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 ; Tue, 14 May 91 02:24:48 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 14 May 91 02:24:42 -0400 (EDT) Subject: SPACE Digest V13 #546 SPACE Digest Volume 13 : Issue 546 Today's Topics: Re: Saturn V and the ALS Shuttle launches Re: Laser launchers Re: Why the space station? Re: Laser launchers SPACE Digest V13 #518 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: Sun, 12 May 91 11:28:40 -0400 From: "Allen W. Sherzer" Subject: Re: Saturn V and the ALS Newsgroups: sci.space Cc: In article <1991May10.165512.2068@aio.jsc.nasa.gov> dbm@icarus.jsc.nasa.gov (Brad Mears) writes: >|> First explain to me why it costs $10 billion and ten years to do what >|> McDonnell and Martin say can be done for $500 million and four years. >uh - less overhead? :) No need for a smiley. That's a large part of the reason. An important part of this contract was that it was outside the Federal Acquisition Regulations (FAR). For this effort the government was buying only launch services for a specified price. From their point of view there was no vehicle to develop. >Seriously, I haven't seen their proposals and can't comment on them. Fair enough. But please do read the article in the September 90 issue of Aerospace America. If for no other reason then you owe it to yourself to be as informed as you can be. >My "seat-of-the-pants" comment is that their low-bid could be a low-ball. Why would they lowball for a fixed price contract? They would lose a lot of money that way. >The quotes I saw from Rockwell to build Shuttle-C were a great deal >more $500M. What will McDonnell and Martin do differently than Rockwell? The only difference is acquisition outside the FARs. I think Shuttle-C could be built for similar development costs outside the FAR. In fact, the government estimate of the cost of Titan V development inside the FAR is twice that of the estimate for outside the FAR [1]. >|> What did NASA learn from the Shuttle? >They learned a LOT about what goes into performing routine space operations. >This is the knowledge that they hope to use in construction of the next >vehicle. How much can they have learned? Since they will spend 20 times what they need to, it can't be much. >|> From what I see they think everything >|> is fine (except that Congress should buy more orbiters). This is also not >|> a flame but a serious question. >I don't know how to address that. It seems to be more a matter of perception than >a matter of fact. I don't understand what you mean here. My perception or NASA's? >As far as asking for more orbiters, NASA asks for more because >they think they need(?) a fleet with N orbiters. Until they get N, they keep >asking. That's hard to understand. If NASA had learned anything they would have said to themselves: "Holy shit, this sucker is expensive. We better not buy any more and put the savings into cheaper approaches". Instead of being upset at the Augustine recommendation that no more be build they would have been glad they where pulled from the fire without needing to admit a mistake. [1] For the government quote see: "Launch options for the future: a buyers guide" by OTA. Quotes outside the FAR come from the Zenith Star proposal. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | Allen's tactics are too tricky to deal with | | aws@iti.org | -- Harel Barzilai | +---------------------------------------------------------------------------+ ------------------------------ Date: 12 May 91 03:41:46 GMT From: taco!eos.ncsu.edu!dfrobins@gatech.edu (DAVID F ROBINSON) Subject: Shuttle launches Was there ever any consideration for launching the shuttle off of the carrier aircraft. It could have been carried to 40-50 kft and after it cleared the aircraft it could ignite its engines. Wouldn't this have greatly reduced the fuel mass required? With this scenario the shuttle also could have glided back in case of any engine problems. *********************************** * David F. Robinson * dfrobins@eos.ncsu.edu * Aerospace Engineering - NCSU *********************************** ------------------------------ Date: 13 May 91 02:37:44 GMT From: cis.ohio-state.edu!magnus.acs.ohio-state.edu!zaphod.mps.ohio-state.edu!wuarchive!rex!rouge!dlbres10@tut.cis.ohio-state.edu (Fraering Philip) Subject: Re: Laser launchers In article <2753@ke4zv.UUCP> gary@ke4zv.UUCP (Gary Coffman) writes: >Well consider that for an electrically powered laser, conversion of >primary fuel to electricity is, at best, 40% efficient. Transmission, >control, and application of the electrical energy is, at best, 80% >efficient. And laser conversion is, at best, 10% efficient. That's >an overall efficiency of 3.2% right there. Then add in the fact that >atmospheric blooming will reduce the delivered energy of the beam >by a factor of 1000 to 1000000 at high altitudes, and you have a system >with terrible efficiency. While for a rocket, the longer it runs, the >faster it goes since it's mass ratio is continually improving right >up until burnout. No, the longer the rocket is supposed to run, the _worse_ its mass ratio was when it started. Usually much worse. You're using semantic tricks to make the rocket look better than it is. "Since it has lower fuel efficiency, it improves faster." I also notice you pick the laser system _you_ would use and then go on to show that it wouldn't work. Basically all you've proven with that argument is that if it's going to be attempted, *you* should *NOT* be in charge of the project. >I wasn't arguing that R&D engineering problems need to be solved so >much as I was arguing that fundamental physical laws prevent the >system from being a practical, efficient, alternative to rockets. We >could throw