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 ; Sun, 28 Apr 91 01:45:15 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 28 Apr 91 01:45:09 -0400 (EDT) Subject: SPACE Digest V13 #474 SPACE Digest Volume 13 : Issue 474 Today's Topics: Re: ALS vs. Saturn V Writer needs help getting his facts straight. Re: NASP Re: Saturn V and the ALS Orbital Elements of Saturnian system Re: Shuttle Reliability (was: Re: Saturn V and the ALS) Re: Incentives Re: Saturn V and the ALS Re: Transportation Tethers (Beanstalks) Alexander Abian wants to blow up the moon? NASP 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: 27 Apr 91 03:00:20 GMT From: agate!lightning.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: ALS vs. Saturn V In article gaserre@isis.isis.cs.du.edu (Glenn A. Serre) writes: >What are examples of proven 1980's rocket technology around? Parts of the >Shuttle seem to be the most recently developed examples of US rocket >technology. The Titan IV and Delta II have been upgraded significantly since the late 1960's (e.g. the technonlgy of the Saturn V). I believe the greatest changes have been in the development of new upper stages. In addition to improvements in the avionics, structural materials now available are vastly better than those used on the Saturn V. While such improvements could be incorporated into a rebuilt Saturn V, a newly designed vehicle could better use these changes. Frank Crary UC Berkeley ------------------------------ Date: 27 Apr 91 01:52:07 GMT From: mips!news.cs.indiana.edu!bsu-cs!vamp@apple.com (Michael G. Rothermel) Subject: Writer needs help getting his facts straight. Hello, all. I am a science fiction writer looking to be one of the few in my profession with a little accuracy. But, I don't really know anything about space. That's why I've just started reading this group. I don't want to bother the general population of sci.space with bothersome questions, so if there is someone out there who would like to answer some questions (low and zero gravity life sciences, development of space technology, space stations and lunar colonization) or recommend some good sources of information, would you please e-mail me? It might be helpful but not imperative that this person enjoy reading science fiction. Thanks for your time, Michael Rothermel ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Happily Forever After, -"I shall live forever." vamp@bsu-cs.bsu.edu -"You call that living?" V V -"I don't call it dying." My opinions do not represent my university, which has no opinions. ------------------------------ Date: 28 Apr 91 03:16:51 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!ub!ubvmsb.cc.buffalo.edu!v071pzp4@tut.cis.ohio-state.edu (Craig L Cole) Subject: Re: NASP In article <1991Apr26.210024.29704@en.ecn.purdue.edu>, irvine@en.ecn.purdue.edu (/dev/null) writes... >Last peep from the NASP I heard was all the contractors >(McDonnell Douglas, General Dynamics, Boeing, Lockheed(?), etc) >were teaming up to design the prototype. > >The budget was $100million from Congress (1990)? > >I was hoping to find out what the status of this was? Any chance anyone out there working on the NASP can post regular updates on progress with the NASP? Scientific/Engineering hurdles & successes, budget concerns, progress on the prototype when its construction is started... I for one am very interested, and can't seem to find enough about it in magazines, etc. I bet a lot of others are interested too. Craig Cole V071PZP4@UBVMS.BITNET V071PZP4@UBVMS.CC.BUFFALO.EDU ------------------------------ Date: 26 Apr 91 21:58:57 GMT From: news-server.csri.toronto.edu!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: Saturn V and the ALS In article <1991Apr26.153811.1@vf.jsc.nasa.gov> kent@vf.jsc.nasa.gov writes: >The shuttle costs less per pound to orbit in adjusted dollars that the Saturn. Can we have some numbers, instead of flat (and frankly, somewhat unbelievable) statements? The comment I saw was that the Apollo-era Saturn V launches, after best-effort adjustment for things like the value of the dollar, cost almost exactly the same per kilogram to low orbit as the shuttle. However, I don't remember the exact assumptions behind that, and those assumptions are crucial. For example, do you estimate shuttle costs per flight by figuring how much it would cost to add another mission to a typical year (ignoring the fact that this is generally impossible, because NASA is launching as many as it can already), or by taking this year's program cost and dividing by the actual number of flights? This makes a big difference. -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 28 Apr 91 00:53:34 GMT From: mcn@lanl.gov (Michael C. Neuman) Subject: Orbital Elements of Saturnian system Does anyone have a table of orbital elements for the moons of Saturn? I would love to have the elements for all 17, but I doubt they've been computed yet. I need: The longitude of the perigee, longitude of the ascending node, and the mass. (All geocentric) Thanks! -Mike Neuman mcn@beta.lanl.gov mimas!mcn@bbx.basis.com ------------------------------ Date: 26 Apr 91 21:01:06 GMT From: usc!rpi!mvk@ucsd.edu (Michael V. Kent) Subject: Re: Shuttle Reliability (was: Re: Saturn V and the ALS) In article <1991Apr25.181422.4698@iti.org> aws@iti.org (Allen W. Sherzer) writes: >There is a good graph of this in the November 12,1990 Avation Week on page >27. It shows Shuttle actual flights vs flights on the manifest for the past >ten years. The first manifest had the 55th flight happening around the end >of 83. Eight and a half years later we have had less than 40 flights. Even >manifests made as recently as the Fall of 89 are off by a factor of two. Aye, but there is more to the story than that. These predictions of 50 flights a year were with a fleet of 6 oribiters, not 3. They were with LRB's, not SRBs. They were with a shuttle with about twice the original R&D as this one, but with operational costs far, far lower. NASA never got the money to build the one they wanted. The one we have is not that Shuttle, and comparing its capabilities to those older (never funded) ones is unfair. Going back to another AvWeek article, this one in the late '87 / early '88 era, we will find NASA complaining that they are short 500 personnel to work on the Return to Flight. They predicted that this Congressionally mandated hiring freeze would push Return to Flight back 3 to 6 months, and that Columbia would probably be delayed until 1989. NASA has been addressing the lower flight rate. They have increased Discovery and Atlantis from 25 to 50 man-day flight-capability, and Columbia to 75 man- days. Columbia is about to undergo further modifications to extend that to 110, with a possible further increase to 200 in the man-tended Space Station era. Endeavour weighs in at 75 man-day capable, with possible increases to the 200 man-day level. With the exception of Skylab, America's longest non-Shuttle flight is in the 20 to 30 man-day range (exact figures not handy). The Shuttle (the one that was actually built) has given us exactly what it promised -- routine access to space. Freedom will give us daily access. Mike ------------------------------ Date: 25 Apr 91 20:03:03 GMT From: van-bc!ubc-cs!alberta!herald.usask.ca!ccu.umanitoba.ca!bison!sys6626!draco!swrdpnt!ford@uunet.uu.net (Scott Young ) Subject: Re: Incentives irvine@en.ecn.purdue.edu (/dev/null) writes: > > If Congress were interested in developing a lot of private > experience for a private buisnesses in space exploration > and development of space resources, I heard somewhere > something like what I propose. > > Congress should allocate (through lotteries, appropriations, > etc) a large cash prize on the order of > US$100,000,000 for the first person/organization to > go to the moon and spend an amount of time on the surface. > > Any comments as to how to make this work? > > > > -- > +-----------------------------------------------------------------------+ > | Brent L. Irvine | These are MY opinions | > | Malt Beverage Analyst | As if they counted...:) | > +-----------------------------------------------------------------------+ First, catch a tiger... ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Reply to: ford%swrdpnt.bison.mb.ca@niven.cc.umanitoba.ca ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ Date: 26 Apr 91 21:38:11 GMT From: aio!vf.jsc.nasa.gov!kent@eos.arc.nasa.gov Subject: Re: Saturn V and the ALS In article , gaserre@isis.isis.cs.du.edu (Glenn A. Serre) writes: > 5) We know the Saturn V design works and has lower launch costs per pound. The shuttle costs less per pound to orbit in adjusted dollars that the Saturn. -- Mike Kent - Lockheed Engineering and Sciences Company at NASA JSC 2400 NASA Rd One, Houston, TX 77058 (713) 483-3791 KENT@vf.jsc.nasa.gov ------------------------------ Date: 27 Apr 91 23:24:03 GMT From: sdd.hp.com!caen!dali.cs.montana.edu!milton!wiml@ucsd.edu (William Lewis) Subject: Re: Transportation Tethers (Beanstalks) In article <1022@igor.Rational.COM> wab@rutabaga.Rational.COM (Bill Baker) writes: >In article <21558@crg5.UUCP> szabo@crg5.UUCP (Nick Szabo) writes: >>* Given a medium-sized comet or carbonaceous chondrite asteroid captured >> into GEO and a mature space manufacturing industry, a Kevlar "beanstalk" >> might be built from GEO all the way to the Earth's surface. The > >>The main research problems are creating high-tensile, low mass fibers >>beyond Kevlar for such structures, and learning how to manufacture them >>from space materials. >> >With all the speculation I read about beanstalks, I've yet to hear >someone say we currently have developed the materials technology to >build one, yet you seem to be saying that Kevlar has the requisite tensile >strength. Is this right? I thought beanstalks were waiting for a >quantum leap in science, like the monomolecular filaments Arthur >Clarke posited in "Gardens in the Sky" (or a title much like that). Well, the other day I was thinking about beanstalks (btw, what are the differences between beanstalks, skyhooks, tethers, etc.? Are beanstalks and skyhooks just different names, or are skyhooks not anchored to