Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_3/V15NO399.TXT

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Date: Mon,  9 Nov 92 05:00:02
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #399
To: Space Digest Readers
Precedence: bulk


Space Digest                Mon,  9 Nov 92       Volume 15 : Issue 399

Today's Topics:
          ANSWER: Recognizing a Dyson sphere if you saw one
                        Astronauts and Vacuum
                 Automated space station construction
                            Dyson Spheres
                                Errors
                Lunar "colony" reality check (3 msgs)
                 Media report on Swift-Tuttle threat.
                             Metric again
        Moon can hold its air (was Re: Mars over the Moon???)
                     More lunar gravity questions
                        NASA Coverup (2 msgs)
                       Putting air on the moon
                    Scandium and Osmium end-users

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Date: 8 Nov 92 21:02:29 GMT
From: "Alan M. Carroll" <[e-mail]>
Subject: ANSWER: Recognizing a Dyson sphere if you saw one
Newsgroups: sci.astro,sci.space

In article <[e-mail]>, [e-mail] (Steve Linton) writes:
> I thought the whole point of a Dyson sphere was to utilise the whle energy of the
> star, reradiating it as waste heat at some low temperature. I suppose the DS
> might not be finished yet, but it strikes me as the sort of thing you build
> completely or not at all.

A physically realizable Dyson Sphere would probably be built
piecemeal. If you're constructing it out of small, independent bodies
(such as large numbers of O'Neill colonies) then it makes perfect
sense to build it one orbiting body at a time, as you need living
space / energy. Each thing you put in orbit requires manufacturing and
maintenance, so there's incentive for doing as few as possible.

> A civilization that is using a substantial proportion of its star's energy would
> look like what you describe, but might simply have a large constellation of
> orbitting power stations.
> I guess it all comes down to definitions.

Yes, and Dyson's original article described the type of Dyson sphere I
have mentioned here, not a solid shell at all. So, pedantically, a
constellation of orbiting powersats is a Dyson Sphere.

--
Alan M. Carroll          "Weren't there yams involved, too?" - J. Ockerbloom
Epoch Development Team
Urbana Il.               "I hate shopping with the reality-impaired" - Susan

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

Date: Sun, 8 Nov 1992 17:18:57 GMT
From: Bruce Dunn <[e-mail]>
Subject: Astronauts and Vacuum
Newsgroups: sci.space

1) With respect to blood boiling

        No.  Body temperature is 37 C.  At this temperature, the vapor
pressure of water is about 47 mm Hg.  Typical minimum blood pressure is
higher than this.

2) With repsect to lungs freezing

        No, on the short term.  Surface liquid/mucous in the lungs would
evaporate, cooling the tissue as it does.  The surface layer however is
constantly warmed by the tissue not at the surface, and while it gets cold it
won't immediately freeze.  This is why your face does not freeze when you go
skiing.


--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: 8 Nov 92 17:41:52 GMT
From: "Kieran A. Carroll" <[e-mail]>
Subject: Automated space station construction
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Frank Crary) writes:
>Is anyone looking into robots with very limited autonomy? That is,
>under direction from a human, but able to execute instructions on
>their own for periods of, say, ten seconds?
>
>                                         Frank Crary
>                                         CU Boulder

Yes. The Canadian Space Agency (who are developing the Mobile
Servicing System for SSF) are spending about CDN$50M per year
on research into automating various aspects of MSS, through their
STEAR (Strategic TEchnologies for Automation and Robotics)
program. The work is being done by various Canadian companies,
including mine (Dynacon Enterprises Ltd.). The idea is that
the baseline MSS will use control technologies very similar to
those used in the Canadarm, in order to expedite development.
Then, improvements will be added over the life of SSF as part of
the ``Evolutionary MSS'' program (funding still TBC). The work being
done now is more in the nature of up-front research and development,
so that the technologies that currently look interesting will have
been tested out prior to setting the requirements for the next
MSS increment.

