Date: Wed, 16 Dec 92 05:09:29 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #551 To: Space Digest Readers Precedence: bulk Space Digest Wed, 16 Dec 92 Volume 15 : Issue 551 Today's Topics: Air Force One Apollo 10 LM (was Re: pre-fire Apollo schedule) Aurora CFP: Workshop on AI and KBSs for Space DoD launcher use fast-track failures Freeman Dyson biographies... liquid fuels No asteroid flybys (was Re: Cassini Undergoes Intense Design Review) Orbit Question? Relay to Follow Galileo? Terminal Velocity of DCX? (was Re: Shuttle ...) (3 msgs) Yet another antigravity device 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). ---------------------------------------------------------------------- From: Curtis Roelle Subject: Air Force One Newsgroups: sci.space Message-Id: Sender: USENET News System Organization: Johns Hopkins University References: Distribution: sci Date: 14 Dec 92 17:03:52 GMT Lines: 24 Source-Info: Sender is really news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU roberts@cmr.ncsl.nist.gov (John Roberts) writes: >-From: gary@ke4zv.uucp (Gary Coffman) >-Subject: Re: absolutely, positively overnight >-Date: 11 Dec 92 17:24:37 GMT >-Organization: Gannett Technologies Group >->I'm sure that if certification were suitable and appropriate facilities >->were widespread, there'd be a few executive DC-1s bought. The Saudi >->royal family would surely buy one. And then there's Air Force One... >-Take a look at Air Force One, or Two. A 747 and a 707. >I was under the impression that there are two 747s. There was a television >special on the history of Air Force One several months ago, but I don't >think I saved the tape. The impession I had was that there are several presidential airplanes, each with different tail numbers. The designaiton "Air Force 1" is used only when the President is actually onboard one of them. Curt Roelle ------------------------------ Date: Tue, 15 Dec 1992 20:59:34 GMT From: Henry Spencer Subject: Apollo 10 LM (was Re: pre-fire Apollo schedule) Newsgroups: sci.space.shuttle,sci.space In article tombaker@world.std.com (Tom A Baker) writes: >>... the Apollo 10 LM *probably* could have >>flown a lunar landing if some fuel had been offloaded to lighten it, but >>the margins would have been slim and hard to predict... > >Scary. As I have often recalled, there was a subtle bug in the LM >software that flew in the Apollo 10 mission. When in ascent mode, the >LM was supposed to automatically stay in contact with the CSM by >directional antenna. If it wasn't, then the LM automatically would >do a "random tumble" to locate it. During Apollo 10's simulation of >ascent, that started happening just at the beginning of the simulated >ascent. Stafford yelled "Son of a bitch!", which we all heard on Earth >a while before we found out the problem. Indeed, before the weight problem was fully clear, there was considerable debate about whether it was worth flying the dress-rehearsal mission -- why go all that way only to back out at the last moment? Some of the more thoughtful people pointed out that there were still substantial unknowns in navigation and communications with two vehicles in lunar orbit, and it would be better to sort these out with a final test. They were right. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Tue, 15 Dec 1992 19:13:40 GMT From: "Stephen R. Willson" Subject: Aurora Newsgroups: sci.space For anyone who is interested, Popular Science had an article in it about two or three years ago that made reference to Aurora. I can't remember what exactly was in the article, but it might be worth taking a look at again. -- -----------------------+------------------------------------------------------- Stephen R. Willson | A fitting end to a screwy campaign year... willson@seas.gwu.edu | Here to swear in the President of the United States, (202) 395-4922 | Larry King! -The Miami Herald ------------------------------ Date: Tue, 15 Dec 92 09:09:56 GMT From: joachim fuchs wgs Subject: CFP: Workshop on AI and KBSs for Space Newsgroups: sci.space 1st Announcement and Call for Papers Artificial Intelligence and Knowledge Based Systems for Space - 4th Workshop - May 17th - 19th, 1993 ESTEC, Noordwijk, The Netherlands Organized by THE EUROPEAN SPACE AGENCY Simulation & Electrical Facilities Division Technical Directorate Purpose ------- The European Space Agency (ESA) has for many years pursued ac- tivities in Artificial Intelli- gence and Knowledge Based Systems for Space. The technology has already been successfully applied in several domains and is now widely considered a viable option in many developments. The objective of this workshop is to obtain an active exchange of information within the European AI community, within industry as well as within ESA. Not only increasing awareness of the new developments and technologies play an important role, but inputs obtained in this workshop will also serve ESA to harmonize and standardize the developments in Artificial Intelligence for Euro- pean Space programmes. Since the domain is still very evolutionary there are two main