Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Sun, 5 Nov 89 01:31:42 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 5 Nov 89 01:31:08 -0500 (EST) Subject: SPACE Digest V10 #206 SPACE Digest Volume 10 : Issue 206 Today's Topics: Re: Fragile Space Shuttle Design for Luna City Re: Moon Colonies / Ant Tanks? Re: Moon Colonies / Ant Tanks? Re: Moon Colonies / Ant Tanks? Re: Moon Colonies / Ant Tanks? Re: Moon Colonies / Ant Tanks? Re: Voyager/Galileo Camera function Re: Design for Luna City ---------------------------------------------------------------------- Date: 4 Nov 89 14:53:55 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: Fragile Space Shuttle (my thesis: it will never be practicable to design and build spacecraft that don't require checking with a fine toothed comb after every flight as the Shuttle does) In article <1989Nov4.071258.9854@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >First, will NASA ever find it practicable to do so? I think we both >agree that the answer is no, although perhaps for different reasons. :-) Or even for the same reasons. Personally I think if NASA found such a design they would have the designer assassinated -- it runs counter to everything NASA exists for. >Second, will *anybody* ever find it practicable to do so? ... [Max Hunter, who designed the Thor missile, says yes] ... [Max points out that the Shuttle uses a zillion times more people/launch than the kludgey, quirky, high tech SR-71] * The Thor is not a spacecraft in the sense of the current discussion. It was a wonderful vehicle and a masterpiece (I am sure) of design, but it was a nonreusable ballistic missile. Care and maintenance BETWEEN LAUNCHES was not a factor in design! I would be more overwhelmed to read the comments of someone who worked on X-15 or the shuttle. To paraphrase Hunter, going into space AND RETURNING and going again is not for the faint of heart! * Anyway his point seems to be that the Blackbird gets it done with fewer people, NOT that the checking doesn't have to be done. I have no problem with the assertion that we can recycle spacecraft a lot more efficiently (although there is a limit to what can be done with the current bird). Getting the man-hour numbers down is not the same as "landing, gassing up and taking off" though. Every subsystem *must* be checked. We just have to learn to do it at the flick of some switches rather than via ruinously expensive hand labor. ------------------------------ Date: 5 Nov 89 03:28:58 GMT From: amdahl!drivax!macleod@apple.com (MacLeod) Subject: Design for Luna City tneff@bfmny0.UU.NET (Tom Neff) says: :Oh by the way, if you have to burrow underground to survive in a :Moon colony, why bother to go? Why not just build underground :colonies here? Sure is easier to ship stuff here. If you have :to spend your whole life in the basement, how much does it matter :which basement? There are basements and basements. The first lunar cubics will be Spartan, but later developments - I'll bet - will take your breath away. I have been fooling around with designs for Luna City lately, based on long-held conceptions of what it would (should) look like. Unfortunately, I have very little visual imagination, so my vision is kind of a utilitarian right-angular conception. I won't try to draw it in ASCII graphics, but my design has a cubical center area a kilometer high surrounded by four cubic extensions a kilometer on a side. The center cube is filled, or unfilled, with a rhombic space (like a cube set on a vertex). Lunar gravity and modern materials should make it possible to build in the upper sides of the rhomboid without undue trouble, save for earthworms' queasyness. The open area inside would be available for human-powered flight, assuming that it's possible, and to give inhabitants a feeling of space. It also serves as an O2 and thermal reservoir. I have no idea how to light it. At the (whatever the opposite of apex is) of the rhomboid, at bottom level, is Heinlein Square, which is, or course, triangular. Each vertex has a bust - Heinlein, Wells, and Verne. The cubic spaces extending from the center area are a more mundane row-column-level scheme. Minor ways run 100 meters apart; major ways every 500 meters. There are 2 levels, plus utilities access passages, per 10 meters of hight, or 200 levels per kilometer. If you look down from above onn the city, you can see four lobes, which we can lable north, south, east, and west for convenience. Addresses would use Heinlein Square as a 0,0 coordinate, like Salt Lake City's use of Temple Square. In this scheme, your address would be something like 147,S6.77,E2. You live on level 147 about 677 meters south