Date: Thu, 31 Dec 92 05:19:54 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #616 To: Space Digest Readers Precedence: bulk Space Digest Thu, 31 Dec 92 Volume 15 : Issue 616 Today's Topics: Aluminum as rocket fuel? averting doom (2 msgs) Government-run programs Was: Re: Justification for the Space Program (2 msgs) How many flights are Orbiters designed for? (2 msgs) Justification for the Space Program Moon Dust For Sale relocating planets satellite costs etc. Saturn lift capabilities Speculation SSTO vs 2 stage (3 msgs) Stupid Shut Cost arguements (was Re: Terminal Velocity Terminal Velocity of DCX? (was Re: Shuttle ...) Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: Thu, 31 Dec 92 00:13 GMT From: Karl Dishaw <0004244402@mcimail.com> Subject: Aluminum as rocket fuel? > For final injection, it occurs to me that using gaseous oxygen to "blow" > the powdered aluminum in might be an option. We concentrated on not letting the fuel and oxidizer mix outside the combustion chamber for safety reasons. That scrapped LOX slurries and blowing the powder. Another project team sprayed molten steel over a blast chamber when their methane/oxygen rocket accidently mixed propellants in the feed lines, which makes me feel pretty strongly about the safety criterion. > >What are the problems with using molten aluminum sprayed into the reaction >area? Keeping the aluminum molten in a vacuum should be relatively easy. What are the weight and power penalties for keeping a tank of molten aluminum on your spacecraft? Could be expensive. But we kicked around some far-out ideas too--shaping the Al into fine wire and burning it off a spool or as a "wool", or feeding the power in through an airlock and burning it in pulses. >Another source of information is the External Tank Study published >by the Space Studies Institute. Cutting up ETs for their aluminum >was listed as an option. Impulse of such an engine would be in the >330 second range. Very viable as a Lunar based fuel source. Is that for a pure Al/O2 engine? The ETs have leftover H2 on board, which SSI might've been including. The exhaust has to be almost all O2 or the energy will be absorbed by the oxide particles with very little thrust resulting. My 118 sec Isp calculation was for about 4% aluminum in the mass flow. Karl sold my soul to Uncle Sam . . . now marked down for resale. ------------------------------ Date: 30 Dec 92 23:46:20 GMT From: Marvin Minsky Subject: averting doom Newsgroups: sci.space,sci.physics In article <1992Dec30.213649.28398@cs.ucf.edu> clarke@acme.ucf.edu (Thomas Clarke) writes: >Newsgroups: sci.astro >Path: cs.ucf.edu!news >From: clarke@acme.ucf.edu (Thomas Clarke) >Subject: Re: averting doom >Message-ID: <1992Dec30.194139.27331@cs.ucf.edu> >Sender: news@cs.ucf.edu (News system) >Organization: University of Central Florida >References: <1992Dec30.165411.25838@cs.ucf.edu> >Date: Wed, 30 Dec 1992 19:41:39 GMT > >In article <1992Dec30.165411.25838@cs.ucf.edu> clarke@acme.ucf.edu (Thomas >Clarke) writes: >> In article jmc@SAIL.Stanford.EDU (John >> McCarthy) writes: >> > By the way, it seems to me that if the above idea is sound, it settles >> > the question of the stability of the solar system - in the negative. >> ... In the most recent Sci Am or Sky and Telescope > >It was Sky and Telescope Feb '93 ppp 13-14. >I remembered wrong. A one millimeter perturbation of Mars' orbit >eventually caused a 500,000 kilometer difference in the position of >Pluto after 100 million years. > >Gerald Sussman and Jack Wisdom used the Supercomputer Toolkit at MIT >to simulate the solar system. McCarthy has been discussing the tame-asteroid proposal with Sussman et al. ------------------------------ Date: 31 Dec 92 00:32:41 GMT From: Dave Michelson Subject: averting doom Newsgroups: sci.astro,sci.space,sci.physics,sci.environment In article <72616@cup.portal.com> lordSnooty@cup.portal.com (Andrew - Palfreyman) writes: >I like the simplicity of this idea (moving the Earth instead of >trying to shield it), but what the heck's all this "elastic >collisions" stuff? Surely you're not serious about the "broken >Kepler" business? > I think John's "broken Kepler" method is essentially the "patched conic" approximation. Please correct me if I've misinterpreted this... -- Dave Michelson davem@ee.ubc.ca ------------------------------ Date: Wed, 30 Dec 1992 23:00:13 GMT From: "Dr. Norman J. LaFave" Subject: Government-run programs Was: Re: Justification for the Space Program Newsgroups: sci.space,talk.politics.space In article <1992Dec30.214118.6461@cs.rochester.edu> Paul Dietz, dietz@cs.rochester.edu writes: >You have to be careful with polls. A poll in which people are asked >"do you want a manned space program?" will ellicit a generally >positive response. However, similar questions on other issues, like >education, health care, and so on, ellicit much more positive >responses. The *relative* support of the space program is not very >high. Another Dietz assertion-without-proof... Please provide data which shows the relative support. Norman Dr. Norman J. LaFave Senior Engineer Lockheed Engineering and Sciences