Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.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 ; Wed, 19 Jun 91 03:10:26 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 19 Jun 91 03:10:20 -0400 (EDT) Subject: SPACE Digest V13 #665 SPACE Digest Volume 13 : Issue 665 Today's Topics: Re: Extra Terrestrial Intelligence Re: The Reasons for a Station? Was Re: Rational next station design... vacuum energies for propolsion Re: Galileo Antenna (was Re: Amputation) Alien Astrophysics Re: Info on spacecraft power storage wanted Re: Moonbase movie *Plymouth* to air Sunday? GIF Files satellite refuelling Re: vacuum energies for propolsion Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 27 May 91 21:09:06 GMT From: news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew!jdnicoll@rutgers.edu (James Davis Nicoll) Subject: Re: Extra Terrestrial Intelligence In article <1991May27.190658.18186@csun.edu> swalton@corona.csun.edu (Stephen Walton) writes: >In article <1991May26.182739.26492@agate.berkeley.edu> >fcrary@earthquake.Berkeley.EDU (Frank Crary) writes: >> >>Clusters are only violent and short lived on an astrononical time scale. >>On the scale of a civilization, they are quite constant. > >Doubt if you'd want to take the risk of a colony being wiped out by >a nearby supernova. If we learned anything from SN 1987A, we learned >that there is essentially no outward warning that a star is about to >blow. Besides, unless your putative colony ships take terraforming >technology along, there won't be any oxygen-atmosphere planets in >open clusters. Earth started with an N2-CO2 atmosphere which only >reached its present composition perhaps half a billion years ago. On that note, *if* Earth is typical, we shouldn't expect many worlds with free O2 in their atmospheres, where ever we look. We should expect most worlds that have life to have only single celled organisms, sice that was the case during most of Earth's existance. James Nicoll ------------------------------ Date: 28 May 91 08:47:48 GMT From: agate!usenet.ins.cwru.edu!magnus.acs.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!jarthur!nntp-server.caltech.edu!hamlet.caltech.edu!carl@ucbvax.Berkeley.EDU (Lydick, Carl) Subject: Re: The Reasons for a Station? Was Re: Rational next station design... In article , purtill@morley.rutgers.edu (Mark Purtill) writes... > Well, for one thing, we might actually like to find out what >happens to women for more than a few days. In case you haven't >noticed, the Russians haven't had any women cosmonauts for some time. >Judging by the comments from various Russians when the British sent a >female cosmonaut (along the lines of "women don't belong in space"), I >don't think it's likely that they'll be giving us any information on >this any time soon. (I omit pointing out that a year isn't really >very long only because someone else already has). > Flames that the Russians are right to /dev/null. Not a flame: Do you suppose it's possible that the reason the Russians no longer have female cosmonauts is that they found severe adverse biological effects? -------------------------------------------------------------------------------- Carl J Lydick HEPnet/NSI: SOL1::CARL Internet: CARL@SOL1.GPS.CALTECH.EDU ------------------------------ Date: 21 May 91 15:40:15 GMT From: agate!spool.mu.edu!sdd.hp.com!elroy.jpl.nasa.gov!jarthur!nntp-server.caltech.edu!ptimtc!rdmei!icspub!astemgw!kuis!rins!will@ucbvax.Berkeley.EDU (will) Subject: vacuum energies for propolsion Ok, so, a long long time ago I read this book by Clarke (The Songs of Distant Earth). Great Book. So in the ACKNOWLEDGMENTS there was this: The first suggestion that vacuum energies might be used for propulsion appears to have been made by Shinichi Seike in 1969. ("Quantum electric space vehicle"; 8th Symposium on Space Technology and Science, Tokyo) Ten years later, H.D. Froning of McDonnell Douglas Astro- nautics introduced the idea at the British Interplanetary Societies'-Interstellar Studies Conference, London (September 1969) and followed it up with two papers: "Propusion Require- ments for a Quantum Interstellar Ramjet" (JBIS. Vol. 33. 