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, 5 Apr 91 01:43:37 -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, 5 Apr 91 01:43:31 -0500 (EST) Subject: SPACE Digest V13 #359 SPACE Digest Volume 13 : Issue 359 Today's Topics: Re: Increasing value/lb. Re: Chemical rocket complexities (was Re: "Follies") Re: "Face" on Mars Re: Why does every SAR have another resolution? KSC Shuttle Launch Passes Shuttle Frequencies Re: solid motor failure at edwards... Space Stations, Money, Startrek Re: How 'bout them Titans? 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: 4 Apr 91 21:33:07 GMT From: dog.ee.lbl.gov!hellgate.utah.edu!caen!zaphod.mps.ohio-state.edu!wuarchive!rex!rouge!dlbres10@ucbvax.Berkeley.EDU (Fraering Philip) Subject: Re: Increasing value/lb. In article <21469@crg5.UUCP> szabo@crg5.UUCP (Nick Szabo) writes: >instead of $1,000/kg or more). This uses "today's technology" in the >sense that no nanotechnology, AI advances, etc. are needed. The biggest >limiting factor: we aren't tracking the #@!$!$#@ comets yet! We _do_ need >advances in astronomy to make this scheme work. I hope to see such >advances in the next 5-15 years -- a combination of the new telescopes >coming on-line, and a new emphasis on comets as space resources by the >space community. Small asteroids (silicon, metals) could be retrieved >with a somewhat more sophisticated effort, but this effort would not >necesarily involve more launch mass. Ice is much easier to mine than >hard dirt and rock, but we will need to also develop techniques for the >latter. As is usual with technology, the expertise and products gained >from the smaller-scale operations will allow us to bootstrap into the >larger-scale tasks of building large-scale space industries and space >colonies at a far lower cost than that of trying to accomplish such a >gargantuan project from scratch. >Now, that is not to say that this is easy. Intellectually, at least, >this path is much more difficult than the old chem rocket/space station/ >Moon/Mars paradigm. However, economically and politically it is far, >far cheaper. If we follow the old failed paths, we are doomed to defeat. >By consiously working towards increasing value/lb. and letting the >solar system do the work for us, we _can_ achieve space colonization, >the "work of generations" (Goddard). If I were you I would not be so hasty designing the apparatus for moving the comet. It would be much more constructive for you to simply devote whatever efforts you intend to make towards finding out about the comets. Our knowledge of comets is extemely limited. Although I think they are important, anything more than reconnisance is unjustified. In short, don't count your eggs before you know whether or not chickens or pterodactyls will result on hatching day. And it might turn out that moving a comet is a more intractable problem than you think. I am trying not to be closed-minded, especially towards your idea about using solar thermal power to move the comets :-) :-) :-) :-) :-) :-) :-) , but we need to keep _all_ of our options open. To summarize, though, you should be working on finding out more about these things instead of making a very general model for moving something. Phil Fraering dlbres10@pc.usl.edu "The reserve of modern assertions is sometimes pushed to extremes, in which the fear of being contradicted leads the writer to strip himself of almost all sense and meaning." - Winston S. Churchill ------------------------------ Date: 4 Apr 91 22:39:18 GMT From: mnemosyne.cs.du.edu!isis!gaserre@uunet.uu.net (Glenn A. Serre) Subject: Re: Chemical rocket complexities (was Re: "Follies") Excuse me, I may have missed some of the Chemical rocket complexities discussion (problems with the news server), but what happened to the technical reasons for why launch costs can't be significantly lowered? So far, I've heard. 1) High-power turbopumps and cryo fuel. 2) Large "ductile" structures. 3) Tracking 4) Control, i.e. gyros, etc. 1) and 2) are bogus, see my recent post , Re: Follies, I think. For 3) and 4), anyone out there have any expertise? Customers causing (at least partially) high costs. 1) Does anyone (else) who has worked for a rocket company have any comment? 2) Are there any customers out there? One last thing: Why is this whole topic being argued as rockets vs. exotic technology? Rocket development should be made more commercial, as opposed to governmental. Anyone out there disagree? Government-sponsored development should concentrate on exotic technologies like gas-guns, EML, tethers, etc. Anyone out there disagree? More ramblings from: -- --Glenn Serre gaserre@nyx.cs.du.edu -- --Glenn Serre gaserre@nyx.cs.du.edu ------------------------------ Date: 3 Apr 91 11:02:09 GMT From: dev8.mdcbbs.com!rivero@uunet.uu.net Subject: Re: "Face" on Mars In article <27f7314b-453.1space-1@oldcolo.UUCP>, burger@oldcolo.UUCP (Keith Hamburger) writes: > Perhaps, if one is interested, he should check his local library for a copy of > the book. If the ideas prove worthwhile he could then purchase other books on > the subject. (please note that I am not going to even get it at the library, > I don't need to be told that I should take anything on faith just because it > might be possible.) > > Keith Are we never to be rid of this? I worked on the Viking flight control team, and have seen many orbital photographs of that same piece of real estate. Only in the one photograph, when the sun is at a particular angle, does the surface feature take on a vague semblance to a face. And the photo most commonly displayed to the public has been severely contrast enhanced to bring up this feature. As to certain sensationalist works claining to see remains of a city hidden in the shadows of that photo, their claims are always "proved" by copies of copies of copies of the photo in question, usually shot through a poor half tone screen. No such artifacts are visable in the original source data. Mars has never had a civilization. The debate is STILL going on as to whether the life science results found