Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_6/V13_665.TXT

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Subject: SPACE Digest V13 #665

SPACE Digest                                     Volume 13 : Issue 665

Today's Topics:
          Re: Extra Terrestrial Intelligence
Re: The Reasons for a Station? Was Re: Rational next station design...
            vacuum energies for propolsion
           Re: Galileo Antenna (was Re: Amputation)
              Alien Astrophysics
         Re: Info on spacecraft power storage wanted
         Re: Moonbase movie *Plymouth* to air Sunday?
                  GIF Files
             satellite refuelling
          Re: vacuum energies for propolsion

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Date: 27 May 91 21:09:06 GMT
From: news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew![e-mail]  (James Davis Nicoll)
Subject: Re: Extra Terrestrial Intelligence

In article <[e-mail]> [e-mail] (Stephen Walton) writes:
>In article <[e-mail]>
>[e-mail] (Frank Crary) writes:
>>
>>Clusters are only violent and short lived on an astrononical time scale.
>>On the scale of a civilization, they are quite constant.
>
>Doubt if you'd want to take the risk of a colony being wiped out by
>a nearby supernova.  If we learned anything from SN 1987A, we learned
>that there is essentially no outward warning that a star is about to
>blow.  Besides, unless your putative colony ships take terraforming
>technology along, there won't be any oxygen-atmosphere planets in
>open clusters.  Earth started with an N2-CO2 atmosphere which only
>reached its present composition perhaps half a billion years ago.

    On that note, *if* Earth is typical, we shouldn't expect many
worlds with free O2 in their atmospheres, where ever we look. We
should expect most worlds that have life to have only single celled
organisms, sice that was the case during most of Earth's existance.

                            James Nicoll

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Date: 28 May 91 08:47:48 GMT
From: agate!usenet.ins.cwru.edu!magnus.acs.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!jarthur!nntp-server.caltech.edu!hamlet.caltech.edu![e-mail]  (Lydick, Carl)
Subject: Re: The Reasons for a Station? Was Re: Rational next station design...

In article <[e-mail]>,
[e-mail] (Mark Purtill) writes...
>    Well, for one thing, we might actually like to find out what
>happens to women for more than a few days.  In case you haven't
>noticed, the Russians haven't had any women cosmonauts for some time.
>Judging by the comments from various Russians when the British sent a
>female cosmonaut (along the lines of "women don't belong in space"), I
>don't think it's likely that they'll be giving us any information on
>this any time soon.  (I omit pointing out that a year isn't really
>very long only because someone else already has).
>    Flames that the Russians are right to /dev/null.

Not a flame:  Do you suppose it's possible that the reason the Russians no
longer have female cosmonauts is that they found severe adverse biological
effects?
--------------------------------------------------------------------------------
Carl J Lydick    HEPnet/NSI: SOL1::CARL    Internet: [e-mail]

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

Date: 21 May 91 15:40:15 GMT
From: agate!spool.mu.edu!sdd.hp.com!elroy.jpl.nasa.gov!jarthur!nntp-server.caltech.edu!ptimtc!rdmei!icspub!astemgw!kuis!rins![e-mail]  (will)
Subject: vacuum energies for propolsion


    Ok, so, a long long time ago I read this book by Clarke (The Songs
    of Distant Earth).  Great Book.  So in the ACKNOWLEDGMENTS there
    was this:

        The first suggestion that vacuum energies might be used for
        propulsion appears to have been made by Shinichi Seike in
        1969. ("Quantum electric space vehicle"; 8th Symposium
        on Space Technology and Science, Tokyo)

        Ten years later, H.D. Froning of McDonnell Douglas Astro-
        nautics introduced the idea at the British Interplanetary
        Societies'-Interstellar Studies Conference, London (September
        1969) and followed it up with two papers: "Propusion Require-
        ments for a Quantum Interstellar Ramjet" (JBIS. Vol. 33. 1980)
        and "Investigation of a quantum ramjet for interstellar
        flight" (AIAA Preprint 81-1534, 1981).

        Ignoring the countless inventors of unspecified "space drives,"
        the first person to use the idea in fiction appears to have
        been Dr. Charles Sheffield, chief scientist of Earth Satellite
        Corporation; he discusses the theoritical basis of the
        "quantum drive" (or, as he has named it, "vacuum energy drive")
        in his novel "The McAndrew Chronicles" (Analog magazine 1981;
        Tor, 1983).

        An admittedly naive conclusion by Richard Feynman suggests that
        every cubic centimeter of vacuum contains enough energy to boil
        all the oceans of Earth. Another estimate by Jojn Wheeler gives
        a value a mere seventy-nine orders of magnitude larger.  When
        two of the world's greatest physicists disagree by a little
        matter of severnty-nine zeroes, the rest of us may be excused
        a certain skepticism; but it's at least an interesting thought
        that the vacuum inside an ordinary light bulb contains enough
        energy to destroy the Galaxy... and perhaps, with a little
        extra effort, the Cosmos.

