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 02:17:33 -0500 (EST) Message-ID: <8bz2G7y00WBw83f04W@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 5 Apr 91 02:17:28 -0500 (EST) Subject: SPACE Digest V13 #362 SPACE Digest Volume 13 : Issue 362 Today's Topics: Re: SPACE Digest V13 #344 New GIFs available in the SPACE archive on ames.arc.nasa.gov Unofficial Ariane Launch Manifest (April 1991) SIGN ME OFF!! flares Re: Mt. Venus Why does every SAR have another resolution? Re: Air Force small launch contract Re: Why does every SAR have another resolution? Another Dinosaur Barfs (Was Re: How 'bout them Titans?) Re: Advancing Launch Technology 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 21:17:59 GMT From: orca!bambam!bpendlet@uunet.uu.net (Bob Pendleton) Subject: Re: SPACE Digest V13 #344 In article <1991Apr4.170238.11789@dsd.es.com>, bpendlet@bambam.dsd.es.com (Bob Pendleton) writes: > One of the reasons I don't think chemical rockets have topped out is > that ideas like this one have been around, and practical, since the > 1930s and know one has even tried them. ^^^^^^^^ Of course this was supposed to be "no one." I'm not sure if this is the worst typo I ever came up with or if it is some sort of a Freudian slip. -- Bob Pendleton, speaking only for myself. bpendlet@dsd.es.com or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet Tools, not rules. ------------------------------ Date: 5 Apr 91 05:51:16 GMT From: usenet@ames.arc.nasa.gov (Peter E. Yee) Subject: New GIFs available in the SPACE archive on ames.arc.nasa.gov Ever wanted to touch the Space Shuttle? Walk around it and look at different parts in minute detail? Well, here's your chance. I've just completed scanning in various photos of the Shuttle (interior and engines) that were provided to me by Ken Hollis down at KSC. These photos go into the gory details of the switch panels and engine parts. In addition to these photos, I've also scanned in a couple of photos from the Hubble Space Telescope deployment and a couple of Atlantis landing at Edward AFB. All of these scans are in GIF format and may be obtained via anonymous ftp to ames.arc.nasa.gov, directory /pub/SPACE/GIF. All photos are named by their label numbers, with the shuttle parts being named ksc*, the HST photos are s31*, and the landing photos are ec*. Descriptions of the photos (not always useful) are found in corresponding files with a .txt extension. Problems with archive operations or access should be sent to me. -Peter Yee yee@ames.arc.nasa.gov ames!yee ------------------------------ Date: 3 Apr 91 22:31:34 GMT From: agate!bionet!uwm.edu!spool.mu.edu!munnari.oz.au!yoyo.aarnet.edu.au!sirius.ucs.adelaide.edu.au!levels!etssp@ucbvax.Berkeley.EDU Subject: Unofficial Ariane Launch Manifest (April 1991) Here is the Ariane launch manifest that was published in the October 1990 issue of Spaceflight. Since V42 was delayed V43 was shifted into April. I am guessing that V44 will shift into May and that the rest of the manifest remains the same. Flight Date Vehicle Payload ------------------------------------------------------------------------- V40 20 Nov. 90 Ar 44P Satcom C1, Gstar 4 ------------------------------------------------------------------------- V41 15 Jan. 91 Ar 44L Eutelsat II-F2, Italsat 1 V42 18?Mar. 91 Ar 44LP Astra 1B, MOP-2 V43 Apr. 91 Ar 44P Anik E1 V44 May 91 Ar 40 ERS-1, Datasat X, Tubsat, Uosat F, SARA V45 Jun. 91 Ar 44L Intelsat VI-F5 V46 Jul. 91 Ar 44LP Eutelsat II-F3, Inmarsat II-F3 V47 Sep. 91 Ar 44P Anik E2 V48 Oct. 91 Ar 44L Intelsat VI-F1 V49 Nov. 91 Ar 44L Superbird E, Inmarsat II-F4 ------------------------------------------------------------------------- Notes: 1) The payloads for V46 and V47 may swap. 2) In V49, Superbird E has a relaunch priority. Telecom 2A may substitute for the V49 payload. -- Steven Pietrobon, Australian Space Centre for Signal Processing School of Electronic Engineering, University of South Australia The Levels, SA 5095, Australia. steven@rex.sait.edu.au ------------------------------ Date: Thu, 04 Apr 91 11:01:08 CST From: ST6900%SIUCVMB.BITNET@BITNET.CC.CMU.EDU () Subject: SIGN ME OFF!! I have tried and tried to get signed off of this listserv. I REALLY like the space-request listserv, but I have NO time for it now....maybe later. I have been trying to get taken off of it for almost a MONTH and still nothing. PLEASE take me off of the list. THANK YOU. ------------------------------ Date: 4 Apr 91 17:40:48 GMT From: agate!stanford.edu!snorkelwacker.mit.edu!usc!