this
    way, primitive life trudged along for the first two billion years after
    life developed (Rood and Trefil, 78-79).  Then, about five hundred
    million years ago, sexual reproduction began.  With the advent of
    sexual reproduction, primitive life suddenly had enormous potential
    for evolution.  Organisms could combine portions of themselves and
    form new combinations which would retain the genetic mutations and
    offer the new creature a greater chance for survival.  Since we know
    that life developed on the only planet which had the very circumstances
    which we think necessary for life, our number for fl could reasonably
    be considered to be 1.

        As we move further away from the realm of the astronomer and
    farther into the realm of the biologist, our numbers rely even more
    heavily upon extrapolation and conjecture.  Though we can not
    necessarily assume that every planet which develops life will evolve
    intelligence, it seems likely that once intelligence manifests, it
    would not die out.  Robert Rood and James Trefil have stated that
    there are six events crucial to the development of intelligence:

        1 - An oxygen-laden atmosphere.
        2 - Migration to land.
        3 - Stable body temperature.
        4 - Hand and eye development.
        5 - Tool use.
        6 - Evolution of a social structure.

        Until one or two billion years ago, oxygen was poisonous to the
    life existing on Earth.  Those species that were able to adapt to the
    new atmosphere gained the advantage of increased metabolic processes.
    As the brain consumes an incredible amount of energy, the elevated
    energy level became the catalyst for increased intelligence.

        The second step, migration to land, would have been impossible if
    there had not been enough oxygen in the atmosphere to filter out the
    damaging ultraviolet radiation from the Sun.  The protection that this
    new layer of oxygen provided offered enough shelter that an organism
    could move with relative comfort to land.

        The brain requires a consistent temperature to continue
    functioning.  The development of a stable body temperature allowed
    the organism to bypass the awkward practice of "sunning itself in
    order to bring its body temperature up." (Rood and Trefil, 88)

        As our Sun radiates light mainly in the visible part of the
    electromagnetic spectrum, the development of sight is advantageous
    for avoiding predators, pitfalls, and other potentially dangerous
    situations.  Once some sort of appendage "exists along with the eyes"
    (88), the organism would be able to fight and manipulate items in the
    environment.

        The use of tools is the next step.  When the organism learns to
    utilize external tools, it immediately gains an immense advantages
    over the less advanced predators.

        The development of a social structure among advanced creatures
    enabled "...groups of thinking animals to coordinate hunting and a
    defense against predators...and survive more often.  Intelligence,
    being a survival trait, would lend strength to the survival of the
    fittest (Simpson, "This View of Life", as quoted by Sullivan, 252).
    At the Green Bank conference where Drake first presented his theory,
    Phillip Morrison argued that "...intelligence would always appear,
    sooner or later, because of 'convergence'...the tendency of species,
    evolving along highly diverse routes, to converge toward life forms
    that, because of certain basic laws, resemble one another."
    (Sullivan, 252)

        Following this chain of reasoning, we assume that any planet which
    develops life will evolve intelligence.  Therefore, our value for fi
    will be 1.

        Frank Drake defines a communicative civilization as "a
    civilization of intelligent beings having a technology sufficiently
    advanced to permit detection of the civilization over interstellar
    distances (324)."  Just because a civilization develops the technology
    advanced enough to communicate does not mean that the society will
    develop the desire to do so.  It could be possible that with the
    emergence of intelligence and technology, a given race would acquire
    curiosity and the urge to make itself known.  Our intelligence,
    technology, and curiosity have pushed us to take our first small
    steps into the Cosmos.  So because the race may have the capacity
    to communicate but not the desire, fc = 0.5.

        Of all of the values in the equation, L is the most uncertain.
    As we must end up with a value for N with no dimensions, L must be
    expressed as a fraction of the age of the civilization's parent star.
    We think that the average life span of a G star is about ten billion
    years, so we would divide the age of the civilization by the life of
    the star.  As of yet, we do not have even one example of the lifetime
    of such an advanced civilization.  Since our society has not yet
    ended, we must rely totally upon guesswork.  A civilization may last
    for one hundred, ten thousand, or one million years.  There are three
    views regarding the value of L:  One can take an optimistic view and
    argue that the civilization will broadcast signals as long as its star
    continues to provide energy.  Or, that the civilization will continue
    to broadcast as long as it is unable to travel in the depths of outer
    space.  Once an efficient means of transport is discovered, humans
    could transverse the galaxy in one million years.  The same could be
    said for another civilization.  Interstellar communication would be
    facilitated by travel because two-way communication would take far
    less time "in person" than with the years or centuries long delays of
    radio.  Thus, the optimists place this value at ten million years
    (Rood and Trefil, 101).

