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 ; Wed, 10 Apr 91 02:29:08 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 10 Apr 91 02:29:01 -0400 (EDT) Subject: SPACE Digest V13 #388 SPACE Digest Volume 13 : Issue 388 Today's Topics: Free Cray Time (reposting) Fluorine Re: comsat cancellations and lawsuits [l/m 7/5] Reminders for Old Farts Re: Launch Technology: RFD: FAQ newsgroup Re: Underground Nuclear Test in Nevada Re: Why does every SAR have another resolution? Re: comsat cancellations and lawsuits 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: 9 Apr 91 20:55:20 GMT From: amdcad!military@ucbvax.Berkeley.EDU (Tom DeBoni) Subject: Free Cray Time (reposting) From: deboni@fernando.llnl.gov (Tom DeBoni) The Sisal Scientific Computing Initiative Contacts: John Feo and Dave Cann The Computing Research Group at Lawrence Livermore National Laboratory (LLNL) announces the Sisal Scientific Computing Initiative (SSCI). The Initiative will award free Cray X-MP time and support to researchers willing to develop their applications in SISAL, a functional language for parallel numerical computation. Members of the Computing Research Group will provide free educational material, training, consulting, and user services. SSCI is an outgrowth of the Sisal Language Project, a collaborative effort by Lawrence Livermore National Laboratory and Colorado State University and funded in part by the Office of Energy Research (Department of Energy), U.S. Army Research Office, and LLNL. SISAL provides a clean and natural medium for expressing machine independent, determinate, parallel programs. The cost of writing, debugging, and maintaining parallel applications in SISAL is equivalent to the cost of writing, debugging, and maintaining sequential applications in Fortran. Moreover, the same SISAL program will run, without change, on any parallel machine supporting SISAL software. Recent SISAL compiler developments for the Alliant FX/80, Cray X-MP, and other shared memory machines have resulted in SISAL applications that run faster than Fortran equivalents compiled using automatic concurrentizing and vectorizing tools. Interested participants should submit a 1-2 page proposal by June 1, 1991 to Computing Research Group, L-306 Lawrence Livermore National Laboratory P.O. Box 808 Livermore, CA 94450 Proposals should describe the research and explain how the work will benefit from parallel execution on a Cray X-MP. We will announce accepted proposals by July 1, 1991. For more information about the Sisal Scientific Computing Initiative please contact John Feo (feo@lll-crg.llnl.gov) at (415) 422-6389 or Dave Cann (cann@lll-crg.llnl.gov) at (415) 423-7875. We look forward to hearing from you. ------------------------------ Date: 9 Apr 91 14:09:04 GMT From: rochester!dietz@louie.udel.edu (Paul Dietz) Subject: Fluorine In article heskett@titan.tsd.arlut.utexas.edu (Donald Heskett) writes: >Needless to say, 1) it's probably not a good idea to operate >fluorine-fueled propulsion systems in proximity to population areas or >the ozone layer and 2) it's not a good idea to carry this stuff in >the Shuttle's payload bay. The combination would only seem to make >sense in the upper stage of an expendable launcher. Without doubt fluorine is a dangerous propellant near inhabited areas, but why should it damage the ozone layer? Fluorine does not catalyze ozone destruction like chlorine does, which undergoes reactions like: Cl + O3 --> ClO + O2 ClO + O3 --> Cl + 2 O2 Fluorinated, as opposed to chlorofluorinated, hydrocarbons are not controlled by the ozone agreements; it doesn't get oxidized by oxygen as the other halogens can be. I expect fluorine molecules would quickly react with water to form hydrofluoric acid and ozone. There are compounds of oxygen and fluorine, in which oxygen gets oxidized. Oxygen difluoride and dioxygen difluoride have somewhat higher boiling points than either fluorine or oxygen (the BP of O2F2 at 1 atmosphere is -57 C). Oxygen difluoride, at least, as been investigated at JPL as an oxidizer for use in space. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 9 Apr 91 22:57:53 GMT From: elroy.jpl.nasa.gov!usc!rpi!mvk@decwrl.dec.com (Michael V. Kent) Subject: Re: comsat cancellations and lawsuits In article <1991Apr9.092224.12289@pbs.org> pstinson@pbs.org writes: >It has not yet been established that a raw deal has in fact occurred in this >situation. That's what the courts are for. >Even if it has it could be a bit counter productive for Hughes to >make too big a stink. There are future contracts to be awarded down the road. >How much do want to bet that if Hughes and another company are the finalists >AND their proposals are ABOUT EVEN, the other company gets it because they are >not Hughes. And get another raw deal. Great! We can't prevent the U. S. government from giving contracters raw deals or else it will give them another one later. Just gotta love the logic in that. -- Michael Kent mvk@itsgw.rpi.edu McDonnell Douglas Rensselaer Polytechnic Institute St. Louis, Missouri Troy, New York Apple II Forever! ------------------------------ Date: 9 Apr 91 11:01:12 GMT From: data.nas.nasa.gov!amelia!eugene@eos.arc.nasa.gov (Eugene N. Miya) Subject: [l/m 7/5] Reminders for Old Farts Hints for old users (subtle reminders) You'll know these. Minimize cross references, [Do you REALLY NEED to?] Edit "Subject:" lines especially if you are taking a tangent. Send mail instead, avoid