interests in organizing this workshop at the Space Research and Technology Centre of the European Space Agency (ESTEC). On one hand the applicability of proven and now almost "standard" methods and technologies of AI should be demonstrated through their use in operational or quasi-operational applications. There is as well the wish to standardize where suitable the development of Artificial Intelligence in order to increase the confidence even further. On the other hand, new methods and techniques should be proposed and their potential domain of application - particular for space - should be identified. In this context AI could as well stand as acronym for "Advanced Informatics". These are the main drivers for the fourth Workshop on Artificial Intelligence at ESTEC. Topics ------ The proposed issues reflect the main issues to be addressed in this Workshop. There is naturally a certain overlap between the different topics (eg the boundary between "established" and "ad- vanced" algorithms will always be fuzzy). The list of topics is not considered exhaustive. Authors are en- couraged to submit papers to topics they consider relevant, even if they are not mentioned below. Those will as well be reviewed. However, the submitted papers should be oriented towards real ap- plications. * Applications - AI in the different phases of the Spacecraft Life-Cycle and the Space Mission - Requirements Definition, Design, Assembly, Integration, Ve- rification and Qualification of S/Cs, Subsystems and Pay- loads - Mission Planning, Mission Preparation and Ground Support (Operations) - Crew Operations, On-board S/W - Data Gathering and Analysis - AI Techniques in the Development of Intelligent Tutoring Sys- tems for Ground and On-board Crew Training * Methodology - Knowledge Acquisition and Representation - Conceptual Models - Knowledge Based Systems Life-cycle (Development Methodology) - User Requirements Definition - Ergonomy of KBS - Validation and Verification of KBS (Reliability, Testabili- ty) * Advanced Algorithms - Machine Learning - Case Based Learning - Generalization through Explanation - Neural Nets - Prediction Methods (eg for Planning) - Constraint Logic Reasoning - Genetic Algorithms/Evolutionary Programming - Fuzzy Logic Round Tables ------------ Round Tables will provide a forum for a more active discussion amongst participants. For this reason presentations of ongoing work are welcome even if there are no final results available. The final definition of subjects and number of Round Tables will be a function of attendance and the nature of abstracts received. The proposed subjects reflect some of the strategic objectives in the Agency: * Autonomy - On-board Autonomy - Ground Support - Reactive/Predictive Planning - "Real Time", Temporal Reasoning * Knowledge Repository - KB-Management - Knowledge Integration and Knowledge Sharing - Query Languages - Visualization Tools and Methods - Operational Aspects, User's View * Model Based Reasoning - Diagnosis and Repair - (Re-) Configuration - Qualitative Reasoning Practical Information --------------------- Workshop participation is free of charge. Working languages will be English and French. However, authors are encouraged to use English as a "de facto" standard because there will no simultaneous translation be provided. Presentation time for the Workshop papers is 30 Minutes, includ- ing the time for possible discussions. Since the character of a Round Table is more oriented towards the active discussion of the participants, the time allocated for each paper will be more flexible, in average longer than for the Workshop (~45 minutes). The infrastructure provided for the presentations includes sup- port for viewgraphs, slides and video films (VHS, U Matic). A particular attention should be given to the fact that viewgraphs should not be copies of the submitted paper, but rather being edited for the purpose of presentation, eg finding more graphical representations of the relevant issues instead of text. There will be accommodation for poster sessions and S/W demons- trations. All demonstrations need to be shipped to ESTEC prior to the Workshop as standalone systems and installed by the demons- trators. Purpose of the demonstration and requirements (power and other connections, size) should be clearly identified and stated to ESTEC not later than March 22nd, 1993. They are subject to ap- proval by ESTEC. Demonstrations showing AI applications will get preference over commercial demonstrations. Papers for the Workshop and the Round Tables will be selected on the base of abstracts not exceeding one A4 page, which should reach ESTEC at latest on February 15th, 1993. The abstracts should include complete information about the author(s) (and af- filiation) and it should be stated under which heading the author would place his proposal. The abstract should be sent to: ESTEC Conference Bureau Postbus 299 NL-2200 AG Noordwijk The Netherlands Fax: +31-1719-85658 Tel: +31-1719-85005 Fax submissions are acceptable to meet the deadline, but authors are requested to send a paper copy to the address above since this will be used for the abstract book which will be available at the workshop. Full length papers (not exceeding 15 pages) should be provided to ESTEC at latest at the Workshop (format A4). Calendar of Events - 1st Announcement, Call for Papers December 14th, 1993 - Abstract submission deadline February 15th, 1993 - Notification of authors March 15th, 1993 - Final Programme March 22nd, 1993 - Registration Deadline April 16th, 1993 - Workshop May 17th - 19st, 1993 - Camera-ready papers at Workshop - Proceedings ready end of June Organizing Committee -------------------- U. Mortensen, ESA/ESTEC (Workshop Chairman) F. Allard, ESA/ESTEC E. Bornschlegl, ESA/ESTEC F.