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Subject: SPACE Digest V11 #298

SPACE Digest                                     Volume 11 : Issue 298

Today's Topics:
               Re: Fermi paradox, SETI
                tomatoes, SETI
              Re: Decompression and 2001
       Re: Pegasus launch planes - Altitude First, speed later?
              Re: Fermi Paradox
         Re: Apollo 13, STS-1, Vostok 1 anniversaries
           Re: Winch Launch as first stage.
               Re: Fermi paradox, SETI
              Re: Decompression and 2001
              Pegsat barium drop
----------------------------------------------------------------------

Date: 21 Apr 90 02:14:30 GMT
From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew![e-mail]  (Brian or James)
Subject: Re: Fermi paradox, SETI

AAAIIIEEE!!! A brief comment on the subject of 'stable deadends' in
evolution. Lifeforms that do not change for a long time are not
called 'dead ends', they are called 'well adapted'. Please note
that the Victorian model of progress is not appropriate as a model of
biology.
                         JDN

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

Date: Fri, 20 Apr 90 16:54:32 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: tomatoes, SETI


>From: pasteur!helios.ee.lbl.gov!hellgate.utah.edu!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew![e-mail]  (Brian or James)
Subject: Re: space tomatoes

> Aren't tomatos related to plants like Deadly Nightshade? I wonder how
>they came to be regarded as a foodstuff, since I know that as recently as
>the 18th century people assumed they were as deadly as their relatives.

Tomatoes are members of the nightshade family. They were grown for many years
as ornamentals before they were widely regarded as a food. That's not unusual -
today very few people eat dandelions ("dent de lion" in French), which I
believe were introduced into America as a vegetable.

Other members of the nightshade family are deadly nightshade, peppers, eggplant,
potatoes, and tobacco. I get the impression that this family tends toward
bad-tasting poisons that warn animals not to eat them. It might be a good
idea to let adults taste the space tomatoes before letting children try them.

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

>Subject: Interstellar Radio Communications

> Most of the discussion I've seen assumes that that communication
>we're trying to 'eavesdrop' is only by chance detectable by us. If
>you are trying to spot other technological cultures, it gets a
>lot easier if they are trying to be heard [I have this mental image
>of forty million civilisations listening carefully to the radio
>bands while trying to be perfectly silent themselves].
>                                                    JDN

Attempting to transmit [CETI?] is much more controversial than attempting to
receive. After all, if there other intelligences out there, it could be
useful to know about them, whether they're friendly or hostile. If they're
hostile, there's no point in drawing attention to ourselves even more than
is already being done with radar, television, etc.

Some people seem to think that the potential for violence is some bizarre
aberration of humanity, and that it's highly improbable that life arising
in the rest of the universe would ever be violent. I don't have much confidence
in this reasoning. Among the life forms we know, violence is a nearly universal
behavioral trait among motile organisms, used to acquire food (hunting), or
to compete for resources (food, shelter, status, territory, mates, etc.)
We therefore have no actual example of a large-scale ecosystem that functions
stably without violence. Humans have considerable capacity for aggression,
much more than is probably needed in a technological society. To a large
extent, this trait was probably inherited from ancestors who needed it to
survive. Today we have to limit hostility in order to survive. There is a
good chance that alien civilizations we encounter will have a similar
background - descended from violent ancestors, but now at least cooperating
with one another to build a civilization. It should not be assumed from this
that they would get along well with us. The Nazis cooperated with one another,
but were highly inimical to their neighbors. Before we announce our presence
to the universe, it makes sense to listen for a while and find out what's
out there. If we find someone who appears to be friendly, it's still important
to learn to avoid what might be perceived as an insult or threat.
                  John Roberts
                  [e-mail]

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

Date: 20 Apr 90 16:29:26 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Decompression and 2001

In article <[e-mail]> [e-mail] (Andrew Bennett) writes:
>The most serious problem(s) are damage to your lungs (the avolii(sp?) don't
>like low pressures) and the 'bends' (nitrogen nucleation in the body).  So
>holding your breath is a good idea, for your lungs' sake.

As any scuba diver will tell you, holding your breath during decompression
is a thoroughly bad idea.  The alveoli don't object to low pressures much
(remember 3psi of pure oxygen in pre-shuttle US spacecraft), but they are
not mechanically strong and it's easy to damage them if there is more
pressure inside than out.
--
With features like this,      |     Henry Spencer at U of Toronto Zoology
who needs bugs?               | uunet!attcan!utzoo!henry [e-mail]

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

Date: 20 Apr 90 15:37:06 GMT
From: skipper![e-mail]  (Mary Shafer)
Subject: Re: Pegasus launch planes - Altitude First, speed later?