of the Square along the second way east of the square. Not a bad neighborhood; it's actually largely commercial, since it's so close to the Dome. Obviously elevator technology will be important...I envisioned half a dozen kinds of lifts, local, express, grab-strap-as-it-goes-slowly-by, commercial, industrial, and so on. Some private lifts might be located together in the core of a rectangular group of cubics to limit access to owners, and commercial lifts would likewise be located in the "rear" of shops. Now, I realize that Bechtel is not ready to run out and build this city, but you have to admit that it has room. For example, if we alot a 100 by 100 meter square - considerable space - to a family of four, that gives us space (in the lobes alone) for 1600 people per level, and we have 200 levels. With a comfortable allowance for industrial, commercial, and farm space, we should be able to maintain a quarter million in relatively spacious surroundings. This is a far cry from a basement. Oh, you want to go there >now > >How deep would you have to dig to get 1/6th earth gravity? :-) > > From what I learnt from school, I recall that the gravitational force > is inversely proportional to the distance between the center of masses. Hence > the gravitational force will increase as you go towards the center of the earth. WRONG! Or at least misleading. This probably belongs in the PHYSICS group, but since it was started here, I feel we need to CLEAR this up. If the EARTH were a uniform density object, the force of gravity would go DOWN as you dig into the earth. The reason is, that given the inverse square law, INSIDE a hollow sphere, there is no influence from that sphere. [See your typical college physics text for an explanation]. So all the dirt in the shells above you no longer pulls, Note, that for the earth, since the density in the center is higher, that as you dig a tunnel, gravity does indeed go up, since you are getting closer to a denser effective mass. Ihor Kinal STANDARD DISCLAIMER + I'm currently a software person - I haven't played at being a physicist for almost 20 years now. ------------------------------ Date: 4 Nov 89 16:38:35 GMT From: mailrus!jarvis.csri.toronto.edu!db.toronto.edu!hogg@tut.cis.ohio-state.edu (John Hogg) Subject: Re: Moon Colonies / Ant Tanks? In article <10450@vaxc.cc.monash.edu.au> cen466p@vaxc.cc.monash.edu.au writes: >>How deep would you have to dig to get 1/6th earth gravity? :-) > >From what I learnt from school, I recall that the gravitational force is >inversely proportional to the distance between the center of masses. Hence the >gravitational force will increase as you go towards the center of the earth. Good point. At least we have a very convenient singularity at the Earth's centre for the next time we want one, but we'll have to find another solution. But don't worry, I already have it. Since we have ~1G at the earth's surface, and ~0G in LEO, all we have to do is go *five sixths* of the way to orbit to get a nice 1/6th G to play around in. (Don't I have something better to do than waste bandwidth?) ------------------------------ Date: 4 Nov 89 20:02:43 GMT From: uceng!dmocsny@iuvax.cs.indiana.edu (daniel mocsny) Subject: Re: Moon Colonies / Ant Tanks? In article <1989Nov4.040318.20394@agate.berkeley.edu>, gwh@sandstorm.Berkeley.EDU (George William Herbert) writes: > In article <10450@vaxc.cc.monash.edu.au> cen466p@vaxc.cc.monash.edu.au writes: > >I recall that the gravitational force is inversely proportional to the > > distance between the center of masses. Hence the gravitational force > > will increase as you go towards the center of the earth. > > Nope. The force is inversely porportional to the distances and directly > porportional to the enclosed mass... anything beyond the distance > of the smaller object has no effect. You decrease off towards zero-g > within an object, with max. at the surface. Every atom of the earth exerts a gravitational attraction on every atom of a body at the earth's surface. The resultant of all the gravitational force vectors is a vector lying on the line through the center of masses of the two bodies. If the body is at or above the earth's surface, the resultant vector has the same magnitude as would result if the earth were really a point mass located where the center of the earth is now. If you dig down into the earth, part of the earth's mass is now above your head, gravitationally attracting you back upstairs. (Something similar happens if you are standing in a valley next to a large mountain...this throws off your surveyor's level, complicating the job of triangulating to obtain the mountain's height.) I believe that you can show with