Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_3/V16NO310.TXT

Internet Message Format | 1993-07-13 | 18KB

Date: Sat, 13 Mar 93 05:42:18
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #310
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 13 Mar 93       Volume 16 : Issue 310

Today's Topics:
                         Acceleration of ice
                   Cancel wars and academic freedom
            Soviet Energia: Available for Commercial Use?
Threat of mass cancellings was Re: Anonymity is NOT the issue (2 msgs)

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
    "Subscribe Space <your name>" to one of these addresses: listserv@uga
    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: Sat, 13 Mar 1993 05:03:27 GMT
From: [e-mail]
Subject: Acceleration of ice
Newsgroups: sci.chem,sci.engr.chem,sci.space,sci.physics

John Papp ([e-mail]) wrote:
: I am currently doing a design project which requires the acceleration
: of a block of ice to about 1500 m/s in an almost pure vacuum (space).
: This block of ice will be under about 6.4e6 Pascals of acceleration
: pressure (m*a/area) in about a 100 K environment.  Once this block has
: reached 1500m/s, the acceleration will be removed.

John, you didn't mention the size of the block.  That's pretty critical
when trying to come up with a design.  You also didn't mention any
design constraints on vehicles or packaging.

A "block" which is a sphere, 1 cm in diameter, might be almost ideal.
They're easy to catch, and it costs you just as much energy to throw a
lot of little blocks as one great big one.  And if one misses the
target, nobody gets hurt.

: Assumptions.  The block will be ice when it begins accelerating.
:               The acceleration will build to a constant value
:                  and will then be removed when the ice has reached 1500m/s.

I further assume that this project is related to the other space ice
scenario:

>Rajesh Batra ([e-mail]) wrote:
>: Scenerio:  You're on the moon, a 1700 m/s container (containing ice) which
>: weighs approximately 120 kg is hurled at you. How do you catch it such
>: that you can salvage the ice? You have free reign over the container-
>: hence the size/material.

(I've attached my response to Mr. Batra's question at the end of this
article.  Note my last paragraph.)

Back to Mr. Papp ([e-mail]):
: My question are:
:      Will the ice liquify or sublime under the acceleration
:         even under the zero pressure of the environment?

Yes, a little, but (a) you can control this with a container, possibly
a thin film on the surface of the ice block, and (b) you might not care,
if the loss is not a large fraction of the launch mass.

:      If the ice liquifies, will it refreeze when the acceleration stops?

Assuming the fluid adheres to the surface or is restrained there by a
container, yes, it will refreeze when the P/T curve reaches the solid
phase.

:      If the ice liquifies, will it explode when the acceleration stops?

No.  Our experience with sudden cessation of acceleration, like what
happens when a thruster turns off in the Space Shuttle Orbiter, is that
blobs of liquid (even with suspended solids) tend to cohere and adhere
to the surface against which they were placed when accelerating.  There
is a transient, oscillitory period while the blob adjusts to the new
acceleration environment, but blobs don't explode.  However, our
experience with zero-G fluid behavior is limited, and we've never tried
an abrupt cessation of heavy acceleration.

Now, a Ken Jenks signature ASCII sketch:

                                                   bbbb
                                                 bbbbbbbb
             bbbbbbbb                            bbbbbbbb
        bbbbbbbbbbbbbbbbbbbb                       bbbb
       ------------------------           -------------------------

   1:Initial acceleration upward       2:Same blob immediately after
                                            acceleration ceases

              bbbbbbbb
             bbbbbbbbbb
            bbbbbbbbbbbb
       ------------------------
    3:Same blob after transient
              settles

In figure 1, the blob spreads out in a puddle on the flat plate.

Note in figure 2 how the blob attains a more spherical shape.  If the
transient is violent enough, some of the fluid may overcome the forces
of cohesion and adhesion and separate from the plate.  But our
experience on the Shuttle shows that it does not "explode."

In figure 3, after the transient motion settles out, the blob will
form a circular mass with a flattened bottom.  This shape is a
balance between cohesion and adhesion.

:      If the ice liquifies, will some of it escape when the
:         acceleration stops but most of it refreeze?

It depends on that transient motion, which is not well understood yet.

: As of yet, I know of no experiment that was done to answer these questions
: and phase diagrams of water are somewhat lacking to what happens during
: transition or just do not go down to the pressure and temperature values
: stated.

There have been some experiments.  Check out material science journals.
But you're looking at acceleration ranges and temperature extremes
we don't typically encounter in the manned space program.

: Any answers or references to answers to these questions would be greatly
: appreciated.