Actually, some of that work looks likely to see
earlier use, perhaps even incorporation into the baseline MSS:
the CSA is looking into adding ground-control capability into baseline
MSS, largely to provide a means for dealing with the predicted
external maintenance task backlog (the existence of this backlog
was the main conclusion of the ``Fisher/Price''
report a couple of years ago; this report was probably the straw
that broke the back of the previous SSF configuration, and led to the
1991 re-design). With ground control, MSS could be operated almost
full-time during the period between flight 3 (when MSS is launched)
and PMC (when SSF will be permanently inhabited); without ground control,
it could be operated during this period only when a shuttle was docked,
which will be for something like 2 weeks out of every 3 months.
--

     Kieran A. Carroll @ U of Toronto Aerospace Institute
     uunet!attcan!utzoo!kcarroll [e-mail]

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

Date: 8 Nov 92 15:09:25 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Dyson Spheres
Newsgroups: sci.space

In article <ida.721202076@atomic> ida@atomic (David Goldschmidt) writes:

>Does anybody know the relationship between the ecliptic of our solar system
>and the Milky Way?

Go out and look. Two planets, or a planet and the moon, can be used to
draw a line roughly showing the plain of the ecliptic.

And the plane of the milky way seems pretty obvious...

>Dave Patterson, guest on this account.

--
Phil Fraering

We'll not fade out too soon
Not in this finest hour
Whistle your favorite tune
We'll send a card and flower, saying "It's a mistake!"

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

Date: Sun, 8 Nov 92 15:11:20 EST
From: John Roberts <[e-mail]>
Subject: Errors

-From: [e-mail] (Andrew Haveland-Robinson)
-Subject: NASA Coverup
-Date: 8 Nov 92 03:34:51 GMT
-Organization: Haveland-Robinson Associates

-As one working in the media as a typesetter typos are a statistical fact,
-following the same lines as bugs in code - they are never eradicated, just
-get less significant.

-It is therefore reasonable to expect that out of the 1000s of articles on
-the subject and the complexity of editorial processes errors will occur.
-Some information will be inaccurate or completely wrong.

And once those errors get in, they tend to propagate indefinitely - it's
impossible to get correction notices to everybody who read the original
articles. That gives refereed publications a considerable advantage in
accuracy.

John Roberts
[e-mail]

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

Date: 8 Nov 92 18:07:19 GMT
From: Nick Szabo <[e-mail]>
Subject: Lunar "colony" reality check
Newsgroups: sci.space,alt.sci.planetary

Lunar "colony" reality check:

* The moon has no significant sources of hydrogen, nitrogen,
  or carbon.  Wishful thinking about polar volatiles or
  scrounging solar wind particles are hardly significant.
* A livable atmosphere is mostly nitrogen, not oxygen.
* Plants and animals need copious amounts of hydrogen, nitrogen,
  and carbon.
* There is no affordable way to crack oxygen out of lunar
  rock or to recycle it.  This would cost, at bare minimum,
  tens of millions of dollars per astronaut per year.
* Because of transportation costs for recycling equipment,
  recycling on the moon is far more expensive than recycling on
  earth.  Even on earth the best attempt at building a livable,
  working biosphere masses hundreds of thousands of tons and leaks
  over tens of tons of air per year.
* Hydrogen is extremely innefficient to transport from
  earth.  The stoichiometric volume of LH to make water is
  _larger_ than the volume of oxygen; huge amounts will
  be wasted on tankage.  Much of the LH will leak before
  it can be used; it's extremely difficult and expensive
  to store even for the few days trip.
* The annual per capita consumption of water in the
  U.S. is over 500 tons.  In this as in many other
  areas, the "colony" will be living in abject
  poverty despite the $billions spent on its
  construction.
* It takes more than a rocket payload full of hydrogen
  to make the water needed by industry.  If we're to have any
  significant manufacturing industry in space, we're going to need
  tons of volatiles.  For example, here is the water used to make
  a few kinds of products on earth:

            gallons/unit
            ------------
finished steel, ton    40,000
automobiles, unit    12,000
trucks, buses, unit    20,000
ref: Mark's Standard Handbook for Mechanical Engineers, 1987

* There is no signficant economic resource on the moon.
  Revenues as a percentage of costs will be 0%.
* SSF bare-bones habitat operations costs will be $2 billion
  per year.  Scaling for transport costs gives over $10 billion
  per year for a bare-bones lunar "base".   Redesign will cost
  even more than SSF cost,  since industry has no reason to
  participate beyond the usual NASA-contractor mode.
* Calling a few astronauts huddled in a Winnebago a "base" is
  a major exaggeration.  Calling it a "colony" is an abominable
  misuse of the word.

