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 ; Fri, 16 Feb 90 01:42:44 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 16 Feb 90 01:42:22 -0500 (EST) Subject: SPACE Digest V11 #51 SPACE Digest Volume 11 : Issue 51 Today's Topics: Re: inter stellar travel ??? What is ' SPACE DIGEST V11 #18 ' ??? Re: Recreation in Space Re: Galileo Update - 02/12/90 Base 12 Re: Fun Space Fact #1: Launcher Development Costs Re: Why we would need a planet. Re: Galileo Update - 02/12/90 Re: Spacecraft drives and fuel efficiency Re: Galileo Update - 02/12/90 Re: Galileo Update - 02/12/90 ---------------------------------------------------------------------- Date: 15 Feb 90 16:01:20 GMT From: cs.utexas.edu!uwm.edu!mrsvr.UUCP@tut.cis.ohio-state.edu (Russ Brown) Subject: Re: inter stellar travel From article <1990Feb14.200816.25598@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer): >> At the speed of light it would take a little over 4 years to reach >>the nearest star. What are the chances that it would have a planet that >>man could live on.... > > Uncertain. One would prefer to know before starting the trip. :-) Current > theory is that planets are normal around Sun-like stars. The chances for > habitable planets are harder to figure. There is no specific reason now > known for Earth to be a low-probability accident (the notion that the > habitable zone around a star is very narrow seems to have been largely > disproven), but it would be nice to have some more data points. > > Of course, the space-colony enthusiasts would reply "who needs planets?". A major space colony would probably be necessary for quite a while after a colony ship reached another system. It is highly unlikely that the colonists would find a ready-made Earth where they could survive unprotected. If the candidate world is barren (like Mars), it would be decades or centuries before planetary engineers could build up an ecosystem and make it habitable. If the planet had some form of life, it could still take years to determine how it would effect our form of life, and what about the planet (or the colonists) would have to modified. The immediate concern for the colonists would be resources. If the candidate planet is life-less, but has water and other vital resources, it might make sense to actually live on it's surface during its develop- ment. If the colonists require significant resources from space, it may be more efficient for them to stay in a space colony (avoiding the overhead of the planet's gravity well) until the planet is ready. ------------------------------ Date: 15 Feb 90 17:57:18 GMT From: mcsun!hp4nl!eutrc3!eutws1!rcstoc@uunet.uu.net (Oscar Craane) Subject: ??? What is ' SPACE DIGEST V11 #18 ' ??? Hi , I am just new in this news section and see all this talking about SPACE DIGEST V11#18. Can someone tell me what this is, i'm very curius about it Please send some explanation to me. thanks in advance Oscar Craane rcstoc@eutws1.win.tue.nl University of Eindhoven Holland --------------------------------------------------------------------- " Y O U A I N ' T M U C H , I F Y O U A I N 'T D U T C H " --------------------------------------------------------------------- ------------------------------ Date: 15 Feb 90 15:45:22 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: Recreation in Space In article <1990Feb14.201604.25893@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: > ... NASA -- apart from not being exactly >a bastion of liberalism itself -- is terrified of provoking an uproar >from the Bible Belt. It's not an accident that the two or three >husband-wife pairs of astronauts never get assigned the same mission.) Gee, I thought the Bible Belt was all for this sort of thing between husband and wife... :-) [btw where is the Canadian Bible Belt, I wonder...] ------------------------------ Date: 15 Feb 90 16:56:26 GMT From: zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jato!mars!baalke@tut.cis.ohio-state.edu (Ron Baalke) Subject: Re: Galileo Update - 02/12/90 In article <1990Feb15.001749.1516@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: > >In any case, we don't get to see the Galileo Venus images for quite a >while yet, since they'd take too long to transmit through the low-gain >antenna. >-- Galileo is already transmitting back Venus pictures. Using a technique called DMS RMO, the images are read off the tape recorder and temporarily stored in Galileo's main computer memory. From here, they are transmitted to earth throught the Low Gain Antenna at 1200 bits per second. Only a limited amount of scientific data is being sent back this way. In October, Galileo will be close enough to earth to be able to transmit the rest of the engineering data at 7.68K bits per second. One of the problems we are experiencing is high winds exceeding 45 mph at Goldstone, which has already caused loss of data from Galileo (we will just have it retransmit). The high winds has caused the antennas to be stored at zenith for safety. