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Date: Mon, 2 Nov 92 05:25:02
From: Space Digest maintainer <digests@isu.isunet.edu>
Reply-To: Space-request@isu.isunet.edu
Subject: Space Digest V15 #370
To: Space Digest Readers
Precedence: bulk
Space Digest Mon, 2 Nov 92 Volume 15 : Issue 370
Today's Topics:
ANSWER: Recognizing a Dyson sphere if you saw one
Automated space station construction
Limits to growth of knowledge
low earth orbits
Moving comets
NASA Coverup (2 msgs)
Swift-Tuttle Comet a threat to earth?
the Happyface on Mars
Why Vote?
Welcome to the Space Digest!! Please send your messages to
"space@isu.isunet.edu", and (un)subscription requests of the form
"Subscribe Space <your name>" to one of these addresses: listserv@uga
(BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
(THENET), or space-REQUEST@isu.isunet.edu (Internet).
----------------------------------------------------------------------
Date: 2 Nov 92 01:01:15 GMT
From: "Alan M. Carroll" <carroll@cs.uiuc.edu>
Subject: ANSWER: Recognizing a Dyson sphere if you saw one
Newsgroups: sci.astro,sci.space
> Did you look at Dyson Spheres suspended on light-presuure?
> They require less mass (They better *have* less mass to float on
> light) and I don't think they suffer the same forces.
In _Farthest Star_, the (solid) Dyson sphere is supported via momentum
transfer effects, in the same way the stations in a Lofstrom Loop
would be supported.
P.S. To solve the mass problem, the Builders were a galactic
civilization and built a single Dyson sphere, i.e. they used entire
other solar systems for material.
--
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: 2 Nov 92 01:28:25 GMT
From: Andrew Haveland-Robinson <andy@osea.demon.co.uk>
Subject: Automated space station construction
Newsgroups: sci.space
In article <1992Oct31.023129.9034@access.usask.ca> choy@skorpio.usask.ca (I am a terminator.) writes:
>Can robots be launched to build the space station? They can work overtime.
>
>Henry Choy
>choy@cs.usask.ca
Of course they could - this is just another area where Virtual Reality
will come into its own...
Virtual space travel and construction is much safer than the real thing!
Major cock-ups needn't involve loss of life, so I think this should
justify more VR space research...
(They don't need feeding or oxygen and don't produce any awkward waste
either... )
Anyone know what's going on?
Andy.
+-----------------------------------------------------------------------+
| Haveland-Robinson Associates | Email: andy@osea.demon.co.uk |
| 54 Greenfield Road, London | ahaveland@cix.compulink.co.uk |
| N15 5EP England. 081-800 1708 | Also: 0621-88756 081-802 4502 |
+-----------------------------------------------------------------------+
>>>> Those that can, use applications. Those that can't, write them! <<<<
------------------------------
Date: Sun, 1 Nov 92 15:19:35 EST
From: John Roberts <roberts@cmr.ncsl.nist.gov>
Subject: Limits to growth of knowledge
-From: arromdee@jyusenkyou.cs.jhu.edu (Ken Arromdee)
-Subject: Re: Comet Collision
-Date: 30 Oct 92 18:16:16 GMT
-Organization: Johns Hopkins University CS Dept.
-In article <Bwxqxw.sq.1@cs.cmu.edu> amon@elegabalus.cs.qub.ac.uk writes:
->You are guilty of the classic fallacies of extrapolation. The first
->fallacy is an overestimate of short term advance. The second is the
->underestimate of the long term. Both are due, in part, to linear
->thinking, straight line extrapolation. Technological capabilities and
->knowledge are accumulating exponententially. If you make a linear
->extrapolation in a particular field, you will tend to "draw a line"
->of some slope that seems "reasonable". But the problems invariably
->turn out to be more difficult in your field than you actually
->believed. So the exponential will for some period of time grow
->slower (lesser slope) than your line, but when it finally does cross
->it...
-There was a non-fiction article in Analog (a science fiction magazine) around
-1960. The author pointed out exactly what you do here: lots of ideas about the
-future are extrapolated linearly. He graphed the maximum speed that human
-beings could travel at, as an example, and showed that it increased faster than
-even an exponential.