        In what may hopefully be an historic paper ("Extracting
        electrical energy from the vacuum by cohesion of charged
        foliated conductors, "Physical Review, Vol. 30B, pp. 1700-1702,
        August 15, 1984) Dr. Robert L. Forward of the Hughes Research
        Labs has shown that at least a minute fraction of this energy
        can be tapped. If it can be harnessed for propulsion by anyone
        besides science-fiction writers, the purely engineering
        problems of interstellar - or even intergalatic - flight would
        be solved.

        But perhaps not. I am extremly grateful to Dr. Alan Bond for his
        detailed mathematical analysis of the sheilding nessasary for
        the mission described in this novel and for pointing out that
        a blunt cone is the most advantageous shape.  It may well turn
        out that the factor limiting high-velocity interstellar flight
        will not be energy but ablation of the shield mass by dust
        grains, and evaporation by protons.

        The history and theory of the "space elevator" will be found in
        my address to the Thirtieth Congress of the International
        Astronautical Federation, Munich, 1979: "The Space Elevator:
        'Thought Experiment' or Key to the Universe?" (Reprinted in
        Advances in Earth Orientated Applications of Space Technology,
        Vol. I, No. 1, 1981, pp.39-48 and Ascent to Orbit: John Wiley,
        1984).  I have also developed the idea in the novel The
        Fountains of Paradise (Del Rey, Gollancz, 1978).

        The first experiments in this direction, involving paylaods
        lowered into the atmosphere on hundred-kilometer long "tethers"
        from the space shuttle, will be commencing around the time
        this novel is published.

    END......


    Robert Forward's paper is very good and people serious in this should
    get it.

                                        William Dee Rieken
                                        Researcher, Computer Visualization
                                        Faculty of Science and Technology
                                        Ryukoku University
                                        Seta, Otsu 520-21,
                                        Japan

                                        Tel: [phone](direct)
                                        Fax: [phone]
                                        [e-mail]

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

Date: 28 May 91 22:01:10 GMT
From: unmvax!uokmax![e-mail]  (Robert W Murphree)
Subject: Re: Galileo Antenna (was Re: Amputation)

The sky and telescope newsline (featuring Kelly Beatty) had an item on the
Gaspara flybye in October 91.  Seems the antennae failure means that they
won't be able to have a close flybye unless the antennae gets fixed.
Maybe it said it would be mostly a stellar occultation event and not result
in very much close-up imagery.  Anyway no more 600 km flybyes for now

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

Date: 29 May 91 04:12:59 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!spool.mu.edu!rex!rouge!pc.usl.edu![e-mail]  (Phil Fraering)
Subject: Alien Astrophysics

I wrote:

pf>Well, the combination of proximity given by interstellar travel and
pf>more advanced science will probably give the colony plenty of warning
pf>if the star is indeed about to blow up.

And Stephen Walton replied:

sw>It won't.  The post-helium-burning stages of fusion in massive stars
sw>(fusion of carbon, neon, oxygen, and silicon) last less than 1,000
sw>years each, much less than the Kelvin-Helmholtz time scale for the
sw>star's envelope.  The time from the start of iron production to
sw>core collapse is less than 24 hours.  At most, they'd get a few hours
sw>warning if they had neutrino detectors, because the neutrinos come
sw>straight from the core while the explosion has to propagate through
sw>the star's outer layers.
[References deleted but good]

Actually, they'd be able to tell that fusion in general had stopped
because they wouldn't be registering anything on their neutrino
detectors :-)

Seriously, long before we send a manned colonizing mission to
other stars, the amount of time stars have been studied since
Eddington did the basic groundlaying work back in the 1910-1930
time period will have doubled. Anyone actually trying to colonize
the galaxy will have been studying stars a lot longer than we have,
and know much much more astrophysics.

You mentioned in one of the references about the 1987A Supernova.
Didn't that event alone make a lot of the theories about Supernovae
at the time obsolete?

I remember reading Astronomy magazine's articles on cosmology
back ten to twelve years ago; I just got in from substitute teaching
an Astronomy course at the University'd Dept. of Continuing Ed.

Cosmology, so I gather from the recent background material I read
for the course, has changed a lot.

I also took a similar course for bright junior high/high school
students about 13 years ago, where I was taught about the only known
extrasolar planets orbited Barnard's Star. Those results are not today
considered valid, and the current "best candidates" for extrasolar
planets change yearly.

And should I mention the Solar Neutrino problem to show how much we
still have to learn?