posting follow ups. [1 mail message worth 100 posts.] Internet mail readers: send requests to add/drop to SPACE-REQUEST not SPACE. Read all available articles before posting a follow-up. [Check all references.] Cut down attributed articles. Summarize! Put a return address in the body (signature) of your message (mail or article), state institution, etc. don't assume mail works. Use absolute dates. Post in a timely way. Don't post what everyone will get on TV anyway. Some editors and window systems do character count line wrapping: please keep lines under 80 characters for those using ASCII terms (use ). ------------------------------ Date: 10 Apr 91 01:51:38 GMT From: agate!headcrash.Berkeley.EDU!gwh@ucbvax.Berkeley.EDU (George William Herbert) Subject: Re: Launch Technology: In article heskett@titan.tsd.arlut.utexas.edu (Donald Heskett) writes: >The book "Ignition!" (written in the '60s, I think) mentioned that the >highest specific impulse that had been achieved at that time was 542 >seconds. This was achieved with near-satanic propellant combination of >lithium, fluorine and hydrogen. Does anyone know if any further work >was ever done with this propellant combination? Don't know about the 3-way combo, but the Russians have recently announced that one of their military upper stages used flourine as an oxidizer, and that the vehicle was going to be offered on the launch market RSN. == George William Herbert == * UNIX ate my last .sig, Waiting for Plan 9! * == JOAT for Hire: Anything, == ######### I do Naval Architecture, ########## ===+++ Anywhere, my price +++=== # Spacecraft Design, UNIX Systems Consulting # == gwh@ocf.berkeley.edu == # RPG writing/development, and lots of other # == gwh@gnu.ai.mit.edu == ## random stuff, of course. I'm a JOAT 8-) ## ------------------------------ Date: 10 Apr 91 03:47:48 GMT From: stanford.edu!snorkelwacker.mit.edu!spool.mu.edu!mips!zaphod.mps.ohio-state.edu!rpi!bounce-back@eos.arc.nasa.gov (Glenn R. Stone) Subject: RFD: FAQ newsgroup (Sorry for the weird selection of newsgroups.... methinks we've got the attention of most of the people who want in on this thing anyway...) Okay, nobody else has, so I will. This is a formal RFD for a group in which to crosspost FAQ lists. Now, I'm not dictatorial by nature, so I need input (after all, isn't that what an RFD is for?) on the following issues. o Name. I'm not about to be responsible for running a debacle like the ongoing you-know-what vote.... I'll not issue a CFV until we've pretty much settled on something. I realize this is a religious issue for people, so we'll do it this way: Starting as soon as this gets posted, and for a week thereafter, I'm running a vote on the name. At the end of that week, I'll sort things out and post results, and we'll work from there. Since the method of determining a name is not formalized, neither will the vote be; you may mail me your top choice only, or a list of names, indicating priority; I will post as to which names got the most support. Mail your name-votes to: glenns@eas.gatech.edu (UUCP: ...gatech!eas.gatech.edu!glenns) o Posting method. Do we allow self-approved crossposting, or run a standard moderated group, or leave it unmoderated? Methinks the latter is Not A Good Thing, in that the FAQ should be discussed in its own group, and that this group should be a "clean" group for easy archival of FAQs.... but I'm open to discussion. o Charter. I don't think there will be too much discussion here, but.... "A newsgroup devoted to assembling various Frequently Asked Question (and answer) lists (FAQ's) in one place for ease of reference and archival." Talk to me. Post. Flame, even, if necessary. But the demand for the group is clear, so let's go ahead and do it ... and this time, let's do it right. Note that I did not include a timetable for CFV, etc. I expect this to go on for >at least< the usual 14 days; I will not post a CFV before March 23rd. On the other hand, the guidelines state that if you don't have it hashed out within 30 days, you take it to mail and start over. I hope we have something before then, but the discussion period will end, one way or the other, on or before May 9th. The voting, if and when it starts, will run for 21 days; the usual rules will apply. Here we go.... -- Glenn R. Stone FAQ discussion to: glenns@eas.gatech.edu Other stuff to: gs26@prism.gatech.edu "I'm not in the book, ya'know, and I'm ding dang dong glad of it!" -- Disney, "Winnie the Pooh" (Gopher wasn't in the Milne books) ------------------------------ Date: 8 Apr 91 15:36:08 GMT From: wuarchive!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!boingo.med.jhu.edu!welch.jhu.edu!jimh@psuvax1.cs.psu.edu (Jim Hoffman) Subject: Re: Underground Nuclear Test in Nevada In article <1991Apr05.201554.20465@ariel.unm.edu> prentice@triton.unm.edu (John Prentice) writes: >In article <1991Apr5.143519.25044@ecf.utoronto.ca> murty@ecf.toronto.edu (MURTY Hema Sandhyarani) writes: >> >> Yesterday there was another underground nuclear test in >> Nevada. Why are we allowing this to continue? >> >> I am sure that if all the readers of sci.space got >> together and denounces such tests by countries of >> the world, they would have to stop. >> > >Are you serious? Somehow I don't think the readers of sci.space have >that kind of political clout! > >> >> And, yes, I would like to hear arguments that any >> might have in favor of these tests. What do they >> accomplish in