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, 15 Jan 91 16:15:03 -0500 (EST) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 15 Jan 91 16:14:55 -0500 (EST) Subject: SPACE Digest V13 #050 SPACE Digest Volume 13 : Issue 50 Today's Topics: Re: Metrics (was Re: Rotating Joints for Habitat) Re: Interplanetary travel Re: SPACE Digest V13 #044 Re: shuttle was answer Re: Humankind's Second Off-world Colony Magellan Update - 01/14/91 Re: Fwd: NASA Plans To Redesign Space Station Re: Fwd: NASA Plans To Redesign Space Station Re: Metrics (was Re: Rotating Joints for Habitat) 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: 14 Jan 91 10:15:19 GMT From: eru!hagbard!sunic!lth.se!newsuser@bloom-beacon.mit.edu (Magnus Olsson) Subject: Re: Metrics (was Re: Rotating Joints for Habitat) In article <1991Jan13.012308.23830@uvm.edu> wollman@emily.uvm.edu (Garrett Wollman) writes: >[I say metric rather than specifically SI because kilograms are an awfully >inconvenient unit for weighing paperclips, thumbtacks, and all those >other things that the government buys in quantity. Ditto for cubic >meters and pen refills. Believe me: The SI does *not* require you to measure everything in the basic units kilograms, metres, seconds, Kelvins and so on. All the familiar prefixes are as much a part of the SI as of the older `metric' systems. Besides, there are `supplementary units' (or whatever the correct term is) like litres, degrees Celsius and tons. We've been using the SI for more than a decade in Sweden, and paperclips are still weighed in grams and pen refills in milliliters. And this is not only true for `ordinary people'; even in scientific works, it is allowed to use prefixes with SI units. >Besides, you will never get Americans to >write "metre" or accent "kilometer" on the first syllable :-). Strange - I always thought it was the English who said `kilo'metre' and that the Americans used the more correct stress. (Why do I call it `correct'? Well, at least it's more consequent - try pronouncing `milliltre' with ante-penultimate stress. :-) ) 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: 12 Jan 91 03:26:40 GMT From: bonnie.concordia.ca!news-server.csri.toronto.edu!helios.physics.utoronto.ca!ists!yunexus!lethe!tvcent!comspec!censor!utzoo!utgpu!cunews!cognos!geovision!gd@uunet.uu.net (Gord Deinstadt) Subject: Re: Interplanetary travel pmk@prometheus.UUCP (Paul M. Koloc) writes: >[I wrote] >> .. .. . . As I understand it this is the ratio that gives the >>minimum energy requirement for a given delta-vee. >Ideal?? Doesn't that depend on the criteria. >Speaking of interplanetary excursions, if the propulsion energy source >is fusion then "WHY, would one want to mimimize energy consumption.?" >It seems to me that payload and perhaps some merit of trip time (few >weeks) should be what is optimized. Delta vee is the independent variable. Knowing it, you will get the miminum energy consumption by applying the formula for that delta vee. You will also get the highest vehicle performance for a given reactor output, even though other ratios yield a lower overall mass. (In other words, your high-energy ship would go both faster and farther if you added some tankage and changed the blend, without changing the ship in any other way.) The only question is whether you also get the minimum cost. Higher power means higher cooling requirements (conversely more propellant means more cooling capacity). Also bigger engines and more fusion fuel (which will cost something). Against this is the cost of more propellant (not highly refined, possibly just pumped out of a lake on some Jovian moon), and the extra cost of the tankage and plumbing. (I imagine direct injection could be used to eliminate the need for a heat exchanger.) I suspect that, incorporating all these costs into the basic relationship, the lowest-cost point will fall near the minimum-energy point. It is of course impossible to know for sure until such a ship is actually built, and even then the optimum point depends on externalities, eg. interest rates. Having said that, I now realize that I have been guilty of