        On the pessimistic side, one could argue that beings with
    technology akin to ours would destroy themselves before they could
    make contact with another planet.  Our global tensions have escalated
    to the point where many people think that we will utilize the nuclear
    weapons that we have at our disposal and therefore destroy the very
    civilization many are trying to preserve.  Because we may not be the
    only beings with the potential for self-destruction, the pessimists
    favor the value for L = 100.

        For our own purposes, we will adopt a more moderate figure which is
    a compromise between the two: L = 10,000/10,000,000,000 or 1/1,000,000.

        There are those who would make strident objections about our
    estimates for some of these factors.

        We are assuming that single stars form planets (Meylan).  We do
    not yet have conclusive proof that other planetary systems exist, so
    our solar system may be unique.

        Thomas McDonough states that "Some scientists claim that the
    evolution of life is so complex, the chances of it happening elsewhere
    are infinitesimal" (9).  Two of these scientists, Fred Hoyle and
    Chandra Wickramasinghe, feel that in the time that we have had on
    Earth, there would be no way for "...randomly assembling the
    particular sequence of DNA atoms which would give rise to life...."
    (as quoted by McDonough, 67).

        The assumption that life develops independently on a planet is
    implicit in the Drake equation.  How do we know that our planet was
    not "seeded" by beings from another planet or by spores from a comet?
    The answer is that we do not know.  Doctors Francis Crick and Leslie
    Orgel are firm believers in the theory that extraterrestrials, either
    deliberately or inadvertently, "planted" some form of microorganism
    and "we evolved from that" (35).  Though we have no way of proving this
    theory wrong, we think that the harsh conditions in outer space would
    kill any organism sent to populate Earth.  As Robert Rood and James
    Trefil point out, if a spore were to be ejected from a planet, the
    gravity of the nearest and largest celestial object would attract
    it.  In our solar system, that would be the Sun (108).  The spore
    would have to navigate the depths of interstellar space and find a
    suitable planet on which to evolve.  The chances of this happening by
    pure coincidence is virtually zero.  Of course, if another civilization
    were to have "seeded" Earth, we must then ask, "Where and how did that
    "seeder" originate?"

        We assume that life will originate on a planet because the
    radiation dangers in outer space work against the seeding hypothesis
    (Rood and Trefil, 107).  If amino acids were to develop in the vacuum
    of space, the chances of their being able to get close enough to form
    chains of any kind are virtually zero.

        The assumption that extraterrestrial life is carbon-based is also
    implicit in the equation.  Carbon is the only element which conforms
    to our expectations of what is necessary.  It is plentiful, it forms
    chains long enough to begin molecular structure, and it operates at
    the temperate limits stated earlier.  Silicon behaves similarly, but
    it falls short for many reasons.  It does not form chains long enough
    to begin molecular structure unless the temperature is low enough to
    support nitrogen in liquid form.  In our experience, this is much too
    low to support life as we know it (Rood and Trefil, 111-113).

        Another question is:  Does the planet need to have a satellite to
    create tidal pools in which the proteins can form?  Earth's Moon is
    one of the largest satellites in our solar system.  There is an ongoing
    debate as to whether the presence of tides aided the primordial
    organisms in their transitions to land.  Those that favor this theory
    suspect that the tidal forces of the Sun would be sufficient to serve
    this purpose (T. Gold, as quoted by Sagan, 143; Meylan).  Therefore,
    while the presence of a moon would be beneficial, its absence would
    not be critical.

        It could be that the planet on which that society resides is
    covered by an invariable blanket of clouds or that the society is
    located under the seas (Rood and Trefil, 97).  The inhabitants would
    have very little way of knowing that there is an "outside" or an
    "outer space".

        But perhaps the biggest fallacy of the Drake equation is the
    assumption that an extraterrestrial civilization would use a readily
    detectable form of communication.  To use an extreme example, if a
    civilization were to develop a means of communication based upon smell
    or taste, how would it be detectable over interstellar distances?  The
    differences in technology could be an insurmountable barrier (Meylan).