Phil Fraering || Usenet (?):[e-mail] || YellNet: 318/365-5418
Standard disclaimer, whatever a disclaimer is, applies.
''It hardly mattered now; it was, in fact, a fine and enviable
madness, this delusion that all questions have answers, and nothing is
beyond the reach of a strong left arm.`` - Larry Niven and Jerry
Pournelle, _The Mote in God's Eye_

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

Date: 29 May 91 06:51:28 GMT
From: agate!lightning.Berkeley.EDU![e-mail]  (Frank Crary)
Subject: Re: Info on spacecraft power storage wanted

In article <[e-mail]> [e-mail] (Phil Fraering) writes:
>The title just about says it all. I'm looking for the best
>currently well understood stable technology for temporary
>power storage, and I'd like statistics like power out/power in
>and kg/kw stored.

I'm not exactly sure what you mean by "stable." I assume it rules out
capacitors, which are not good for long term storage. I do not know about
fly-wheels, but I have some numbers on batteries:

Secondary (or Rechargable) Batteries:

Ni-Cd: >25,000 cycles, 36 W-hr/kg
Ag-Zn: <50 cycles, ~100 W-hr/kg
Advanced Stuff: (E.g. in labs but not production)
Varrious materials, usually >500 cycles, 100-200 W-hr/kg.

                     Frank Crary
                     UC Berkeley

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

Date: 29 May 91 13:41:18 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!caen!news.cs.indiana.edu!ux1.cso.uiuc.edu![e-mail]  (Ed Otto)
Subject: Re: Moonbase movie *Plymouth* to air Sunday?

[e-mail] (Steven Grimm) writes:

>My housemate pointed out that the whole sequence inside the colony where people
>were scurrying for the radiation shelters was silly.  The whole colony, or at
>least all the living areas, would have to be shielded; otherwise, wouldn't all
>those pretty plants have to be ripped out and replaced after every severe
>solar flare?

Actually, not.  All of those plants were in the greenhouse which was
probably buried - I saw no windows in the several shots of it they had.
AND, the shelters were set up for people; the greenhouse was set up for plants.


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

Date: 29 May 91 02:14:37 GMT
From: munnari.oz.au!yoyo.aarnet.edu.au!sirius.ucs.adelaide.edu.au!ra![e-mail]  (Catherine Conway)
Subject: GIF Files


Not sure if I am am spelling it correctly ;-) but can anyone
tell me where I can get GIF pictures (in particular those sent
back from Maggellan) from? FTP is OK.

Please reply by mail as I may miss the reply in this newsgroup.


Regards

Catherine Conway

[e-mail]

Adelaide, South Australia

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

Date: 29 May 91 20:00:06 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: satellite refuelling

In article <[e-mail]> [e-mail] writes:
>... It costs more in complexity and energy
>to refuel than to launch sufficient fuel in the first place.

Unless you're up against something like a launcher weight limit, that is.
Spacecraft with maneuvering engines usually carry every milligram of fuel
that can possibly be loaded in, and not infrequently they would benefit
from more if they only could carry it.  One has to weigh the cost of a
refuelling mission against the cost of a larger launcher and larger
satellite; it is not at all clear that the balance is always against
refuelling.
--
"We're thinking about upgrading from    | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 to SunOS 3.5."              |  [e-mail]  utzoo!henry

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

Date: 29 May 91 23:49:00 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!execu!sequoia![e-mail]  (John K. Gibbons)
Subject: Re: vacuum energies for propolsion


The argument that the energy of the vacuum is the zero-point and thus cannot
be extracted may miss the point of proposed vacuum energy drives as
thoroughly as the NY Times famous editorial about "no air to push on" missed
the point about rocketry principals [:-)].  The starting assumption of such
vacuum drive ideas is either that a) vacuum fluctuation continuosly produces
particle-antiparticle pairs which almost immediately annihilate each other,
or b) the vacuum state we are familiar with is not truly a zero-energy state,
but is in some sense a "local minimum" that could be pushed over a barrier
and then allowed to fall to an even lower state, thereby producing energy.

Idea (a) continues by supposing some mechanism to extract useful energy from
the anihilation of the particle pairs.  This presents several apparently
insoluable problems, as it is the energy of that anihilation that created
the pair in the first place, and the whole concept smells very bad from a
QM viewpoint.  On the other hand, we know damned little about what is
happening at the Planck length, where vacuum fluctuations become significant.

Idea (b) is not quite as crazy as it sounds at first hearing, because it
is based on the inflationary theories of the Big Bang, which suggest that
precisely such a phenomenon occurred at an early stage of the universe.
Supposedly the original "vacuum state" was actually a "false vacuum" at an
incredibly high energy level above the current "true vacuum".  This is
theorized to have decayed into true vacuum at the time that symmetry
breaking separated the strong force from the electro-weak, and the consequent
release of energy far exceeded the original Big Bang.  Supposing yet another
level of vacuum energy even lower than ours is not incredible, but triggering
a conversion would be outside of any known physics.  It might also be rather
dangerous... :-)  (A great SF story on this back in July 88 Asimov's)

I hope I haven't mangled the physics too bad.  Before you flame, please note
that I don't suggest this has any measurable probability of working.  I
would place it on about the same likelihood as time travel.
--

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End of SPACE Digest V13 #665
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