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 ; Fri, 14 Jun 91 01:31:43 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 14 Jun 91 01:31:33 -0400 (EDT) Subject: SPACE Digest V13 #637 SPACE Digest Volume 13 : Issue 637 Today's Topics: Mars Colonization Re: Amputation Re: Calculating delta-V Re: Budget Numbers Wanted Re: What comes after Fred's death? ESA promises to carry on! Re: Rational next station design process Re: The Un-Plan Re: Fred vs. Exploration: head-to-head competition Re: The Un-Plan Re: Colonizing the galaxy Re: Extra Terrestrial Intelligence 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: 24 May 91 17:58:09 GMT From: rlsmith@speedy.wisc.edu (Robert L. Smith) Subject: Mars Colonization The science-fact article in the current (July) issue of Analog contains a well thought-out and stimulating plan to reach Mars without requiring an intermediate step -- no space station -- and at rela- tively little cost. The name of the article is "Mars Direct: A Proposal for the Rapid Exploration and Colonization of the Red Planet". Recommended reading. Regards, rLs ------------------------------ Date: 24 May 91 18:44:17 GMT From: mojo!SYSMGR%KING.ENG.UMD.EDU@mimsy.umd.edu (Doug Mohney) Subject: Re: Amputation In article , jim@pnet01.cts.com (Jim Bowery) writes: >The only damage that will be done to JPL et al will be as a result >of Galileo, which: > >1) is the closest thing to big science JPL has done and therefore should >be punished on general principles, Who will punish them? Congress? NASA internalists? After committing so much money for it? >2) was damaged because by insisting on everything flying on Shuttle, >JSC ensured Galileo would have to take a trajectory it was never >designed for -- one which damaged it, You are implying that Galileo's antenna deployment problems are a direct result of the trajectory. or that flying it on Shuttle damaged it. Could you please produce some direct evidence of this? I wasn't aware that JPL had figured out why the antenna was gorked. Could be just a part which failed. Could be a lot of things. I'm sure both sci. space and JPL would appreciate the documentation of failure and why. Signature envy: quality of some people to put 24+ lines in their .sigs -- > SYSMGR@CADLAB.ENG.UMD.EDU < -- ------------------------------ Date: 23 May 91 18:51:01 GMT From: van-bc!rsoft!mindlink!a752@ucbvax.Berkeley.EDU (Bruce Dunn) Subject: Re: Calculating delta-V > henry@zoo.toronto.edu writes: > In article <16394.283cd090@levels.sait.edu.au> steven@rex.sait.edu.au writes: > > >A good solution is to give SI as the ratio of thrust (in Newtons) to > >propellant consumption (in kg/s). This will give SI in m/s ... > > In fact, this amounts to forgetting specific impulse entirely and simply > stating the effective exhaust velocity. Definitely the right approach. I have heard it suggested that the easiest way to regard specific impulse is that it ***is*** exhaust velocity, but that for obscure reasons it has been measured in units of 9.8 m/sec^2. For a quick and dirty conversion between specific impulse and exhaust velocity in meters/sec, ignore units and divide or multiply by 10 in your head (close enough to 9.8xxxx for many purposes). -- Bruce Dunn Vancouver, Canada Bruce_Dunn@mindlink.bc.ca ------------------------------ Date: 25 May 91 18:37:08 GMT From: agate!lightning.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: Budget Numbers Wanted In article <1991May23.224548.22728@sequent.com> szabo@sequent.com writes: >What is the difference between not losing money to Fred, and >getting money taken away from Fred? _Both_ of these categories -- >a good chunk of NASA's valuable programs -- have greatly benefited in >this budget from the Fred cut. Drawing any other conclusion is, to >quote some nay-sayer, "dreaming". It makes a great difference. As this week's Aviation Week and also a post to this newsgroup say, the OTHER agencies (VA, HUD etc...) recieved an additional 800 million ABOVE thier budget requests. In general, NASA programs did not recieve LESS than thier budget request. Which of the two would YOU say got a better deal from Freedom's death? Are you trying to say that they both benifited, and it it pointless to draw distinctions? My conclusion from the budget figures posted is that Freedom was eliminated to benifit social programs, and that at the same time, other NASA programs were given some limited additional support to keep the scientific community quiet. Frank Crary ------------------------------ Date: 25 May 91 23:23:45 GMT From: agate!lightning.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: What comes after Fred's death? ESA promises to carry on! In article <2066@mpirbn.mpifr-bonn.mpg.de> p515dfi@mpirbn.UUCP (Daniel Fischer) writes: >Crazy speculations follow. The Soviets have all the experience, plans for MIR-2 >but no money. ESA and Japan have the money (sort of). The US has neither. >Shouldn't that lead to an USSR-ESA-NASDA collaboration to put a truly interna= >tional space station into orbit where they can learn whether it makes sense - >and rent some space to the (very few) U.S. researchers who'd like such a thing? More to the point, the Soviet Mir station has two unused docking ports, designed for lab modules in the 20-tonne size range. They are just waiting for the (soviet) modules to be built and tested. Might they not, instead, simply allow NASDA or the ESA to attach their (modified to fit) Freedom lab module? While Mir lacks extra power (each module was launched with its own solar pannels) and has only a little extra perminant living space, a habitat/support module could be added to the other available port. This would give either NASDA or ESA more or less what they had expected from Freedom. Frank Crary ------------------------------ Date: 25 May 91 23:37:04 GMT From: agate!lightning.