There are dozens of other pathways to space colonization.
Fixation on obsolete concepts like the "lunar base" and oxymoronic
concepts like the "lunar colony" is one of the main reasons why
the space colonization movement lies mired in failure.


--
Nick Szabo                     [e-mail]
Hold Your Nose: vote Republocrat  ////////  Breathe Free: vote Libertarian

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

Date: 8 Nov 92 21:12:00 GMT
From: [e-mail]
Subject: Lunar "colony" reality check
Newsgroups: sci.space,alt.sci.planetary

In article <[e-mail]>, [e-mail] (Nick Szabo) writes...
>Lunar "colony" reality check:
>

Nick, Nick, Nick, at it again I see.

>* The moon has no significant sources of hydrogen, nitrogen,
>  or carbon.  Wishful thinking about polar volatiles or
>  scrounging solar wind particles are hardly significant.

Until there is a lunar polar orbiting spacecraft with a neutron spectrometer
this question will remain unanswered, not wishful thinking. Calculations
that you can do Nick old boy shows that the temperature in some of the
northern and southern lunar craters is low enough that water could exist there
for several billion years. If you doubt this look at the voyager pictures. Some
of the permanently dark craters have temps well below that of the surface of
the Jovian and Saturn moons. Comments like yours above merely reflects your
bias and not the state of knowledge in this area. Also underground water and
volatiles are a definite possiblity. What about carbonaceous meteor impact
areas? Would this not enrich the surrounding area and the underground where
the meteor penetrated with voliatiles or even water in the case of a comet?

>* A livable atmosphere is mostly nitrogen, not oxygen.
>* Plants and animals need copious amounts of hydrogen, nitrogen,
>  and carbon.
>* There is no affordable way to crack oxygen out of lunar
>  rock or to recycle it.  This would cost, at bare minimum,
>  tens of millions of dollars per astronaut per year.

Apparanently you have missed the last few lunar resource conferences. The
carbotek process which is ALREADY producing oxygen from lunar simulants is
a viable and relatively low cost process for making oxygen out of native
materials. By the way the Shimzu corporation is paying for that research. I
guess the Japanese see no promise?

>* Because of transportation costs for recycling equipment,
>  recycling on the moon is far more expensive than recycling on
>  earth.  Even on earth the best attempt at building a livable,
>  working biosphere masses hundreds of thousands of tons and leaks
>  over tens of tons of air per year.

References for this statement?

>* Hydrogen is extremely innefficient to transport from
>  earth.  The stoichiometric volume of LH to make water is
>  _larger_ than the volume of oxygen; huge amounts will
>  be wasted on tankage.  Much of the LH will leak before
>  it can be used; it's extremely difficult and expensive
>  to store even for the few days trip.

Funny that the Apollo SIII stage had no problem with that. It worked for
several days at a time to push the astronauts to the moon. Here is another
idea for you Nick. Refigure this if you ship WATER. Well you solve both
problems. You get inexpensive transport (you don't need 100% rocket reliablity)
and you get a power source by the stepwise conversion of excess water to H & O
during the lunar day and back again for power generation during the lunar night.
Nick please open your mind a little.

>* The annual per capita consumption of water in the
>  U.S. is over 500 tons.  In this as in many other
>  areas, the "colony" will be living in abject
>  poverty despite the $billions spent on its
>  construction.

This is because we americans love to take a bath every day.

>* It takes more than a rocket payload full of hydrogen
>  to make the water needed by industry.  If we're to have any
>  significant manufacturing industry in space, we're going to need
>  tons of volatiles.  For example, here is the water used to make
>  a few kinds of products on earth:
>
>            gallons/unit
>            ------------
>finished steel, ton    40,000

These are nice true numbers but are not applicable to space. most of the
water you quote here is used in the reduction process that gets the iron from
the ore. In space this is eliminated by  using pure sources from Nickel iron
meteors and simply melting by electrical induction.

>automobiles, unit    12,000

I dont think we will make many cars up there or buses for that matter.

>trucks, buses, unit    20,000
>ref: Mark's Standard Handbook for Mechanical Engineers, 1987
>
>* There is no signficant economic resource on the moon.
>  Revenues as a percentage of costs will be 0%.