-J. Demond, ESA/EAC H. Laue, ESA/ESOC A. Moya, Commission of the European Communities (DG XIII) G. Muehlhauser, ESA/ESRIN S. Valera, ESA/ESTEC J. Fuchs, ESA/ESTEC (Workshop Organizer) ===== CUT HERE ===== CUT HERE ===== CUT HERE ===== CUT HERE ===== Response Card 1st Announcement and Call for Papers Artificial Intelligence and Knowledge Based Systems for Space - 4th Workshop - May 17th - 19th, 1993 ESTEC, Noordwijk, The Netherlands I intend to submit a paper: O YES O NO (Preliminary) Title _____________________________________________ Particular requirements (video, viewgraphs, slides...)___________ _________________________________________________________________ I intend to submit a poster: O YES O NO (Preliminary) Title _____________________________________________ Requirements (space...)__________________________________________ _________________________________________________________________ I intend to make a S/W demonstration: O YES O NO Purpose _________________________________________________________ Requirements (Connections, space...)_____________________________ _________________________________________________________________ Name _________________________________ Affiliation _________________________________ Mailing address _________________________________ __________________________________________________ Telephone _________________________________ Fax _________________________________ Please mail or fax this form to the address listed above. ------------------------------ Date: Tue, 15 Dec 1992 20:48:01 GMT From: Henry Spencer Subject: DoD launcher use Newsgroups: sci.space In article jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes: >>>... SR71s and U2s that can fly above anything Iraq had right? >>I don't know whether Iraq had any of the Soviet heavy SAMs, but unless >>those aircraft have capabilities far beyond what's revealed, they can't >>fly above *those* missiles' ceilings. > >Just what is the ceiling on those missiles? And it should be noted that even >if they can reach the required altitude they probably are no match for SR-71 >speeds and ECM. Ceilings are poorly known and references differ, but the SA-5 Gammon must surely have a ceiling of at least 100,000ft and probably more -- it's substantially larger than the Nike-Hercules, which has made practice intercepts (of missiles!) at 150,000. Reaching extreme altitudes briefly is no big deal for a large, heavy SAM. There is no requirement to match the SR-71's speed. Being in the right place at the right time is sufficient. The SR-71 may be fast, but it is not very maneuverable, meaning it can't dodge much. Countermeasures are a valid point, but now we're into ECM and ECCM and etc. -- a seesaw battle rather than inherent invulnerability. >>As far as I know, SR-71s never actually overflew the USSR... > >According to Burrows' _Deep Black_ "The Russians have repeatedly charged that >they have been overflown by SR-71s, and the Cubans have made the same >allegation: the Pentagon has denied the former and admitted the latter." Now >just who you believe (and what definition of "overflown" you use) is up to >you. But the Soviets have repeatedly expressed frustration over the fact that >they can't shoot Blackbirds down... Partly because, according to Belenko, the SR-71s never did come in close to give the air defences a chance to function at full effectiveness. There's a big difference between taunting them with occasional approaches and routinely flying overhead saying "go ahead, do your worst". -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Tue, 15 Dec 1992 21:25:19 GMT From: Henry Spencer Subject: fast-track failures Newsgroups: sci.space In article <1992Dec14.145351.14521@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >In article henry@zoo.toronto.edu (Henry Spencer) writes: >>Just which aircraft were you thinking of, Gary? I can think of one >>aircraft that had a bad performance shortfall but was redesigned and >>continued into a successful program (the F-102). I can't think of >>*any* F-series "gap" in the last 40 years that fits your description. > >Yeah, bad line of argument, most of the systems that made it as far >as being assigned a number weren't technical failures even if they >were market failures. Actually I was thinking of the P-39... Actually, in fairness I should say that on doing a bit more digging out of curiosity, I did discover that the F-103 was having problems with its engines and this was a minor factor in its cancellation... although the problems were not in the Mach 3.7 ramjet or in the turbojet- ramjet switchover, but in the supposedly-off-the-shelf turbojet. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Tue, 15 Dec 1992 16:06:35 GMT From: Greg Moore Subject: Freeman Dyson biographies... Newsgroups: sci.space In article pgf@srl03.cacs.usl.edu ("Phil G. Fraering") writes: >/Also, for a good read, check out "The Starship and the Canoe" a biography >\of both Freeman Dyson and his son Chris. Talks about Freeman's work on >/Daedelus. > >I've read it. It's passable in most parts, but altogether it's horrible. >The author feels so much more morally superior to both Dysons but >apparently especially to Freeman Dyson himself. > I must admit it has been years since I've read it, but I do want to defend it a bit. I agree taht the author in some ways comes across believing himself to be morally superior that Freeman. In the case of his son Chris, the author seems to be saying "Nice, quaint, but someday he'll have to grow up." I disagree with it being horrible though. I was greatly intrigued by the idea of canoeing up and down the west Canadain coast. The builind og the canoes was interesting also. The author tries to paint a picture in contrasts of the son exploring "inner-space" and the father exploring "outer-space". While a neat idea, it falls flat. >I was also disturbed by the general attitude its author seemed to >have towards people working in the physical sciences and/or engineering. > This I don't recall to be honest. >If you want to read a good biography of Dyson, that is fair and >still (IMHO) doesn't pull any punches, try the biographical parts >scattered through his own works. They're better written, more fun, >and also have a lot of good ideas, _firsthand_. > For a good biography, I'd ahve to agree. On the same token, if you've not yet read any of the books by Dr. Feynman, I highly suggest them. The man had a ready wit and led an interesting life. >-- >Phil Fraering >"...drag them, kicking and screaming, into the Century of the Fruitbat." ><<- Terry Pratchett, _Reaper Man_ >PGP key available if and when I ever get around to compiling PGP... ------------------------------ Date: Tue, 15 Dec 1992 21:33:20 GMT From: Henry Spencer Subject: liquid fuels Newsgroups: sci.space In article <1992Dec14.011954.2338@ee.ubc.ca> davem@ee.ubc.ca (Dave Michelson) writes: >>>The major problem with cryogenic fuels is that they boil off and the >>>gas must be vented. This becomes a real problem if the upper stage >>>is located inside the shuttle cargo bay. The modifications that must >>>be made to the shuttle are non-trivial. >> >>Sorry, wrong. Cryogenic fuels fly in the payload bay on every extended- >>duration shuttle flight. The shuttle's fuel cells use liquid hydrogen >>and liquid oxygen, and the extended-duration pallet for the cargo bay >>(first flown recently) is basically a set of LH2 and LOX tanks. > >Are you disputing that the modifications that must be made to the shuttle >to accomodate Centaur are non-trivial? ... Nope. My point is that these are accidents of design details of Centaur, and are *not* fundamental obstacles to carrying liquid fuels in the payload bay. It can be done -- it *has* been done -- without such difficulty. The EDO modifications for this are minor. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 15 Dec 92 12:10:08 GMT From: Ben Burch Subject: No asteroid flybys (was Re: Cassini Undergoes Intense Design Review) Newsgroups: sci.space,sci.astro,alt.sci.planetary In article Richard A. Schumacher, schumach@convex.com writes: >Swell. WIth our luck the damn thing will probably wind up colliding >with an asteroid, which collision would have been recognized had >we but continued the search for flyby possibilities... I should probably let this one go... Oh well... Have you ANY concept of: A. How unlikely this is? I mean, I am more likely to win the lottery by a long stretch, and I don't buy tickets. B. How lax this would be on the part of mission planners? I'm quite sure that they know of all of the close encounters with asteroids, probably this is spit out from a standard piece of mission planning software. I mean, its very slightly likely that this mission could run afoul of a misplaced pebble, but one can hardly plan around that. -Ben Burch ------------------------------ Date: Tue, 15 Dec 1992 21:29:37 GMT From: Henry Spencer Subject: Orbit Question? Newsgroups: sci.space In article tombaker@world.std.com (Tom A Baker) writes: >[Molniya series] >they spend only about a half an hour south of the equator, and the other >11 and a half north of it. Very efficient. I wonder why the Canadians >don't lease time on the CIS's satellites? Canada doesn't do much in the far Arctic, where Clarke-orbit satellites are impractically low on the horizon, so we don't really have the need for the extra complexities of moving satellites. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Tue, 15 Dec 1992 21:20:52 GMT From: Henry Spencer Subject: Relay to Follow Galileo? Newsgroups: sci.space In article <1992Dec14.034918.7060@mnemosyne.cs.du.edu> rkornilo@nyx.cs.du.edu (Ryan Korniloff) writes: >Well why did the HGA have to be cloed up in the first place? If it is too >big, then couldn't they have used a more powerful transmitter? I would >have rather tried to avoid such a chance for failure... They would have preferred a rigid antenna, and some early Galileo designs had one. But power is always in very limited supply aboard a spacecraft, and as they got more ambitious the data-rate requirements grew, and once the rim of the dish got big enough to hit the edges of the shuttle cargo bay, there wasn't much to do except go for a folding antenna. Very similar antennas have worked very reliably on the TDRS series. It looked okay, especially since the plan was to unfold it before Centaur ignition, when the astronauts could have dealt with problems (in the same way they dealt with Compton's snagged antenna). The revised flight plan, including the Venus encounter that required keeping the antenna folded for thermal protection, was put together on a shoestring in the wake of Challenger. (This is also why they can't back off the antenna motor -- the relay that would have permitted that got used for something else in the hardware changes needed for the new flight plan.) -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Tue, 15 Dec 1992 20:07:52 GMT From: Paul Dietz Subject: Terminal Velocity of DCX? (was Re: Shuttle ...) Newsgroups: sci.space >In <1992Dec11.175719.24880@ke4zv.uucp> gary@ke4zv.uucp (Gary Coffman) writes: > Snide remarks not withstanding, chamber pressure isn't the only form > of stress on a vehicle. While I like Truax's Sea Dragon proposal > on several grounds, the low chamber pressures lead to very high > loads on the turbopumps because so much more fuel per unit time > has to flow to achieve the high thrust required with low pressure > engines. Reducing stress in one area can lead to increased stress > in another area when the objective remains to get a vehicle from > surface to orbit in a single leap. The high speed pumps, not combustion > chamber stresses, are the main reliability concern of liquid fuel rockets > anyway. Uh, Gary, the Sea Dragon concept used *pressure fed* engines, which don't *have* pumps. Instead, it used big, dumb, strong fuel tanks, pressurized with compressed gas. This limits you to lower chamber pressures than in pump fed engines (otherwise the tanks are too heavy), but can be much simpler. Moreover, your comment is nonsense even without this fact. Lower chamber pressure lowers thrust mainly because it lowers the mass flow rate through the engine (the coefficient of thrust also decreases a bit, but not enormously). Viewed another way, the mass flow required to get a given amount of thrust is proportional to one over the Isp. Isp does increase somewhat with increasing chamber pressure, but rather slowly. The load on a pump increases linearly with the pressure it is required to supply, however. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 15 Dec 1992 20:57:31 GMT From: Pat Subject: Terminal Velocity of DCX? (was Re: Shuttle ...) Newsgroups: sci.space In article <1992Dec11.175719.24880@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >on several grounds, the low chamber pressures lead to very high >loads on the turbopumps because so much more fuel per unit time >has to flow to achieve the high thrust required with low pressure >engines. Reducing stress in one area can lead to increased stress > I dont think that is an unsolvable problem. THe Saturn F-1's sucked fuel like no tomorrow. The soviet's haul fuel to feed those big protons and energiya engines. I suspect packaging and design are bigger problems then just mass flow. >tankage and structure are required as well. Certainly I agree that HTHL >is most efficient since you don't need as much fuel to get to orbit, or >to get landing fuel to orbit when aerodynamic lift can help out. That >means your vehicle can be smaller and have a better mass ratio than the >pure brute force approaches. Certainly a launcher that is never intended >to re-enter the atmosphere is more efficient without wings, but if the >wings can handle the bulk of the return trip as passive systems not >requiring high speed high precision machinery, they deserve serious >consideration. These have been consifdered and dropped. Horizontal take off is not simple. while it makes people comfortable it means the bird has to sit a long time in the soup, sucking in O2 and feeding the engines. The stress is high. the heat buildup is enormous. NASP is going berserk on this problem. Flight near MACH 12 can be a real trick. McDaC, chaose to just fly right out of this soup and take a simpler approach. Wings are not useful if they only generate lift up to abou;t 20 miles, and you have to keep climbing another 130 miles. Henry posted something on this. Also if an HTHL, is going to be mostly lifting body, then so will the DC. As i understand it, it will blunt fly down to mach 3 and