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Subject: SPACE Digest V12 #99

SPACE Digest                                      Volume 12 : Issue 99

Today's Topics:
        Re: Is an asteroid capture possible/feasible?
        Information needed on AEROSPIKE engine
            Re: World Space Agency
        Re: Is an asteroid capture possible/feasible?
          Re: Can a Twinkie survive launch to orbit?
              Galileo Update - 07/19/90
        Re: Is an asteroid capture possible/feasible?
              Re: NSS elections
            Science article on HST
           Payload Status for 07/19/90 (Forwarded)
       New director named for Jet Propulsion Laboratory

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 19 Jul 90 14:31:21 GMT
From: usc!samsung!emory!hubcap!mephisto!prism![e-mail]  (Matthew DeLuca)
Subject: Re: Is an asteroid capture possible/feasible?

In article <[e-mail]> [e-mail] (Dieter Kreuer) writes:

>How about ice as a heat shield? In a SF story by Arthur C. Clarke (don't
>remember the name of the book) they used hexagonal tiles of frozen water
>to protect a spacecraft from being punctured by atoms at a speed close to c.

Just for the record, the book is _The Songs of Distant Earth_.

--
Matthew DeLuca
Georgia Institute of Technology      Do not meddle in the affairs of wizards,
Office of Information Technology     for they are subtle, and quick to anger.
Internet: [e-mail]

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

Date: 19 Jul 90 15:42:34 GMT
From: agate!shelby!portia.stanford.edu![e-mail]  (aaron thode)
Subject: Information needed on AEROSPIKE engine


    I would be very grateful if anyone could provide me with any of the
following information:

    a) The location of a fluid dynamics code that has been configured to
evaluate aerospike engine performance. A reference to an article in the
literature would also be helpful.
    The codes at Los Alamos National Laboratory, where I work, can
calculate the performance of conventional bell and certain plug nozzles,
but not nozzles that utilize any sort of base bleed.

    b) The index numbers of any reports since 1984 that concern aerospike
designs.  I have conducted two database searches for papers on this subject,
but the latest references I can locate are the work of Diem and Kirby (1977)
and Reding and Jecmen (1984).

                    Thank you,
                    Aaron Thode

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

Date: 19 Jul 90 14:03:43 GMT
From: eagle![e-mail]  (Gregory Fedor)
Subject: Re: World Space Agency

In article <[e-mail]> [e-mail] (Worth Henry A) writes:
>   First, "the walls are tumbling down"...Ironically, in the very near
>future the Soviets may become a member of the "reformed" NATO (Western
>leaders have already been dropping some broad hints along this line), and
>eventually, may even become one of the USA's best allies.

A thought came to mind reading this...if the Soviets become our allies, whom
would the group we'd be allied with them against?

>   But..., before anything like a WSA can come about, the major space
>players, especially the USA, must be willing to give up CONTROL. Europe,
>Japan and Canada can attest to the USA's insistence upon control over
>joint projects, and an embarrassing tendency for the USA to back out from
>its project commitments at the last minute (Europe and Japan currently seem

I support the idea of a WSA especially since there are many compitent groups
both public and private who've demonstrated their ability to use space
effectively.  I think that the USA needs to get its house in order above all
else.  IMHO it's been the attempts to perform joint projects that have have
caused the USA to be the failing partner it is.  Up until WWI the USA held
to an isolationist policy that put us in the best position when the World
Wars broke out.  Maybe the same attitude needs to be done in the USA space
program.  I'm not talking about private USA concerns, this is still a free
and open market, but rather the governments role.

I`d like to see NASA return to what it has demonstrated it does best, research.
Feed the research to industry, let them use it and they can participate in the
WSA for the obvious commercial gains.  Any thoughts on this idea???

DISCLAIMER:  The views and comments expressed here do not reflect the policy
of my employer or agency at which I work.  Participation in this forum is
done with knowledge of my employer and does not interfere with the course of
my duties.

.


--
===============================================================================
Hailing frequencies closed...

Gregory Fedor                 [phone]  FTS: 297-8468
Sverdrup Technology           [e-mail] (128.156.10.14)
NASA Lewis Research Center    Cleveland, Ohio 44135
===============================================================================

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

Date: 19 Jul 90 18:28:33 GMT
From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Is an asteroid capture possible/feasible?

In article <[e-mail]> [e-mail] (Dieter Kreuer) writes:
>> As witness the Voyager navigation, zero-defects precision navigation is
>> possible.  It just has to be done right...
>
>Agreed, but the Voyagers don't have to be moved by nuclear charges. I'm no
>expert, but I assume their thrusters to be based on simple retropulsion
>of compressed gas, thus there is no ignition. What I mean to say is that
>explosions or open flames are difficult to control...

