Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v13_6/v13_637.txt

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Subject: SPACE Digest V13 #637

SPACE Digest                                     Volume 13 : Issue 637

Today's Topics:
              Mars Colonization
                Re: Amputation
               Re: Calculating delta-V
              Re: Budget Numbers Wanted
     Re: What comes after Fred's death? ESA promises to carry on!
           Re: Rational next station design process
               Re: The Un-Plan
      Re: Fred vs. Exploration: head-to-head competition
               Re: The Un-Plan
              Re: Colonizing the galaxy
          Re: Extra Terrestrial Intelligence

Administrivia:

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

Date: 24 May 91 17:58:09 GMT
From: [e-mail]  (Robert L. Smith)
Subject: Mars Colonization


    The science-fact article in the current (July) issue of Analog
contains a well thought-out and stimulating plan to reach Mars without
requiring an intermediate step -- no space station -- and at rela-
tively little cost.  The name of the article is "Mars Direct:  A
Proposal for the Rapid Exploration and Colonization of the Red
Planet".  Recommended reading.

Regards, rLs

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

Date: 24 May 91 18:44:17 GMT
From: mojo![e-mail]  (Doug Mohney)
Subject: Re: Amputation

In article <[e-mail]>, [e-mail] (Jim Bowery) writes:
>The only damage that will be done to JPL et al will be as a result
>of Galileo, which:
>
>1) is the closest thing to big science JPL has done and therefore should
>be punished on general principles,

Who will punish them? Congress? NASA internalists? After committing so much
money for it?

>2) was damaged because by insisting on everything flying on Shuttle,
>JSC ensured Galileo would have to take a trajectory it was never
>designed for -- one which damaged it,

You are implying that Galileo's antenna deployment problems are a direct
result of the trajectory. or that flying it on Shuttle damaged it. Could you
please produce some direct evidence of this? I wasn't aware that JPL had
figured out why the antenna was gorked.

Could be just a part which failed. Could be a lot of things. I'm sure both sci.
space and JPL would appreciate the documentation of failure and why.


     Signature envy: quality of some people to put 24+ lines in their .sigs
  -- >                  [e-mail]                        < --

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

Date: 23 May 91 18:51:01 GMT
From: van-bc!rsoft!mindlink![e-mail]  (Bruce Dunn)
Subject: Re: Calculating delta-V

> [e-mail] writes:
> In article <[e-mail]> [e-mail] writes:
>
> >A good solution is to give SI as the ratio of thrust (in Newtons) to
> >propellant consumption (in kg/s). This will give SI in m/s ...
>
> In fact, this amounts to forgetting specific impulse entirely and simply
> stating the effective exhaust velocity.  Definitely the right approach.


     I have heard it suggested that the easiest way to regard specific impulse
is that it ***is*** exhaust velocity, but that for obscure reasons it has been
measured in units of 9.8 m/sec^2.  For a quick and dirty conversion between
specific impulse and exhaust velocity in meters/sec, ignore units and divide or
multiply by 10 in your head (close enough to 9.8xxxx for many purposes).
--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: 25 May 91 18:37:08 GMT
From: agate!lightning.Berkeley.EDU![e-mail]  (Frank Crary)
Subject: Re: Budget Numbers Wanted

In article <[e-mail]> [e-mail] writes:
>What is the difference between not losing money to Fred, and
>getting money taken away from Fred?  _Both_ of these categories --
>a good chunk of NASA's valuable programs -- have greatly benefited in
>this budget from the Fred cut.  Drawing any other conclusion is, to
>quote some nay-sayer, "dreaming".

It makes a great difference. As this week's Aviation Week and also a post
to this newsgroup say, the OTHER agencies (VA, HUD etc...) recieved an
additional 800 million ABOVE thier budget requests. In general, NASA
programs did not recieve LESS than thier budget request. Which of the
two would YOU say got a better deal from Freedom's death? Are you trying
to say that they both benifited, and it it pointless to draw distinctions?
My conclusion from the budget figures posted is that Freedom was eliminated
to benifit social programs, and that at the same time, other NASA programs
were given some limited additional support to keep the scientific community
quiet.

                         Frank Crary

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

Date: 25 May 91 23:23:45 GMT
From: agate!lightning.Berkeley.EDU![e-mail]  (Frank Crary)
Subject: Re: What comes after Fred's death? ESA promises to carry on!

In article <[e-mail]> [e-mail] (Daniel Fischer) writes:
>Crazy speculations follow. The Soviets have all the experience, plans for MIR-2
>but no money. ESA and Japan have the money (sort of). The US has neither.
>Shouldn't that lead to an USSR-ESA-NASDA collaboration to put a truly interna=
>tional space station into orbit where they can learn whether it makes sense -
>and rent some space to the (very few) U.S. researchers who'd like such a thing?

More to the point, the Soviet Mir station has two unused docking ports,
designed for lab modules in the 20-tonne size range. They are just waiting
for the (soviet) modules to be built and tested. Might they not, instead,
simply allow NASDA or the ESA to attach their (modified to fit) Freedom
lab module? While Mir lacks extra power (each module was launched with its
own solar pannels) and has only a little extra perminant living space, a
habitat/support module could be added to the other available port. This
would give either NASDA or ESA more or less what they had expected from
Freedom.

