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 ; Fri, 1 Mar 91 02:35:50 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 1 Mar 91 02:35:46 -0500 (EST) Subject: SPACE Digest V13 #218 SPACE Digest Volume 13 : Issue 218 Today's Topics: Magellan Images Re: Numerology, theology Re: Government vs. Commercial R&D FTP site for satellite data re request for combined Earth satallite photo Re: ET...Again (was ONE SMALL STEP - REPLY) Re: Terraforming, sun shield Re: SOLAR TERRESTRIAL FORECAST AND REVIEW GGreetings Re: Mars Mystery? -clarification & dilemma 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: 1 Mar 91 05:18:01 GMT From: agate!bionet!uwm.edu!caen!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucbvax.Berkeley.EDU (Ron Baalke) Subject: Magellan Images =================== MAGELLAN IMAGES February 28, 1991 =================== I've placed two more Magellan images at the Ames SPACE archives, bringing the Magellan total to 12 images. They can be obtained via anonymous ftp from ames.arc.nasa.gov (128.102.18.3), and are in the ftp/pub/SPACE/VICAR directory. The two new files are called arach.img and lavinia.img. All of these images are in VICAR format, and each image has a corresponding caption in text files (with a .txt extension) which contain detailed descriptions of the image. The two new caption files are appended to the end of this message. Most of the VICAR images are 1MB in size. The VICAR images can be viewed on an IBM PC computer with the IMDISP program stored in a zip file called imdisp56.zip located in the ftp/pub/SPACE/IMDISP directory. I've converted all of the Magellan images into GIF format in 640x480 resolution, and they can be retrieved from the ftp/pub/SPACE/GIF directory. I've decided to do something a little different this time. In order to fit the entire image into a pixel space of 640x480, I've had to subsample the image by a factor of 2 (equivalent to zooming out twice), and this resulted in some of the details in the images being lost. So I've created additional GIF images which zoom in on the more interesting features of the images. From the arach.img and lavinia.img images, there are 6 GIF files. The files arach.gif and lavinia.gif show the entire image. I've created arach1.gif and arach2.gif, which were extracted out of the arach.gif image and show a subsection of arach.gif, but in greater detail. Similarly, lavinia1.gif and lavinia1.gif were created from lavinia.gif. ============================================================================ ARACH.TXT Arachnoids, one of the more remarkable features found on Venus, are seen on radar-dark plains in this Magellan image mosaic in the Fortuna region. The image is centered at about 40 degrees north latitude, 18 degrees longitude. As the name suggests, arachnoids are circular to ovoid features with concentric rings and a complex network of fractures extending outward. In this image, the arachnoids range in size from approximately 50 kilometers (29.9 miles) to 230 kilometers (137.7 miles) in diameter. Since arachnoids are similar in form but generally smaller than coronae (circular volcanic structures surrounded by a set of ridges and grooves as well as radial lines), one theory concerning their origin is that they are a precursor to coronae formation. The radar-bright lines extending for many kilometers may have been caused by an upwelling of magma from the interior of the planet which pushed up the surface to form "cracks." Radar-bright lava flows are present in the central part of this image, also indicative of volcanic activity in this area. Some of the fractures cut across these flows, indicating that the flows occurred before the fractures appeared; such relations between different structures provides good relative age dating of events. At present, arachnoids are found only on Venus and can now be more closely studied with the high resolution (120 meter/0.07 mile) radar imagery from Magellan. ============================================================================ LAVINIA.TXT This is a Magellan full-resolution radar mosaic of the Lavinia region of Venus. The mosaic is centered at 50 degrees south latitude, 345 degrees east longitude, and spans 540 kilometers (338 miles) north to south and 900 kilometers (563 miles) east to west. As with all Magellan images acquired thus far, the illumination of the radar is from the left-hand side of the image. This area shows a diverse set of geologic features. The bright area running from the upper right to the lower left is interpreted as part of a belt of ridges, formed by compression and thickening of the upper layers of the planet. The areas between ridges suggest flooding by radar dark (and thus presumably) smoother lavas. The varied textures of the lavas can be seen in the mottled appearance