Hey! Have you been there? Geez there has not been even one resource mapping
mission to the moon and you are prepared to live or die by this statement?
Come on, that sounds like the people on the Spanish court who were against
Columbus. You have absolutly zero basis for that statement. Just from the
Apollo 15 and 16 gamma ray spectrometers we found economically feasible
concentrations of titanium and aluminum. This was only a few days of
survery with a crude instrument!

>* SSF bare-bones habitat operations costs will be $2 billion
>  per year.  Scaling for transport costs gives over $10 billion
>  per year for a bare-bones lunar "base".   Redesign will cost
>  even more than SSF cost,  since industry has no reason to
>  participate beyond the usual NASA-contractor mode.
>* Calling a few astronauts huddled in a Winnebago a "base" is
>  a major exaggeration.  Calling it a "colony" is an abominable
>  misuse of the word.
>

Calling this post a reality check is also abominable. You don't have to go
you do not have to particpate. Just get the heck outta our way.

>There are dozens of other pathways to space colonization.
>Fixation on obsolete concepts like the "lunar base" and oxymoronic
>concepts like the "lunar colony" is one of the main reasons why
>the space colonization movement lies mired in failure.
>
>

Tell you what Nick. You do it your way and we will do it this way and lets
see who comes out ahead.


>--
>Nick Szabo                     [e-mail]
>Hold Your Nose: vote Republocrat  ////////  Breathe Free: vote Libertarian

Hell with all of em be an American and do something with your life and do not
count on any politician.


Dennis, University of Alabama in Huntsville

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

Date: 8 Nov 92 22:27:41 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Lunar "colony" reality check
Newsgroups: sci.space,alt.sci.planetary

[e-mail] (Nick Szabo) writes:

>Lunar "colony" reality check:

>* The moon has no significant sources of hydrogen, nitrogen,
>  or carbon.  Wishful thinking about polar volatiles or
>  scrounging solar wind particles are hardly significant.

If you can experimentally prove the non-existance of polar ice, we'd all be very
greatful.  If you can't, please label the above as opinion.

>* There is no affordable way to crack oxygen out of lunar
>  rock or to recycle it.  This would cost, at bare minimum,
>  tens of millions of dollars per astronaut per year.

There may more may not be any economical ways of doing it (because you can
define "economical" to mean anything you want).  This doesn't mean there won't
be.

>* Because of transportation costs for recycling equipment,
>  recycling on the moon is far more expensive than recycling on
>  earth.  Even on earth the best attempt at building a livable,
>  working biosphere masses hundreds of thousands of tons and leaks
>  over tens of tons of air per year.

This Biosphere was of course designed for Earth conditions.  A lunar station
won't have plate glass windows or it's own rainforest.  Besides, using current
launch costs only proves that Moon bases aren't economical now -- something I
won't debate you on.  Assuimg that none of the current attempts to lower launch
costs will succeed is as ludicrous as auuming they all will.

>* Hydrogen is extremely innefficient to transport from
>  earth.

So get it from comets.  If we don't colonize the moon, just what do you think
will be the market for your comet resources?

>* The annual per capita consumption of water in the
>  U.S. is over 500 tons.

Sure.  But the astronauts won't be living in the U.S.  They won't have cows that
drink water and eat irrigated corn.  They won't use ships for transportation or
water cooled engines. They won't wash their cars.  In short, they won't be
using water for the same things we do.

>* It takes more than a rocket payload full of hydrogen
>  to make the water needed by industry.  If we're to have any
>  significant manufacturing industry in space, we're going to need
>  tons of volatiles.  For example, here is the water used to make
>  a few kinds of products on earth:

Nick, they won't be making products on Earth.  Even if they had all the water
they wanted they be using different proccess due to low gravity, dust problems,
thermal conductivity etc.  Show us that it's impossible to produce goods without
water and I'll sympathize.  Tell me that we don't do it now and I'll ignore you.

>* There is no signficant economic resource on the moon.
>  Revenues as a percentage of costs will be 0%.

Except for clean power, bulk materials off Earth and the best sites for
telescopes in the known universe you may be right about that.

>* Calling a few astronauts huddled in a Winnebago a "base" is
>  a major exaggeration.

So what do you call it?

>Calling it a "colony" is an abominable
>  misuse of the word.

It is indeed.  Who's called it that?