Company When the going gets weird, the weird turn pro Hunter Thompson ------------------------------ Date: Thu, 31 Dec 1992 01:59:03 GMT From: Paul Dietz Subject: Government-run programs Was: Re: Justification for the Space Program Newsgroups: sci.space,talk.politics.space In article <1992Dec30.230013.4102@aio.jsc.nasa.gov> Dr. Norman J. LaFave writes: >>You have to be careful with polls. A poll in which people are asked >>"do you want a manned space program?" will ellicit a generally >>positive response. However, similar questions on other issues, like >>education, health care, and so on, ellicit much more positive >>responses. The *relative* support of the space program is not very >>high. > Another Dietz assertion-without-proof... Please > provide data which shows the relative support. Well, Doc, I can't, because I do not recall where or just when this poll was conducted (it was some years ago). However, if you wish to call me a liar about it, I shall try to cope. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 30 Dec 92 20:49:25 GMT From: Chris Marriott Subject: How many flights are Orbiters designed for? Newsgroups: sci.space Reply-To: chris@chrism.demon.co.uk Organization: None Lines: 12 X-Mailer: Simple NEWS 1.90 (ka9q DIS 1.19) Source-Info: Sender is really news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU What is the design lifetime of a shuttle orbiter? ie, how many times is it designed to be reused? Chris -- -------------------------------------------------------------------------- | Chris Marriott | chris@chrism.demon.co.uk | | Warrington, UK | BIX: cmarriott | | (Still awaiting inspiration | CIX: cmarriott | | for a witty .sig .... ) | CompuServe: 100113,1140 | -------------------------------------------------------------------------- ------------------------------ Date: 30 Dec 92 22:53:42 GMT From: Henry Spencer Subject: How many flights are Orbiters designed for? Newsgroups: sci.space In article <725748565snz@chrism.demon.co.uk> chris@chrism.demon.co.uk writes: >What is the design lifetime of a shuttle orbiter? ie, how many times is >it designed to be reused? If memory serves, they are supposed to be good for 100 flights each. Doubts have been expressed about whether they are actually good for that lifetime. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Wed, 30 Dec 1992 17:55:18 GMT From: Joe Trott Subject: Justification for the Space Program Newsgroups: talk.politics.space,sci.space dj@ekcolor.ssd.kodak.com (Dave Jones) writes: >John McCarthy (jmc@SAIL.Stanford.EDU) wrote: >> Let me add to the previous post the estimate that the total amount of >> matter humanity has processed in its history is less than 10^12 tons. >> -- >> John McCarthy, Computer Science Department, Stanford, CA 94305 >> * >> He who refuses to do arithmetic is doomed to talk nonsense. >> >So let's do arithmetic: assume 5e10 people have lived to date. That's >20 tons per person across all of human history. Divide by a human life: >0.5 to 0.3 tons per year. Say a few pounds a day. Well, I think we know >what kind of processing this number figures to represent. Alimentary, my >dear Watson. That sounds like a lot of crap to me! (Sorry, I couldn't resist...:)) -JTT ------------------------------ Date: Wed, 30 Dec 1992 23:02:13 GMT From: Mike Ross Subject: Moon Dust For Sale Newsgroups: sci.space,sci.astro,alt.sci.planetary In article henry@zoo.toronto.edu (Henry Spencer) writes: >In article <30DEC199217541542@kelvin.jpl.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes: >>...2 inch piece of transparent tape which has some Moon dust on it. This is >>the first time that Moon dust is being offered for sale. The Moon dust ... >>to be genuine by Superior Galleries and is expected to be sold >>in the price range of $75,000 to $100,000... > >unless things have changed recently, the ownership of this Moon dust is >best described as "disputed". NASA's position is that all, repeat all, >lunar material returned by Apollo is US government property, and any >offered for private sale is stolen goods. > If NASA 'officially' knows this and allows the sale, does it waive future rights to go after Moondust Marauders? I'd love to know how much the original technician got out of the whole deal. - mike -- ******************************** mike@drseus.jsc.nasa.gov ***** * Michael L. Ross/C33 | Lockheed Engineering & Sciences Co. * * Robotics Department | 2400 Nasa Rd. 1, Houston, TX 77062 * *(713)333-7094 voice,(713)333-7201 fax**********boring, eh?