In article <[e-mail]> [e-mail] (Vincent Cate) writes:

   And how expensive is the Concorde to operate?  Well, they sell one-
   way tickets from New York to London for $3,607.  This is an expensive
   plane.  I don't know many people who would pay $3,607 for a one-way
   ticket to London.  There are about 100 seats so this comes to about
   $400,000/flight.  Yes, this is alot of money; however, it is far below the
   the ~ $5,000,000 value of the increased payload to orbit!!!!!  Even
   expensive planes are very cheap compared to rockets!!!!  Maybe British
   Airways should stop selling tickets to people and start launching
   rockets.

British Airways admits, quite cheerfully, that the cost of Concorde is
subsidized.

   Looks like OSC may be planning on going just for altitude first off.
   As I said above, an extra 6 miles up is about equal in energy to
   an extra 1,000 MPH.  So extra altitude probably gives the best return
   on investment at this time.  My guess is that they want to use a DC-10
   or a 747 to get their little payload up really high.  A loaded 747
   can go to 50,000 feet, so I would not be at all surprised if one with
   about half the flying weight (tanks not nearly full and little payload)
   could get to over 70,000 feet.  This should be worth millions per flight
   and does not seem to be any where near as hard as using a supersonic plane.

Service ceiling is limited by many factors, only one of which is
weight.  For example, how robust is the pressure vessel?  Will the
pressurization system work at this altitude?  How's the stability?
How big is the envelope?  What happens to thrust at this altitude?

Making the airplane light is just part of the problem.

--
Mary Shafer  [e-mail]  ames!skipper.dfrf.nasa.gov!shafer
         NASA Ames Dryden Flight Research Facility, Edwards, CA
                   Of course I don't speak for NASA

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

Date: Fri, 20 Apr 90 16:13:43 PDT
From: [e-mail]
X-Vmsmail-To: UTADNX::UTSPAN::AMES::"[e-mail]"
Subject: Re: Fermi Paradox

Subject: Re: Fermi Paradox

In SPACE_Digest V11 #283, hoptoad![e-mail]  (Tim Maroney)
writes:

>It seems inevitable that within a thousand years, our own nature as a
>species will have changed greatly -- through genetic engineering as
>well as through the integration of artificial and biological neural
                                                   ^^^^^^^^^^^^^^^^^
>networks.
^^^^^^^^^

You mean like a BRAIN?

In a thousand years the speed of light will still be about 300,000 km/s and
the radius of an atom will still be .1 nm.  Not to say that the computers
and software of tomorrow won't be vastly more powerful than today's, but at
some point the curves that measure technological progress must break from
their current exponential increase, and begin to approach an asymptote.
As far as computers/software are concerned, this asymptote could lie above
or below the performance of the human brain.  Who can say at this point?
Maybe the human brain can't create something smarter than itself.

>  I simply can't see how this could *not* be true within a

    It's also possible that a thousand years hence, our descendants might
have figured out how to live happily with a minimum of technology, as many
people do today.  In the future they might even have competitions to see how
little technology they can live with.  What we think is normal now might be
seen as aberrant in the future, as, for example, smoking used to be almost
the norm, whereas today it seems insane.

_____________
Dale M. Greer, whose opinions are not to be confused with those of the
Center for Space Sciences, U.T. at Dallas, UTSPAN::UTADNX::UTDSSA::GREER
      While the Bill of Rights burns, Congress fiddles. -- anonymous

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

Date: 20 Apr 90 20:22:33 GMT
From: altos!altos86![e-mail]  (Jerry Gardner)
Subject: Re: Apollo 13, STS-1, Vostok 1 anniversaries

}Trivia time:  The nickname of the Apollo 13 command module was Odyssey,
}after the ship in the movie "2001".  The lunar module, which served as
}the astronauts' "lifeboat", was nicknamed Aquarius.

The ship in 2001 was named Discovery.



--
Jerry Gardner, NJ6A                    Altos Computer Systems
UUCP: {sun|pyramid|sco|amdahl|uunet}!altos86!jerry    2641 Orchard Parkway
Internet: [e-mail]                San Jose, CA  95134
Guns don't kill people, bullets do.                     [phone]

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

Date: 20 Apr 90 00:37:31 GMT
From: swrinde!cs.utexas.edu!texbell!uhnix1!nuchat![e-mail]  (Steve Nuchia)
Subject: Re: Winch Launch as first stage.

In article <[e-mail]> [e-mail] (A JETSON News User) writes:
>You want a winch to do the job. Take a helicopter rotor hub, gearbox
> and turbine engine. add a cable drum. should make one fast winch.

Actually, one of the constraints on helicoptor design is that
the rotor *tips* must be subsonic.  You'd have to change the
gearbox if you wanted it to pull the cable at a supersonic rate.
We are still assuming we want to add about Mach 1 above the
aircraft's speed, right?  Then you wouldn't have enough torque.

You'd also have to cope with the cable accumulating on the drum or
a takeup reel/bin at supersonic speeds.

