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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
  [e-mail].  Other mail, esp. [un]subscription requests,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

----------------------------------------------------------------------

Date: 9 Apr 91 20:55:20 GMT
From: amdcad![e-mail]  (Tom DeBoni)
Subject: Free Cray Time (reposting)


From: [e-mail] (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 ([e-mail]) at [phone]
or Dave Cann ([e-mail]) at [phone].  We look forward to
hearing from you.

------------------------------

Date: 9 Apr 91 14:09:04 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Fluorine

In article <[e-mail]> [e-mail] (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
    [e-mail]

------------------------------

Date: 9 Apr 91 22:57:53 GMT
From: elroy.jpl.nasa.gov!usc!rpi![e-mail]  (Michael V. Kent)
Subject: Re: comsat cancellations and lawsuits

In article <[e-mail]> [e-mail] 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                                  [e-mail]
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![e-mail]  (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 <CR>).

------------------------------

Date: 10 Apr 91 01:51:38 GMT
From: agate!headcrash.Berkeley.EDU![e-mail]  (George William Herbert)
Subject: Re: Launch Technology:

In article <[e-mail]> [e-mail] (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 #
 ==   [e-mail]   ==  # RPG writing/development, and lots of other #
  ==   [e-mail]   ==   ## 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![e-mail]  (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:

        [e-mail] (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: [e-mail]
Other stuff to: [e-mail]
"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![e-mail]  (Jim Hoffman)
Subject: Re: Underground Nuclear Test in Nevada

In article <[e-mail]> [e-mail] (John Prentice) writes:
>In article <[e-mail]> [e-mail] (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![e-mail]  (Eric Fielding)
Subject: Re: Why does every SAR have another resolution?

In article <[e-mail]>,
[e-mail] (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
[e-mail]

------------------------------

Date: 9 Apr 91 15:34:37 GMT
From: fernwood!uupsi!pbs.org![e-mail]
Subject: Re: comsat cancellations and lawsuits

In article <[e-mail]>, [e-mail] 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
*******************