: Thanks.
: --
: -------------------------------------------------------------
: |                  |                            |
: | John L. Papp        | "You sound like a manure salesman   |
: | [e-mail]  |  with a mouth full of samples."     |

-- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office
      [e-mail]  [phone]

     "Even considering the improvements possible... the gas
      turbine could hardly be considered a feasible application to
      airplanes because of the difficulty of complying with the
      stringent weight requirements."
    -- US National Academy of Sciences, 1940

     "It may not be possible to build a vehicle with single-stage-
      to-orbit capability in the mid 1990s."
        -- US National Academy of Sciences, 1990

>Subject: Re: Help on catching this
>Newsgroups: sci.space,sci.physics
>Followup-To: sci.space
>References: <[e-mail]>
>From: [e-mail]
>Organization: NASA/JSC/GM2, Space Shuttle Program Office
>Distribution: na
>
>Rajesh Batra ([e-mail]) wrote:
>: Scenerio:  You're on the moon, a 1700 m/s container (containing ice) which

>: weighs approximately 120 kg is hurled at you. How do you catch it such
>: that you can salvage the ice? You have free reign over the container-
>: hence the size/material.
>
>Start with a smooth container (or no container at all -- ice itself is
>fine).  Aim it at a large, long funnel.  The funnel narrows down into a
>chute with gas injectors in it.  Inject a little gas ahead of the block
>of ice and let friction do its job and let the pressure build up in the
>chute, slowing the block.  Slide baffles into the tube as the ice
>passes to recapture & recycle most of the gas.
>
>                      _______
>                             \______
>                                    \______________
>      --- O --->                     ______________  chute ->
>          ^ ice, incoming     ______/
>                      _______/
>
>In the chute:
>    __________________________________________________________________
>    ___________________|_O_________________________ __________________
>                       |                        |
>                         ^ gas injector         |  ^ gas injector
>
>                       ^ baffle (in)            ^ baffle (not in yet)
>
>If the angle of the funnel is slight enough, the block of ice won't
>fragment too much as it bounces in toward the chute.  If you miss the
>funnel, don't worry about that one -- it won't do much harm, if you
>arrange its orbit right.
>
>The funnel will get dinged up rapidly as you bounce blocks of ice off
>of it.  You might need to resurface it frequently (try more ice).  To
>avoid wear on the funnel, make the blocks of ice spherical.  That way,
>you won't care if they tumble and "hit wrong."  Your chute may get
>scraped up from ice which shatters in the funnel.
>
>If your funnel is too difficult to hit with a purely balistic ice ball,
>you could either add a guidance package to each ball (expensive), or
>you could add "terminal guidance."  There would be a position sensing
>mechanism (possibly a couple of strings of photo sensors and a bright
>light, maybe the Sun) and either a fluid impact (squirt gun) or
>projectile impact device on the incoming path to the funnel.  The
>sensors figure out where the ice ball is, a computer figures out where
>it should be, and the impact devices give it a nudge.  If the ice ball
>is unsalvagable, either nudge it high (so it misses the funnel
>completely) or nudge it into an impact area (dump it, but keep most of
>the mass on the moon).  But this is expensive and complicated.  You're
>probably better off spending your money on better precision launch
>equipment than better capture equipment.  If you hit dead on every
>time, you don't need to worry about all this.
>
>You'll get a little bit of help from the moon's atmosphere, which is
>small but will get larger in the area of operation of your catcher as
>the ice sublimes into vapor.
>
>Your chute will get warm -- even hot -- as the gas compresses and you
>turn the massive kinetic energy of the ice ball into temperature and
>pressure.  Oh, and don't forget that pressure building up.  If you
>don't stop it, the ice ball will compress a column of gas in the chute,
>come to a stop, then go spitting out the funnel again as the gas
>expands.  But don't let this be a disadvantage.  If you arrange it
>right, you'll have a terrific steam generation plant which can be used
>to drive turbines and generate electricity.  And the source of
>energy is the kinetic energy of the incoming ice balls.
>
>If you arrange the pressures and temperatures right, and prevent
>escaping vapor with the baffles, you could have a trough of water at
>the bottom of the chute.  If you wait long enough between ice balls,
>that water could be as smooth as glass, and you could skim the ice ball
>off the water until friction slows it down and it melts into the
>puddle.  But waiting for the water to get smooth decreases your
>plant capacity.
>
>Or maybe you don't care about smooth water.  As a block of ice comes
>screaming in the funnel, the chute opens into a large, STRONG reservoir
>of liquid water.  SPLASH!  Blub!  Waves everywhere.  Friction with the
>water and the turbulence you've caused will slow that puppy down fast.
>You've just turned all of that kinetic energy into thermal energy in
>the water.  More steam turbines.  This option assumes you already have
>a large body of water on-site on the moon -- certainly not a valid
>assumption at the start of operations, but 120 kg blocks add up fast.
>Maybe your second funnel ends in a splash.
>
>You probably don't care if your ball of ice is intact at the end of
>this process, as long as you capture most of its mass.  So you might
>want to fragment it (by inelastic collision[s]) as it comes in, and
>catch the fragments in a big funnel.  Since some of the balls will
>probably fragment anyway, you might be in this state by accident rather
>than design.  Do a lot of testing.
>
>Now the hard part: how do you hurl a 120 kg ice ball at 1700 m/s with
>millisecond timing and microradian accuracy?  'Cuz that's what you'd
>need in the launch equipment to make this crazy scheme work.  But that
>may not be part of your assignment.  If this is homework, give credit
>where it's due.
>
>-- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office
>      [e-mail]  [phone]
>
>     "Good ideas are common -- what's uncommon are people who'll
>      work hard enough to bring them about." -- Ashleigh Brilliant