--
Josh Hopkins                                          [e-mail]

"We can lick gravity, but the paperwork's a bit tougher."  Wernher von Braun

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

Date: Sun, 08 Nov 92 11:02:57 GMT
From: Cameron Newham <[e-mail]>
Subject: Media report on Swift-Tuttle threat.
Newsgroups: sci.space,sci.astro

Well, I've just had a good laugh after reading a half page article on the
possible Swift-Tuttle impact in our Sunday paper.

Although the article contains the usual misinformation, speculation and
sensationalism that the papers (and this one in particular) are renowned
for, I note some rather disturbing comments made by Dr Ken Russell at the
Anglo-Australian observatory.

In it he is quoted as saying "A chance of one in 400 is not small when you
are talking about the extinction of the human race."

1 in 400?  Where did this figure come from?  I thought it was 1 in 10000, and
that at a back-of-the-envelope calculation.  Has the knowledge about Swift-
Tuttle's non-gravitational forces suddenly taken a gigantic leap forward?
Hardly.

He is also quoted as saying "All life would be grilled to death."  I presume
he was quoted out of context here.

At least they got the bit about the recovery of the comet correct.

The article goes on to say that the "International Astronomical Union then
warned its member nations that Swift-Tuttle would cross earth's path in
August 2126."

News to me!  Anyone care to comment?

- cameron.

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

Date: Sun, 8 Nov 1992 17:03:22 GMT
From: Bruce Dunn <[e-mail]>
Subject: Metric again
Newsgroups: sci.space

> John Roberts writes:
>
> By the way, I think you'll be much happier in the long run if you do your
> calculations in SI (metric) units. I often do simple calculations in
> standard
> units, but the tough problems are much more easily handled using SI.


        I am delighted to find that NASA seem finally to be moving toward
metric, not just in theory but in reality.  Ron Baalke's postings about
various spacecraft now use metric units as the primary system, with
traditional American units in brackets.  About a week ago I joined a public
tour through the Goddard Space Flight Center (just north of Washington DC).
Goddard has a backup Shuttle mission control center which can take over
Shuttle operations if the Houston center is down.  There was a Shuttle up at
the time, and data related to the mission were being displayed in real time
on a large display at the front of the control room (the tour saw the room
from behind a glass wall).  Shuttle altitute was listed in km, and velocity
was listed in km/sec.
        Does anyone know if NASA uses degrees C for reporting things like the
Shuttle cabin temperature and the temperature of experiments?



--
Bruce Dunn    Vancouver, Canada   [e-mail]

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

Date: 8 Nov 92 22:26:15 GMT
From: Bruce Scott <[e-mail]>
Subject: Moon can hold its air (was Re: Mars over the Moon???)
Newsgroups: sci.space

"The Oxygen Barons", a novel by G Feeley, concerns this situation: a
short-term atmosphere on the moon, fought over by several interest
groups. His was of getting the gas mass to the moon seemed very
far-fetched to me: creating a "soliton" in the solar wind, which
consisted of a direct "river" of solar-composition gas to the Moon
(actually, I don't remember whether the composition was to be altered
at the Sun or the Moon). He gave a reference to some soliton papers
in an Appendix, but methinks he misunderstood the concept. Pressure
expansion in such a jet needs some positive effect to stop it; without
strong magnetic fields (like near compact objects) I can't see how
that would work.

On the subject: it is true that an atmosphere placed at the Moon would
last for "historically relevant times".

Gruss,
Dr Bruce Scott                             The deadliest bullshit is
Max-Planck-Institut fuer Plasmaphysik       odorless and transparent
bds at spl6n1.aug.ipp-garching.mpg.de                 -- W Gibson



--
   The opinions expressed are not necessarily those of the University of
     North Carolina at Chapel Hill, the Campus Office for Information
        Technology, or the Experimental Bulletin Board Service.
           internet:  laUNChpad.unc.edu or 152.2.22.80

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

Date: Sun, 8 Nov 92 15:02:44 EST
From: John Roberts <[e-mail]>
Subject: More lunar gravity questions

-From: [e-mail] (Andrew Haveland-Robinson)
-Subject: Ten embarrassed questions about the moon (very long)
-Date: 8 Nov 92 03:34:44 GMT
-Organization: Haveland-Robinson Associates

-In article <[e-mail]> [e-mail] writes:
-...
-An excellent article!  I have a couple of questions...