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: Rational next station design process In article <1991May24.052940.3281@agate.berkeley.edu> gwh@headcrash.Berkeley.EDU (George William Herbert) writes: > You could do a cheap compromise and fly an unmanned "LabRatSat" for >a year or two, but I don't know if it's feasable to handle lab animals for >that long purely by machinery. Reinserting IV test lines etc. by teleoperation >is an (as far as I know) untested idea... I'd count this as of questionable >practicality. A "LabRatSat" could be done quite well from a man-tended platform. Just have a crew visit the rats every month or two. While this limits some of your data (you could not, for example, have blood samples on a daily basis.) you could still get quite a bit of good data. I think a "LabRatSat" would be limited by the lifetime of a rat. (Anyone know how long that is, I think less than 2 years...) Since there might well not be a next greneration of rats. (e.g. if they all were in individual cages, or due to zero-gravity pregnency problems...) Frank Crary ------------------------------ Date: 26 May 91 04:25:45 GMT From: usc!wuarchive!rex!rouge!dlbres10@apple.com (Fraering Philip) Subject: Re: The Un-Plan Okay, I guess I'll be the straight man (it seems I usually am). Who is Amgen? -- Phil Fraering || Usenet (?):dlbres10@pc.usl.edu || YellNet: 318/365-5418 Standard disclaimer, whatever a disclaimer is, applies. ``But in her present straits he could not trouble her with disclaimers.'' Stephen R. Donaldson, _The Wounded Land_ ------------------------------ Date: 26 May 91 02:28:50 GMT From: usc!rpi!dali.cs.montana.edu!milton!sumax!polari!crad@apple.com (Charles Radley) Subject: Re: Fred vs. Exploration: head-to-head competition >More efficient are worthwhile projects include Goddard's SMEX >program extended into deep space, a new generation of small telescope >satellites (eg an infrared telescope dedicated to asteroid and comet >search), an infrared telescope put into a meteor-shower orbit to study >the mass distribution and makeup of comets and their fragments, > - Huh ? Totally boring and uninteresting. Irrelevant to the average man in the street. Do you really think programs like this can compete with HUD ? Is this superior to a space station ? Who gives a rat's *## about deep space ? This is purely a boondoggle for tenure track professors, with absolute job security, to write totally academic papers in obscure scientific journals which will never be read by anybody, and rightly so. Who needs it ? Not me ! I would rather have a space station.- The makeup of comets......I would rather have skin makeup for my wife. Really Mr. Szabo, your attempts at justifying space science as being somehow more worthwile than manned spaceflight are absolutely parochial to the point of silliness. Nobody in this newsgroup has made any mention of the TECHNOLOGY stimulus to American industry which is provided by manned space programs. Science program simply to not represent a shadow of the technology stimulus which gets fed back into industry and the economy as new products, materials and processes. This is a very large part of the attraction of manned programs. Indeed a few weeks ago the European Space Agency published a report saying that economic payback of European space programs is about three to one. This value would be increased greatly by expanding Europe's manned effort, which today is very small. They estimated about seven to one payback for manned programs. ESA certainly recognizes the importance of manned programs to boost technology. The world does not exist to benefit scientists in their search for obscure knowledge of dubious value. We need to place more priority in creating jobs for our populations by stimulating economic development. Small scale science programs contribute nothing to this high priority item. >several Lunar and Mars orbiters, ground telescope construction and >operation, analysis of asteroid samples fallen to Earth, and a host >of other projects. > We have already sent orbiters to Mars and the Moon. Why do we need to send any more ? Sounds like another boondoggle to me. We already have thousands of ground space telescopes, really Mr Szabo, you are boring me to death. Analysis of asteroid samples ( I presume you mean meteorites ) heck that is being done and costs next to nothing. I notice you made no mention at all of EOS, and CRAF / Cassini. Since these big ticket mission do not appear in your wish list I imagine that any anti-NASA congressmen reading this conference will say.... aha here is a vocal scientists, let's analyse what he says. Hmmm, no mention of CRAF / Cassini. We funded CRAF / Cassini by cancelling Freedom and the scientists do not even consider them to be important; guess which programs go on the chopping block next year....... Hehehe......NASA's days are numbered, pretty soon we will have succeeded in our long term strategy of whittling them down to nothing. They won't know what hit 'em ! . ------------------------------ Date: 25 May 91 18:07:15 GMT From: swrinde!