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

Date: Fri, 12 Mar 1993 22:18:25 GMT
From: 8 February 1993 <[e-mail]>
Subject: Cancel wars and academic freedom
Newsgroups: alt.privacy,sci.space,sci.astro,comp.org.eff.talk,news.admin.policy

If do not think Richard E. Depew's ([e-mail]) threat to censor
the postings *you* may wish to read by beginning a "canceling war,"
please write directly to:

Prof. John Docherty, M.D., Ph.D., Director,
Department of Microbiology/Immunology
NEOUCOM (Northeastern Ohio Universities College of Medicine)
Rootstown, OH  44272

or call him at [phone]

You may also wish to copy:

William Dorsey, Manager,
Computer Services NEOUCOM
Rootstown, OH  44272

Express your concern for this threatened instance of network vandalism and
damage to academic freedom throughout the world by a reputed representative
of his organization.

-------------------------------------------------------------------------
To find out more about the anon service, send mail to [e-mail].
Due to the double-blind system, any replies to this message will be anonymized,
and an anonymous id will be allocated automatically. You have been warned.
Please report any problems, inappropriate use etc. to [e-mail].
*IMPORTANT server security update*, mail to [e-mail] for details.

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

Date: Fri, 12 Mar 1993 23:44:08 GMT
From: Dennis Newkirk <[e-mail]>
Subject: Soviet Energia: Available for Commercial Use?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Simon E. Booth) writes:
>No N-1 on public display at Baikonour? :-)  Seriously, I'm curious at to why
>it seemed to take so long for them to get Energia (and ultimately Buran)
>off the ground- if the work on desiging Energia was started in the early
>70's.

According to some articles, Energia was officially approved in 1976 and Buran
in 1980. Since these were military projects I wouldn't be surprised to see the
dates vary between sources. It is interesting that the reaction to the US
shuttle project was so slow in the USSR, but they apparently had a hard time
deciding on their reaction. There was also Glushko's Vulcan booster concept
similar to the Energia and his lunar base plan to confuse approval for the
Energia. And, on Buran's side there was the Spiral project and Energia NPO's
alternative wingless shuttle concept, not to mention Chelomie's second
generation Almaz military space station work and 'Star Module' crew transport,
to confuse the issue of which path to follow.

Hopefully, we will learn more about these plans and the politics before too
long. The Russian researcher responsible for revealing much of the above is
working on an English version of his book. The Russian version was translated
by the JPRS folks last year. I hope he will add more material to the English
version, if it's still in the works...

Dennis Newkirk ([e-mail])
Motorola, Land Mobile Products Sector
Schaumburg, IL

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

Date: Sat, 13 Mar 1993 06:44:55 GMT
From: Brad Templeton <[e-mail]>
Subject: Threat of mass cancellings was Re: Anonymity is NOT the issue
Newsgroups: news.admin.policy,news.admin,comp.org.eff.talk,sci.space,alt.privacy

Note that in Newsclip the one line of code:

    reject if from has "@sitename$";

Is sufficient to ensure you see to anonymous postings.  Add:


    reject if References @!= nilarray && References has "@sitename>";

And you will not see any followups to anon postings.  It will be as though
the anon site isn't even on the net as far as you can tell.


Newsclip is on ftp.clarinet.com and on uunet in vendor/ClariNet in the
file nc.tar.Z.
--
Brad Templeton, ClariNet Communications Corp. -- Sunnyvale, CA 408/296-0366

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

Date: Fri, 12 Mar 1993 22:56:33 GMT
From: Ed McGuire <[e-mail]>
Subject: Threat of mass cancellings was Re: Anonymity is NOT the issue
Newsgroups: news.admin.policy,news.admin,comp.org.eff.talk,sci.space,alt.privacy

In <[e-mail]> [e-mail] (David Clunie) writes:

>I would also be interested to hear a legal opinion on this matter. Cancelling
>someone else's posts may well be infringing on their First Ammendment rights,
>not to mention a potential breach of that Electronic Privacy Act or whatever
>it is called. I am sure your institutions lawyers will be real impressed when
>the ACLU and the EFF come knocking on their doors on behave of some angry
>plaintiff.

Well, here's a lay opinion.  I think your speculations are entirely
baseless.  The First Amendment simply guarantees that the USA
government will not take certain rights away from its citizens.  I
don't see that the USA government can be held responsible for a private
action!  As far as the Privacy Act, how can it possibly apply to a
public communication?  Please think before you shoot.

Also keep in mind that control messages such as cancel are advisory in
nature and the responsibility for whether the article is deleted from
the local spool rests entirely on the local news admin, not the person
who posts the cancel.

This doesn't change the fact that I also oppose automatic issuance of
cancel control messages.
--
Ed McGuire                   1603 LBJ Freeway, Suite 780
Systems Administrator/       Dallas, Texas 75234
 Member of Technical Staff   214/620-2100, FAX [phone]
Intellection, Inc.           <[e-mail]>

Raise Usenet quality.  Read news.announce.newgroups and vote.

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

End of Space Digest Volume 16 : Issue 310
------------------------------