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucbvax.Berkeley.EDU (Henry Spencer) Subject: flares In article KENTILER@KSUVM.KSU.EDU (Kent P. Iler) writes: >... It was that a major flare could cause serious injury-even death- >to any astronauts in orbit at the time of the resulting storm. Soviet cosmonauts have been aloft during all the major flares of the last few years, and at least one shuttle mission happened to be up at the time of one too. They did get more radiation than usual, but I don't believe there is major risk, unless perhaps we got the great-granddaddy of all flares. -- "The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology SunOS 4.1.1 are all true." -D. Harrison| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 5 Apr 91 04:58:24 GMT From: theory.tn.cornell.edu!schinder@THEORY.TN.CORNELL.EDU (Paul Schinder) Subject: Re: Mt. Venus In article <1991Apr5.034141.1082@helios.physics.utoronto.ca> neufeld@aurora.physics.utoronto.ca (Christopher Neufeld) writes: > So, putting my hand to these equations, using the adiabatic model for >atmosphes, as recommended in an undergraduate course I once took, I get, >using P0 = 9E+6 Pa, T0 = 800K, g = 8.87 m/s^2, molecular weight = 44, >gamma = 7/5: >P(h=914m) = 85 atm >T(h=914m) = 787K > > Something looks funny about this, but the equation does say that the >atmosphere ought essentially to disappear at 50km altitude, and that >doesn't seem completely unreasonable. Maybe somebody could check my >numbers, just to be on the safe side. The numbers are: at 0 km: P = 93.0 bar, T = 731K at 10 km: P = 47.5 bar, T = 650K at 50 km: P = 0.97 bar, T = 346K The sensible atmosphere extends to about 100 km. These numbers were computed using a mean fit by Young et al. (J. Atmos. Sci., 44, 2628) to actual spacecraft measurements of the atmosphere. The atmosphere is not quite adiabatic because of the sun and it's own thermal radiation (simple radiative equilibrium models give good agreement with what's observed), and has at least one planetary scale convective region. This probably accounts for the failure of the simple adiabatic model. >-- > Christopher Neufeld....Just a graduate student | Flash: morning star seen -- Paul J. Schinder Department of Astronomy, Cornell University schinder@astrosun.tn.cornell.edu ------------------------------ Date: 4 Apr 91 13:05:35 GMT From: math.fu-berlin.de!fauern!unido!mpirbn!p515dfi@uunet.uu.net (Daniel Fischer) Subject: Why does every SAR have another resolution? 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? Furthermore, there are rumors that the Lacrosse satellite's SAR can resolve features down to 1 meter in size (how official is that?). ------------------------------ Date: 4 Apr 91 16:18:30 GMT From: agate!bionet!uwm.edu!rpi!news-server.csri.toronto.edu!utzoo!henry@ucbvax.Berkeley.EDU (Henry Spencer) Subject: Re: Air Force small launch contract In article <1991Apr3.223100.5947@cs.cmu.edu> vac@crux.fac.cs.cmu.edu (Vincent Cate) writes: >Assuming this is true, does anyone know why? It seems there are a >number of companies bidding on the Motorola replacement launches and >I would think these same companies would be interested in the Air Force >contract too. Maybe OSC is the only one that can stomach the government paperwork... :-) -- "The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology SunOS 4.1.1 are all true." -D. Harrison| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 4 Apr 91 17:38:32 GMT From: rex!samsung!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo!henry@g.ms.uky.edu (Henry Spencer) Subject: Re: Why does every SAR have another resolution? In article <1923@mpirbn.mpifr-bonn.mpg.de> p515dfi@mpirbn.UUCP (Daniel Fischer) writes: >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? Radarsat's main advantage is a much bigger, and custom-built, antenna. Magellan is SAR on the cheap, using hardware out of NASA's junkbox. An important secondary issue is the ten years or so that separates their design efforts. I also wouldn't be surprised if Radarsat is quite a bit heavier, although I don't have numbers handy. >Furthermore, there are rumors that the Lacrosse satellite's SAR can resolve >features down to 1 meter in size (how official is that?). The official word is "Lacrosse? What's that?". -- "The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology SunOS 4.1.1 are all true." -D. Harrison| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 3 Apr 91 02:29:34 GMT From: unisoft!fai!sequent!crg5!szabo@ucbvax.Berkeley.EDU (Nick Szabo) Subject: Another Dinosaur Barfs (Was Re: How 'bout them Titans?) In article shafer@skipper.dfrf.nasa.gov (Mary Shafer) writes: >[Titan IV looks pretty] How about those Dinosaurs (oops, I mean Titans)? Yes, $300+ million in a ball of smoke sure looks pretty, if you are into expensive fireworks shows, and don't care too much about reliable transporation. Titan IV costs will now rise to Shuttle levels, and we will be lucky if Titan IV can catch up to Shuttle's reliability %. So much for the "expendable vs. reusable" debate. In the long run, they are both losers, and those of us who want to get our payloads into orbit are the biggest losers of all. It's time for USAF to go to smaller, more redundant payloads and launchers, and start looking at the alternatives to chem