thinking like a rocket designer from *blush* 1991. ;) Who says that a given ship will always be used for the same route? We're not talking NASA missions here... In fact, the bulk of transportation has to do with moving cargo, and for shipping cargo in space (especially vacuum class cargo) all you need is a *barge*. There should be a tug based at each port to supply the delta vee when it is required. The tugs should have separate throttles for reactor power and propellant flow, so the crew can optimize for different loads, costs, and deadlines. -- Gord Deinstadt gdeinstadt@geovision.UUCP ------------------------------ 1,, Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Received: from po9.andrew.cmu.edu via trymail for space+@andrew.cmu.edu (->space-usenet+) (->ota+space.incoming) ID ; Mon, 14 Jan 91 09:57:22 -0500 (EST) Received: from po3.andrew.cmu.edu via qmail ID ; Mon, 14 Jan 91 09:55:51 -0500 (EST) ReSent-Message-ID: Received: from uga.cc.uga.edu by po3.andrew.cmu.edu (5.54/3.15) id for space+; Mon, 14 Jan 91 09:55:41 EST Received: from UGA.CC.UGA.EDU by uga.cc.uga.edu (IBM VM SMTP R1.2.2MX) with BSMTP id 4403; Mon, 14 Jan 91 09:53:37 EST Received: from UGA.CC.UGA.EDU by UGA.CC.UGA.EDU (Mailer R2.07) with BSMTP id 1439; Mon, 14 Jan 91 09:53:35 EST Resent-Date: Mon, 14 Jan 91 09:50:41 EST Resent-From: Harold Pritchett Resent-To: Space discussion group Received: from UGA.BITNET by UGA.CC.UGA.EDU (Mailer R2.07) with BSMTP id 4049; Sun, 13 Jan 91 05:13:12 EST Received: from ncsuvm.ncsu.edu by UGA.CC.UGA.EDU (Mailer R2.07) with BSMTP id 4044; Sun, 13 Jan 91 05:11:59 EST Received: from NCSUVM by ncsuvm.ncsu.edu (Mailer R2.07) with BSMTP id 8533; Sun, 13 Jan 91 05:13:48 EST Received: from mcnc.mcnc.org by ncsuvm.ncsu.edu (IBM VM SMTP R1.2.2MX) with TCP; Sun, 13 Jan 91 05:13:44 EST Received: by mcnc.mcnc.org (5.59/MCNC/6-11-90) id AA14375; Sun, 13 Jan 91 05:13:05 -0500 for space%UGA.bitnet@ncsuvm.ncsu.edu Received: from sdcmvs.mvs.sas.com by mozart.unx.sas.com (5.64+/SAS/Domains/5-6-90) id AA21750; Sun, 13 Jan 91 05:00:39 -0500 Message-Id: <9101131000.AA21750@mozart.unx.sas.com> Received: from SDCMVS.MVS.SAS.COM by MVS.SAS.COM (IBM MVS SMTP R1.0.1) with BSMTP id 8002; Sun, 13 Jan 91 05:09:47 EST Date: Sun, 13 Jan 91 05:07 EST From: "Mike Bishop" T  0, unseen,*** EOOH *** Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Received: from po9.andrew.cmu.edu via trymail for space+@andrew.cmu.edu (->space-usenet+) (->ota+space.incoming) ID ; Mon, 14 Jan 91 09:57:22 -0500 (EST) Received: from po3.andrew.cmu.edu via qmail ID ; Mon, 14 Jan 91 09:55:51 -0500 (EST) ReSent-Message-ID: Received: from uga.cc.uga.edu by po3.andrew.cmu.edu (5.54/3.15) id for space+; Mon, 14 Jan 91 09:55:41 EST Received: from UGA.CC.UGA.EDU by uga.cc.uga.edu (IBM VM SMTP R1.2.2MX) with BSMTP id 4403; Mon, 14 Jan 91 09:53:37 EST Received: from UGA.CC.UGA.EDU by UGA.CC.UGA.EDU (Mailer R2.07) with BSMTP id 1439; Mon, 14 Jan 91 09:53:35 EST Resent-Date: Mon, 14 Jan 91 09:50:41 EST Resent-From: Harold Pritchett Resent-To: Space discussion group Received: from UGA.BITNET by UGA.CC.UGA.EDU (Mailer R2.07) with BSMTP id 4049; Sun, 13 Jan 91 05:13:12 EST Received: from ncsuvm.ncsu.edu by UGA.CC.UGA.EDU (Mailer R2.07) with BSMTP id 4044; Sun, 13 Jan 91 05:11:59 EST Received: from NCSUVM by ncsuvm.ncsu.edu (Mailer R2.07) with BSMTP id 8533; Sun, 13 Jan 91 05:13:48 EST Received: from mcnc.mcnc.org by ncsuvm.ncsu.edu (IBM VM SMTP R1.2.2MX) with TCP; Sun, 13 Jan 91 05:13:44 EST Received: by mcnc.mcnc.org (5.59/MCNC/6-11-90) id AA14375; Sun, 13 Jan 91 05:13:05 -0500 for space%UGA.bitnet@ncsuvm.ncsu.edu Received: from sdcmvs.mvs.sas.com by mozart.unx.sas.com (5.64+/SAS/Domains/5-6-90) id AA21750; Sun, 13 Jan 91 05:00:39 -0500 Message-Id: <9101131000.AA21750@mozart.unx.sas.com> Received: from SDCMVS.MVS.SAS.COM by MVS.SAS.COM (IBM MVS SMTP R1.0.1) with BSMTP id 8002; Sun, 13 Jan 91 05:09:47 EST Date: Sun, 13 Jan 91 05:07 EST From: "Mike Bishop" T ------------------------------ X-Ns-Transport-Id: 0000AA00047AA70E2B27 Date: Mon, 14 Jan 1991 07:19:46 PST From: JCastro.El_Segundo@xerox.com Subject: Re: SPACE