No, the Voyager thrusters ignite a monopropellant.  Compressed-gas thrusters
have relatively poor performance and are generally used only when there is
some special reason (e.g. minimizing surface contamination).

>... if the rock is rather massive and you need lots and lots of charges
>to move it slightly, the effect of a single failure is negligible and you
>can compensate for it with the next charges.

The estimate I saw said one thousand 100MT bombs to shift a 1km asteroid,
so it's definitely not something that happens suddenly, and there are plenty
of chances to make corrections.

>But then you need a whole lot of missiles to intercept the rock, and that
>will cost mucho dinero. There ought to be enough mineral resources in the
>asteroid, or the expenses won't pay off...

The mass of that 1km asteroid is billions of tons, so it doesn't take very
many dollars per kilogram to make it worthwhile.  The sheer scale of the
project is a more difficult problem, as the up-front investment is huge
even if you expect a massive profit in the end.
--
NFS:  all the nice semantics of MSDOS, | Henry Spencer at U of Toronto Zoology
and its performance and security too.  |  [e-mail]   utzoo!henry

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

Date: 19 Jul 90 23:24:52 GMT
From: uoft02.utoledo.edu![e-mail]
Subject: Re: Can a Twinkie survive launch to orbit?

In article <[e-mail]>, [e-mail] writes:
>
>         In article <[e-mail]>, Bill Higgins (HIGGINS
> [e-mail]) writes:
>
>>                                                                 A typical
>>Twinkie was selected, placed into a plastic bag, and attached to a 2-meter
>>rope.  Our centrifuge operator first practiced by whipping an inert object (a
>>roll of masking tape) around his head on a rope. Once he could sustain constant
>>angular acceleration of the desired magnitude, we began the Twinkie run.
>
>

I did not see the original post but I presume you are talking about a
standard Hostess Twinkie.  Well, since the official shelf life of
said Twinkie is *20yrs* I think it could survive!!!  Its amazing
what they can do with plastics these days....

Robert Dempsey
Ritter Observatory


(That info is in the patent if you wish to check.)

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

Date: 20 Jul 90 00:44:49 GMT
From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Galileo Update - 07/19/90


                     GALILEO MISSION STATUS
                          July 19, 1990

     The Galileo spacecraft is 84.6 million miles from Earth, its
orbit very slightly changed by Tuesday's successful trajectory
correction maneuver.  The round-trip communication time is now 15
minutes, 10 seconds.  Speed relative to the Sun is more than
51,000 mph.

     This maneuver, the fifth since launch and third since the
Venus gravity assist, was designed to refine the flight path
toward the desired conditions for the Earth gravity assist.  The
spacecraft departed from Venus in February with, as expected, a
heading almost but not quite toward its December 8 Earth
rendezvous.  A small part of the velocity change were to be
contributed by spacecraft maneuvers in April and May and this
week.  The small maneuvers scheduled for October and November
will do the final fine-tuning.  The resulting Earth flyby will
occur at 20:35 GMT or 12:35 p.m. PST December 8, more than 500
miles above the western Atlantic.

     This week's maneuver was itself small: 228 axial pulses and
160 lateral pulses changed the spacecraft velocity by 0.92 meters
per second (about 2 mph), compared with 24 and
11 m/sec in the two previous maneuvers.

     Spacecraft health continues to be excellent, and
system performance also excellent.  The Deep Space Network
provided round-the-clock tracking and telemetry coverage of
Galileo for the few days around the maneuver; normal cruise
coverage at this time is about one pass per day.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 19 Jul 90 12:42:01 GMT
From: mcsun!unido!rwthinf![e-mail]  (Dieter Kreuer)
Subject: Re: Is an asteroid capture possible/feasible?

In article <[e-mail]>, [e-mail] (Donald Heskett) writes:
> Getting large chunks of astroidal mining products down to earth safely
> involves non-trivial engineering, of course, but I think
> straightforward theoretically.  Chunks of metal larger than, say,
> 1-foot on a side, seem to survive reentry from LEO without any
> protection, although a considerable portion of their mass is ablated
> away; larger bodies should make it through with proportionally less
> ablation loss (Note: there will be absolutely more loss, but a larger
> percentage of the original will survive until impact.).  More
> sophisticated approaches should do much better.

How about ice as a heat shield? In a SF story by Arthur C. Clarke (don't
remember the name of the book) they used hexagonal tiles of frozen water
to protect a spacecraft from being punctured by atoms at a speed close to c.
As water can absorb heat very effectively, especially when being vaporized,
it should be possible to enclose a piece of metal as large as a football
into a snow ball of cometary material and drop it into the atmosphere.
I think the best place to aim at is a large dune of sand. Water, shallow or
not, will be as hard as concrete for an object at about 1000 mph (my personal
estimation). Or, drop it into the snows of Antarctica, so you don't risk to
hit anybody's home, you get an effective shock absorber and you find the
dark material more easily in the white snow (I don't think it will get
covered with snow; most of the impact energy will vaporize snow, so
that a crater will be formed; any material falling from the edge of the
crater will melt from the hot metal; the rock may sink somewhat into the
ice, but it will cool off fast enough to stay on the surface).