the earth? ... just curious) and worked out the math for what I think is called a log taper going from the Earth's surface to somewhere past geosynch. The idea is that you vary the diameter of the cable as needed to support the tension so you don't spend too much cable just holding up other cable. I simplified assuming that the only forces on any segment of the cable are the tensions at either end, the Earth's gravity, and "centrifugal force" (I know it doesn't exist, but it holds satellites up...). I got this: dT ---- = T S^-1 ( G Me / r^2 - phi^2 r ) dr dr where T is the tension on the cable at radius r, G and Me are the gravitational constant and the mass of the Earth, and phi is the rotational velocity of the Earth in radians/sec. S is the cable's tensile strength divided by its density (which I think is called the specific tensile strength). These numbers come out to: G*Me = 3.99 * 10^14 N*m*m/kg phi = 7.27 * 10^-5 rad/sec Tensile strength of Kevlar ~ 3 * 10^9 Pascals Density of Kevlar ~ 1.5*10^3 kg/m^3 S = 2*10^6 m^2/s^2 (actually, my source here is unclear, this is probably a Kevlar- epoxy composite; it will do for ballpark computation...) Anyway, the equation above solves to this mess: G Me phi^2 r^2 ------- + --------- T^-1 = k e^ S r 2 S Setting the tension at sea level to, oh, 10^9 N (this being a margin for safety and for payloads), k works out to 2.5 * 10^-23 1/N. Then the tension at geosynchronous orbit (r=4.23*10^7 meters) is 3.4 * 10^19 N, for a cable diameter of about 60 kilometers. Yikes. (The cable tension and diameter are largest at geosynch, for reasonably obvious reasons.) Shedding a few orders of magnitude, if the sea level tension is 10^6 N (100 tons), k=2.5 * 10^-20 1/N, and the tension at geosynch is 3.4 * 10^16 N, diameter maybe 2 km. Slightly more reasonable but still pretty farfetched. Note that the dependence on S is (like everything else) exponential. A single order of magnitude improvement in S would reduce the cable diameter at GEO to a bit over four feet! Given, an order of magnitude *is* a "quantum leap in technology", but less than an order of magnitude will still have a very good effect on cable size... I'm also leaving out such things as structural redundancy for what amounts to a thirty-thousand-mile-high skyscraper, shielding it from weather (and terrorists), maintenance, insurance (what if it breaks and falls on your insurer?) ... not to mention the incredibly difficult job of putting the beanstalk *up* in the first place. -- wiml@milton.acs.washington.edu Seattle, Washington (William Lewis) | 47 41' 15" N 122 42' 58" W "Just remember, wherever you go ... you're stuck there." ------------------------------ Date: 26 Apr 91 21:31:35 GMT From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!midway!ellis.uchicago.edu!esti@ucbvax.Berkeley.EDU (Paul A. Estin) Subject: Alexander Abian wants to blow up the moon? Very late last night (around 4 or 5 AM) I tuned in to CBS's "Nightwatch" news program in the middle of a "debate" between Bevan French of NASA and some crazy loon at Iowa State University named Alexander Abian. My question is basically... who IS this Abian guy and what exactly is he trying to say? Maybe it was made clearer in the segment's beginning (which I missed), but while I watched, Abian was ranting maniacally about changing the system of the Universe and moving satellites to Earth orbit and blowing up the moon to change the Earth's axis... or something like that. He wasn't terribly clear. Abian also used some weird analogies, such as {refusing to accept the possibility of working to a different possible configuration for our solar system} is like {refusing to accept the possibility of nonrealistic painting like Picasso's} (to which French replied, "Having a nose on the side of the face may be nice artistically, but on a real person it's rather hard to breathe that way."). More generally, he seemed more of an "artiste" gone wild than an astrophysicist. Now, has anyone heard of this guy Abian, and does anyone understand what he's talking about? He's one of the more interesting nuts I've come across. ----- "Think of terraforming as a very large example of performance art." - James Nicoll Paul Andrew Estin esti@midway.uchicago.edu 1216 E. 54th St. #1 Chicago, IL 60615 ------------------------------ Date: 26 Apr 91 21:00:24 GMT From: pasteur!dog.ee.lbl.gov!hellgate.utah.edu!caen!news.cs.indiana.edu!noose.ecn.purdue.edu!en.ecn.purdue.edu!irvine@ucbvax.Berkeley.EDU (/dev/null) Subject: NASP Last peep from the NASP I heard was all the contractors (McDonnell Douglas, General Dynamics, Boeing, Lockheed(?), etc) were teaming up to design the prototype. The budget was $100million from Congress (1990)? I was hoping to find out what the status of this was? -- +-----------------------------------------------------------------------+ | Brent L. Irvine | These are MY opinions | | Malt Beverage Analyst | As if they counted...:) | +-----------------------------------------------------------------------+ ------------------------------ End of SPACE Digest V13 #474 *******************