**** ------------------------------ Date: Wed, 30 Dec 1992 17:14:30 MST From: "Richard Schroeppel" Subject: relocating planets There's no need for the nuclear reactors to move Ceres. You can use a much smaller asteroid to tranfer angular momentum & energy between Ceres & (say) Vesta. Ceres needs to be moved only enough to either approach Mars, or a resonance with Jupiter; probably the resonance is closer. And, of course, the smaller asteroid could be manipulated with a still smaller asteroid, etc. The same scheme could be used to eject Ganymede from its orbit around Jupiter, giving you a larger working mass. Of course, the tides from even a Ceres close approach might be a problem: Assuming Ceres's mass is 1/8 that of the moon, it would cause equivalent tides at 1/2 the Lunar distance, ~ 30 Earth radii. If it passes at 1 Er, that's 27000 times the tidal force. Could be fun to watch, from a safe distance. Wrt accurate gravity measurement & orbit prediction, I'd guess that the uncertainty principle is the greatest problem; you can't know Ceres position & velocity accurately enough to predict more than (say) 100 encounters ahead. The steering rockets would have to be capable of influence exceeding hbar; pea shooters would do. Rich Schroeppel rcs@cs.arizona.edu ------------------------------ Date: 31 Dec 92 00:29:00 GMT From: Gary Coffman Subject: satellite costs etc. Newsgroups: sci.space In article <1hfromINN3a5@mirror.digex.com> prb@access.digex.com (Pat) writes: >In article henry@zoo.toronto.edu (Henry Spencer) writes: > >Actually, henry. both of you are sticking to the clarke orbit model. > >Most of the effort in the Telecom industry is oriented towards >LEO comm sats. store and forward or multiple fast relay satellittes. [deleted] >Oncve again, for LEO commsats, rendevous is quite feasible. > >you could even use the shuttle to grab them up. I'd note that we haven't actively been using LEO commsats since Telestar for video or other high bandwidth downlinks. The Iridium concept is a narrow band quasi-cellular phone proposal. Seamless handoff for video and high bandwidth data is a thorny problem, but can likely be solved as we move from analog to digital transmissions. High bandwidth still requires high link budgets, however, and Earth stations are not necessarily going to get cheaper unless the satellites get much more powerful, and larger, than is currently projected for LEO. Clarke orbit has the real advantage of allowing high gain fixed dishes to set the link margin. Gary -- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary 534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | | emory!ke4zv!gary@gatech.edu ------------------------------ Date: Thu, 31 Dec 1992 01:02:56 GMT From: Dave Michelson Subject: Saturn lift capabilities Newsgroups: sci.space A lot of people obviously feel that Skylab was worth saving. Was it? Although items such as food and clothing could have been replenished rather easily, I'm under the impression that oxygen and nitrogen could not. Skylab was essentially designed as a "throw-away" workshop not a real space station. I assume that there was a comfortable safety margin built into Skylab, but how much life support capability was left after the last crew departed? I suppose that one could have docked an "environmental module" with replenishable O2 and N2 tanks at the docking port and, with suitable ventilation, kept the workshop habitable. Were plans for such a "life extension" module ever considered? -- Dave Michelson davem@ee.ubc.ca ------------------------------ Date: Thu, 31 Dec 92 00:14 GMT From: Karl Dishaw <0004244402@mcimail.com> Subject: Speculation >The most straightforward way to impart a delta-v to Ceres is to install >a large number of nuclear reactors on it, and use the energy to expel >fragments of Ceres in a desired direction and at an appropriate velocity. Gives you some perspective on the "Delta Clipper can/will/should/may/won't work" controversy, doesn't it? ;-) Karl sold my soul to Uncle Sam . . . now marked down for resale. ------------------------------ Date: Wed, 30 Dec 1992 22:52:56 GMT From: "Edward V. Wright" Subject: SSTO vs 2 stage Newsgroups: sci.space In <1992Dec30.211506.19286@netcom.com> ckp@netcom.com (Charles Pooley) writes: >People keep debating the merits of 2sto vs ssto, and are overlooking what >I think is the main consideration. >The 2nd stage will have the highest Isp possible, a large nozzle for the >vacuum conditions, and little or no consideration for aerodynamics. Unfortunately, you have what Max Hunter calls "Isp on the brain." The goal of the SSTO development program is not to maximize Isp, minimize mass ratio, or build "the most powerful launcher in the West" (whatever the hell that means). It is to reduce the cost of putting payload into orbit. Period. ------------------------------ Date: 30 Dec 92 22:51:28 GMT From: Henry Spencer Subject: SSTO vs 2 stage Newsgroups: sci.space In article <1992Dec30.211506.19286@netcom.com> ckp@netcom.com (Charles Pooley) writes: >So, for the 1st environment, the 1st stage should have the durability to >cope with the aerodynamic loads and have engines optimised for use in >atmpsphere... In practice, even first-stage engines are necessarily a compromise between atmosphere and vacuum operation. If you look at the cutoff altitudes of typical first stages (ignoring little strap-ons and the like), a substantial fraction of their burn time is spent in near-vacuum. >The general idea, it seems, is not to take any component or capability >of the rocket past the point it is needed. ie, wings, landing gear, >parachutes, rugged construction etc for low altitude conditions not go >beyond staging point... Of course, the same is true for aircraft. The design of an aircraft's