some calculus that the net gravitational force you feel a distance X away from the earth's center, with X cen466p@vaxc.cc.monash.edu.au writes: >In article <9987@attctc.Dallas.TX.US>, ltf@attctc.Dallas.TX.US questions >>How deep would you have to dig to get 1/6th earth gravity? :-) > >From what I learnt from school, I recall that the gravitational force >is inversely proportional to the distance between the center of masses. Hence >the gravitational force will increase as you go towards the center of the earth. That assumes we have two point masses. Once you dig underground, there is some mass of the earth pulling upward on you, and some still pulling downward, resulting in a smaller net force. -- Tom Egelston Internet: tlegelst@uokmax.ecn.uoknor.edu All opinions expressed are mine. Universities aren't allowed to have opinions. "I'm out of it for a little while and everyone gets delusions of grandeur!" -Captain Han Solo ------------------------------ Date: 4 Nov 89 23:41:15 GMT From: thorin!alanine!leech@mcnc.org (Jonathan Leech) Subject: Re: Moon Colonies / Ant Tanks? In article <127376@sun.Eng.Sun.COM> jmck@sun.UUCP (John McKernan) writes: >In a larger sense man's mass migration into space is exactly like his >migration to other parts of the Earth. Whenever it was possible to move to >an area with new resources to exploit, we have moved there and exploited >those resources. Once it is possible for mankind to move in large numbers >into space, all of man's history shows that it is inevitable that man >will do so. I suspect you've been reading too much Pournelle and Stine. People could move in large numbers to Antarctica or the ocean floor, but aren't doing so. The millenia+ delay between the enabling technology for crossing the Atlantic and large scale immigration to the New World provides no encouragement. -- Jon Leech (leech@cs.unc.edu) __@/ ``God is more interested in your future and your relationships than you are.'' - Billy Graham ------------------------------ Date: 4 Nov 89 11:35:40 GMT From: nuchat!steve@uunet.uu.net (Steve Nuchia) Subject: Re: Voyager/Galileo Camera function In article <2734@cbnewsl.ATT.COM> sw@cbnewsl.ATT.COM (Stuart Warmink) writes: >(Fred Kokaska) writes: >> Can the cameras on the Voyager and Galileo spacecrafts be aimed back at >Even if the cameras could be pointed in such a fashion, the picture would be >hopelessly out of focus...the depth of field of telelens cameras, especially What is "hopeless" with modern image processing? We have excelent knowledge of the optics, the imaging geometry, and the object being imaged. From what little I know about image processing I think that makes for a doable deal. -- Steve Nuchia South Coast Computing Services uunet!nuchat!steve POB 270249 Houston, Texas 77277 (713) 964 2462 Consultation & Systems, Support for PD Software. ------------------------------ Date: 5 Nov 89 05:16:31 GMT From: voder!dtg.nsc.com!andrew@ucbvax.Berkeley.EDU (Lord Snooty @ The Giant Poisoned Electric Head ) Subject: Re: Design for Luna City In article <2553A8FA.EEB@drivax.UUCP>, macleod@drivax.UUCP (MacLeod) writes: > tneff@bfmny0.UU.NET (Tom Neff) says: > :Oh by the way, if you have to burrow underground to survive in a > :Moon colony, why bother to go? Why not just build underground > :colonies here? Sure is easier to ship stuff here. If you have > :to spend your whole life in the basement, how much does it matter > :which basement? > > There are basements and basements. The first lunar cubics will be Spartan, > but later developments - I'll bet - will take your breath away. The one overriding factor which attracts me, for one, is that LOW GRAVITY ENVIRONMENT. This is not only enjoyable inside - simply getting around would be so ...unique, deserving of creative approaches, etc.... but, with the development of more flexible and less cumbersome vacuum-suits, R&R outside would truly be something to look forward to. Even scientists need a break from research, and what a place that would be to discover and participate in new kinds of sport and friendly competition. I truly don't think boredom is a problem; especially since, in the next decade, high-bandwidth telecomms will be prevalent, so Earthly diversions can be experienced and participated in, albeit vicariously. What a great place that would be to grow up. Just a few problems left like money, motivation and the supporting infrastructure... -- ........................................................................... Andrew Palfreyman a wet bird never flies at night time sucks andrew@dtg.nsc.com there are always two sides to a broken window ------------------------------ End of SPACE Digest V10 #206 *******************