hundreds of billions into an R&D engineering program to >develop anti-gravity too, but fundamental physical laws would have to >be broken for it to pay off. At the power levels required to loft real >payloads into orbit, atmospheric blooming is an intractable physical >problem. Once the air is ionized into a plasma, the plasma is >optically opaque cutting off further power transfer. Talk to the guys >who have actually fired high power lasers, the laser fusion folks, and >see what they say about the absolute necessity of having a hard vacuum >to fire the beam through. What's that exchange from "The Princess Bride?" "Inconceivable!" (for the 50th time) "I don't think that means what you think that means." I think I've seen this argument before, word for word. I even think that this post gives me a strong sense of deja-vu. It probably got posted twice due to some strange machination within the net. I've also heard the phrase "Fundamental physical laws" before. It sounds _very_ familiar. Specifically, Nick Szabo's arguments about chemical launchers and cost. Anyway, the laser fusion people want to produce a plasma with a pressure and heat product several magnitudes higher than the core of the sun. The amount of energy concentration is much higher here than will be needed in an operational laser launcher. Granted, research does need to be done. But you seem to be implying that NASA shouldn't do it. Then who? The size of a prototype laser launcher is about $100 million, beyond the range of any universities. Private Enterprise? Oh sure, the lead times in the research is 20 years too long for the government to do it, so we'll have the people so capital-short they're seeling their grandparent's internal organs put money into the thing which won't pay off for a couple decades (as _you_ seem to believe). SDI is investigating it and they have an urgent military need to fill. They, as well as private industry, the military, et al, have vast pressures against their doing {\em {\em {\em BASIC RESEARCH }}} (btw, {\em whatever} in TeX puts the whatever in boldface) when they are compared to NASA. People say we need NASA because there are things private industry is too short sighted to look into. And it probably wouldn't make that much more sense for private industry to put money into it now. But if NASA won't do basic research, what do we have it for, and if NASA is to handle mainly operational aspects, why have a private space industry? Why limit this to space? If the governments going to do operations and all that, there certianly isn't any need for the Gannett Technologies Group to exist, it can be nationalized and taken over by something like the Dept. of Redundancy Dept... Basically, if NASA can't do the basic research, who can? They're much better suited to do it than anyone else. >Tethers need to exceed the theoretical strength of materials limits by >orders of magnitude to work. Again, a fundamental scientific breakthrough, >not engineering R&D, needs to occur before tethers can become reality, if >ever. Not for smaller tethers. They could even reboost themselves by coupling with the Earth's angular momentum via the Earth's magnetic field, to make up for losses when something gets picked up from ye olde suborbital rocket. -- Phil Fraering dlbres10@pc.usl.edu ''It's a Flash Gordon/E.E. Smith war, with superior Tnuctip technology battling tools and weapons worked up on the spot by a billion Dr. Zarkovs.`` - Larry Niven, describing the end to _Down in Flames_. ------------------------------ Date: 13 May 91 05:42:37 GMT From: sequent!muncher.sequent.com!szabo@uunet.uu.net Subject: Re: Why the space station? In article <2803@ke4zv.UUCP> gary@ke4zv.UUCP (Gary Coffman) writes: > >If you assume that you are never going to do large scale in space assembly We won't need in in they _way_ you or NASA think we will need it. Large scale assembly isn't very valuable unless there are a lot of materials lying around with which to scale. Fred does nothing about the need for cheap building materials, which is the real problem. Rather, it sucks up money from missions of exploration that would give us knowledge about solar system resources with which to solve the problem. Right _now_, Congress is deciding on Fred vs. SIRTF, a powerful infrared telescope which would discover thousands of new asteroids and comets. Fred is incredibly destructivce of the long-term potential for large scale space assembly. >and that you are never going to need to launch really large probes into >deep space or to the planets using exotic propulsion systems, or if you The explorers want many more, smaller probes, and none of the exotic systems require assembly. Fred does not doing anything about this need, instead it sucks up money from exploration. >assume that large scale human presence in space is never going to occur At 1,000,000 times the cost of a Winnebago for the same living quarters, Fred does nothing but take us further away from this. >and that you don't need life science data for long term zero G existence, There is a small need for this, but it won't be met by putting statistically insignificant sample sizes in an unrepresentative space environment (underneath the Van Allen belts) at only one gravity level. A mission with only 1% the cost of Fred would put statistically valid samples of near-human biology into many different kinds of radiation, shielding, and gravity environments, including micro, lunar, Martian, and full gravities. This would give us over 10 times the knowledge on the subject for 1/100 the cost. How's this for an argument: "if you assume we will never build a starship, then we don't need to build a starship right now." "If you assume we will never want a