                    Frank Crary

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

Date: 25 May 91 23:37:04 GMT
From: agate!lightning.Berkeley.EDU![e-mail]  (Frank Crary)
Subject: Re: Rational next station design process

In article <[e-mail]> [e-mail] (George William Herbert) writes:
>    You could do a cheap compromise and fly an unmanned "LabRatSat" for
>a year or two, but I don't know if it's feasable to handle lab animals for
>that long purely by machinery.  Reinserting IV test lines etc. by teleoperation
>is an (as far as I know) untested idea... I'd count this as of questionable
>practicality.

A "LabRatSat" could be done quite well from a man-tended platform. Just have
a crew visit the rats every month or two. While this limits some of your
data (you could not, for example, have blood samples on a daily basis.)
you could still get quite a bit of good data.
I think a "LabRatSat" would be limited by the lifetime of a rat. (Anyone
know how long that is, I think less than 2 years...) Since there might
well not be a next greneration of rats. (e.g. if they all were in individual
cages, or due to zero-gravity pregnency problems...)

                                    Frank Crary

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

Date: 26 May 91 04:25:45 GMT
From: usc!wuarchive!rex!rouge![e-mail]  (Fraering Philip)
Subject: Re: The Un-Plan

Okay, I guess I'll be the straight man (it seems I usually am).

Who is Amgen?

--
Phil Fraering || Usenet (?):[e-mail] || YellNet: 318/365-5418

Standard disclaimer, whatever a disclaimer is, applies.

``But in her present straits he could not trouble her with
disclaimers.'' Stephen R. Donaldson, _The Wounded Land_

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

Date: 26 May 91 02:28:50 GMT
From: usc!rpi!dali.cs.montana.edu!milton!sumax!polari![e-mail]  (Charles Radley)
Subject: Re: Fred vs. Exploration: head-to-head competition



>More efficient are worthwhile projects include Goddard's SMEX
>program extended into deep space, a new generation of small telescope
>satellites (eg an infrared telescope dedicated to asteroid and comet
>search), an infrared telescope put into a meteor-shower orbit to
study
>the mass distribution and makeup of comets and their fragments,
>
-
Huh ?  Totally boring and uninteresting.   Irrelevant to the average

man in the street.    Do you really think programs like this can
compete with HUD ?   Is this superior to a space station ?    Who
gives a rat's *## about deep space ? This is purely a boondoggle for
tenure track professors, with absolute job security, to write totally
academic papers in obscure scientific journals which will never be
read by anybody, and rightly so.   Who needs it ?   Not me !   I would
rather have a space station.-
    The makeup of comets......I would rather have skin makeup for my
wife.    Really Mr. Szabo, your attempts at justifying space science
as being somehow more worthwile than manned spaceflight are
absolutely parochial to the point of silliness.
    Nobody in this newsgroup has made any mention of the TECHNOLOGY
stimulus to American industry which is provided by manned space programs.
 Science program simply to not represent a shadow of the technology
 stimulus which gets fed back into industry and the economy as new
products, materials and processes.    This is a very large part of the
 attraction of manned programs.
     Indeed a few weeks ago the European Space Agency published a
report saying that economic payback of European space programs is
about three to one.      This value would be increased greatly by
expanding Europe's manned effort, which today is very small.    They
estimated about seven to one payback for manned programs.     ESA
certainly recognizes the importance of manned programs to boost
technology.
     The world does not exist to benefit scientists in their search
for obscure knowledge of dubious value.   We need to place more
priority in creating jobs for our populations by stimulating economic
development.    Small scale science programs contribute nothing to
this high priority item.

>several Lunar and Mars orbiters, ground telescope construction and
>operation, analysis of asteroid samples fallen to Earth, and a host
>of other projects.
>
  We have already sent orbiters to Mars and the Moon.    Why do we
need to send any more ?    Sounds like another boondoggle to me.    We
already have thousands of ground space telescopes, really Mr Szabo,
you are boring me to death.   Analysis of asteroid samples ( I presume
you mean meteorites ) heck that is being done and costs next to
nothing.
    I notice you made no mention at all of EOS, and CRAF / Cassini.
Since these big ticket mission do not appear in your wish list I
imagine that any anti-NASA congressmen reading this conference will
say.... aha here is a vocal scientists, let's analyse what he says.
Hmmm, no mention of CRAF / Cassini.  We funded CRAF / Cassini by
cancelling Freedom and the scientists do not even consider them to be
important;  guess which programs go on the chopping block next
year.......
   Hehehe......NASA's days are numbered, pretty soon we will have
succeeded in our long term strategy of whittling them down to nothing.
They won't know what hit 'em !

.

