Date: Mon, 2 Nov 92 05:25:02 From: Space Digest maintainer 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 " 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" 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 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 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 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 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 Subject: Moving comets Newsgroups: sci.space In article 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 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 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@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 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 ------------------------------ 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 ------------------------------