My thought would be to pass the line around a pulley, hook a big
parachute to the end, and toss it out.  The chute goes backwards
and the payload goes forwards at twice the speed.  The load on
the pulley attachment point is also twice the force on the payload,
instead of equal to it.

Better than an ordinary winch is a great big hydraulic cylinder
with a large number of pulleys at each end, like a block-and-tackle
in reverse.  If there are N passes of the line along the cylinder
and it is expanding at rate r then the line is coming in at Nr.
The force exerted by the cylinder is also N times the force on the payload.
The total length of the stroke is N times the stroke of the cylinder,
and you can pay out extra line to keep the load from skewering you.

You still have to cope with bearings carrying over twice the weight
of the rocket turning at *very* high speeds.

All of which is gold-plating on a silly idea.  The right approach
is to build an air-breathing horizontal take-off horizontal landing
first stage.  An aircraft on the scale of the Concorde but with
a cargo area open to the rear, and able to fly with the door open,
at least at altitude, would do the job.  Carry the rocket internally
to high altitude and ~Mach 2, then push it out the back in a second
or so (-100 fps won't kill you) so your center of gravity doesn't
move around.  Use a small drogue chute on the rocket to keep
it pointed the right way for ~5 seconds, then fire it.

The key is to have the upper stages carried internally.

If the upper stage stack is very narrow (no fins needed at altitude)
you could even fire it through the nose of the first stage.  One
could envision fitting a C-5 with a flow-through cargo area and
firing large stacks from it, but you probably couldn't design
a supersonic flying sewer pipe.

One solution to the aerodynamic problems that an opening to the
rear in a supersonic aircraft might cause would be to build
a disposable tailcone onto the back of the stack.  Have the
permanent tailcone attached to the payload sled so it pops into
place as part of the separation sequence.

Lots of fun.  Who's going to build it?

--
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: 20 Apr 90 16:13:43 GMT
From: usc!cs.utexas.edu![e-mail]  (Donald A. Varvel)
Subject: Re: Fermi paradox, SETI

This is speculation and has very little to do with space, other
than as a possible explanation of Why They Haven't Visited Us.

Anyone who deals with computers knows that lacking input, computer
systems either stop or stabilize in a loop.  (At some level, they
may be viewed as the same thing.)  Similarly (and for the same
reasons) biological systems left undisturbed long enough (possibly
the catch) will reach a stable point -- possibly unchanging, but
more likely cycling.  Change requires either that stability has
not yet been achieved or that the system is constantly being
disturbed.  The disturbance must be just enough to upset the
stable state but not enough to destroy the entire system.  Earth
seems to provide that.  How likely is it elsewhere?

Let us accept for a moment, and as an example mechanism rather than
as the sole explanation, the comet theory of periodic extinction.
``Disturbed stability'' requires that a comet impact the earth
at intervals widely enough separated to allow some evolution,
but close enough together that not too much time is wasted in
stable deadends.  Furthermore, the impact has to be big enough
to break the equilibrium and small enough not to destroy all
life.  Assuming you think people are A Good Thing (rather than
a noxious infection), don't you think Earth has been incredibly
lucky?

And how likely is it that another planet is similarly lucky?

Moving on from biological systems to social systems, the same
argument applies.  If humanity ever achieves a stable, sustainable,
global civilization, we can kiss technological innovation goodbye.
Such a civilization simply can't allow it.  I believe exactly that
has happened in restricted areas, and the equilibrium has been
disturbed by outside forces.  In a global civilization there might
be no external forces.

How likely is it that an intelligent race can avoid that, while
not destroying itself?  Can we?

-- Don Varvel ([e-mail])

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

Date: 20 Apr 90 19:56:46 GMT
From: janus.Berkeley.EDU![e-mail]  (Blake Philip Wood)
Subject: Re: Decompression and 2001

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>As any scuba diver will tell you, holding your breath during decompression
>is a thoroughly bad idea.  The alveoli ... are not mechanically strong
>and it's easy to damage them if there is more pressure inside than out.

But this situation is not really analogous to decompression to a vacuum.
In scuba you can have a differential of several atm, but in decomp to
a vacuum the maximum is 1 atm.  The proper question is whether something
less than 1 atm can rupture the alveoli.  In being exposed to a vacuum
you certainly wouldn't want to simply open your mouth, because with no
air in your lungs you have only about 15 sec of consciousness.  The best
strategy may be to exhale and hold that.  Then you'd still have air, but
the alveoli would only be exposed to some fraction (what is it?) of an atm.




                 Blake P. Wood - [e-mail]
                 Plasmas and Non-Linear Dynamics, U.C. Berkeley, EECS

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

Date: 20 Apr 90 06:52:17 GMT
From: [e-mail]  (KIRSTEIN DALE)
Subject: Pegsat barium drop


 What ever happened to the barium drop experiment launched on
 Pegsat? Was the first cannister dropped on schedule, did anyone see it,
and what is the schedule for the second cannister drop



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End of SPACE Digest V11 #298
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