-The curve also showed, however, that (by extrapolation) humanity would surpass
-the speed of light by the year 1985.
-I believe that in the 1980's he (or someone, anyway) wrote another article
-recognizing the existence of S-shaped curves that eventually level off.
-The moral is that some barriers can't be found by extrapolation from points
-before the barriers have any significant effect. It's legitimate to argue that
-advances require solving a difficult or impossible problem; just noting that
-you can graph past that point is not an answer.
-(How do you conclude that technological capabilities are accumulating
-exponentially, anyway?)
There's a limit to growth of knowledge that doesn't seem to be getting as
much attention as it warrants in light of the seriousness of the problem:
the huge amount of information now available is pushing the limits of the
traditional library system.
If I need a specific item of physics or technology for a calculation, I can go
to the library and look through the Handbook of Chemistry and Physics,
Eshbach's Handbook of Engineering Fundamentals, and various encyclopedias.
If I can get the information there, then all's well, and I can often find it
in a few minutes to an hour. However, there is a considerable amount of
information in those publications that is not adequately covered in the
index, so I may have to think of all the related topics and run an
exhaustive search through them, which could take hours. If the information
is not there, I have to look for the specialized books and periodicals that
cover the topic (we do have a computerized card catalog, which helps
considerably with this). The specialized books tend to have pretty poor
indexes, so I often end up having to read a considerable portion of each
book to see if what I need is there. Sometimes the book is not available
locally, and it may take days to weeks to find a copy. (Assuming I don't
get fed up and postpone the entire line of investigation.)
When I finally find the information, it is often expressed in terms that are
highly specific to that particular field of study, since specialized books
are mainly intended for specialists. So I may have to study the subject for
days just to convert the information to a form that I can use.
The end result is that I may have to spend hours to weeks just to assemble
the information I need, before I can begin to work on my own design or
calculation. That's the status quo, and researchers seem to accept it more
than complain about it. But it does slow down further advances considerably,
and the problem continues to get worse as more information is added.
I think much greater use of computer technology can aid substantially in
dealing with this problem. Data bases, pattern searches, and greatly
improved indexing offer considerable hope. For instance, when the Grolier's
Encyclopedia came out on CD-ROM, magazine articles claimed that it had an
exhaustive index generated in advance by computer, which is actually larger
than the text of the encyclopedia itself. With aids such as these, research
time can potentially be cut tremendously. (Anyone know whether the CRC and
Eshbach's handbooks are available on CD-ROM yet?)
Another change that's very important in the long run for cross-pollination of
different fields is to make the notation and terminology more uniform, and
to include more explanations in the text - with conversion to electronic
format, the pressure to condense the text as much as possible to minimize
the number of printed pages is greatly reduced. Ideally, much of the
information in specialized fields would be usable by non-specialists
for peripherally related projects.
Putting reference materials on CD-ROM is a considerable step forward, but
perhaps an equally important advance is the development of huge centralized
data bases that can be accessed by multiple users. Having multiple terabytes
on-line at all times can nearly eliminate the task of sorting through stacks
of CD-ROMs. Fully implementing this may require changes in policies toward
copyrights and royalties.
Additions can also be made to the field of indexing. A permuted index (?)
allows the researcher to find every instance of a term in the text. It's
also possible (though very difficult) to create a "search tree", in which
the researcher enters one or more keywords or phrases, and the system
responds with a suggested range of topics that are relevant. (For instance,
to go back to the encyclopedia example, entering "Thomas Jefferson" might
bring a response of "President", "US History", etc., and entering "Thomas
Jefferson" and "Monticello" might produce "architecture".) This might be
an interactive system, in which the user is led through a sequence of topics
to find what is needed. (Encyclopaedia Britannica has one volume that
essentially does this. I don't usually find that implementation particularly
helpful, but at least it's a step in the right direction, within the limits
of what can be done in a printed format.)
For the present, and at least for specific topics, the computer networks
are a valuable resource. It's not too difficult to select interesting
posts and file them by category, after which they can be searched by topic
or by pattern match. Even without a regular data base program, "grep" is
usually fast enough to produce useful results.
