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 ; Mon, 30 Oct 89 04:24:54 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 30 Oct 89 04:24:17 -0500 (EST) Subject: SPACE Digest V10 #175 SPACE Digest Volume 10 : Issue 175 Today's Topics: Re: Asteroids as weapons of mass destruction Cognitive Dissonance Over Fake Space Program Re: More whining about Galileo Re: Asteroids as weapons of mass destruction Re: "Terraforming", so-called... Re: Orbital Grit Balloon Launch attempt of a High Power Rocket (40 Miles). Re: Exhaust velocity Space Shuttle SRB exhaust gas makeup. Re: finally! ---------------------------------------------------------------------- Date: 23 Oct 89 16:39:49 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: Asteroids as weapons of mass destruction Let's take two cases: city busters and planet busters. Aiming big rocks at your enemy's cities is just missiles in space by another means. How you prevent it is by knowing in advance who's in business to do it, and making sure they don't get any foolish ideas. Clearly any Earthside state that pulled such shennanigans would be clobbered immediately thereafter. "Independent" terrorists could always try it, but in the foreseeable future no such group could possibly mount the required technological effort without the backing of a superpower, which would then be responsible by extension. This is not like buying SAM-7's on the black market, y'know. Also, to the extent that a citybuster threat is useful for ransom, it must be deflectable. If deflectable, there may be defenses. (Hmm, am I channeling Dan Quayle here??) Planetbusters are a different kettle of fish. No one state would be the exclusive victim; all would suffer. A conceivable weapon for a hostile off-Earth state to employ; however any such state is going to be far more vulnerable than we for the foreseeable future. What a pleasant topic. Can we talk about radon buildup in space stations for a while now? :-) -- Hey, where'd the Colombian Coffee ads go all of %8 Tom Neff a sudden! Is Juan Valdez hiding in Panama? 8% tneff@bfmny0.UU.NET ------------------------------ Date: Sun, 22 Oct 89 21:28:06 PDT From: mordor!lll-tis!oodis01!riacs!rutgers!pnet01.cts.com!jim@angband.s1.gov (Jim Bowery) To: ucsd!nosc!crash!space@angband.s1.gov Subject: Cognitive Dissonance Over Fake Space Program Here are excerpts from messages received from people upset by some of my recent postings: > You're about one millimeter from going into my kill file. This was a charmer: >You, are comparable to the street anarchists. >They have an agenda of destruction, >because they enjoy destruction, but no real plan of how to make anarchy work. >Not only do you not have a plan, I wouldn't want to be shipwrecked with you. >You might rationalize yourself into some late-night cannibalism. > >Nasty? You bet! Take your intellectual terrorism elsewhere, please. One worthy comment: > I find the WAY you say things makes me WANT to >disagree with you. Even when I AGREE with you. It makes me WANT to >ridicule you. Advice well taken. I do deliberately tell-it-like-it-is without sanding off any of the corners so that people will get the message straight to first order and then consider that their emotional reactions may bear little relation to reality in such impersonal matters as space policy and global destiny. It is the "feeling" (religious) nature of NASA's imagery that has so hypnotized us into believing we get a space program in return for our $10B/yr. Those that follow their religious feelings into "holy war" mode in reaction to the congnitive dissonance are usually people who belong in the middle ages (or the middle east) to begin with. and finally: > ...I see that you wish >to see an orbiter blow up... > ...to save the space program, hmmm, maybe we should >engage in a world-wide nuclear war to get rid of all the nuclear weapons on >Earth. This isn't exactly right. I believe we have no space program to save. The reason another shuttle disaster could be good for opening the space frontier is that it would help more people to actually realize that we have no space program and haven't really had one in the last twenty years. With that realization, we might finally terminate the FAKE space program we frequently refer to as "NASA", take stock in our real situation and get on with the business of moving into space in fact. At present, the dream is still alive, but it is ONLY a dream being generated by NASA's highly sophisticated technology in psychologically appeasing imagery (with experts located primarily in Houston, Huntsville and Washington). As for what we SHOULD be doing to open the space frontier, I refer you to "A Space Program Derived from American Values". The paper is too large to post in this newsgroup, although I would be happy to provide a machine readable copy to anyone that wants to make it available via ftp on their system. If you would like a copy of the paper, send $2 for copying and postage to the US mail address given below. If you want it in machine-readable form, send a disk (5.25" or 3.5" (Mac or IBM)) in an enclosure appropriate for return-mail. --------------------------------------------------------------------------- Jim Bowery PHONE: 619/295-8868 BE A SPACE ACTIVIST PO Box 1981 GET OFF THE NET AND SET UP AN APPOINTMENT WITH YOUR La Jolla, CA 92038 CONGRESSMAN! --------------------------------------------------------------------------- UUCP: {cbosgd, hplabs!hp-sdd, sdcsvax, nosc}!crash!pnet01!jim ARPA: crash!pnet01!jim@nosc.mil INET: jim@pnet01.cts.com ------------------------------ Date: Sun, 22 Oct 89 16:53:53 EDT From: "Keith F. Lynch" Subject: Re: More whining about Galileo To: cik@l.cc.purdue.edu, "mmm@cup.portal.com"@mintaka.lcs.mit.edu Cc: KFL%AI.AI.MIT.EDU@mintaka.lcs.mit.edu, space@andrew.cmu.edu mmm@cup.portal.com writes: > ... that neat display of an authentic Saturn V booster in the > National Air & Space Museum. cik@l.cc.purdue.edu writes: > The display of a Saturn V booster in the National Air & Space > Museum is the waste of money. There is no Saturn V booster in (or near) the National Air & Space Museum. It wouldn't fit. ...Keith ------------------------------ Date: 23 Oct 89 16:57:07 GMT From: kr0u+@andrew.cmu.edu (Kevin William Ryan) Subject: Re: Asteroids as weapons of mass destruction Notes concerning deflecting asteroids: If the asteroid is already in an elliptical orbit crossing Earths, then the delta vee needed is that which changes the period of the asteroids orbit just enough so that it crosses Earths orbit when the Earth is there, some time in the future. I'm not knowledgeable enough to say how much delta-vee this requires - I'll leave that to the orbit jockeys. Second, concerning propulsion of said asteroid - nobody has mentioned mass drivers! I had thought that mass drivers were a major part of anyones moving project. Put a mass driver on the asteroid, grind up asteroid chunks, and using power from solar or nuclear generators, fling it away at high speed. The asteroid goes the other direction. The mass driver doesn't even have to be terribly large - as I understand it the projected length of the highly accurate Moon-Lunar orbit mass slinger for materials transport is on the order of a couple hundred yards, including aiming devices. This gives a 2.6 (?) K/s exhaust, and the asteroid mass driver doesn't have to be terribly accurate, just short and powerful. You do need to get asteroid mass into the mass driver, but that's just a little detail :-). Continuous low-thrust drive, without the need to bring all your reaction mass. Much better in my mind than having to bring all that hydrogen for the plasma drive... kwr "Jest so ya know..." ------------------------------ Date: 23 Oct 89 19:17:09 GMT From: crdgw1!crdos1!davidsen@uunet.uu.net (Wm E Davidsen Jr) Subject: Re: "Terraforming", so-called... I think that "terraforming" is an ambitious concept. I have no doubt that there are a number of companies today which could produce some living thing which would survive on, say, Jupiter. I think there's a very good chance that it could be made to reproduce rapidly. The problem is can it be made to excrete something closer to habitable than what's there? If I had to bet I would bet against it. Any biological processes are chemical. They can turn one set of hydrocarbons into another, but not gold or paladium. They can recombine what's there, but not make new elements. Therefore, within those limitations, I think the following things are likely. Venus: something which would fix the carbon in the atmosphere would eliminate CO2 (greenhouse effect) and release oxygen. This *might* reduce the temperature of the planet. If the oxygen combines with something which helps hold heat no gain. If it combines with something to make a high dense cloud layer, the temperature is likely to drop. If we could put a large reflecting cloud between the sun and Venus the temperature *would* drop. We might be able to do that if there were a very good reason, or maybe just bomb hell out of the planet and see if nuclear winter works. None of this is more than a tiny start. Mars: would need a lot of CO2 to get the temperature up. Unless it's locked in the planet in a way subject to release, I don't see much hope here. On the other hand, men could live on Mars now more easily than Venus, because we have good insulation technology and waste body heat works for us. Depending on who's numbers you believe, it's marginal that a person in an insulated suit with a face mask could survive for some time on the surface, barring storms, etc. I have seen enough figures on the surface pressure and pressure needed to make lungs work that I can only claim this is probable. What's needed here is lots of energy to warm the planet, and if we can't get the Sun to provide it by better heat capture I see no viable alternative. The stars: hell, let's just find one with some nice planets and move there. Leave terraforming to fiction. -- bill davidsen (davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen) "The world is filled with fools. They blindly follow their so-called 'reason' in the face of the church and common sense. Any fool can see that the world is flat!" - anon ------------------------------ Date: 23 Oct 89 18:45:33 GMT From: crdgw1!crdos1!davidsen@uunet.uu.net (Wm E Davidsen Jr) Subject: Re: Orbital Grit In article , PKLINKMN@BROWNVM.BITNET (Paul Klinkman) writes: | | Low Earth Orbit has been forecasted to be unusable around the year | 2050. The problem is our existing space junk. | | This is according to Don Kessler of Johnson Space Center in Houston, | as reported by Kathy Sawyer in the Washington Post, probably 10/12/89 | and reprinted in a local paper the next day. I would like to see some serious proof on that one... if we assume