Date: Fri, 26 Mar 93 05:44:54 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #370 To: Space Digest Readers Precedence: bulk Space Digest Fri, 26 Mar 93 Volume 16 : Issue 370 Today's Topics: Aurora spotted ? Craf's Budget DC-X Flame Derby Flame Derby (was Re: Luddites in space) Flight time comparison: Voyager vs. Gallileo How long to cool Venus How to cool Venus Life in the Galaxy Magellan Update - 03/22/93 Play the Hat Game (was Re: Goldin's comment on Station) Predicting gravity wave quantization & Cosmic Noise (2 msgs) Robots, intelligence, and luddites :-) SR-71 Maiden Science Flight Stockman, Mark, and Keyworth (was Re: Flight time comparison...) STS-55 (Columbia) abort (was Aurora?) temperature of Lunar soil Understatements Why use AC at 20kHz for SSF power 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: 25 Mar 93 22:38:08 GMT From: Dillon Pyron Subject: Aurora spotted ? Newsgroups: sci.space In article , PHARABOD@FRCPN11.IN2P3.FR writes: >>For example, the SR-71 flying at Mach 3+/85,000 ft. normally took >>about 200 miles to decelerate/decend when coming in for a landing. >>Dean Adams (Tue, 23 Mar 93 07:17:28 GMT): > >From Mach 3.5 to speed 0 across 200 miles => mean deceleration a >little less than 0.2 g. Is this a good performance ? How does work >the SR-71 used by the NASA ? Sudden and rapid decelleration and descent are unhealthy for aircraft. You need to allow for airframe cooling and to avoid shock cooling of the engines. There is also a danger of flameout if you just pull the throttle back to idle. > >>> "Airquakes" seem not pleasant. (J. Pharabod) >>It does not seem to be that much of a problem. (D. Adams) > >Why then these articles in the Los Angeles Times and Los Angeles >Daily News? It seems that many people were afraid of a possible >earthquake. And if there were a real earthquake, wouldn't some >people stay home saying "that's just Aurora"? Trying living in LA for a year. Earthquakes are not some rare occurance. The only thing of note was that the seismologists were saying that there was nothing in the ground to cause that. If they hadn't said anything, no one would have taken much notice. I went through 6 quakes in one year. Even had one of my glasses break when it popped off a counter. -- Dillon Pyron | The opinions expressed are those of the TI/DSEG Lewisville VAX Support | sender unless otherwise stated. (214)462-3556 (when I'm here) | (214)492-4656 (when I'm home) |God gave us weather so we wouldn't complain pyron@skndiv.dseg.ti.com |about other things. PADI DM-54909 | ------------------------------ Date: Thu, 25 Mar 93 19:10:56 EST From: Tom <18084TM@msu.edu> Subject: Craf's Budget >>>CRAF was cancelled because it had overrun its budget massively, and Congress >>>was giving clear signals that this would not be tolerated. This had nothing >>>to do with the manned/unmanned wars. > >>I have a quibble: FRED has overrun it's budget, but it lives. Why the >>'selective prosecution', if it's not about manned/unmanned, or at least >>an effect of un/manned? >Because Congress gave CRAF/Cassini an absolute total overall budget cap >(with the stipulation that CRAF died first if there were overruns), >something that has not been done for most other projects, including Fred. >Few NASA projects, manned or unmanned, would survive to fly if they had >firm budget limits. Overruns are a way of life for NASA space projects. So why the change? When you say 'congress', do you mean all of them, for this particular project, suddenly got fiscally concious, only to forget the whole discipline thing for the next project that came down the pike? Or were there particular people, in Congress or NASA, say, that had an attitude or an axe to grind, or what? Surely there is more to this kind of uncharacteristic behavior than just whim. Any ideas? Or was this just a year that congress got tight-wad, and CRAF was chosen by people at NASA when the cut-or-lose-funding ultimatum was delivered? -Tommy Mac ------------------------------------------------------------------------- Tom McWilliams | 517-355-2178 (work) \\ Inhale to the Chief! 