-What is the ratio of density of the mascons to the "masdeps" (depletions)?

Here's what I can find in the reference:

p.27: "The laser altimetry experiment also revealed that the center of mass
[of the moon] was displaced 2-3 km from the geometric center, toward the
earth. This offset cannot be accounted for by the mascons, which shift the
center of mass only about 40 m. The displacement is compatible with a thicker
far-side crust of highland material."

p.277: "The mean lunar radius is 1738 km and the mean density is 3.34 g/cm^3.
The density of the highland rocks lies within the range 2.75-3.0 with a mean
value of 2.95. The maria basalts have higher densities (3.3-3.4), about equal
to the bulk density of the moon. The density of the lower crust ...is probably
about 3.0-3.1. Assuming that the crustal average density is 2.95, the bulk
density of the moon below the crust will be 3.39 g/cm^3." [Latest value of
coefficient of moment of inertia (0.395 +- .005) does not rule out the
possibility of a core.] "The data permit the existence of an iron core
of radius 450 km, for which there is no seismic evidence, or of a Fe-FeS
core of radius 700 km, which corresponds to the S wave seismic discontinuity."

p.277: "The smallest example [of a filled crater with a positive mascon]
is Grimaldi (150 km diameter). The positive gravity anomaly over the mare
basin Grimaldi (+60 mgal) is just the reverse of the -60 mgal anomaly over
the crater Copernicus. The largest anomalies are +220 mgal, under Mare Imbrium
and Mare Serenitatis. Smaller positive anomalies exist under the following
circular maria: Crisium, Nectaris, Humorum, Humboltianum, Orientale, Smythii,
and under Sinus Aestuum and Grimaldi, and some other minor features. [Have
to do something about those names, if people ever colonize the place. :-) ]
Frequently, the anomalies possess a ringlike structure... as shown by Mare
Orientale. In this example, the positive anomaly of +150 mgal is confined to
the central, basalt filling. Commonly, negative anomaly rings surround the
mascons.

"...Filled craters less than about 200 km in diameter have negative gravity
anomalies. Sinus Iridium, the Bay of Rainbows on the coast of the Sea of
Rains (Mare Imbrium), possesses a negative anomaly of -90 mgal.

"Large mountain ridges, such as the Apennines, have small positive anomalies.
This great feature, standing 7 km above Mare Imbrium, has a small positive
gravity anomaly of +85 mgal. If the mass of the Apennines were totally
uncompensated, a positive anomaly of +300 mgal would result, so that some
isostatic readjustment has occurred."

[I don't know what a "mgal" is, but I guess this gives some idea of the
relative magnitudes.]

-Are the mascons responsible for the locked orbit? If so, then that would
-explain why the Marias are dense and are only found facing the Earth.

The book doesn't say, but I would suspect that the maria and the current
mascons were formed only after the moon's rotation was locked to its orbit
around the Earth. From the previous post, the maria are disproportionately
common on the near side because the crust is thinner there, making the flow
of lava easier. The difference in crust thickness is presumably the result
of the Earth's gravitational influence, which would be uneven only if the
moon's rotation were already locked to the Earth. (This would also account
for the above-mentioned displacement of the center of mass.)

The mascons could only form after the point at which the outer part of the
moon had solidified sufficiently that isostatic adjustment would not take
place. From the quote above, the Apennines must have formed around the
beginning of that period.

-References I've seen indicate that Earth's tides are responsible for
-locking the moon's rotation to the orbit.

I believe the main effects of the tides on Earth are to slow the Earth's
rotation and to cause the moon to gradually move further from the Earth.
If one assumes that the moon once rotated faster than it revolved, then the
tidal forces must have been much greater than those we see on Earth, because
of the greater mass of the Earth. If the moon were liquid at the time (which
would fit the Earth impact model), then those tides would have stirred the
entire body of the moon, generating tremendous friction.

One aspect I'm more uncertain of: if the moon continues to move outward
from the Earth, then the period of its revolution about the Earth must
be increasing. If its rotation continues to remain tidally locked, then
there must be some currently active mechanism that maintains this state.
It would be a subtle effect, and I can think of several possible mechanisms
to explain it, but I'm not sure of the relative magnitudes. Perhaps drag
from the "rocking" (what's the word?) of the moon relative to the Earth is
sufficient to account for it.