that the common orbital volume for LEO is at least 50 miles high and 50 miles "wide" (+/- a few degrees from the equator), and of course 25000 miles around the circumference of the earth... that's something like 62e6 cubic miles (about 2.5e17 m^3 for metric weenies). That makes me doubt that we have enough stuff up there to make LEO unusable in the near future, given that (a) drag is bringing some of the stuff down and (b) if it's in the same orbit delta v is going to be fairly small. This is one of those things which needs a better source than the Washington Post, and some figures to show the cause and magnitude or the problem. Even if it is true, someone suggested a large icecube in a retrograde orbit as a good way to do spring cleaning. -- bill davidsen (davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen) "The world is filled with fools. They blindly follow their so-called 'reason' in the face of the church and common sense. Any fool can see that the world is flat!" - anon ------------------------------ Date: 23 Oct 89 14:24:57 GMT From: att!cbnewsd!rjungcla@ucbvax.Berkeley.EDU (R. M. Jungclas) Subject: Balloon Launch attempt of a High Power Rocket (40 Miles). I just got permission to make this public. The quote is from email sent to me by someone keeping me informed on the project. "I will give you more info on the balloon rocket project by (name deleted) as more info is available for release. For now, he's going to be launching a 2.6" diam. rocket from a balloon at an altitude of about 120,000 feet. A J450 motor "ought" to take the model to 40 miles, maybe more, meaning the fringes of space. A lawyer is helping with the legal stuff, (name deleted) is working on the mathmatics, and some of us are helping to assemble the vehicle. A tv camera on the balloon will be able to cover the launch (hopefully). The rocket will carry a flight computer and transmitter, and will be monitored by ham radio people. The flight will likely take place in late November from the Mohave desert." The goal of this project is to launch a high power rocket (large overgrown model rocket) into "space". The nozzle on the J450 will be a custom design (by the manufacturer) to operate at this altitude. This attempt is a milestone for a slightly more ambitious project. I will keep you informed of any further developments. R. Michael Jungclas UUCP: att!ihlpb!rjungcla AT&T Bell Labs - Naperville, IL. Internet: rjungcla@ihlpb.att.com ------------------------------ Date: 23 Oct 89 20:33:06 GMT From: cs.utexas.edu!wuarchive!brutus.cs.uiuc.edu!zweig@tut.cis.ohio-state.edu (Johnny Zweig) Subject: Re: Exhaust velocity conor@inmos.co.uk (Conor O'Neill) writes: >In article <1989Oct18.174154.23242@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >>In general, correct. For one thing, it's easier to build solid motors >>in large sizes (i.e. high thrusts). For another, the average molecular >>weight of the exhaust is higher, which is bad for getting maximum velocity >>but good for getting maximum thrust. >I've seen this said before (many times) but never with a simple explanation. >My school physics seemed to imply that it is exhaust momentum which matters, >not simply velocity nor molecular weight. Could someone please elaborate. Note that the exhaust's momentum involves its velocity relative to the spacecraft's motor. There are actually 2 kinds of thrust: Momentum Thrust and Pressure Thrust. The first has to do with the momentum of the stuff going out of the motor, the other has to do with the crose-sectional-area of the nozzle and the difference between ambient pressure outside and the exhaust gas pressure. (According to the "Space Handbook", available from the US Gov't Printing Office). I can't quite hack all the Isp, TC/m, and other mumbo-jumbo. I think it boils down to the fact that the mass-flow (Kg/S) out the back of the motor gives you part of your thrust, and the interaction between what comes out the back "pressing against" the atmosphere is another. So if I have two rockets that spit out the same mass of stuff per second, but one has higher nozzle pressure, that one will give me somewhat more thrust off the launchpad (once up in space there should be no difference since there's no atmosphere). I would also be interested in a more accurate explanation, if someone who can avoid simply stating some equation and saying "see, dummy?" would care to post one. -Johnny Non-physicist ------------------------------ Date: 23 Oct 89 19:52:50 GMT From: wrksys.dec.com!klaes@decwrl.dec.com (N = R*fgfpneflfifaL 23-Oct-1989 1549) Subject: Space Shuttle SRB exhaust gas makeup. Could someone please post information concerning the exhaust gases from the Space Shuttle's solid rocket boosters during takeoff. Does it contain hydrogen oxide? Thanks in advance. Larry Klaes klaes@wrksys.dec.com or - ...!decwrl!wrksys.dec.com!klaes or - klaes%wrksys.dec@decwrl.dec.com or - klaes@wrksys.enet.dec.com N = R*fgfpneflfifaL ------------------------------ Date: 23 Oct 89 20:36:04 GMT From: elsie!ado@cvl.umd.edu (Arthur David Olson) Subject: Re: finally! > It was meant to have a local distribution restriction in it, but I goofed. > Sorry about that. We'll simply be thankful that the above remark doesn't apply to plutonium. -- Arthur David Olson ado@alw.nih.gov ADO is a trademark of Ampex. ------------------------------ End of SPACE Digest V10 #175 *******************