And of course the frequently-asked-questions list is very helpful, though
I'd like it to be much bigger than it is, and to include a section for
speculative proposals and calculations, so at least people can see what's
been discussed before, and in how much detail. (Maybe a section for
calculations and proposals that have to be "refereed" by independent checks
before they can "graduate" to the main body of the list.)
John Roberts
roberts@cmr.ncsl.nist.gov
------------------------------
Date: 2 Nov 92 03:27:44 GMT
From: Adrian Hassall Lewis <u926135@tasman.cc.utas.edu.au>
Subject: low earth orbits
Newsgroups: sci.space
I admit that this is a bit of a dumb question, but I have had absolutely
no luck trying to find an explanation in any textbook on space dynamics.
The question: Why is 28.5 degrees such a common orbit?
I can understand the US launching to this inclination as the KSC is at 28.5N,
but I've read that the ESA also launches to this orbital plane as well. Isn't
it most efficent for them to launch to a 1 degree orbit? Is it something to do
with GTO? and if so, what?
Any help greatly appreciated.
Adrian.
------------------------------
Date: 2 Nov 92 01:21:11 GMT
From: Andrew Haveland-Robinson <andy@osea.demon.co.uk>
Subject: Moving comets
Newsgroups: sci.space
In article <Bwypxr.Au5.1@cs.cmu.edu> roberts@cmr.ncsl.nist.gov (John Roberts) writes:
>
>-From: henry@zoo.toronto.edu (Henry Spencer)
>-Subject: Re: Scenario of comet hitting Earth
>-Date: 29 Oct 92 18:16:02 GMT
>
>-Bombs are actually a relatively good way to move asteroids. Comets
>-are a difficult case, because they are probably fragile and because they
>-probably have a thin crust with concentrated volatiles underneath. A
>-small nearby nuclear explosion would blow off the crust on one side, and
>-the result would be a tremendous spill of gas from the comet itself.
>-If you knew what you were doing, and did it carefully, this could permit
>-steering a comet with far less effort than the brute-force approach.
>
>How far could a well-placed 10-magaton explosion divert the path of
>Swift-Tuttle over the course of 120 years?
>
>I've seen calculations of this type in the past, but I don't have access
>to them now.
>John Roberts
>roberts@cmr.ncsl.nist.gov
An awful lot I should think... 1000kg of Semtex would probably be enough..
I read once that the average underground nuclear explosion created spaces
in rock half a mile across. (Anyone confirm this?)
This is a big fraction of the size of the comet and would cause a big
perturbation in the orbit. If this could be directed at one of the
poles then is should throw it far enough out of the ecliptic plane to
not be a problem...
Of course, if they were really clever they'd get put it on a trajectory
into the Sun!
Andy.
+-----------------------------------------------------------------------+
| Haveland-Robinson Associates | Email: andy@osea.demon.co.uk |
| 54 Greenfield Road, London | ahaveland@cix.compulink.co.uk |
| N15 5EP England. 081-800 1708 | Also: 0621-88756 081-802 4502 |
+-----------------------------------------------------------------------+
>>>> Those that can, use applications. Those that can't, write them! <<<<
------------------------------
Date: Sun, 01 Nov 92 11:09:42 PST
From: snarfy@cruzio.santa-cruz.ca.us
Subject: NASA Coverup
Newsgroups: sci.space,alt.conspiracy
snarfy to NASA Physicists - "YOU'RE ALL BUSTED!"
According to conventional theories of science , the Moon (Luna) has only
1/6th of the Earth's gravity. Newton formulated his famous Laws of
Universal Gravitation in 1666 which led to this conclusion. This
conclusion was based on assumptions that (1) The density and composition
of the moon was similar to the earth's, and (2.) This density and
composition was fairly uniform throughout the lunar globe.The calculated
mass of the moon would not be sufficient to cause very significant
density increases as one approached the moon's center of gravity. It has
never been disputed , nor do I dispute here that the gravitational pull
that one body has upon another depends on the product of the masses of
the two bodies divided by the distance between them.