rockets. These dinosaurs are history. >Before everyone gets excited and blames the wound casing, >[metal fails too] Wound casing or metal, they both fail far too frequently for reliable transportation. No, I'm blaming $tens of billions down the tubes for chemical rocket research, money that could have been much better spent on the basic science behind superconductors, gas guns, lasers, et. al. Well, that's all water under the bridge, but the future lies ahead -- let's do it right this time! -- Nick Szabo szabo@sequent.com "If you want oil, drill lots of wells" -- J. Paul Getty The above opinions are my own and not related to those of any organization I may be affiliated with. ------------------------------ Date: 2 Apr 91 18:09:55 GMT From: unisoft!fai!sequent!crg5!szabo@ucbvax.Berkeley.EDU (Nick Szabo) Subject: Re: Advancing Launch Technology In article <1991Apr1.172946.11907@eplrx7.uucp> leipold@eplrx7.uucp (Walt Leipold) writes: >What *are* the absolute minimum costs of a a *practical* EML system? .... [a reasonable analysis] >For >the sake of discussion, let's assume a modest 500g acceleration in a purely >horizontal launcher.... We can actually get much more than this right now in the lab, but perhaps this is a good number for a system with low materials costs. >Energy: [$1/lb.] Reasonable for EML. Depending on the fuel used, a light gas gun might lower this by a factor of 5, since electricity is a fairly inefficient form of energy. >Hardware: > >How much does a linear foot of high-capacity, reliable, maintainable, >weatherproof railgun cost? Ten thousand dollars? If so, your 26-km >railgun will cost $850 million dollars. To avoid wear, a coilgun is probably a better option than railgun. The above estimate is also pretty good for a first generation coilgun; Sandia projects $1,0000 million for the whole first-generation project. At least two possible technical advances, if they pan out, could greatly reduce this cost for subsequent projects: * Building practical systems at >500g * Mass-produced warm superconductors Given these, we could go down to 10 km and $1,000/foot, or $32 million. But currently, $850 million is pretty good estimate for the first-generation system. >Real estate: >...I'll assume that this piece of land will cost about $100 million The best thing to do might be to bridge the gun across several used oil tankers or platforms, hundreds of miles away from inhabited areas, to avoid noise pollution. This could also cost up to $100 million. >Management: > >We'll assume a revolution in management styles gives us an administration >cost of only $4 million/month.... This doesn't take any management revolution, since many smaller airports, handling much larger amounts of cargo, operate at an overhead of $4 million per _year_. However, $4 million/month sounds reasonable for the first generation project. >Liability insurance is a big unknown.... Not necessarily. Insurance costs are based on reliability, which in guns is typically 2-3 orders of magnitude greater than for rockets. >[total cost of] $9/lbm doesn't sound like a lot, but remember that this >kind of rough estimate was used to predict $100/lbm for the Shuttle a >couple of decades ago.... Well, if you want to doom _any_ attempt to lower launch costs based on one NASA chem rocket project, there's not much to say about that.... But there are many, many differences between EML and yet another chemical launcher like the Shuttle: * Even your projection, which contains several pessimistic assumptions, is 10 times lower than any chemical rocket launch projection, and is 500 times lower than realistic rocket launch cost projections and actual rocket launch practice. * A totally different technology: fuel is not stored on board. Shuttle is, when all is said and done, another chemical rocket, which follows the curve of costs for internally chemical powered vehicles. * The first EML is to be designed be Sandia, not NASA, and subsequent EML's should be designed, owned and operated privately. Therefore, we will avoid aerospace/chem rocket world concepts of launch cost and operation. The choice is between large ($4-5 billion) chemical rocket projects, which are proven incapable of significantly lowering launch costs, or smaller ($100-$500 million) R&D/prototyping projects to demonstrate a whole suite of new technologies (gas gun, EML, laser launch, etc.). If EML passes this phase, we would go to a $1 billion first-generation system, which would dramatically and quickly lower launch costs. We can introduce a greatly superior technology for less than the cost of building yet another chemical rocket. This is a whole new ballgame. -- Nick Szabo szabo@sequent.com "If you want oil, drill lots of wells" -- J. Paul Getty The above opinions are my own and not related to those of any organization I may be affiliated with. ------------------------------ End of SPACE Digest V13 #362 *******************