wings, in particular, is heavily driven by takeoff and emergency-landing requirements. (Normal landings, at least for long-haul aircraft, are made at substantially lower weights than takeoffs and worst-case emergency landings.) Would it make sense to build two-stage aircraft, with the upper stage optimized for high speed at high altitude (plus landing at relatively low weights after fuel is burned)? Well, yes, in a way, and it's even been done occasionally, for research aircraft like the X-15. But nobody would buy a commercial aircraft built that way, even though performance would be better, because staging is simply too much trouble and expense when one-stage designs work fine. There will be a place for staging throughout the foreseeable future. No propulsion system likely to be practical soon would be capable of launching a short-flight-time mission to Pluto without staging; even if the DCs work perfectly, missions like that will use upper stages. But it's not necessary or desirable for hauling payloads into low Earth orbit; we have the technology to do without it, and doing so has potential to reduce costs quite substantially. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Thu, 31 Dec 1992 01:51:57 GMT From: Paul Dietz Subject: SSTO vs 2 stage Newsgroups: sci.space In article ewright@convex.com (Edward V. Wright) writes: >>chemical rocket propulsion, for rather fundamental reasons. It is >>therefore not inconceivable that multistage launchers would be >>appropriate even though multistage aircraft are not. >I didn't ask if you could say "It is not inconceivable." I asked >if you could prove it. No, what you did was deride a careful and thoughtful analysis by Bruce Dunn by offering a strained analogy between aircraft and spacecraft. I merely pointed out your analogy was flawed. Since Bruce was the one who posted the quantitative argument, it seems to me that it is incumbent on *you* to offer concrete evidence why he is wrong. Paul ------------------------------ Date: 30 Dec 1992 20:05 CST From: wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov Subject: Stupid Shut Cost arguements (was Re: Terminal Velocity Newsgroups: sci.space In article <1992Dec30.205940.28699@iti.org>, aws@iti.org (Allen W. Sherzer) writes... >In article <72597@cup.portal.com> BrianT@cup.portal.com (Brian Stuart Thorn) writes: > >> GRO and UARS are both candidates for return to earth. > >Doing that would cost more then they are worth. It would be cheaper to >build new ones and launch them commercially. > I would dearly love to see your cost analysis on this Allen. Since the marginal cost for a Shuttle mission is only 37 million dollars, this is what it would cost for a reflight. By the way your Titan IV cannot lift a payload like HST due to its adverse dynamic envelope. For a reference NASA publishes a guide to the environments of all major vehicles. Titan is about 1.5 times more harsh from a dynamics standpoint than the Shuttle. Many Shuttle payloads are dynamically designed for the realtively benign environment of the Shuttle. (+/- 10 g in the thrust direction, +/- 6 g for the other two axes) This is worst case dynamic load. The 3 g max acceleration helps to keep the true values much below this on an average basis. This helps the designer of a large sat flying on the shuttle to build a lighter satellite or this can be used to build a structure (such as HST) that would have a hard time on Titan. Don't drag our your tired tale of the Spy sats either. You have no idea what actually goes into them other than their mass. >> LDEF and > >LDEF would have been better flown as a series of smaller platforms. >Under those conditions it would be simple to build a vehicle which >returns them to Earth. That way each experimenter would get custom >time on orbit and the taxpayers would save billions. > That is your opinion Allen not an engineering judgment. There was much value in flying the LDEF like it was. One thing is that this gave a level environment for all of the experiments. If they were flown seperately, and at different times and orbits, there would be no conclusive comparative data to allow the careful analysis of the properties of the materials flown. >> The Hubble repair could still prove too much for orbiting >> astronauts and thus require return to Earth for mirror replacement, > >No for two reasons: 1) it would be cheaper to build another and fly it >and 2) in testimony before the House the program manager said Hubble >wouldn't survive the return trip. For 1) see the above. For 2) from what I have heard from the HST program manager at Marshall, they could bring it back down. That is a contingency if the solar array replacement goes awry. > >To date there are no payloads which can be returned by Shuttle in a >cost effective manner. > Again this is your opinion that simply is not based upon the facts. >> All I'm saying is that Shuttle >> did not meet its objectives, so don't be so sure about DC. > I hope very much that DC meets all of its objectives. I support the DC program. >Same old arguement. I guess Boeing better cancel plans for the 777. >After all, Shuttle