These assumptions and observations, taken together , lead one to the
conclusion that the moon has "1/6" of the earth's gravitational pull at
it's surface. This figure has been accepted for centuries. In a
pre-Apollo Astronomy textbook "Exploration of the Universe" by George
Abell (Holt ,Reinhart 1966), there is a statement on page 179 that ,given
the formula a=G*(M/R^2)
where G is the Gravitational Constant
it follows that :
a(moon)/a(earth) = 1/81.3/(.273)^2 = .165 ( @ 1/6 )
This calculation is apparently based on the observed distance of 2903
miles of the earth's distance from the earth-moon barycenter as that
distance is divided into the observed distance to the moon. This
calculation yields a distance to the moon of 81.3 times the distance of
earth's center to the barycenter, locating this barycenter well inside
the earth.
Throughout the fifties and sixties , the so called "neutral point" where
the gravitational forces of the earth-moon system balance,was given over
and over again as being between 22,100 and 25,200 miles from the surface
of the moon in the direction of the earth. These figures were presumed to
represent logical guesses from trained scientists. However , it is
acknowledged in Abell's book that only by observing falling or orbiting
bodies in the moon's vicinity could the actual neutral point distance,
hence the moon's true gravity , be determined.
Using the above neutral point and assumed gravity for their
calculations, the U.S. and the Soviet Union began to send space probes to
the moon in the late fifties. They met with miserable failure. The
Russians were first to launch a successful probe , Luna 1 , on January 2,
1959. It flew to within 4660 miles of the moon and broadcast back
information before continuing into deep space. The U.S. made three
unsuccessful attempts before achieving a fly-by of 37,000 miles from the
surface some months after luna 1 with Pioneer 4. The Russian's Luna 2
became the first space probe to hit the moon and Luna 3 circled the far
side of the moon, approached within 4,372 miles, and sent back photos of
the far side. Strangely , Russian moon exploration came to a four year
stop after these successes. Furthermore the Russians were intensely
secretive about the data they collected.
The American efforts were almost laughable at first. The Ranger space
probes were designed to hard land with seismometers in spherical
containers intended to withstand the impacts. Ranger 3 , launched on
January 26th 1962 ,missed it's target completely and went into a solar
orbit. Ranger 4 hit the moon but did not send back any usefull
information. Ranger 5 missed the moon by 450 miles and then the effort
was put off for two years while the entire program was re-organized. It
was evident that something was wrong with their calculations.
Ranger 6, launched on January 30th 1964, allegedly had it's electrical
system burn out in flight and no pictures were sent. Subsequent Ranger
Probes were more successful . The Russians reactivated their space
probes , but their Luna 5, launched on May 9, 1964, crashed at full speed
on the moon, when it was intended to make a soft landing. Luna 6 utterly
missed the moon , and Luna 7 crashed on the the moon's surface when it's
retro rockets supposedly fired too soon. Luna 8 also crashed on the moon,
but Luna 9 became the first probe to succesfully soft land.
Missions became more successful after this, this possibly attributable
to the notion that the Soviets and the Americans had been able to
recalculate the neutral point and the correct gravity of the moon from
the many failures (and few successes).
The strangest thing to come out of the re-analyzing of " observing
bodies falling toward and orbiting the moon " was for NASA to come up
with a new neutral point between the Earth and the moon. This then
becomes the key to a possible "NASA Coverup" .
The July 25th , 1969 issue of TIME magazine stated that the neutral
point was 43,495 miles from the center of the moon. Werner von Braun
stated in the 1969 edition of "History of Rocketry and Space Travel" that
the neutral point was 43,495 miles the center of the moon . The
pre-Apollo distances were given as 20,000 to 25,000 miles from the center
of the moon. NASA , it appears, had re-calculated the neutral point,
which would indicate that the moon's gravity is not 1/6th, as Newton had
stated.
Using the inverse square law to calculate gravitational effects at a
given distance ,we derive that the weight of an object at a distance D
from the center of a gravitating body ,and Ds equaling the radius of that
body , the gravitational effect Wd at that distance = (Ds/D)^2 of the
weight on the surface of that body.