of the plains which are cut by the ridges; brighter, rougher flows are also quite common. The particularly bright flows in the lower right corner are the northern extension of Mylitta Fluctus. The bright ridges adjacent to Mylitta Fluctus at the bottom center of the image also appear to have been affected by the volcanic activity. Some of these bright features have been interpreted as down-dropped areas roughly 5 kilometers (3 miles) wide. This would imply a region of extension where the crust has been pulled apart and thus was more easily flooded by the later lava flows. The thinner fractures running from the upper left seem to end at the ridge belt in the center of this mosaic. These thinner fractures are a continuation of a pattern seen throughout much of Lavinia and suggest a pattern of compression over a very large region. At the bottom of the image, overlying the ridges, is an impact crater 10-15 kilometers (6-10 miles) in diameter. The double or overlapped crater structure and asymmetrical ejecta pattern suggests that the incoming body broke up shortly before it hit, leaving closely-spaced craters. The placement of the crater on top of the ridges implies it is younger than the ridges; in fact, the crater may be one of the youngest features in this image. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@mars.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | Is it mind over matter, ___| | | | |__) |/ | | |___ M/S 301-355 | or matter over mind? /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | Never mind. |_____|/ |_|/ |_____|/ | It doesn't matter. ------------------------------ Date: 28 Feb 91 12:40:29 GMT From: eru!hagbard!sunic!lth.se!newsuser@bloom-beacon.mit.edu (Magnus Olsson) Subject: Re: Numerology, theology In article <9102271935.AA29338@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >> Will it someday happen that 2 + 2 != 4? > >Well, since you ask, yes, it could. :-) >A pure mathematical expression such as 2 + 2 = 4 exists by human definition, >and humans can change the definition any time they feel like it. This is true, but it's not quite that simple. Suppose you want to redefine mathematics so that 2+2 = 5, for example. In that case, you'd obviously have to redefine what you mean by addition. If you'd want the "new" addition operation to be reasonably like the old one, you'd have to redefine your notion of "number" (i.e., the "definition" of 2) as well. The point is: Can this be done without creating inconsistencies? THIS IS HIGHLY NON-TRIVIAL. In the case of non-Euclidean geometry, what Gauss et.al. found out was that yiu can replace Euclid's parallell axiom by a different axiom and still get a consistent, non-equivalent theory. This doesn't mean that *any* axiom could be changed to say *anything* else. In short, having a theory where 2+2=5 might not be possible, at least not if this theory should be non-trivial and have any resemblance to "ordinary" arithmetic (trivial theories, such as where addition is defined only for 2+2, or where you rename the number 4 to 5, are of course easy to think of). There is actually a mathematical theory, aptly called meta-mathematics, for this kind of stuff. It was created by Hilbert around the turn of the century and culminated in Goedel's famous theorem in the 1930's (any axiomatic system powerful enough to contain the laws of arithmetic must either be inconsistent or incomplete, i.e. there must be either contradictions or statements that can't be proved.) Magnus Olsson | \e+ /_ Dept. of Theoretical Physics | \ Z / q University of Lund, Sweden | >----< Internet: magnus@thep.lu.se | / \===== g Bitnet: THEPMO@SELDC52 | /e- \q ------------------------------ Date: 28 Feb 91 17:14:42 GMT From: usc!sdd.hp.com!zaphod.mps.ohio-state.edu!ub!uhura.cc.rochester.edu!rochester!dietz@ucsd.edu (Paul Dietz) Subject: Re: Government vs. Commercial R&D In article <21258@crg5.UUCP> szabo@crg5.UUCP (Nick Szabo) writes: >The idea that per-pound launch costs can be _radically_ lowered by >chemical rockets is nonsense. Space settlement, and perhaps also >the large-scale industries leading up to it, require such a radical >lowering of launch costs -- by over a factor of 10. Here we part company, Nick. I am unconvinced that existing chemical launchers are anywhere near optimal. The ultimate cost limit, set by the cost of fuel, is orders of magnitude less than current cost. One would need a reusable vehicle capable of flying repeatedly with minimal labor-intensive overhaul between launches (i.e., not the shuttle), but that is not, in principle, impossible. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: Fri, 1 Mar 1991 00:33 CST From: "In the immortal words of Socrates, 'I drank what?'" Subject: FTP site for satellite data I'm looking for an ftp site for satellite data. I noticed when I was subsribed to this list that there was an ftp site out there. I'm no longer on this list so will you please send you responses directly to me. Thank you Dan Wihela Lupis%bsu.decnet@msus1.bitnet ------------------------------ Date: 28 Feb 91 00:59:18 GMT From: agate!bionet!uwm.edu!spool.mu.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!Paul.Blase@ucbvax.Berkeley.EDU (Paul Blase) Subject: re request for combined Earth satallite photo Re the recent posting asking for information concerning a composite photograph, derived from satellite photographs, showing all of the Earth's surface through a cloudless sky: The photo is by Tom Van Sant, of Santa Monica, CA, and L. Van Warren of JPL. It is featured on p127 of the Nov. 1990 National Geographic. Try writing to them for copies. (sorry, I couldn't find the original posting again to reply to it) --- via Silver Xpress V2.26 [NR] -- Paul Blase - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!Paul.Blase INTERNET: Paul.Blase@nss.FIDONET.ORG ------------------------------ Date: 28 Feb 91 01:03:50 GMT From: agate!bionet!uwm.edu!spool.mu.edu!samsung!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!Paul.Blase@ucbvax.Berkeley.EDU (Paul Blase) Subject: Re: ET...Again (was ONE SMALL STEP - REPLY) K > It seems to me that if there were a market for such 'pre-fab' K > stations, the Soviets would be leading the way with their K > Salyut/ Mir 'line' of stations. I'm not aware of any K > (successful) efforts on the part of the Soviets to sell or K > lease entire modules/stations outright, although they do seem K > to lead the way when it comes to accomodating paying K > passengers and customers. They recently sold one to the Japanese (for use as an engineering model, I believe). --- via Silver Xpress V2.26 [NR] -- Paul Blase - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!Paul.Blase INTERNET: Paul.Blase@nss.FIDONET.ORG ------------------------------ Date: 25 Feb 91 23:15:45 GMT From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!Paul.Blase@ucbvax.Berkeley.EDU (Paul Blase) Subject: Re: Terraforming, sun shield 2> Question (doozie!): 2> I am a senior CS undergrad who has had some physics but my 2> imagination is going way beyond my ability to compute, and I'm 2> a'thinkin' maybe somebody thinks this is an interesting problem, 2> too: 2> Problem: Terraform Venus. ... 2> Another idea is instead of opaque, how about circular (would 2> just be lines, really, at that diameter) diffraction grating 2> that focused on a single point and then having a very, very 2> polished mirror do some reflecting? 1) Go get the last 5 years or so of Analog magazine and read the science- fact articles. Most of what you propose has already been mentioned there. 2) Get ahold of the reports on advanced space propulsion concepts by R. L. Forward (references posted earlier - ask and I'll post again). --- via Silver Xpress V2.26 [NR] -- Paul Blase - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!Paul.Blase INTERNET: Paul.Blase@nss.FIDONET.ORG ------------------------------ Date: 25 Feb 91 23:02:44 GMT From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!Paul.Blase@ucbvax.Berkeley.EDU (Paul Blase) Subject: Re: SOLAR TERRESTRIAL FORECAST AND REVIEW SC> Inquiry: To which latitudes does the phrase "northerly middle SC> latitudes" refer? The ones right between the "northerly upper latitudes" and the "northerly lower latitudes". --- via Silver Xpress V2.26 [NR] -- Paul Blase - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!Paul.Blase INTERNET: Paul.Blase@nss.FIDONET.ORG ------------------------------ Date: 28 Feb 91 01:12:23 GMT From: agate!bionet!uwm.edu!spool.mu.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!Paul.Blase@ucbvax.Berkeley.EDU (Paul Blase) Subject: GGreetings Hi Buzz, long time no see Blase --- via Silver Xpress V2.26 [NR] -- Paul Blase - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!Paul.Blase INTERNET: Paul.Blase@nss.FIDONET.ORG ------------------------------ Date: 28 Feb 91 01:11:52 GMT From: agate!bionet!uwm.edu!spool.mu.edu!sdd.hp.com!elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!Paul.Blase@ucbvax.Berkeley.EDU (Paul Blase) Subject: Re: Mars Mystery? -clarification & dilemma Actually, I think that there was more than one photo. There was a rather extensive article about it in Analog a couple of years back. The author never claimed that it HAD to be an artifact, merely that it LOOKED a great deal like one and bore further investigation. If we are going to land a Mars Rover anyway, here would be as good a place as any. --- via Silver Xpress V2.26 [NR] -- Paul Blase - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!Paul.Blase INTERNET: Paul.Blase@nss.FIDONET.ORG ------------------------------ End of SPACE Digest V13 #218 *******************