18084tm@ibm.cl.msu.edu | 336-9591 (hm)\\ Zonker Harris in 1996! ------------------------------------------------------------------------- ------------------------------ Date: Wed, 24 Mar 93 22:39:51 CST From: "Norman P. Paterson" Subject: DC-X Newsgroups: sci.space John R. Manuel writes: > In article I write: > > >Are there any articles in Aviation Week, or somewhere similar, about DC-X > >that someone can refer me to? I'm curious to see the design of the thing > >and in particular, how it will manage re-entry and still be re-usable. > > I've got a bit more information about DC-X (thanks everyone for the > pointers), but I still have my question about re-entry: how is DC-Y* > going to be able to re-enter the atmosphere without experiencing engine > damage? If it assumes an Apollo-like attitude on re-entry, I'd think that > there would be a lot of ablative damage to the engines. What do the > designers plan to do to prevent such damage and still make DC-Y > immediately reuseable? > > * - Apparently DC-X isn't intended to go any higher than a few tens of > thousands of feet so it won't experience the worst effects of re-entry. > > --------------------------------------------------------------------------- > John R. Manuel srgpjrm@grv.grace.cri.nz > 64-4-570-4024 (office) NIWAR Atmospheric Division > 64-4-566-6166 (fax) Wellington, New Zealand > --------------------------------------------------------------------------- According to my limited knowledge, DCX is only to fly within the atmosphere - it is a testbed for a VERY much larger version which will be a space truck - a replacement for the Shuttle. norm@inqmind.bison.mb.ca The Inquiring Mind BBS, Winnipeg, Manitoba 204 488-1607 ------------------------------ Date: Thu, 25 Mar 93 20:10:56 EST From: Tom <18084TM@msu.edu> Subject: Flame Derby Geo. Wm. Herbert suggests; > Nick: hold your breath for a minute and don't post anything tomorrow. > Dennis: hold your breath for a minute and don't post anything tomorrow. > You two are both smart enough not to have to get into flame wars every > few months... Bill Higgins responds; >Maybe they should both take a break and gang up on Allen. Huh? I'm confused. I can't keep track of the interwoven web of harmonious and divergent ideologies referred to here. Maybe we could save a whole lot of bandwidth and time if we could get a statement from each of our potential contenders on the things they won't budge on. Y'know, Nick could tell us what he thinks, then Allen, Pat, et. al, followed by ONE rebuttal each, explaining why they disagree or agree with each in turn. Then, since each contender had had their say about each other, all this back and forth would end. NOT! If anyone starts this, I say give points for enjoyability of reading, like humor, flow, clarity, rather than 'winnable' points, like volume, logic, or, God forbid, facts. If we aim for audience enjoyment, at least the exercise would have some redeeming value. :-) Bill again; >What do you think, George, are pat and Steinn promising new contenders >in the Flame Derby? Well, Pat, yes, but I'd have to go with Fred McCall over Steinn :-) Sorry Steinn. -Tommy Mac ------------------------------------------------------------------------- Tom McWilliams | 517-355-2178 (work) \\ Inhale to the Chief! 18084tm@ibm.cl.msu.edu | 336-9591 (hm)\\ Zonker Harris in 1996! ------------------------------------------------------------------------- ------------------------------ Date: 25 Mar 93 22:40:38 GMT From: Brad Whitehurst Subject: Flame Derby (was Re: Luddites in space) Newsgroups: sci.space,talk.politics.space In article <1993Mar25.184843.333@mksol.dseg.ti.com> mccall@mksol.dseg.ti.com (fred j mccall 575-3539) writes: >In <1or2vi$2rs@access.digex.com> prb@access.digex.com (Pat) writes: [etc.] >>| What do you think, George, are pat and Steinn promising new contenders >>| in the Flame Derby? >>| >>|Eek, and here I've been holding my breath for a whole day now! >>|Definitely time to stop - no point anyway, I can never equal the >>|ideological purity of previous champions ;-) >>| >>I'll have to agree with Stein. Neither of us even vaguely come >>close to Dennis or Nick, although, I may be close to fred :-) > >No, Pat; you're clearly in the lead. I generally only flame back; you >seem to be self-starting. > Hmm, so maybe the pair is hypergolic? :-) -- Brad Whitehurst | Aerospace Research Lab rbw3q@Virginia.EDU | We like it hot...and fast. ------------------------------ Date: 25 Mar 93 17:41:00 GMT From: Eric H Seale Subject: Flight time comparison: Voyager vs. Gallileo Newsgroups: sci.space davem@ee.ubc.ca (Dave Michelson) writes: >In article <824@rins.ryukoku.ac.jp> will@rins.ryukoku.ac.jp (William Reiken) writes: >>> >>> A dearth of funding for planetary science didn't help much either. As I >>> recall, Reagan's "Science Advisor" recommended cancelling ALL funding >>> >> >> Can you please give a name for this quy. > >According to the account given by Bruce Murray in "Journey into Space", the >man with the black hat (and the secret "Black Book") was Reagan's budget >director, David Stockman. > >Apparently Stockman's "hit list" included the American part of the Inter- >national Solar Polar Mission (the European part was later named Ulysses), >the Venus Orbiting Imaging Radar (scaled back to the Venus Radar Mapper, >later named Magellan), Shuttle-Centaur (which wasn't finally cancelled >until after the 51L accident) and, by September 1981, NASA's entire >solar system exploration program. Only deft maneuvering saved Galileo >and, ultimately, JPL. Only the Shuttle was off limits to Stockman's axe >because of its importance to National Security. > >George Keyworth, Reagan's science advisor, was apparently a good friend >to Science in general but lacked the influence enjoyed by either his >predecessors or his colleagues. I guess I haven't used those particular neurons in a while... :-) I could have sworn I remembered some off-the-cuff remark by Keyworth (in his earlier days) to the effect that space exploration was a "waste" of funds "better" spent on SDIO (grrrr...). Musta' been Stockman. I'll have to pick up the book so I can recover that part of my brain. Eric Seale #include ------------------------------ Date: 25 Mar 93 17:07:49 GMT From: Del Cotter Subject: How long to cool Venus Newsgroups: sci.space jdnicoll@prism.ccs.uwo.ca (James Davis Nicoll) writes: > Could one of the thermodynamics-literate people on the net make >a guesstimate as to how long it would take for the the Venerian atmosphere to >cool enough so that the various components of the atmosphere liquified/ >solidified, given a sudden lack of illumination from the sun? I have a >gut feeling it would take an inconvenient amount of time for Venus to >cool, but I trust math over gut feelings. I tried it once, and got between 200 and 2000 years to snow out the CO2, depending on the assumptions about emissivity, heat capacity, latent heat, and so on. Several other factors need to be taken into consideration, not least convection, but I *think* (ICBW) that 2000 years could be taken as an upper bound. Even so, it's a surprisingly short time. BTW, I think the idea of snowing out Venus was Dyson's idea originally, and Freitas wrote a paper suggesting: Snow out CO2 Ship out CO2 as blocks Warm up again and terraform but I haven't got the references here. -- ',' ' ',',' | | ',' ' ',',' ', ,',' | Del Cotter mt90dac@brunel.ac.uk | ', ,',' ',' | | ',' ------------------------------ Date: 25 Mar 93 13:56:10 GMT From: Gary Coffman Subject: How to cool Venus Newsgroups: sci.space In article <1993Mar24.205219.18620@cs.rochester.edu> dietz@cs.rochester.edu (Paul Dietz) writes: >In article <1993Mar24.141613.6149@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: > > > I think you're wrong about this, in practice if not in principle. > > And I'd point to the same Soviet test as a counter argument. It's > > been reported that the Soviet test was intended to be a 100 MT > > device, but that their hydrocodes weren't advanced enough to > > allow them to make a bomb that big that wouldn't disassemble > > itself prematurely. > >And what *I've* heard is that they did not wrap a U-238 blanket around >that device (which would have boosted the yield to 100 MT), perhaps >because they didn't want that much fallout. Dissassembly is >less of a problem in larger devices, since the time it takes >to dissassemble increases with device size. Note that a U238 blanket wouldn't be to prevent disassembly. It's to tap *fission* energy from the U238 fast fissioned by the high neutron flux from the fusion core. That's a fission->fusion->fission device. > > Of course a star is a perfect counterexample > > as well. Fusion only occurs in the core areas where both compression > > and temperature are extremely high. Trying for an intermediate > > yield, between the Soviet bomb and the Sun, presents formidable > > technical challenges. > >Actually, the history of the development of thermonuclear weapons >is that big ones were developed first. The first one, a bulky >device using liquid deuterium/tritium, achieved 10 MT; the first >"dry" bomb with Li6-D achieved 15 MT. Only later were the devices >made smaller, prompted in part by the need for smaller reentry >vehicles for increasingly accurate MIRVed missiles. Well big computers came first too. I think that's mostly a matter of technical prowess and not fundamental limitations. >Laser fusion targets are to achieve yields of about 1 ton of TNT, with >about .01 tons of driver energy, with core densities around 1000x >normal. Therefore, yields of about 1 MT with a 10 kT driver would >naively require no compression (in practice, driving with a bomb is >different from driving with lasers, so some compression is required >here). But clearly going to still larger bombs gives more slack, as >the fuel density stays constant. And we know we can build > 10 MT >drivers, so there's three orders of magnitude of slack to play with. I don't think I understand any of this. Laser fusion is supposed to work by heating the target via compression. The two effects are completely intertwined. I don't see how you're going to heat the material without compressing it. What's to prevent an isothermal expansion if the target material isn't constrained by compression? My understanding of nuclear explosives is that the fundamental problem is to prevent the device from dissassembling before sufficient captures occur. 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 | | ------------------------------ Date: 25 Mar 1993 17:13:53 GMT From: Carl J Lydick Subject: Life in the Galaxy Newsgroups: sci.space,alt.sci.planetary In article <1or09bINNp9m@darkstar.UCSC.EDU>, bafta@cats.ucsc.edu (Shari L Brooks) writes: = =In article PHARABOD@FRCPN11.IN2P3.FR writes: = =>From "Nature", Vol 362, 18 March 1993 (p. 204): = => With these twin conditions, the authors estimate the size of =>habitable zones around various types of star (fortunately, Venus and Mars =>fall outside the limits for the Sun). = =why is this fortunate, somebody tell me. Because if Venus and Mars fell within the range, the article wouldn't've been published. -------------------------------------------------------------------------------- Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL Disclaimer: Hey, I understand VAXen and VMS. That's what I get paid for. My understanding of astronomy is purely at the amateur level (or below). So unless what I'm saying is directly related to VAX/VMS, don't hold me or my organization responsible for it. If it IS related to VAX/VMS, you can try to hold me responsible for it, but my organization had nothing to do with it. ------------------------------ Date: 25 Mar 93 13:33:43 GMT From: Pat Subject: Magellan Update - 03/22/93 Newsgroups: sci.space,sci.astro,alt.sci.planetary In article <1ooojhINN50e@senator-bedfellow.MIT.EDU> pgf@space.mit.edu writes: |In article <1onp5v$lu3@access.digex.com> prb@access.digex.com (Pat) writes: |> How long will Magellan funding last, now that the conversion has been |> made to the LMGT? And once the gravity data is collected after the |> aero-braking exercise, is their any hope of collecting further radar |> data, or does it look like the transmitters are pretty much shot. | |I think that Magellan project science support is due to expire at |the end of September, although a NASA-sponsored "Venus Data Analysis |Program" will taken over, so Magellan data will continue to be studied |for years to come. The experiment has already generated about 400 |Gbytes of imagery and 10 Gbytes of altimetry. | |The degradation in down-link performance has been progressive. The |last wide-band radar telemetry sent back in September 1992 was only |partially readable, and even this was only made possible by heating |the transmitter to the limit of its thermal tolerance. The target |area (large volcanos named Hathor, Innini, and Ushas) hadn't yet |been imaged by Magellan, so this high-temperature operation was |adjudged worth the risk of melting something! | |No wide-band telemetry is needed for aero-braking or gravity mapping. |While there is no lack of