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | ------------------------------ Date: Thu, 15 Feb 90 20:10:32 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Base 12 >From: helios.ee.lbl.gov!pasteur!ic.Berkeley.EDU!eta@ucsd.edu (Eric T. Anderson) >Subject: Re: measurement standards (aerospace) >Hey, let's just use base 12! or so! Then we can divide by lots of >numbers... We just need a lot more fingers. =-) How about it? Actually, I believe at least one ancient civilization used base 60. I suspect that civilization may have collapsed because the children were dying of old age before they could memorize their multiplication tables. :-) ------------------------------ Date: 15 Feb 90 22:29:02 GMT From: manta!simpkins@nosc.mil (Michael A. Simpkins) Subject: Re: Fun Space Fact #1: Launcher Development Costs >Including explode with seven astronauts aboard, and exert a paralyzing >effect on a decade's worth of space exploration. > >No $30 million organization could even dream of accomplishing such things! > >All it could do would be to orbit stuff. Jeez, how boring. :-) > ___________________________________________________________________________ How about sitting on the launch pad and burning like a stack of old Roadhandlers, I'll bet that would make the news every night!!! EVERYBODY thinks they can do a better job. Boy, NASA ought to start new program: MAKE THIS BOZO DIRECTOR FOR A DAY! Now THAT would certainly be entertaining. -simpkins- :-) oadhandlers ------------------------------ Date: 15 Feb 90 20:49:43 GMT From: rochester!dietz@louie.udel.edu (Paul Dietz) Subject: Re: Why we would need a planet. In article <1990Feb15.195633.27342@ncsuvx.ncsu.edu> noble@shumv1.ncsu.edu (Patrick Brewer) writes: > The point that I wanted to make is that during the exploration >of space we must be careful about how much raw materials we steal from >planet Earth. Why? Planets are a terribly inefficient way to use mass. All that inaccessible matter just to provide gravity, when rotating structures (of sufficiently large size) would do just as well, using much less material. I predict future generations will decide to exploit the earth by dismantling it completely, from crust to core. >While >at the present time we are not able to remove enough resources from >mother Earth to do very serious damage. But if we speak of "generation >ships" then we are talking of huge amounts of raw material. A single generation ship would consume a negligible fraction of the earth's mass. > Where do we expect to get the water needed for a venture of >such size? Here (Earth) we have always considered water a limitless >resource because there is so much of it. But with the event of space >travel based on self supporting ships the water here could go very >quickly! You've been watching too many "V" reruns. Water is made of hydrogen and oxygen, both of which are available in enormous quantities beyond the Earth. > Then think of what >would happen if the land were remove from the planet and put on a ship >never to return again. Cutting down forests is bad, but imagine >removing all that organic matter from here permanently. I can imagine. The effect would be utterly negligible, since most of the Earth's carbon is not in biomass. However, if this worries you, we can import some carbon from Venus, Jupiter or the asteroids. How many gigatons do you want? > We need planets just to get the resources for existence. In principle, this is wrong. There is no reason why a purely space-based civilization could not exist, given reasonable future technologies. >We can't consider Earth as a disposable item. Why can't future generations do so, if they find the existence of Earth serves no useful purpose? >We need to always have >Earth as something to fall back on if some disaster destroys colonies. Even if you have billions of colonies, spread over this and other solar systems? > YES, we need planets so long as we are carbon based, oxygen >breathing organisms. If all humans were in ships and the ships began >malfunction then the race would most likely die! ALL the ships and colonies malfunctioning at the same time? Uh huh. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 15 Feb 90 05:25:49 GMT From: cs.utexas.edu!usc!brutus.cs.uiuc.edu!uakari.primate.wisc.edu!uflorida!haven!uvaarpa!hudson!astsun9.astro.Virginia.EDU!gsh7w@tut.cis.ohio-state.edu (Greg S. Hennessy) Subject: Re: Galileo Update - 02/12/90 In article <1990Feb14.093523.18240@uokmax.uucp> noel@uokmax.uucp (Bamf) writes: # Maybe I'm a bit early here, but what is the possibility of #public access to the images returned by the craft, (at some later #date, I figure) Are they generally made available in some format, #somewhere? Or do we just have to wait for the newsweek photo's? Nasa is very good at releasing the data they get. What will happen is that there will be a bunch of PR pictures released, which many people will make available by anonymous ftp. The main images are considered "propriatary" for a period of time (usually one year after the last image of the sequence has been taken) and then the pictures are public domain. NASA has released the Uranus images on CD-ROM, and are preparing the Neptune images. The disks also come with the software needed to read in the images. The way NASA works it, if you are going to do research, they basically give the disks to you, and if you are not planning to do research, they give the disk to you at cost. Note that is the way it has seen to me, the official policy might be different. An astronomer two blocks away has his CD-ROM reader accessable to anonymous ftp, so whatever disk he has in his reader is available to everyone with internet connections. I was holding the disk containing the Uranus images, and also the ENTIRE Einstein database only yesterday. -Greg Hennessy, University of Virginia USPS Mail: Astronomy Department, Charlottesville, VA 22903-2475 USA Internet: gsh7w@virginia.edu UUCP: ...!uunet!virginia!gsh7w ------------------------------ Date: 15 Feb 90 17:38:06 GMT From: wuarchive!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!aplvax.jhuapl.edu!jwm@decwrl.dec.com (Jim Meritt) Subject: Re: Spacecraft drives and fuel efficiency In article <10166@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes: }You have to realize just how enormous the energy costs are in }interstellar travel. Only if you are in a hurry. If you make it a biology question instead of a physics question it takes a LOT less. }Unfortunately, the speculative "gate" approaches such as the Kerr }metric warp are even worse. Has anyone done any estimates on the }energy needed to keep a Kerr warp contained and spinning? Since you are a participant in the discussion going on right now on exactly that, you know the answer. }We may have to figure out some way around the conservation of }energy (e.g., realizing the infinite energy densities of pre-normalized }quantum physics.) That's a long way off, if ever. JBIS had an interesting article on this last year. For fiction, but with a good technical appendix, see _The Mc(whatever) Chronicles_. Vacuum Power! That that is is that that is. That that is not is that that is not. That that is is not that that is not. That that is not is not that that is. And that includes these opinions, which are solely mine! jwm@aplvax.jhuapl.edu - or - jwm@aplvax.uucp - or - meritt%aplvm.BITNET ------------------------------ Date: 15 Feb 90 22:56:30 GMT From: zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!jarthur!elroy.jpl.nasa.gov!jato!mars!baalke@tut.cis.ohio-state.edu (Ron Baalke) Subject: Re: Galileo Update - 02/12/90 In article <8521@xenna.Xylogics.COM> barnes@Xylogics.COM (Jim Barnes) writes: > >A local radio station news bit stated that several images of Venus had >been successfully returned by Galileo. This is contrary to all that I >had read here and in other sources. Can anyone confirm/deny the news >report? This is true. Some (but not all) of the Venus pictures have been sent back to earth and have already been released to the press. As I had already indicated in a couple of earlier postings, the images were read off the tape recorder into the computer's main memory, and then transmitted using the Low Gain Antenna. More picture are still forthcoming. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | ------------------------------ Date: 15 Feb 90 18:13:34 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: Galileo Update - 02/12/90 In article <1990Feb15.001749.1516@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >In any case, we don't get to see the Galileo Venus images for quite a >while yet, since they'd take too long to transmit through the low-gain >antenna. Henry wrote this at dinnertime Wednesday, so he loses no points for failing to keep up with the news, but his crystal ball needs polishing. It has since been announced that impatient engineers found a way to piggyback data packets onto the low-gain feed and so we WILL see three of the pictures in a few weeks, instead of waiting for everything until the Earth approach this fall. ------------------------------ End of SPACE Digest V11 #51 *******************