gazebo, then we don't need to build the gazebo this summer." If we ever want to do these fun things, the only alternative is to rush out do them right now? Sheesh. -- Nick Szabo szabo@sequent.com "If you understand something the first time you see it, you probably knew it already. The more bewildered you are, the more successful the mission was." -- Ed Stone, Voyager space explorer ------------------------------ Date: 13 May 91 05:16:14 GMT From: sequent!muncher.sequent.com!szabo@uunet.uu.net Subject: Re: Laser launchers In article dlbres10@pc.usl.edu (Fraering Philip) writes: >I've also heard the phrase >"Fundamental physical laws" before. It sounds _very_ familiar. > >Specifically, Nick Szabo's arguments about chemical launchers and cost. Whoops, nope, BZZZT, I never said that. I said "fundamental limits". And that probably connotes something harder than what I meant. The limits are those of technology learning curves, not of the ultimate nature of the universe. The chemical launch cost curve, and comparisons to other internal-chemical transportation systems confirm that that the cost/learning curve is approaching a limit at about $1,000/max lb LEO. Meanwhile, over 100 times as much funding has gone into chemical rocket research than all of the other methods combined during the last 20 years, confirming that chemical rocket research is well-trod ground, while the other technologies are a freshly plowed field. In AI terminology, this branch of the search tree has been thoroughly scoured. The laser-launch, tether, etc. branches have barely been looked at. A review of the whole thesis point by point: * The cost/learning curve for chemical rocket vehicles is approaching a limit at about $1,000/max lb. LEO, well above what is needed for affordable space emigration (between $1-$10/max lb. to LEO, depending on whether it is affordable only to upper class, or to upper and middle class. This stranslates to $4-$40/lb. to a Lagrange point space colony, or $5-$50/lb. to a lunar or asteroid colony.) * A discovery significantly changing that curve will also change the cost curves of other internal-chemical vehicles, such as cars, airplanes, etc. And vice versa. An advance dropping chem rocket launch costs to $1/max lb LEO. will just as likely drop the cost of a new car to $3, or a round-trip ticket NY-Tokyo to $.75. * The search space for this kind of technology is well-trod, making curve-changing advances highly unlikely. * The search space for laser launch, tethers, EML is fresh territory, making it much more likely that R&D on these fronts will provide fundamental, curve-changing advances. * Government lab's primary role is research on technologies with high potential for breakthroughs, which is too long-term for private industry to undertake. In other words, government should be breaking new ground. * Private industry's role is R&D, and operations, on technology demonstrably profitable in the current or near future. * _Therefore_, government labs should be doing R&D on the advanced. new-field launch technologies. Chemical rocket research should be the job of private industry. In other words, looking for big chemical rocket cost reductions is like going out today and looking for a big gold nugget at Sutter's Mill. It is like being the last in line at an Easter-egg hunt. Chances are, somebody already found the good stuff. If private industry can prove me wrong, I'm all in favor of that. -- Nick Szabo szabo@sequent.com "If you understand something the first time you see it, you probably knew it already. The more bewildered you are, the more successful the mission was." -- Ed Stone, Voyager space explorer ------------------------------ ReSent-Message-ID: Resent-Date: Mon, 13 May 91 13:38:08 EDT Resent-From: Tom <18084TM@msu.edu> Resent-To: space+@andrew.cmu.edu Date: Fri, 10 May 91 02:10:53 EDT Reply-To: space+%ANDREW.CMU.EDU@msu.edu From: space-request+%ANDREW.CMU.EDU%CARNEGIE.BITNET@msu.edu Subject: SPACE Digest V13 #518 Comments: To: space+@ANDREW.CMU.EDU To: david polito <15432DJP@MSU.BITNET>, Tom McWilliams <18084TM@MSU.BITNET> Subject: Re: Ethics of Terraforming (was Re: Terraforming Venus) >henry@zoo.toronto.edu (Henry Spencer) writes: >>kcs@sso.larc.nasa.gov (Ken Sheppardson) writes: >>> Is there anyone else out there who questions the ethics of tampering >>> with other planets (with or without the presence of life) to make them >>> more 'earthlike'? ... >> >>How do you feel about the Hawaiian Islands, which were bare volcanic rock >>until all those foreign plants and animals moved in and started tampering? >>If what nature did there was right, how can it be wrong for nature (which >>includes us) to do the same thing elsewhere? >Anybody else out there getting this strange feeling of deja vu? I even >checked the dates to make sure these weren't ghost postings resurrected >from the dead (as occasionally happens). Yup. >This point (Hawaiian Islands) is where I jumped into the conversation last >time ... I'm not gonna bother again. Didn't anybody out there save all the >discussion of the ethics of terraforming from last time around? Seems >pointless to rehash all this when we just did it a few weeks ago ..... I don't rememeber where I came in. All I can say (that I don't remeber saying beofore) is that I think the orignal poster may be suffering from an acute case of 'White Liberal Guilt' What was/is being done to the cultures and ecologies of the planet are are real tragedy and loss. But avoiding frontiers in space because of the effects of frontiers on this planet sort of misses the point of the guilt in the first place, huh? Tommy Mac Acknowledge-To: <18084TM@MSU> ------------------------------ End of SPACE Digest V13 #546 *******************