        With our numerical values in place of the variables, the equation
    now looks like this:

        N = 125 million x 0.25 x 0.1 x 1 x 1 x 0.5 x 1/1,000,000

        When we compute the numbers, we discover that N = 1.56.  According
    to these calculations, there is at least one intelligent, communicative
    civilization at any given time in the Milky Way Galaxy.

        We must keep in mind that the Drake equation is only a tool and
    can be used to support one's own viewpoint.  If one had a preconceived
    notion as to what one would wish N to be, one could alter the values
    of the numbers and increase or decrease them drastically.  For
    instance, if one were to expand R to include F and K stars, then one
    could get a much higher result.  One could assign a much larger number
    to L on the assumption that a more advanced civilization would
    discover an artificial means of living indefinitely.  On the other
    hand, one could significantly reduce the numbers on any available
    pretext, and get a value for N less than one.

        We know that N cannot be much less than one because of the nature
    of the problem.  The value for N seems to be a reasonable and it
    corresponds with our observations.  We may conclude that, while the
    Drake equation is not infallible, it offers adequate means of guiding
    our thinking in the search for extraterrestrial life.

        References -

        Clement, Hal, WHERE THERE'S LIFE..., Byron Preiss Visual
         Publications, In Press.

        Crick, F. H. C., and L. E. Orgel, "Directed Panspermia", THE QUEST
         FOR EXTRATERRESTRIAL LIFE: A BOOK OF READINGS, Donald Goldsmith,
         University Science Books (Mill Valley, California, 1980)

        Drake, F. D., "Radio Search for Extraterrestrial Life", CURRENT
         ASPECTS OF EXOBIOLOGY, edited by G. Mamikunian, Pergammon
         Press (1965)

        Edelson, Edward, WHO GOES THERE?, Doubleday and Company, Inc.
         (New York, 1979)

        Goldsmith, D., and Tobias Owen, THE SEARCH FOR LIFE IN THE
         UNIVERSE, Benjamin/Cumming Publishing Co. Inc. (Menlo Park,
         California, 1980)

        McDonough, Thomas R., THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE,
         John Wiley and Sons, Inc. (New York, 1987)

        Ridpath, Ian, MESSAGES FROM THE STARS: COMMUNICATION AND CONTACT
         WITH EXTRATERRESTRIAL LIFE, Harper and Row (New York, 1978)

        Rood, Robert T., and James S. Trefil, ARE WE ALONE?, Charles
         Scribner's Sons (New York, 1981)

        Sagan, Carl, editor, COMMUNICATIONS WITH EXTRATERRESTRIAL
         INTELLIGENCE (Cambridge, Massachusetts, 1973)

        Sagan, Carl, "Direct Contact Among Galactic Civilizations by
         Relativistic Space Flight", THE QUEST FOR EXTRATERRESTRIAL LIFE:
         A BOOK OF READINGS, Donald Goldsmith, University Science Books
         (Mill Valley, California, 1980)

        Sagan, C., Drake, F. D., "The Search for Extraterrestrial
         Intelligence", SCIENTIFIC AMERICAN, 232, May, 1975.

        Shklovski, I. S., and Carl Sagan, INTELLIGENT LIFE IN THE UNIVERSE,
         Holden-Day, Inc. (San Francisco, California, 1966)

        Sullivan, Walter, WE ARE NOT ALONE: THE SEARCH FOR INTELLIGENT
         LIFE ON OTHER WORLDS, McGraw-Hill Book Company (New York, 1964)

        Talcott, Richard "Possible Planetary Systems Discovered",
         ASTRONOMY, v15, September, 1982.

        Tipler, Frank J., "Extraterrestrial Intelligent Beings Do Not
         Exist", FRONTIERS OF MODERN PHYSICS, Rothman, Tony et al.,
         Dover Publications Inc. (New York, 1985)

        Consultants -

        Ingemar Furenlid, Associate Professor of Astronomy, Georgia
    State University.

        Tom Meylan, Graduate Student, Department of Astronomy, Georgia
    State University.

        Special thanks to the Georgia State University Department of
    Astronomy.


         SUGGESTIONS FOR AN INTRAGALACTIC INFORMATION EXCHANGE SYSTEM

                              by Lars W. Holm

        This article is pure speculation on how to operate and manage
    an information interchange ultimately through the Milky Way Galaxy.
    The technicalities and economics of such an undertaking are not taken
    into consideration here, only some fundamental issues as I see them.
    The pros and cons of SETI (Search for ExtraTerrestrial Intelligence)
    have been discussed ad nauseam, and I will only briefly state the
    crucial points in my view.