1980) and "Investigation of a quantum ramjet for interstellar flight" (AIAA Preprint 81-1534, 1981). Ignoring the countless inventors of unspecified "space drives," the first person to use the idea in fiction appears to have been Dr. Charles Sheffield, chief scientist of Earth Satellite Corporation; he discusses the theoritical basis of the "quantum drive" (or, as he has named it, "vacuum energy drive") in his novel "The McAndrew Chronicles" (Analog magazine 1981; Tor, 1983). An admittedly naive conclusion by Richard Feynman suggests that every cubic centimeter of vacuum contains enough energy to boil all the oceans of Earth. Another estimate by Jojn Wheeler gives a value a mere seventy-nine orders of magnitude larger. When two of the world's greatest physicists disagree by a little matter of severnty-nine zeroes, the rest of us may be excused a certain skepticism; but it's at least an interesting thought that the vacuum inside an ordinary light bulb contains enough energy to destroy the Galaxy... and perhaps, with a little extra effort, the Cosmos. In what may hopefully be an historic paper ("Extracting electrical energy from the vacuum by cohesion of charged foliated conductors, "Physical Review, Vol. 30B, pp. 1700-1702, August 15, 1984) Dr. Robert L. Forward of the Hughes Research Labs has shown that at least a minute fraction of this energy can be tapped. If it can be harnessed for propulsion by anyone besides science-fiction writers, the purely engineering problems of interstellar - or even intergalatic - flight would be solved. But perhaps not. I am extremly grateful to Dr. Alan Bond for his detailed mathematical analysis of the sheilding nessasary for the mission described in this novel and for pointing out that a blunt cone is the most advantageous shape. It may well turn out that the factor limiting high-velocity interstellar flight will not be energy but ablation of the shield mass by dust grains, and evaporation by protons. The history and theory of the "space elevator" will be found in my address to the Thirtieth Congress of the International Astronautical Federation, Munich, 1979: "The Space Elevator: 'Thought Experiment' or Key to the Universe?" (Reprinted in Advances in Earth Orientated Applications of Space Technology, Vol. I, No. 1, 1981, pp.39-48 and Ascent to Orbit: John Wiley, 1984). I have also developed the idea in the novel The Fountains of Paradise (Del Rey, Gollancz, 1978). The first experiments in this direction, involving paylaods lowered into the atmosphere on hundred-kilometer long "tethers" from the space shuttle, will be commencing around the time this novel is published. END...... Robert Forward's paper is very good and people serious in this should get it. William Dee Rieken Researcher, Computer Visualization Faculty of Science and Technology Ryukoku University Seta, Otsu 520-21, Japan Tel: 0775-43-7418(direct) Fax: 0775-43-7749 will@rins.ryukoku.ac.jp ------------------------------ Date: 28 May 91 22:01:10 GMT From: unmvax!uokmax!rwmurphr@ucbvax.Berkeley.EDU (Robert W Murphree) Subject: Re: Galileo Antenna (was Re: Amputation) The sky and telescope newsline (featuring Kelly Beatty) had an item on the Gaspara flybye in October 91. Seems the antennae failure means that they won't be able to have a close flybye unless the antennae gets fixed. Maybe it said it would be mostly a stellar occultation event and not result in very much close-up imagery. Anyway no more 600 km flybyes for now ------------------------------ Date: 29 May 91 04:12:59 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!spool.mu.edu!rex!rouge!pc.usl.edu!dlbres10@ucbvax.Berkeley.EDU (Phil Fraering) Subject: Alien Astrophysics I wrote: pf>Well, the combination of proximity given by interstellar travel and pf>more advanced science will probably give the colony plenty of warning pf>if the star is indeed about to blow up. And Stephen Walton replied: sw>It won't. The post-helium-burning stages of fusion in massive stars sw>(fusion of carbon, neon, oxygen, and silicon) last less than 1,000 sw>years each, much less than the Kelvin-Helmholtz time scale for the sw>star's envelope. The time from the start of iron production to sw>core collapse is less than 24 hours. At most, they'd get a few hours sw>warning if they had neutrino detectors, because the neutrinos