terms of science? They seem more >> like muscle-flexing to me. >> > >Why should they have ANY scientific value? The issue is not science, >it is military. There are lots of reasons for testing weapons, not >the least of which is verifying that the stockpile is still working. The issue is one of science. Maybe there are some "good" reasons to test these weapons, BUT what are the effects of these explosions???? I don't claim to know and with all the arguements this way and that way, I don't think anyone knows!! Who knew the far reaching effects of the nuclear accident in Russia, but the reindeer herders in Northern Europe shure do! >I am not advocating nuclear testing or denouncing it here, but your >comment suggests that there is no plausible reason to do it >and that is nonsense. That the U.S. and Soviets might be able to >cease and not destabilize their deterrents, perhaps so. But the very >fact that they are worried about this possiblity suggests that there >are very real military concerns which nuclear testing addresses. > >I will say this. The arguments against nuclear weapons and weapons >testing do not move me a great deal. I would be more impressed by >attempts to eliminate world strife and the root causes of conflict >than attempts to control the means by which nations wage war. I >am also struck by the fact that for all the noise made over this >issue in recent years, the really terrifying weapons are conventional, >not nuclear. The chances of a nuclear war between the superpowers >is almost nil and the consequences of a third world nation using a nuclear >weapon, while serious, are not going to be affected in the least by >what the superpowers do to limit or control their arsenals. On the >other hand, the chances of conventional war in the world are obviously >rather high. If one wants to make a difference in arms control, you would >do better to address conventional weapons rather than getting >wrapped up over exotic and unlikely ones. I would agree that a conventional war, if you can consider our Air Force conventional anymore, is a big threat becuase it would be a nuclear war. I live in Baltimore and I would hate to think what a bomb would do to us here if a bomb hit 3-mile island, Peach Bottom, and Calvert Cliffs. This is, in my opinion, a very serious science problem. Science has given the military the ability for mass destruction on a global level and the military needs to know if they are doing something that is self destructive like the ever increasing environmental problems. In fact, if there is something that ALL scientist of ALL types could come together over, the environment would win my vote! We can't live without a sound ecology. Jim ------------------------------ Date: 10 Apr 91 02:17:59 GMT From: geology.tn.cornell.edu!eric@THEORY.TN.CORNELL.EDU (Eric Fielding) Subject: Re: Why does every SAR have another resolution? In article <1923@mpirbn.mpifr-bonn.mpg.de>, p515dfi@mpirbn.mpifr-bonn.mpg.de (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? Gee, this is from my slightly fuzzy memory on Synthetic Aperture Radar (SAR), but since no one else has answered (at least where I saw this in sci.optics)... SAR resolution has two nearly independent components of resolution, in the cross-track (range) direction and the along-track (azimuth) direction. The range resolution is determined by the time resolution of the emitted pulses, which depends on the frequency of the radar and the repitition frequency. The azimuthal resolution is determined by the bandwidth of the pulses, I think, and by the processing. There is a trade-off between better azimuthal resolution and better signal to noise ratio depending on how the data is processed. Interestingly, neither resolution depends on the height of the orbit! The biggest limitation on the Magellan resolution is the data rate that can be sent back. They have a much slower link to the receivers on earth. ++Eric Fielding eric@geology.tn.cornell.edu ------------------------------ Date: 9 Apr 91 15:34:37 GMT From: fernwood!uupsi!pbs.org!pstinson@apple.com Subject: Re: comsat cancellations and lawsuits In article <1991Apr9.092224.12289@pbs.org>, pstinson@pbs.org writes: What you think about the Hughes lawsuit, may well depend upon were you first learned about it. In my case it was an article in a satellite communications journal delivered to the Satellite Replacement Office at PBS. It was implied in that article that the industry in general had not reached a consensus on whether Hughes really had a case. In fact, a Hughes V.P. quoted in the article said the action was prompted partly because of "cut-throat competition" [from other aerospace firms]. If other firms have better costumer relations departments than Hughes, that isn't NASA's fault. It should also be remembered the White House Commission set up to study the CHALLENGER disaster and suggest remedial action, included representatives from the aerospace industry. It was the Commission's suggestion that comsat launches, among other activities, be taken away from the space shuttle. NASA had little choice in the matter. The fact that this action, which the industry had a hand in bringing about, was implimented does not sound like a clear cut "raw deal" perpetrated by NASA against Hughes in particular. This is NOT the black and white case that Henry made it appear to be in his posting. ------------------------------ End of SPACE Digest V13 #388 *******************