John Roberts
[e-mail]

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

Date: Sun,  8 Nov 1992 11:56:34 -0500
From: Lawrence Curcio <[e-mail]>
Subject: NASA Coverup
Newsgroups: alt.conspiracy,sci.space

Further Edvidence: I dropped a hammer and a feather and they hit the
ground at *DIFFERENT* times! :)

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

Date: Sun, 8 Nov 1992 17:16:45 GMT
From: Chip Salzenberg <[e-mail]>
Subject: NASA Coverup
Newsgroups: sci.space,alt.conspiracy

According to [e-mail]:
> TEN EMBARRASSING QUESTIONS ABOUT THE MOON

I am reminded of "66 Questions and Answers about the Holocaust",
published by "revisionist" neo-nazis with a similar distaste for
simple truth.
--
Chip Salzenberg at Teltronics/TCT  <[e-mail]>, <[e-mail]>
   "I am truly as big a genius as all other Rush fans." -- Bruce Bufalini

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

Date: Sun, 8 Nov 92 15:46:03 EST
From: John Roberts <[e-mail]>
Subject: Putting air on the moon

-From: [e-mail] (Bill Higgins-- Beam Jockey)
-Subject: Moon can hold its air (was Re: Mars over the Moon???)
-Date: 6 Nov 92 15:45:20 GMT
-Organization: Fermi National Accelerator Laboratory

-In article <[e-mail]>, [e-mail] (Dr.Savory) writes:
-> Any body to be terraformed should have sufficient gravity to retain
-> an atmosphere (obvious?), so exclude the moon, OK ;)

-This is unfair to the Moon.  If it were magically given an atmosphere,
-the Moon would retain it for a long time, at least thousands of years.

-As somebody already mentioned, the Moon is not a good candidate for
-terraforming because it has no large native source of volatiles.
-However, claiming that it can't hang on to an atmosphere is not valid
-for short timescales.

Another very good reason not to do this is that the moon is just
about the only readily accessible place where you can set up optical arrays
hundreds of miles across, and maintain the dimensions of the array to within
a fraction of a wavelength of light, and also not have to worry about
atmospheric turbulence. (You probably need active feedback to adjust for
thermal expansion, tides, etc., but that's easier than doing it over long
distances on the Earth, and much easier than controlling the spacing of
multiple spacecraft.) Once we get the 1AU-diameter optical array set up
beyond the orbit of Pluto, I withdraw the objection.

The formula I found for the diffraction resolution limit of a telescope
(which ought to be put in the FAQ list) is
  alpha = 2.1E5 x lambda / d
where alpha is the resolution in arc seconds, lambda is the wavelength
being observed, and d is the diameter of the telescope (same units as lambda).
If that's correct, then a 1000 km array on the moon could potentially give
a resolution at 10 light years of about 50 km. (Imagine mapping the continents
on the planets of nearby star systems!) Solar-system-size radio telescope
arrays don't need the same precision of placement of optical arrays, and
could potentially give even higher resolution, but getting sufficient
signal strength from planets might be an even greater problem than for
optical arrays.

-(Should I mention this?  Oh, what the heck, go ahead, Bill.  In the
-absolutely clunker TV series *Space 1999* there is an episode where
-precisely this happens: a mysterious alien cylinder suddenly gives the
-Moon a breathable atmosphere.
-...We see a shot
-from outside a window of Barbara Bain and Martin Landau watching this
-magic moment. Then one of them touches a control AND THE MOONBASE
-ALPHA WINDOW SLIDES OPEN ELECTRICALLY.

There's an even better example in the Mad Magazine version of "Lost in Space".

John Roberts
[e-mail]

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

Date: 8 Nov 92 06:24:00 GMT
From: Chris Hanson <[e-mail]>
Subject: Scandium and Osmium end-users
Newsgroups: sci.space

I am doing some research into current uses of Scandium
and Osmium 187.  Does anyone have information on
how these substances are used in industry and
manufacturing?  I am especially interested in
identifying end-users.

Thanks for your help.

Chris Hanson
E-mail:  [e-mail]
Telephone:  [phone]
Fax:  [phone]

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End of Space Digest Volume 15 : Issue 399
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