Digest V13 #044 Cc: JCastro.El_Segundo@xerox.com Can someone please remove my name from this DL. Thank you ------------------------------ Date: 14 Jan 91 15:36:10 GMT From: snorkelwacker.mit.edu!usc!samsung!noose.ecn.purdue.edu!mentor.cc.purdue.edu!mace.cc.purdue.edu!dil@bloom-beacon.mit.edu (Perry G Ramsey) Subject: Re: shuttle was answer In article <20900@crg5.UUCP>, szabo@crg5.UUCP (Nick Szabo) writes: > In article <91009.085316GIPP@GECRDVM1.BITNET> GIPP@gecrdvm1.crd.ge.com writes: > >Henry Spencer quips: > >-if the space shuttle was the answer, what was the question- > >How about: > >what is a bargain compared to many of the other Gov't "spending" > > Ah, the good old "they're wasting money so we can waste money too!" Don't forget the most important resource being wasted: smart people. Because our technical staff is running around trying to keep the inappropriately designed shuttle in the air, (or quitting the business out of frustration like yours truly), they aren't available to make better stuff or get down to the real business of making a go of space flight. Just because HHS wastes hecto-gigabucks doesn't make NASA's waste of deca-gigabucks an inconesquential loss. -- Perry G. Ramsey Department of Earth and Atmospheric Sciences perryr@vm.cc.purdue.edu Purdue University, W. Lafayette, IN USA dil@mace.cc.purdue.edu Why waste time learning when ignorance is instantaneous? -- Hobbes ------------------------------ Date: 14 Jan 91 17:05:47 GMT From: wk1.acd.ucar.edu!chucks@handies.ucar.edu (Chuck Smythe) Subject: Re: Humankind's Second Off-world Colony In article <4404@mindlink.UUCP> a684@mindlink.UUCP (Nick Janow) writes: > >Another problem of building on ice might be creep (slow movement into the ice). >Does anyone know if this is a problem in Antarctica? Yes, I understand that it is. Most Antarctic stations have more of a problem with getting buried and crushed by drifting snow, but South Pole Station has had some problems with shifting foundations due to ice creep. Chuck Smythe ------------------------------ Date: 14 Jan 91 22:23:02 GMT From: agate!shelby!snorkelwacker.mit.edu!think.com!zaphod!swrinde!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucbvax.Berkeley.EDU (Ron Baalke) Subject: Magellan Update - 01/14/91 MAGELLAN STATUS REPORT January 14, 1991 The Magellan spacecraft and its radar system continue to perform nominally. All STARCALS (star calibrations) and DESATS (desaturations) during the weekend were successful with an average attitude update of 0.016 degree. The spacecraft experienced another spurious shutoff of the high power transmitter on the morning of January 11 at 9:50 AM PST. It occurred at the end of a mapping pass, just as the transmitter was powering up to begin playback. The switch to TWTA-A went smoothly and less than five minutes of radar data was lost. During the weekend, commands were sent to reset the fault protection flags. Also on January 11, the spacecraft controllers detected an error in the mapping command sequence being sent to the spacecraft later that day. The error related to a necessary adjustment in the nominal start of the first orbit of the sequence and the corresponding radar control parameters. This adjustment occurs only as the spacecraft comes out a period of occulted mapping and would have executed properly if the initial orbit of the new sequence has been a delayed orbit. Various options for correcting the error were reviewed, but there was not time to build a new command sequence or generate new radar control parameters. It was decided to continue with the command sequence "as is" with the likely result of some image loss on the initial orbit of the sequence. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 14 Jan 91 15:47:21 GMT From: agate!bionet!uwm.edu!wuarchive!usc!samsung!noose.ecn.purdue.edu!mentor.cc.purdue.edu!mace.cc.purdue.edu!dil@ucbvax.Berkeley.EDU (Perry G Ramsey) Subject: Re: Fwd: NASA Plans To Redesign Space Station In article , dg1v+@andrew.cmu.edu (David Greene) writes: > WASHINGTON -AP- The National Aeronautics and Space Administration > said it will go back to the drawing board to design a simpler, less > costly space station as recommended by a panel of experts. This is not to suggest that Fred doesn't need some serious re-work, but does anybody remember when the original design studies were done? Try 1984. Six years down, and not a single screw to show for it. Just for comparison's sake, Kennedy inagurated the Apollo program in 61. Six years later in 67, the first Saturn V flew. -- Perry G. Ramsey Department of Earth and Atmospheric Sciences perryr@vm.cc.purdue.edu Purdue University, W. Lafayette, IN USA dil@mace.cc.purdue.edu Why waste time learning when ignorance is instantaneous? -- Hobbes ------------------------------ Date: 14 Jan 91 18:54:15 GMT From: rochester!sol!yamauchi@louie.udel.edu (Brian Yamauchi) Subject: Re: Fwd: NASA Plans To Redesign Space Station In article <6571@mace.cc.purdue.edu> dil@mace.cc.purdue.edu (Perry G Ramsey) writes: In article , dg1v+@andrew.cmu.edu (David Greene) writes: > WASHINGTON -AP- The National Aeronautics and Space Administration > said it will go back to the drawing board to design a simpler, less > costly space station as recommended by a panel of experts. This is not to suggest that Fred doesn't need some serious re-work, but does anybody remember when the original design studies were done? Try 1984. Six years down, and not a single screw to show for it. Just for comparison's sake, Kennedy inagurated the Apollo program in 61. Six years later in 67, the first Saturn V flew. Given that the US has already launched a space station and the Soviets have launched several (including a modular/expandable station), my question is: what are the hard technical problems that are making the Freedom design process so long (and expensive)? I can think of four areas in which Freedom seems technically challenging: 1) Robotics: Flight Telerobotic Servicer, EVA Retriever, Canada's manipulator system. 2) The Truss: In particular, building it in orbit. Someone mentioned that the truss was cut in the latest redesign -- did this refer to just the dual keel design (which was cut earlier) or the *entire* truss? 3) On-orbit assembly. 4) The 30-year lifespan: This seems like a major mistake to me -- is NASA really going to maintain and support Freedom for three decades? How much does this add to the expense and complexity of the station? I suppose this makes more sense if Freedom is going to be expanded into a staging/assembly area for interplanetary craft, as suggested by Buzz Aldrin (Air & Space, Sept/Oct 1990), but I haven't heard any official plans from NASA. Other than these, the technologies required for Freedom seem to be relatively straightfoward extrapolations of the technology used in Skylab/Salyut/Mir. Are there are another major technological hurdles I have overlooked? Or is the problem not one of technology, but of incompetent management and/or ignorant politicians? -- _______________________________________________________________________________ Brian Yamauchi University of Rochester yamauchi@cs.rochester.edu Computer Science Department _______________________________________________________________________________ ------------------------------ Date: 14 Jan 91 19:52:09 GMT From: snorkelwacker.mit.edu!thunder.mcrcim.mcgill.edu!bonnie.concordia.ca!news-server.csri.toronto.edu!utzoo!henry@bloom-beacon.mit.edu (Henry Spencer) Subject: Re: Metrics (was Re: Rotating Joints for Habitat) In article <1991Jan14.101519.25331@lth.se> magnus@thep.lu.se (Magnus Olsson) writes: >... even in scientific works, it is allowed to use >prefixes with SI units. There is one minor exception to this. Some branches of engineering, having been burned too many times by unit conversions, pick a single unit of (say) length and use that for *everything*, no prefixes allowed. Metric machine shops, for example, often do everything in millimeters, even if they're working on something big like an airliner wing. -- If the Space Shuttle was the answer, | Henry Spencer at U of Toronto Zoology what was the question? | henry@zoo.toronto.edu utzoo!henry ------------------------------ End of SPACE Digest V13 #050 *******************