Therefore,
The figure of 43,495 miles from the moon's center for the neutral point
given above by Time magazine represents a relative gravitation of the
moon compared to the earth of approximately 64% !
SIXTY FOUR PERCENT (!)
The problems this figure represents for the allegation that we actually
landed and lifted off from the moon using conventional rockets is
obvious.
NASA physicists..... YOU ARE withholding the truth from the American
People. If you want to argue about the merits of my calculations
fine,let's flame! You are going to lose.
Below is an ascii printout of a GWBasic language computer program I wrote
to aid in my calculation process.To those accustomed to mathematical
sophistry, it may seem a rather inelegant number cruncher, but it is
based on straightforward math right out of one of Beiser's physics texts.
For those of you not using DOS machines or not otherwise familiar with
how to load and run a GWbasic ascii file program , download this file and
remove this text with a word processor. Rename the resulting file with a
".bas" extension , for example:"moongrav.bas". Put the file into the same
directory as the GW or IBM Basic interpreter program. At the Dos prompt
"C>" Type "GWBASIC moongrav". Hit F2 (RUN) and answer the questions
presented.
"The Laws of Physics just went out the window!"
"and why shouldn't they...their so inconvenient!"
-Dialog overheard on "Star Trek-the Next Generation ", Halloween
Night, October 31,1992
------------------------Remove this line and above-----------------------
10 INPUT "Weight of object on earth surface ";Z
20 INPUT "Postulated weight of same object on moon surface ";ZM
30 GMOON=ZM/Z
40 PRINT "Moon Gravity =";GMOON;" Earth gravity"
50 INPUT "Estimated MAXIMUM Neutral Point distance from moon center ";EMAX
60 INPUT "Estimated MINIMUM Neutral Point distance from moon center";EMIN
70 X=4000:XM=1080:MD=238857!:SP=MD-EMAX
80 YE=SP
90 A=X/YE
100 B=A^2
110 WE=B*Z
120 YM=EMAX
130 A=XM/YM
140 B=A^2
150 WM=B*ZM
160 PRINT "Calculating, please wait"
170 IF WE>WM THEN 180 ELSE 210
180 YE=YE+50
190 EMAX=YM-50
200 GOTO 90
210 PRINT "Moon weight = ";WM;" lb "
220 PRINT "Earth weight =";WE;" lb"
230 PRINT "Neutral Point :";YM;" miles from moon center."
------------------------------
Date: Mon, 2 Nov 1992 03:18:18 GMT
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: NASA Coverup
Newsgroups: sci.space,alt.conspiracy
In article <4578@cruzio.santa-cruz.ca.us> snarfy@cruzio.santa-cruz.ca.us writes:
> NASA physicists..... YOU ARE withholding the truth from the American
> People...
Oh, come now. A conspiracy that large, held together for that long? In
a government that couldn't suppress Watergate or Iranscam? Come now.
This is laughable.
I also note that the conspiracy must extend to Japan, since their first
near-Moon navigation efforts, for Hiten, worked flawlessly.
>If you want to argue about the merits of my calculations...
What merits? Just for starters, your calculations assume that the Earth
and Moon are motionless with respect to each other. This will not yield
physically meaningful answers; the Moon's orbital motion (and thus that
of the neutral point) is *not* negligible. Indeed, you get a better first
approximation for lunar trajectories by assuming that the Moon's mass is
zero than by assuming that its velocity is zero.
--
MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology
-Hal W. Hardenbergh (1985)| henry@zoo.toronto.edu utzoo!henry
------------------------------
Date: 1 Nov 92 16:38:56
From: Steinn Sigurdsson <steinly@topaz.ucsc.edu>
Subject: Swift-Tuttle Comet a threat to earth?
Newsgroups: sci.astro,sci.space
In article <1992Oct30.134857.23107@esfra.sub.org> holger@esfra.sub.org (Holger Stegemann) writes:
steinly@topaz.ucsc.edu (Steinn Sigurdsson) writes:
>In article <ALTI.92Oct28201543@tanera.dcs.ed.ac.uk> alti@dcs.ed.ac.uk (Thorsten Altenkirch) writes:
> I understand that it is pretty unlikely that Swift-Tuttle will hit
> earth in 2126. However, I would like to know what would happen in the
> case such a big object would collide with our planet? I am not sure
>You die, I die, Everybody dies!