traces of life, or merely the chemical precursors to life which stopped evolving when Mars lost its water. If you want to look for non-terrestrial life, current thought holds that the most likely place to find it will be floating high in the atmosphere of Jupiter. ------------------------------ Date: 4 Apr 91 18:54:40 GMT From: usc!elroy.jpl.nasa.gov!jato!vsnyder@ucsd.edu (Van Snyder) Subject: Re: Why does every SAR have another resolution? In article <1923@mpirbn.mpifr-bonn.mpg.de> p515dfi@mpirbn.UUCP (Daniel Fischer) writes: >From NASA NEWS RELEASE 91-34 of February 27, 1991 on the RADARSAT spacecraft: >> The satellite's synthetic aperture radar (SAR) will be ... scanning the >> Earth in swaths varying from 50 to 500 km. The SAR will produce high-resolu= >> tion (10 to 100 meters pixel size) images of the Earth's surface... > >Now we all know that the Magellan in its orbit around Venus produces swaths >some 25km wide, with a resolution of approx. 120 meters. Why can the resolution >of RADARSAT's SAR be so much better, about a factor of 10? This can't be due >to a lower orbit alone, I presume. Also, why can RADARSAT have many more >pixels across the swath's width (according to this article 5000) compared to >Magellan (200)? Does that depend on their antennas or on the data processing? The SAR resolution depends on the orbit, transmitter power and antenna aperture.RADARSAT has a more powerful transmitter, a bigger antenna and a lower orbit. The downlink data rate, and thus a reasonable limit on the number of pixels one should collect per orbit, depends, in order of importance, on: distance, transmitter power, antenna aperture and efficiency, data processing. Distance is by far the most important. Since the transmitter power on Magellan is essentially fixed, as is the antenna aperture, the possible data rate at a given signal-to-noise ratio varies inversely as the square of the distance. The data rate today is 268k baud. From near earth orbit, several mega-baud is possible with the same transmitter power and antenna aperture. -- vsnyder@jato.Jpl.Nasa.Gov ames!elroy!jato!vsnyder vsnyder@jato.uucp ------------------------------ Date: Thu, 04 Apr 91 14:45:44 EST From: Michael Petersen Subject: KSC Shuttle Launch Passes Can anyone tell me how I can obtain a KSC visitor pass for a shuttle launch. I've seen a launch before from a location on the space coast, but I hear the view from the visitor area in KSC is magnificient! Thanks! --Mike ENGDHFC@BUACCA.BITNET ------------------------------ Date: 4 Apr 91 16:55:13 GMT From: dog.ee.lbl.gov!hellgate.utah.edu!caen!zaphod.mps.ohio-state.edu!wuarchive!emory!ducvax.auburn.edu!eng.auburn.edu!bh@ucbvax.Berkeley.EDU (Brian Hartsfield) Subject: Shuttle Frequencies Could somebody post or e-mail me a list of frequencies where the shuttle air-to-ground communications can be picked up? I am in Auburn, AL. Brian Hartsfield ------------------------------ Date: 4 Apr 91 20:57:46 GMT From: orca!bambam!bpendlet@uunet.uu.net (Bob Pendleton) Subject: Re: solid motor failure at edwards... In article <2077@gorn.santa-cruz.ca.us>, everyman@gorn.santa-cruz.ca.us (arvey j. shier) writes: > ....it is possible that > an advanced version of the 7 segment motor is in development... Hercules Aerospace has a contract to build an advanced version of the Titan IV solid boosters. I don't know all the details. But it has a larger diameter and a graphite fiber/epoxy wound case. -- Bob Pendleton, speaking only for myself. bpendlet@dsd.es.com or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet Tools, not rules. ------------------------------ Date: 4 Apr 91 23:27:25 GMT From: tahoe!jimi!herbert!doug@apple.com (Doug Phillipson ) Subject: Space Stations, Money, Startrek Hi net world! Please indulge me for a moment on FRED. First, I love space science, and almost anything that will get us (Human race) off this rock called Earth. But I believe the Freedom station is a waste of taxpayers money. It can not be manned for any great period of time by the same people due to the lack of gravity. Yes I know that is the whole purpose of the darn thing. Well the follow on to FRED must be a cylindrical station that rotates for LONG duration living, I'm talking years here. And the micro gravity experiments can be done at the zero G hub of the station. Now with FRED you are going to have to take a lot of exercise equipment up to orbit just to keep the scientists from becoming silly putty. And a good measure of their time will be taken up using that exercise equipment. Why don't we start our space research from the start in a station we won't have to scrap in 10 to 15 years. I would strongly support even with a tax hike (oh there is that republican dirty word) a deluxe rotating station. But to throw billions of dollars into a station that is doomed from the start to obsolescense is insanity. Yes I know your building it to be expandable. So now we will have a expanded obsolete station that people still can't remain at for extended periods. Lets not throw money at a station just to have a station. Lets not make another Skylab. Lets build one that will take us into the next century proudly. Quayle are you listening? NASA are you feeling the real pulse of the people? Mr President are you serious about space? Douglas Phillipson Visionary Programmer ------------------------------ Date: 4 Apr 91 07:27:01 GMT From: hao.hao.ucar.edu!murphy@handies.ucar.edu (Graham Murphy) Subject: Re: How 'bout them Titans? I'd be interested in knowing where the sound track for CNN's footage of the explosion came from---presumably not the control room. Shortly after the Titan was destroyed, one hears a voice in the background say, "Is it supposed to do that?" followed by another voice giving a very emphatic "No!" Graham Murphy High Altitude Observatory National Center for Atmospheric Research P.O. Box 3000, Boulder CO 80307-3000. Ph:(303)497-1565; Fax:(303)497-1137. INTERNET: murphy@hao.UCAR.EDU; Solar PO: GMurphy@SOLAR ------------------------------ End of SPACE Digest V13 #359 *******************