come sw>straight from the core while the explosion has to propagate through sw>the star's outer layers. [References deleted but good] Actually, they'd be able to tell that fusion in general had stopped because they wouldn't be registering anything on their neutrino detectors :-) Seriously, long before we send a manned colonizing mission to other stars, the amount of time stars have been studied since Eddington did the basic groundlaying work back in the 1910-1930 time period will have doubled. Anyone actually trying to colonize the galaxy will have been studying stars a lot longer than we have, and know much much more astrophysics. You mentioned in one of the references about the 1987A Supernova. Didn't that event alone make a lot of the theories about Supernovae at the time obsolete? I remember reading Astronomy magazine's articles on cosmology back ten to twelve years ago; I just got in from substitute teaching an Astronomy course at the University'd Dept. of Continuing Ed. Cosmology, so I gather from the recent background material I read for the course, has changed a lot. I also took a similar course for bright junior high/high school students about 13 years ago, where I was taught about the only known extrasolar planets orbited Barnard's Star. Those results are not today considered valid, and the current "best candidates" for extrasolar planets change yearly. And should I mention the Solar Neutrino problem to show how much we still have to learn? Phil Fraering || Usenet (?):dlbres10@pc.usl.edu || YellNet: 318/365-5418 Standard disclaimer, whatever a disclaimer is, applies. ''It hardly mattered now; it was, in fact, a fine and enviable madness, this delusion that all questions have answers, and nothing is beyond the reach of a strong left arm.`` - Larry Niven and Jerry Pournelle, _The Mote in God's Eye_ ------------------------------ Date: 29 May 91 06:51:28 GMT From: agate!lightning.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: Info on spacecraft power storage wanted In article <31912@rouge.usl.edu> dlbres10@pc.usl.edu (Phil Fraering) writes: >The title just about says it all. I'm looking for the best >currently well understood stable technology for temporary >power storage, and I'd like statistics like power out/power in >and kg/kw stored. I'm not exactly sure what you mean by "stable." I assume it rules out capacitors, which are not good for long term storage. I do not know about fly-wheels, but I have some numbers on batteries: Secondary (or Rechargable) Batteries: Ni-Cd: >25,000 cycles, 36 W-hr/kg Ag-Zn: <50 cycles, ~100 W-hr/kg Advanced Stuff: (E.g. in labs but not production) Varrious materials, usually >500 cycles, 100-200 W-hr/kg. Frank Crary UC Berkeley ------------------------------ Date: 29 May 91 13:41:18 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!caen!news.cs.indiana.edu!ux1.cso.uiuc.edu!edotto@ucbvax.Berkeley.EDU (Ed Otto) Subject: Re: Moonbase movie *Plymouth* to air Sunday? koreth@twitterpater.Eng.Sun.COM (Steven Grimm) writes: >My housemate pointed out that the whole sequence inside the colony where people >were scurrying for the radiation shelters was silly. The whole colony, or at >least all the living areas, would have to be shielded; otherwise, wouldn't all >those pretty plants have to be ripped out and replaced after every severe >solar flare? Actually, not. All of those plants were in the greenhouse which was probably buried - I saw no windows in the several shots of it they had. AND, the shelters were set up for people; the greenhouse was set up for plants. ******************************************************************************* * * Netmail addresses: * * Edward C. Otto III * edotto@uipsuxb.ps.uiuc.edu * * University of Illinois * edotto@uiucux1.cso.uiuc.edu * * Printing Services Office * UIPSA::OTTO (Decnet node 46.99) * * 54A E. Gregory Dr. * otto@uipsa.dnet.nasa.gov * * Champaign, IL 61820 * Office phone: 217/333-9422 * * * * ******************************************************************************* "As knowledge is to ignorance, so is light unto the darkness." --- GO 'PODS! --- -- ******************************************************************************* * * Netmail addresses: * * Edward C. Otto III * edotto@uipsuxb.ps.uiuc.edu * * University of Illinois * edotto@uiucux1.cso.uiuc.edu * ------------------------------ Date: 29 May 91 02:14:37 GMT From: munnari.oz.au!yoyo.aarnet.edu.au!sirius.ucs.adelaide.edu.au!ra!conway@uunet.uu.net (Catherine Conway) Subject: GIF Files Not sure if I am am spelling it correctly ;-) but can anyone tell me where I can get GIF pictures (in particular those sent back from Maggellan) from? FTP is OK. Please reply by mail as I may miss the reply in this newsgroup. Regards Catherine Conway conway@tais.telecom.com.au Adelaide, South Australia ------------------------------ Date: 29 May 91 20:00:06 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo!henry@ucbvax.Berkeley.EDU (Henry Spencer) Subject: satellite refuelling In article <1991May29.184556.10643@sequent.com> szabo@sequent.com writes: >... It costs more in complexity and energy >to refuel than to launch sufficient fuel in the first place. Unless you're up against something like a launcher weight limit, that is. Spacecraft with maneuvering engines usually carry every milligram of fuel that can possibly be loaded in, and not infrequently they would benefit from more if they only could carry it. One has to weigh the cost of a refuelling mission against the cost of a larger launcher and larger satellite; it is not at all clear that the balance is always against refuelling. -- "We're thinking about upgrading from | Henry Spencer @ U of Toronto Zoology SunOS 4.1.1 to SunOS 3.5." | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 29 May 91 23:49:00 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!execu!sequoia!jkg@ucbvax.Berkeley.EDU (John K. Gibbons) Subject: Re: vacuum energies for propolsion The argument that the energy of the vacuum is the zero-point and thus cannot be extracted may miss the point of proposed vacuum energy drives as thoroughly as the NY Times famous editorial about "no air to push on" missed the point about rocketry principals [:-)]. The starting assumption of such vacuum drive ideas is either that a) vacuum fluctuation continuosly produces particle-antiparticle pairs which almost immediately annihilate each other, or b) the vacuum state we are familiar with is not truly a zero-energy state, but is in some sense a "local minimum" that could be pushed over a barrier and then allowed to fall to an even lower state, thereby producing energy. Idea (a) continues by supposing some mechanism to extract useful energy from the anihilation of the particle pairs. This presents several apparently insoluable problems, as it is the energy of that anihilation that created the pair in the first place, and the whole concept smells very bad from a QM viewpoint. On the other hand, we know damned little about what is happening at the Planck length, where vacuum fluctuations become significant. Idea (b) is not quite as crazy as it sounds at first hearing, because it is based on the inflationary theories of the Big Bang, which suggest that precisely such a phenomenon occurred at an early stage of the universe. Supposedly the original "vacuum state" was actually a "false vacuum" at an incredibly high energy level above the current "true vacuum". This is theorized to have decayed into true vacuum at the time that symmetry breaking separated the strong force from the electro-weak, and the consequent release of energy far exceeded the original Big Bang. Supposing yet another level of vacuum energy even lower than ours is not incredible, but triggering a conversion would be outside of any known physics. It might also be rather dangerous... :-) (A great SF story on this back in July 88 Asimov's) I hope I haven't mangled the physics too bad. Before you flame, please note that I don't suggest this has any measurable probability of working. I would place it on about the same likelihood as time travel. -- ---------------------------------------------------------------------------- John K. Gibbons | UUCP: ...!cs.utexas.edu!execu!jkg Comshare, Inc. Austin, Tx. | Internet: execu!jkg@cs.utexas.edu #include "std.disclaimer" | jkg%execu.uucp@cs.utexas.edu ---------------------------------------------------------------------------- ------------------------------ End of SPACE Digest V13 #665 *******************