Calm down. Do you expect to live until 2126? OK.
No, I expect I'll be long dead of frustration as an ever decreasing
fraction of the population retains the ability to recognise allusions.
(I'll refrain from claiming it is a literary allusion in deference
to the sensibilities of some of my colleagues...)
| Steinn Sigurdsson |I saw two shooting stars last night |
| Lick Observatory |I wished on them but they were only satellites |
| steinly@lick.ucsc.edu |Is it wrong to wish on space hardware? |
| "standard disclaimer" |I wish, I wish, I wish you'd care - B.B. 1983 |
------------------------------
Date: Sun, 1 Nov 1992 23:25:45 GMT
From: Ed McCreary <mccreary@sword.eng.hou.compaq.com>
Subject: the Happyface on Mars
Newsgroups: sci.space,sci.astro
Well, I'm happy, I received my Mars CDROMs in just the other
day. I like to find the images that show the "Happyface" on
mars and the Kermit the Frog. If anyone has either the Lat/Long.
or the image id of the pics, I'd appreciate hearing from you.
I've got the both the raw and the MDIM sets.
--
In the midst of the word he was trying to say,|McCreary@sword.eng.hou.compaq.com
In the midst of his laughter and glee, |Me, speak for Compaq?
He had softly and suddenly vanished away--- |Yeah, right.
For the Snark *was* a Boojum, you see. |#include <stddisclaimer.h>
------------------------------
Date: 2 Nov 92 07:33:33 GMT
From: U56503@uicvm.uic.edu
Subject: Why Vote?
Newsgroups: talk.abortion,soc.motss,sci.space
WHY VOTE?
The reward of a thing well done
is to have done it.
--Emerson
One never notices what has been done;
One can only see what remains to be done.
--Marie Curie
Everyone feels instinctively that
all the beautiful sentiments in the world
weigh less than a single lovely action.
--James Russell Lowell
Democracy is the recurrent suspicion that
more than half of the people are right
more than half of the time.
--E.B. White
I believe that every right implies a
responsibility; every opportunity, an
obligation; every possession, a duty.
--John D. Rockefeller, Jr.
The bitterest tears shed over graves are
for words left unsaid and deeds left
undone.
--Harriet Beecher Stowe
A right is not what someone gives you;
it's what no one can take from you.
--Ramsey Clark
When written in Chinese the word crisis
is composed of two characters. One
represents danger and the other
represents opportunity.
--John Kennedy
Eternal vigilance is the price of
liberty--power is ever stealing from the
many to the few.
-- Wendell Phillips
An idealist believes that the short run
doesn't count. A cynic believes the long
run doesn't matter. A realist believes
that what is done or left undone in the
short run determines the long run.
--Sydney J. Harris
In the long-run, every Government
is the exact symbol of its People,
with their wisdom and unwisdom.
--Thomas Carlyle
America. . . . It is a fabulous
country, the only fabulous country;
it is the only place where miracles
not only happen, but where they happen
all the time.
--Thomas Wolfe
I shall be telling this with a sigh
Somewhere ages and ages hence;
Two roads diverged in a wood, and I--
I took the one less traveled by,
And that has made all the difference.
--Robert Frost
.-~~-.--.
: VOTE )
.~ ~ -.\ /.- ~~ .
> VOTE `. .'VOTE <
( .- -. )
`- -.-~ `- -' ~-.- -'
( VOTE : VOTE ) _ _ .-:
~--. : .--~ .-~ .-~ }
~-.-^-.-~ \_ .~ .-~ .~
\ \' \ '_ _ -~
`.`. //
. - ~ ~-.__`.`-.//
.-~ . - ~ }~ ~ ~-.~-.
.' .-~ .-~ :/~-.~-./:
/_~_ _ . - ~ ~-.~-._
~-.<
VOTE! AS IF YOUR FUTURE DEPENDED ON IT
--IT DOES!
------------------------------
End of Space Digest Volume 15 : Issue 370
------------------------------