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew!jdnicoll@ucsd.edu (James Davis Nicoll) Subject: Re: The Un-Plan In article jim@pnet01.cts.com (Jim Bowery) writes: >Nick Szabo writes: > Material deleted >> * Our sample size of earth-crossing and Jupiter-crossing asteroids and >> comets is increased 1,000-fold, so that we find several small objects >> that can be captured into earth orbit for less than 500 m/s impulse >> delta-V. > >Another bad idea on 2 counts: > >1) Ever read "The Moon is a Harsh Mistress"? Even "small" objects that >hit the earth from space are exceedingly destructive. If they break >the objects up into "bite sized" chunks of box-car size or so before they >get anywhere near Earth, I'll consider not assassinating them. Box-cars >would only cause H-Bomb devistation if they hit the Earth. That's >acceptable compared to wiping out a continent or so. > >Keep in mind that even an impact on the Moon or Mars of an >asteroid would create enough flux, for a few minutes, to ignite >flammable material in the Earth's biosphere. > Just how large do you envision the objects Mr Szabo was talking about to be? Perhaps I'm missing something, but doesn't exploiting ET resources imply moving those resources to the intended market at some point? In any case, in the near run, I strongly doubt that we'll be moving dinosaur-killer asteroids into LEO, or Earth-intersecting orbits (At least on purpose). How large a rock do you need (and moving at what velocity) to generate enough heat to light fires at 380,000 km? Is it reasonable to assume that's the size & velocity of the rocks Mr Szabo is talking about? James Nicoll ------------------------------ Date: 26 May 91 03:45:03 GMT From: rochester!yamauchi@cu-arpa.cs.cornell.edu (Brian Yamauchi) Subject: Re: Colonizing the galaxy In article <12440@uwm.edu> markh@csd4.csd.uwm.edu (Mark William Hopkins) writes: > Thus one year (the speed of light divided by 1G acceleration) is the limit >on how long you can maintain 1G thrust using ANY fuel stored on the ship. >Thus, the implication is that you're extracting fuel from space as you go. >All that just to get to the nearest star in a lifetime!! > So ANY practical means to get to another star in decent time for >colonization will also enable any other part of the galaxy (or neighboring >galaxies) to be colonized as well. Interesting point... How does the intragalactic hydrogen density compare with the intergalactic hydrogen density? If the latter is much lower, it might present a barrier to intergalactic exploration and colonization. -- _______________________________________________________________________________ Brian Yamauchi University of Rochester yamauchi@cs.rochester.edu Department of Computer Science _______________________________________________________________________________ ------------------------------ Date: 25 May 91 18:01:16 GMT From: agate!lightning.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: Extra Terrestrial Intelligence In article <91143.125932A6014BB@HASARA11.BITNET> A6014BB@HASARA11.BITNET writes: >(2) Why wasn't the entire galaxy colonized thousands of millions of >years ago? The time for a colonization wave to travel across the galaxy, >even with spacecraft traveling well below the speed of light, is only >a fraction of the age of the universe. Our solar system has apparently >not been colonized; we see no evidence of large scale engeneering in >the asteroid belt or on the moon, for example. (Paul F. Dietz) I have two big problems with this logic: First of all, the age of the universe is not the correct time scale. Before any intelligent life could begin to colonize the galaxy: The first generation of star formation must progress to the point of supernovae. This is necessary since these early stars were "metal poor" meaning lacking in materials other than hydrogen and helium. Many stars must have become supernovae before the intersteller medium had sufficient carbon, nitrogen, oxygen and other heavier elements for life to be possible. Once this occured, stars (and planets) must then have formed and life evolved on these planets. This whole process would take a considerable ammount of time. At a guess, I would say at least 7 to 10 billion years. This cuts down the time in which a extra-terrestrial civilization could have spread across the galaxy to 7 to 4 billion years (taking the age of the universe to be 14 billion years.) My second objection is the speed at which a civilization is assumed to expand. While the actual exploration crafts could have spread all over the galaxy, even at 0.001c and in only 500 million years, what the colonies would do is a totally different issue. At the speed I guessed at, travel between stars would take roughly 5000 years (at approximately 5 light years between stars.) But how long would it take a new colony to settle an entire new world, grow to the point where people want to leave it (and form a new colony) and have developed the industrial base to support an interstellar colonization effort? Even if they worked as hard as they could at it, I suspect it would take at least a few thousand years. In fact, however, these colonists might easily get distracted. If they suffered a civil war/interstellar war/collapse of government the above process could be set back a great deal. In short, I feel the "colonization wave" would propogate at a much slower rate than suggested, and that this rate would be dominated by social, rather than technical, issues Finally, I don't like this model of a "wave of colonization" A difussion process (or a random walk) seems to me a better model. There will be empty worlds to be settled TOWARD as well as away from the home world of our hypothetical extraterrestrials. New collonies are as likley to "fill in the blanks" missed by earlier settelers as go out into new and uncharted space. Also, they might preferentially settle stars totally unlike out sun. For example, a planet in an open star cluster would be an ideal place for a colony. There would be many planetary systems, all within a few light years. If these were setteled first, it might be quite a while before anyone bothered with a single star system. Frank Crary ------------------------------ End of SPACE Digest V13 #637 *******************