then roll tail first. engines will provide terminal management. most velocity will be shed by passive shielding. ------------------------------ Date: Tue, 15 Dec 1992 16:10:47 GMT From: "Michael V. Kent" Subject: Terminal Velocity of DCX? (was Re: Shuttle ...) Newsgroups: sci.space In article <1992Dec15.134936.15434@iti.org> aws@iti.org (Allen W. Sherzer) writes: >In article kentm@rebecca.its.rpi.edu (Michael V. Kent) writes: >It would include finishing >the tests of prototype cryogenic tanks and test the composite structures. Are these the same cryo tanks that McDonnell Douglas is building for NASP? >>What I don't believe is that you'd get any knowldgeable >>volunteers to fly a Spacelab mission on a Titan IV. >Well we will launch that 400 pound Italian satellite. You remember, the >one NASA spent half a billion launching instead of putting it on a $10M >Pegasus? Could NASA have put the IRIS upper stage on that Pegasus too? While I have not heard it stated explicitly, I suspect that launching IRIS was every bit as important to the Italians as launching LAGEOS. (They sunk several hundred million into its development only to have its intended market banned from the Shuttle.) Was the development effort of integrating Pegasus and IRIS also included in that $10 million? What about Mephisto? The Lambda point experiment? The United States Micro- gravity Payload (which carried the two aforementioned experiments)? What about the Space Vision System and all of the rest of the CanEx payloads? Could these all have been launched on the Pegasus? The same $10 million Pegasus? Could they also have flown the Lower Body Negative Pressure appar- atus and several astronauts to wear it? Could that Pegasus have returned the robot arm, USMP, and our brave Pegasus-riding astronauts? Can't you just admit that a lot more happened on STS-52 than the launch of LAGEOS so we can put this issue to rest? Mike -- Michael Kent kentm@rpi.edu Flight Test Engineer Tute-Screwed Aero '92 McDonnell Douglas Rensselaer Polytechnic Institute These views are solely those of the author. Apple II Forever !! ------------------------------ Date: Tue, 15 Dec 1992 14:41:46 GMT From: Thomas Clarke Subject: Yet another antigravity device Newsgroups: sci.physics,sci.space J. Baez's posting of a plausible antigravity device inspires me to describe one of my own. Imagine a spinning superconducting rotor of suitably clever configuration. I think of something like one of those toy flying devices with a hub, several radially disposed airfoils with non-zero angle of attack, and an outer ring surrounding all the airfoils: _________ /___ __\ // | | \\ // | | \\ // | | \\ ||_____/ \____|| / \ | _____ ____ | | || \ / || | \\ | | // | \\ | | // \\__| |__// \________/ Now the magnetic field equations have the same form as the hydrodynamic equations and since the devide is superconducting these will be the Euler equations. Thus in the earth's magnetic field the rotor will act like the toy and produce lift. Since the conduction is perfect, the lift will be without drag (Euler equation paradox). The spinning rotor will thus produce a constant force against the earth mediated by the magnetic field. If the force vector is oriented vertically and the rotor is large enough and spins fast enough it should levitate. Note that nothing is violated. As the rotor rises, it will loose mechanical energy of rotation and slow down until its weight balances the magnetic lift. Conversely if it falls, gravitational potential energy increases the speed increasing the mangetic lift. Thus the rotor should leviatate stably at a fixed height. To raise it spin the rotor faster, to lower it decrease the spin rate. [This reminds me not only on Dick Tracy's space coupe, but of the levitation devices described by Heinlein in _Door into Summer_ Don't worry how they work, just absorb the engineering properties and use them.] Lots of problems of engineering problems of course, probably need counterotating pairs to counter torque reactions. There would be difficulties in handling the varying direction of the geomagnetic field. How do you start the rotor: rotate then cool or cool then rotate? etc. etc. More seriously, could it work? Is there a clever superconducting rotor design that losslessly converts angular rotation into magnetic lift? Given the in-principle possiblity of such a rotor, could one built out of realistic materials be rotated fast enough to generate useful lift in the earth's magnetic field? If these devices were practicle and came into general use, would they cause some environemntal catastrophe like reversing the earth's magnetic field :-)? I'm not sure about how to answer these questions. Given indefinitely large currents in the rotor, the answer would seem to be yes. But maybe I'm missing something. -- Thomas Clarke Institute for Simulation and Training, University of Central FL 12424 Research Parkway, Suite 300, Orlando, FL 32826 (407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu ------------------------------ End of Space Digest Volume 15 : Issue 551 ------------------------------