hope in this business, the odds seem to be |stacked against receiving any more radar data. | |Peter Ford |MIT Center for Space Research | Now, the rest of the next cycle is going to be eaten up by aero-braking and the gravity mapping mission, but if they can get teh transmitters running, it'd be nice to try and get some more detailed radar data, but from what you say, it looks like the radar has just about had it. oh well. but on the other hand, the mission has already exceeded the nominal mission profile by about 4 times. pat ------------------------------ Date: Thu, 25 Mar 1993 15:48:00 GMT From: Barry Schlesinger Subject: Play the Hat Game (was Re: Goldin's comment on Station) Newsgroups: sci.space In article <1ons6r$q4h@access.digex.com>, prb@access.digex.com (Pat) writes... >In article <1993Mar22.174146.1@fnalf.fnal.gov> higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey) writes: >| >|Goldin's speech suggests a whole new parlor game: Trying to imagine what >|these hats look like. >| What this hat question brings to my mind is what the NASA official told the Thiokol people who were reluctant to launch Challenger -- to take off their engineer's hat and put on their manager's hat. BMS ------------------------------ Date: 25 Mar 93 20:54:29 GMT From: Matt McIrvin Subject: Predicting gravity wave quantization & Cosmic Noise Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary gary@ke4zv.uucp (Gary Coffman) writes: >Why would there be an amplitude change? The EM wave is transverse, >the G wave is compressive. Compressive? I thought gravitational waves were transverse quadrupole oscillations. The oscillating tidal forces are transverse to the direction of motion of the wave. -- Matt McIrvin ------------------------------ Date: 25 Mar 1993 10:32 PST From: SCOTT I CHASE Subject: Predicting gravity wave quantization & Cosmic Noise Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary In article <1993Mar25.140107.7414@aio.jsc.nasa.gov>, tes@motif.jsc.nasa.gov. (Thomas E. Smith) writes... >crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes: >>In article <1993Mar25.014429.10077@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >>>>But that brings up a point. What is the relativistic interaction between two >>>>waves moving at light speed? How do they view eachother? >>> >>>I wish there were an easy way to pass drawings in this medium. It would >>>make explanations so much simpler. First lets clear up some differences >>>in terminology and conditions here. A gravity wave can be viewed, like >>>a sound wave, as a compression wave in spacetime. It alternately compresses >>>and stretches the fabric of space (hackneyed term) like a steel ball > >I don't think that it ever compresses space, only stretches. Not only does it compress space, but it does so at the same time as it stretches it in the perpendicular direction. Gravity waves have spin 2, which means that they produce quadrapole deformations of space. In one direction they stretch, and in the other direction they compress. -Scott -------------------- Scott I. Chase "It is not a simple life to be a single cell, SICHASE@CSA2.LBL.GOV although I have no right to say so, having been a single cell so long ago myself that I have no memory at all of that stage of my life." - Lewis Thomas ------------------------------ Date: 25 Mar 93 16:54:12 GMT From: Henry Spencer Subject: Robots, intelligence, and luddites :-) Newsgroups: sci.space In article <1or8bpINNs07@darkstar.UCSC.EDU> bafta@cats.ucsc.edu (Shari L Brooks) writes: >In this context, intelligence is the ability to analyse an unfamiliar >situation and make a decision. Wait. No, that is intelligence in >*any* situation... Actually, what we really want is competence, which is not quite the same thing. Competence is the ability to get yourself out of trouble when you get yourself into it. It doesn't absolutely require intelligence, if the environment is simple enough. Unfortunately, planetary-surface environments are not. -- All work is one man's work. | Henry Spencer @ U of Toronto Zoology - Kipling | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 25 Mar 93 10:48:02 -0600 From: Bill Higgins-- Beam Jockey Subject: SR-71 Maiden Science Flight Newsgroups: sci.space In article <1993Mar24.020725.5283@sed.stel.com>, bobc@sed.stel.com (Bob Combs) writes: > And I think the public should have the opportunity for > review of government programs. There is too little > accountability in the government in general. Well, > I better shut-up on this or people will start flaming > me and telling me to take it to alt.gripe.government or > something. And nobody will *ever* offer you a ride on an SR-71... Submarines, flying boats, robots, talking Bill Higgins pictures, radio, television, bouncing radar Fermilab vibrations off the moon, rocket ships, and HIGGINS@FNALB.BITNET atom-splitting-- all in our time. But nobody HIGGINS@FNAL.FNAL.GOV has yet been able to figure out a music SPAN: 43011::HIGGINS holder for a marching piccolo player. --Meredith Willson, 1948 ------------------------------ Date: 25 Mar 93 22:23:13 GMT From: "John S. Neff" Subject: Stockman, Mark, and Keyworth (was Re: Flight time comparison...) Newsgroups: sci.space In article <1993Mar25.212542.19296@ee.ubc.ca> davem@ee.ubc.ca (Dave Michelson) writes: >From: davem@ee.ubc.ca (Dave Michelson) >Subject: Stockman, Mark, and Keyworth (was Re: Flight time comparison...) >Date: Thu, 25 Mar 1993 21:25:42 GMT >In article <1993Mar25.174100.19966@den.mmc.com> seale@possum.den.mmc.com (Eric H Seale) writes: >>> >>>George Keyworth, Reagan's science advisor, was apparently a good friend >>>to Science in general but lacked the influence enjoyed by either his >>>predecessors or his colleagues. >> >>I guess I haven't used those particular neurons in a while... :-) I >>could have sworn I remembered some off-the-cuff remark by Keyworth (in >>his earlier days) to the effect that space exploration was a "waste" of >>funds "better" spent on SDIO (grrrr...). Musta' been Stockman. I'll >>have to pick up the book so I can recover that part of my brain. > >There is no doubt that Keyworth was a big fan of SDIO, but he was also >a strong promoter of the Hubble Space Telescope and Shuttle-based astronomy >(like the Astro mission flown last year). Privately, he wasn't a big fan of >JPL but then he was from LANL :-) Notice that I only said he was "a good >friend to Science in general". > >The real bad guys were David Stockman (the man with the Black Book) and >Hans Mark (the man with the Blue Hat). > >--- >Dave Michelson University of British Columbia >davem@ee.ubc.ca Antenna Laboratory In the book "The Power Game" by Kedrick Smith he tells how SDIO came about. According to McFarlane and Keyworth and others, Pres. Reagan wanted to prevent leaks and had the staff of the National Secruity Council do the draft the SDI speech. Keyworth was brought into the loop by McFarlane to provide scientific support. Keyworth felt at that stage all he could do was engage in damage control. I realize that this could be just self serving BS on the part of Keyworth, but I don't think it was because of his subsequent actions and speeches. ------------------------------ Date: 25 Mar 93 16:50:35 GMT From: Henry Spencer Subject: STS-55 (Columbia) abort (was Aurora?) Newsgroups: sci.space In article <1993Mar25.011212.9759@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >... So liquid or solid, once you light the >boosters, you're committed to getting enough altitude to do a RTLS. The >holddowns can't keep the Shuttle on the pad against both main engines and >boosters. There's no good reason why they couldn't. The Saturn V holddowns could, and did. And they didn't even use pyrotechnic release -- they were 100% mechanical. -- All work is one man's work. | Henry Spencer @ U of Toronto Zoology - Kipling | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 25 Mar 93 10:41:57 CST From: Greg Titus Subject: temperature of Lunar soil Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1993Mar24.154822.9922@pmafire.inel.gov> russ@pmafire.inel.gov (Russ Brown) writes: >>>(This is why we can separate day-night variation from steady-state >>>temperature. The day-night variation is zero at the depths in question.) >> >>The measurements above 1.5 m were subject to the constantly changing >>surface conditions. > >You're overestimating this greatly. The temperature variation at a >depth of 0.5m is only a few degrees, and it tapers off to zero at >maybe 0.8m. ... >The regolith is a *really* good insulator. Think of it as a rammed-earth wall with somewhat more than 1000 miles