failed so 777 will as well. > No what this poster is saying Allen is that the claims that you are making for the DC are exactly the claims made for the Shuttle. You through all of your postings have made it clear that the DC can do everything the shuttle can and more, which is untrue. >> A few weeks ago I mentioned one way that we could have kept some of >> that market in the U.S. until NLS, DC or whatever was ready. You >> said that it (maintaining Shuttle launches of commercial payloads) >> was too costly. Maybe so (definitely so) but those subsidies would >> have at least kept customers in the U.S. > >And at the same time killed any chance of a sustainable independent >commercial effort. If your going to do that it would be cheaper to >simple end all space activity. > Fact is no one wanted the capablility. The great leap in the market for communications satellites did not come until the 80's. The market for small LEO sats did not exist until the late 80's and now. Fact is that the Shuttle proved the viability of the large lift capability that is now embodied by its competitor the Titan IV. This market did not exist and I submit that it would not now if the Shuttle had not been there for designers to design big payloads for. >> Why wasn't DC-X built in 1983 > >You mean when the government was spending billions killing competition >with Shuttle subsidies? You can't be serious; who would be that stupid? > You left out the most important reason in your ad hominim attack. The materials technology to support the possibility of the DC series SSTO did not exist prior to 1987. It was those pesky government supported programs like the B2 bomber and the NASP that provided the new generation of materials that allows the DC to do its job. This is straight off of the MacDac and SDIO fact sheet Allan. >> your argument that the next generation of boosters be a commerical >> endeavor? What is it they say about building a better mousetrap? > >It is hard to convince investors when they see that the largest customer >doesn't care about cheaper costs. > By the way that largest customer is that same pesky government that is keeping all of your space dreams from coming true. The largest customer has a great case of CYA. That customer cares more about the safest way to get a payload to space, not the cheapest. That is why uncle sugar spent three quarters of a billion on new boosters and over a half a billion on pad modifications. By the way you never answered my qestion of whether you would be willing to include the 1960 dollar cost of the development of the Atlas (5 billion) and the cost of the development of the Titan (5 billion for Titan I) and add another 4 billion for II and III. Also from what I have read, inflation is about 375% of the 1967 level today. That precludes a 400% rise from 74 to 86. Also to jump to another subject. The 1993 farmers Almanac lists that there are 111 operating nuclear plants in the US generating 21.7 percent of our domestic electrical energy needs. There are 8 construction permits that are in progress. Dennis, University of Alabama in Huntsville ------------------------------ Date: 31 Dec 92 00:19:42 GMT From: Gary Coffman Subject: Terminal Velocity of DCX? (was Re: Shuttle ...) Newsgroups: sci.space In article <1hfqr6INN387@mirror.digex.com> prb@access.digex.com (Pat) writes: >Consider that the russians/CIS/USSR built a major space program with >the GNP the size of France. And by the Way, unlike the germans, or chinese >i dont believe the russians have ever been charged with using slave >labor. Now the russians had a strange command economy, but things still >cost, but there were major problems in distribution. the russian/SU >economy was sorta like massachusetts meets new york via sweden. > >high taxes, severe rent control and social provision of major services. > >SUre, they didnt pay their scientists what we paid them here, but they >provided them with housing, medicine, etc. Also, the motivation of most >russian space workers was so great, that they didn't mind the bad conditions. > >the problems within the russian system, were of productivity, design cycle, >and provision of consumer goods. > >The chinese use slave labor, and then sell it over here. the russians >paid their workers poorly, and the workers pretended to work. > >the gulags were not used as factories to my knowledge. I agree with all of this. My point was that all those social services, which in our system are paid out of worker salaries, were paid out of a different account that wasn't charged against their space program. So using their numbers is an invalid comparison with numbers from a differently organized economy because many of their costs are "hidden" in other government accounts. That looks like it's changing, and we may soon discover that Russian costs *aren't* really much lower than ours for similar launchers. Gary -- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary 534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | | emory!ke4zv!gary@gatech.edu ------------------------------ End of Space Digest Volume 15 : Issue 616 ------------------------------