        1 - The existence of other planetary systems comparable to
            our solar system.

        2 - The existence of other planets with Earthlike conditions.

        3 - The existence of intelligent life forms other than humans.

        4 - The existence of other technical civilizations.

        5 - The desire for information exchange.

        There need not be any necessary causal relationship between these
    points, even if it is natural to suspect that this is the case; but
    disregarding the question of an intelligence not emerging on a planet,
    these point should be affirmed to establish a "common ground" with
    humankind as of today.  To my knowledge, not even Point One has been
    answered positively.  Point Five does merit some discussion:  What is
    the sender and receiver gaining by such a project?  For the sender, it
    must be a bit more than a "Kilroy was here" message, and the receiver
    does not wish to open the box of Pandora.  The only answer to the
    last question is that we will have to wait and see when a message
    arrives, if ever.  One kind of safe and meaningful information will
    be briefly mentioned later.

        Setting the ifs aside, let us assume there are other civilizations
    distributed around our galaxy, communicating with each other and
    working on establishing contact with new civilizations like ours.
    How could this be achieved in a practical and rational way?

        As a carrier of information, electromagnetic radiation presents
    itself as an obvious solution.  The technical problems of which
    frequencies, bandwidth, encoding and signal strength to be used is
    beyond my knowledge and will not be mentioned here.  The main problem
    is that we have not managed to detect any intelligent signals yet.
    One conclusion of this may be that the Milky Way Galaxy is not full
    of intelligence lining up to shout at newcomers, or on the other hand,
    they might be politely waiting for the upstarts to knock on the door.
    I do not see any clearcut answer to this dilemma; then again, we might
    not even be deemed fit for polite company by more advanced beings.

        The question of time lag is worth some consideration; indeed, it
    is one of the main problems of effective interstellar communication:
    How to exchange information across tens, hundreds, even thousands of
    light years in roughly the same time span.  It is very important to bear
    in mind that we are not talking about telephone conversations or radio
    hams DX-ing (transmitting overseas) on the shortwave.  Everybody who
    considers the problems of SETI knows this very well, but instant two-way
    communication is an integral part of our civilization, so the concept
    of communication with a time lag of generations is quite alien to us
    at present.  However, it is not necessary to go back further than to
    the area of sea exploration in human history before we have a similar
    situation, to set out into the unknown and hopefully return years later
    with tales of wonder.  An even better analogy regarding a large time
    span is the Melanesian kula chain:  Tokens of good faith were once
    exchanged among the peoples of the islands of the Western Pacific Ocean,
    constantly passed along in a great circuit, the means of transportation
    being sail and oar.  How long information transfer will take depends
    on the available medium, not on what our culture regards as conversation.
    These examples illustrate that the problems of considerable time lag
    are not insurmountable.

        The concept of what I have in mind is a network of "nodes",
    constantly sending and receiving information to and from other nodes,
    without waiting for confirmation.  An analogy may be a WAN (Wide Area
    Network, with emphasis on Wide).  To make this a bit more feasible
    on the galactic scale discussed here, a couple of additions may be
    suggested:  The message is returned to the sending node, with some
    additional information to serve as a "receipt", and most important,
    the message is beamed further on to star systems having a potential
    to serve as new nodes.  In several hundred thousand years, a network
    like this might span the whole of the galaxy.  The basic assumption
    for a scheme like this to succeed is that a minimum number of
    civilizations exist to "pick up the ball and pass it on".

        What is important to consider in this network concept is that the
    nodes are to function more or less on a peer-to-peer basis, and it
    must be possible for new nodes to place their information among the
    existing information; and at the same time leaving room for still
    more information further down the chain.  On the other hand, at least
    some nodes must have the role of "moderator" to prevent the signal
    from being saturated with information.  A node firmly established in
    the network will receive the signal from various nodes and, depending
    on the size of the network and how long the node has been connected to
    the network, will receive some of their own earlier messages.  The
    signal should be regarded as an everchanging stream of information
    criss-crossing its own path, partly repeated and constantly deleted
    from and added to.  The topology of the net should be regarded as
    non-deterministic; i.e., new nodes appearing and old ones disappearing
    and reappearing randomly.