of concrete behind it for thermal mass. ;-) greg -- -------------------------------------------------------------- Greg Titus (gbt@zia.cray.com) Compiler Group Cray Research, Inc. Santa Fe, NM Opinions expressed herein (such as they are) are purely my own. ------------------------------ Date: Thu, 25 Mar 93 19:58:59 EST From: Tom <18084TM@msu.edu> Subject: Understatements Gary Coffman sez; > Trying for an intermediate yield, between the Soviet bomb and the Sun, >presents formidable technical challenges. James Nicoll comments: > Now, that's sig.file fodder. Sounds like the answer I heard to the claim that space colonization was a moribund idea, since it came from the same drive the hurt vast numbers of indigenous cultures and entire ecologies: "But space is not like a continent. There is somewhat more than a lot of it." Sorry, forgot who said it. -Tommy Mac ------------------------------------------------------------------------- Tom McWilliams | 517-355-2178 (work) \\ Inhale to the Chief! 18084tm@ibm.cl.msu.edu | 336-9591 (hm)\\ Zonker Harris in 1996! ------------------------------------------------------------------------- ------------------------------ Date: 25 Mar 93 17:30:00 PST From: "RWTMS2::MUNIZB" Subject: Why use AC at 20kHz for SSF power On 23 Mar 1993 15:25:37 -0500, Pat writes: /Boeings revenues. are probably not more then 15 billion, but /they are now sharing that market with Lockheed, McDac, Airbus...... / /The COmmercial aviation market is probably 100 Billion. Aviation Week, 15 March 1993, chart on p. 61: total dolar sales of U.S.-manufactured fixed-wing aircraft over 33 klb, including exports =~ $35 billion (1992), estimate for 1994 =~ $30 B. Ibid., chart on p. 65: total large transport sales worldwide =~ $60 B (1992), (1994 estimate =~ $50 B.) Ibid., p. 73: estimate for next 20 years, ~ 13,000 new transports worth up to $1 trillion. /PS. Aviation is a fairly large segment of the US economy. Larger /then you think. Dallas, Wichita, Seattle and St Louis make /aircraft a substantial part of their business. Agreed. Ibid., p. 38: total U.S. 1993 aerospace sales = $100 B (2/3rds of total market). Ibid., chart on p. 38: 1992 global aerospace sales =~ $50 B military aircraft, $15 B missiles, $10 B military space, $ 60 B civil aviation, $ 8 B civil space; total =~ 150 B. (declines to 1996, then increases). (yes, I know that doesn't add up but the scale of the graph is small, and I cheated on civil space - see next line). of special note: Ibid., p. 38: estimated growth in civil space manufacturing of 40 % between 1991 and 2000 (up to $13 B), not including the ground-bases segment equipment. BTW, I've seen it said in various places that the aerospace industry is the largest single contributor to a positive balance of trade for the U. S. Ibid., chart on p. 83: total U.S. 1993 aerospace exports = $45 B. Does anyone have the import or net numbers, and any comparitive numbers between aerospace and other industries, e.g. automobiles, consumer electronics, etc.? Final related $ note: 1992 NASA's budget ~1/3 U.S. military space budget and ~ 2/3 1967 NASA budget in constant dollars [from memory, refernce may be suspect :-) ] Disclaimer: Opinions stated are solely my own (unless I change my mind). Ben Muniz MUNIZB%RWTMS2.decnet@consrt.rockwell.com w(818)586-3578 Space Station Freedom:Rocketdyne/Rockwell:Structural Loads and Dynamics "Man will not fly for fifty years": Wilbur to Orville Wright, 1901 ------------------------------ Received: from crabapple.srv.cs.cmu.edu by VACATION.VENARI.CS.CMU.EDU id aa22934; 25 Mar 93 19:11:07 EST To: bb-sci-space@CRABAPPLE.SRV.CS.CMU.EDU Path: crabapple.srv.cs.cmu.edu!cantaloupe.srv.cs.cmu.edu!das-news.harvard.edu!ogicse!network.ucsd.edu!lutherlab.ucsd.edu!rabjab From: Jeff Bytof Newsgroups: sci.space Subject: 25 kg. to Venus, how much would it cost? Message-Id: Date: 25 Mar 93 20:38:53 GMT Article-I.D.: golem.rabjab.83.733091933 Organization: sio Lines: 5 Nntp-Posting-Host: lutherlab.ucsd.edu Sender: news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU Using existing technology and launch vehicles, what would be the cheapest way to deliver a 25 kg. payload to the upper Venusian atmosphere? -rabjab ------------------------------ End of Space Digest Volume 16 : Issue 370 ------------------------------