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

Date: 25 May 91 18:07:15 GMT
From: swrinde!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew![e-mail]  (James Davis Nicoll)
Subject: Re: The Un-Plan

In article <[e-mail]> [e-mail] (Jim Bowery) writes:
>Nick Szabo writes:
>

    Material deleted

>> * Our sample size of earth-crossing and Jupiter-crossing asteroids and
>>   comets is increased 1,000-fold, so that we find several small objects
>>   that can be captured into earth orbit for less than 500 m/s impulse
>>   delta-V.
>
>Another bad idea on 2 counts:
>
>1) Ever read "The Moon is a Harsh Mistress"?  Even "small" objects that
>hit the earth from space are exceedingly destructive.  If they break
>the objects up into "bite sized" chunks of box-car size or so before they
>get anywhere near Earth, I'll consider not assassinating them.  Box-cars
>would only cause H-Bomb devistation if they hit the Earth.  That's
>acceptable compared to wiping out a continent or so.
>
>Keep in mind that even an impact on the Moon or Mars of an
>asteroid would create enough flux, for a few minutes, to ignite
>flammable material in the Earth's biosphere.
>

    Just how large do you envision the objects Mr Szabo was talking about
to be? Perhaps I'm missing something, but doesn't exploiting ET resources
imply moving those resources to the intended market at some point? In any
case, in the near run, I strongly doubt that we'll be moving dinosaur-killer
asteroids into LEO, or Earth-intersecting orbits (At least on purpose).

    How large a rock do you need (and moving at what velocity) to
generate enough heat to light fires at 380,000 km? Is it reasonable to
assume that's the size & velocity of the rocks Mr Szabo is talking about?

                                James Nicoll

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

Date: 26 May 91 03:45:03 GMT
From: rochester![e-mail]  (Brian Yamauchi)
Subject: Re: Colonizing the galaxy

In article <[e-mail]> [e-mail] (Mark William Hopkins) writes:

>   Thus one year (the speed of light divided by 1G acceleration) is the limit
>on how long you can maintain 1G thrust using ANY fuel stored on the ship.
>Thus, the implication is that you're extracting fuel from space as you go.
>All that just to get to the nearest star in a lifetime!!

>   So ANY practical means to get to another star in decent time for
>colonization will also enable any other part of the galaxy (or neighboring
>galaxies) to be colonized as well.

Interesting point...

How does the intragalactic hydrogen density compare with the
intergalactic hydrogen density?  If the latter is much lower, it might
present a barrier to intergalactic exploration and colonization.
--
_______________________________________________________________________________

Brian Yamauchi                University of Rochester
[e-mail]        Department of Computer Science
_______________________________________________________________________________

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

Date: 25 May 91 18:01:16 GMT
From: agate!lightning.Berkeley.EDU![e-mail]  (Frank Crary)
Subject: Re: Extra Terrestrial Intelligence

In article <[e-mail]> [e-mail] writes:
>(2) Why wasn't the entire galaxy colonized thousands of millions of
>years ago? The time for a colonization wave to travel across the galaxy,
>even with spacecraft traveling well below the speed of light, is only
>a fraction of the age of the universe. Our solar system has apparently
>not been colonized; we see no evidence of large scale engeneering in
>the asteroid belt or on the moon, for example. (Paul F. Dietz)

I have two big problems with this logic: First of all, the age of the universe
is not the correct time scale. Before any intelligent life could begin to
colonize the galaxy: The first generation of star formation must progress
to the point of supernovae. This is necessary since these early stars were
"metal poor" meaning lacking in materials other than hydrogen and helium. Many
stars must have become supernovae before the intersteller medium had sufficient
carbon, nitrogen, oxygen and other heavier elements for life to be possible.
Once this occured, stars (and planets) must then have formed and life evolved
on these planets. This whole process would take a considerable ammount of time.
At a guess, I would say at least 7 to 10 billion years. This cuts down the
time in which a extra-terrestrial civilization could have spread across the
galaxy to 7 to 4 billion years (taking the age of the universe to be 14 billion
years.)
My second objection is the speed at which a civilization is assumed to expand.
While the actual exploration crafts could have spread all over the galaxy, even
at 0.001c and in only 500 million years, what the colonies would do is a
totally different issue. At the speed I guessed at, travel between stars would
take roughly 5000 years (at approximately 5 light years between stars.) But
how long would it take a new colony to settle an entire new world, grow to the
point where people want to leave it (and form a new colony) and have developed
the industrial base to support an interstellar colonization effort? Even if
they worked as hard as they could at it, I suspect it would take at least a
few thousand years. In fact, however, these colonists might easily get
distracted. If they suffered a civil war/interstellar war/collapse of
government the above process could be set back a great deal. In short, I feel
the "colonization wave" would propogate at a much slower rate than suggested,
and that this rate would be dominated by social, rather than technical, issues
Finally, I don't like this model of a "wave of colonization" A difussion
process (or a random walk) seems to me a better model. There will be empty
worlds to be settled TOWARD as well as away from the home world of our
hypothetical extraterrestrials. New collonies are as likley to "fill in the
blanks" missed by earlier settelers as go out into new and uncharted space.
Also, they might preferentially settle stars totally unlike out sun. For
example, a planet in an open star cluster would be an ideal place for a
colony. There would be many planetary systems, all within a few light years.
If these were setteled first, it might be quite a while before anyone bothered
with a single star system.

                       Frank Crary

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

End of SPACE Digest V13 #637
*******************