        One kind of information that would be relevant to transmit in a
    network like this would be astronomical data, perhaps the only kind of
    information being universally (no pun intended) comprehensible.  For
    one thing, civilizations participating in the network would, per se,
    have astronomical knowledge.  In addition, nodes will have a different
    view of the Milky Way Galaxy depending on their location:  Our solar
    system, for example, has a fairly poor viewing angle on phenomenon
    occurring along the galactic plane except in our relative vicinity.
    Among Earth's meteorologists the World Weather Watch (WWW) is a
    necessity for good weather forecasts, so why not a Galactic Astronomy
    Watch (GAW)?  On the time scale of an interstellar network,
    considerable changes should be noticable among the stars, nebulas,
    and other celestial objects of our galaxy.

        Here I have tried to present some ideas of how contact between
    stars might operate.  There are many unanswered and unposed questions,
    but one thing is for certain:  The human race may never know if there
    is anybody else among the stars if we do not knock on the galactic
    door and listen.


                       A VIEW FROM DOWN UNDER

                         by Michael Carini

        One of the benefits of being an astronomer is having the
    opportunity to travel to places you normally might not have the
    chance to visit.  One example is the South American country of Chile,
    home to three observatories, including the Cerro Tololo Interamerican
    Observatory (CTIO).  For seven nights in September of 1988, I had
    the unique opportunity to observe.

        It is a long trip to CTIO, starting with a roughly ten hour
    commercial jet ride to the capitol, Santiago.  Usually, there is a
    stopover at some place like Lima, Peru, or Buenos Aires, Argentina.
    Once the international flight lands and you survive customs, there is
    either an eight hour bus ride, or an hour and a half flight (La Deco,
    the national airline) to the coastal town of La Serena.  This is the
    home of the observatory headquarters.  Only an hour and a half ride
    into the Andes remains to get to the Observatory.

        So two days after you've left Atlanta, Georgia, you find yourself
    on top of a mountain, somewhere in the Andes; but life at the
    observatory is easy for a visiting astronomer.  The lodge rooms are
    nice with patios that overlook a valley.  On the other side are the
    Andes - a spectacular view, especially if the higher peaks have snow
    on them.  Meals are provided and are very good - it's easy to gorge
    yourself even if you're not quite sure what it is you are eating!  The
    lodge lies below the telescopes, so you are given a Volkswagen Beetle
    to move around the mountain.  Believe me, you need the car; it's quite
    a hike up to the observatory.

        On clear days, the sunsets are something to behold.  Usually you
    can see the so-called "green flash" - a flash of green light that
    appears on the western horizon just after sunset.  I had never seen
    this before and was expecting a single flash of green.  Instead, what
    I saw was several consecutive flashes of green along the western
    horizon; but the best treat comes after twilight:  On a dark, Moonless
    night, the southern sky is spectacular.  The Magellanic Clouds,
    satellite galaxies of our Milky Way Galaxy, are an amazing sight; M42,
    the Orion Nebula, pales in comparison.  The Milky Way stretches across
    the sky and really looks "milky".  There are some odd sights, too,
    such as the constellation Orion rising upside down, or Canis Major on
    his back.  Scorpius fills almost a quarter of the sky - talk about a
    big bug!  Looking north, you can find some old friends - Cygnus, Lyra,
    etc., were all there, but very far north.

        Since the purpose of the trip was scientific, let me spend a
    minute on the science I did.  I was observing on the 90-centimeter
    (36-inch) telescope, using a CCD (Charge Coupled Device) camera.  The
    objects I was observing were two BL Lacertae objects.  BL Lacs are a
    subclass of quasars; they undergo large amplitude variations in visual
    brightness.  In particular, I was searching for optical variations on
    time scales of less than one day, and with amplitudes of a tenth of
    a magnitude or less.  These particular objects are at southern
    declinations, hence the obvious need to observe from a southern
    hemisphere observatory such as CTIO.

        I could continue, but the idea should be clear.  As beautiful as
    the southern sky is, however, I still prefer the northern sky and all
    its wonders.  Perhaps that is because no matter where I go, I'll
    always be a Yankee at heart!


     THE ELECTRONIC JOURNAL OF THE ASTRONOMICAL SOCIETY OF THE ATLANTIC

                       November 1989 - Vol. 1, No. 4

                         Copyright (c) 1989 - ASA

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End of SPACE Digest V10 #244
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