-------------------------------------------------------------------------------
   Dieter Kreuer, Lehrstuhl Informatik IV, RWTH Aachen, D-5100 Aachen
         [e-mail] = [e-mail]
-------------------------------------------------------------------------------

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

Date: 19 Jul 90 19:21:06 GMT
From: usc!samsung!rex!uflorida!mephisto!utkcs2![e-mail]  (Melissa Wauford)
Subject: Re: NSS elections

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>
>My own suggestion is the same as last year:  if you vote for the petition
>candidates and against the nominations-committee candidates, this is quite
>a bit better than voting at random.

Ah, but what do you do about people who are both petition candidates and
chosen by the nominations-committee?  The only person on the list that I
actually know, Glenn Reynolds, fits this category.  On the plus side
he's young blood, smart, knowledgable, and has no ties to the aerospace
industry.  On the minus side he's a lawyer (well, ok, I probably
shouldn't hold that against him) and tends to be a bit conventional in
his thinking about space issues, though not stodgy.  I suspect we
shouldn't hold it against him that he's on the nominations committee
slate.

--

                                            Melissa
                                            [e-mail]

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

Date: 19 Jul 90 21:48:29 GMT
From: uvaarpa!murdoch![e-mail]  (Greg S. Hennessy)
Subject: Science article on HST


The 13 Jul 1990 issue of Science has a very nice article on HST, and
what the point spread function looks like, verses what it was supposed
to look like. The pictures are almost certainly not on the same scale
however, the peak in the actual psf is lower than the peak of the
desired psf. The article is one of the best I have seen so far. Near
the end is an interesting bit about how early fears may have been
overestimated. They mention that at least half a dozen radio
astronomers have offered to help with the image deconvolution. One of
the half dozen is probably Don Wells, who has posted several excellent
(IMHO) articles to sci.astro and sci.space. WF/PC team member Todd
Lauer is quoted as saying the (deconvolved) images look nice, but he
isn`t sure he'd like to do science with them. The optical community is
understandably cautious about the deconvolution, but as they get more
used to it, it will be used more often.

The article asserts that the image processing algorithms require
supercomputer scale number crunching. This is misleading. I do image
deconvolution on my Sun 3/260, althought naturally the more cpu power
you have the better.
--
-Greg Hennessy, University of Virginia
 USPS Mail:     Astronomy Department, Charlottesville, VA 22903-2475 USA
 Internet:      [e-mail]
 UUCP:        ...!uunet!virginia!gsh7w

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

Date: 19 Jul 90 17:52:50 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Payload Status for 07/19/90 (Forwarded)


    Daily Status/KSC Payload Management and Operations 07-19-90.


    - STS-35 ASTRO-1/BBXRT (at OPF) -

    Experiment monitoring continues.


    - STS-37 GRO (at PHSF) -

    The GRO/POCC end-to-end test continues today.


    - STS-40 SLS-1 (at O&C) -

    The STT will be transferred to the CITE stand today.


    - STS-41 Ulysses (at Hanger AO) -

    PAM-S integrated testing in CITE will begin today.


    - STS-42 IML-1 (at O&C) -

    Rack, floor, and module staging is continuing.


    - Atlas-1 (at O&C) -

    Freon line, electrical cable and experiment installations
    are continuing.


    - STS-46 TSS-1 (at O&C) -

    MLI installation will continue today.


    - STS-47 Spacelab-J (at O&C) -

    Rack staging continues.

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

Date: 19 Jul 90 21:21:42 GMT
From: usc!jarthur!nntp-server.caltech.edu!deimos.caltech.edu![e-mail]  (Karl Stapelfeldt)
Subject: New director named for Jet Propulsion Laboratory

Dr. Edward C. Stone, Voyager Project Scientist and Caltech Vice-President
for Astronomical Facilities, has accepted the job of director,
Jet Propulsion Laboratory.  He will succeed Dr. Lew Allen, who is
retiring at age 65.  After a transition period Dr. Stone will
take over in December 1990.

In my opinion, Dr. Stone is an excellent choice for the post.  He knows
the institution well, has an distinguished research record, and he
has management experience with both academia and space projects.
I must admit that I am slightly surprised that he took the job -
he has several other significant science projects such as Chairman
of the Board, CARA (the organization building the 10 meter Keck
telescope) and Project Scientist for the Advanced Composition
Explorer mission.  It will be very interesting to see what he
does in this post in the coming years.

                                     Karl Stapelfeldt
                                     Pasadena CA

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

End of SPACE Digest V12 #99
*******************