Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_3/V11_305.TXT

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Subject: SPACE Digest V11 #305

SPACE Digest                                     Volume 11 : Issue 305

Today's Topics:
     890000 A ROBOTIC ASSISTANT FOR SPACE STATION FREEDOM
                 re: Re SETI
              Re: Fermi paradox
              Re: Dyson spheres?
               Re: voyager images on cd
      Fwd: 890000 A ROBOTIC ASSISTANT FOR SPACE STATION FREEDOM
            Re: Aerobrake Vehicles
             I would like to join
              Re: Decompression and 2001
         Re: Apollo 13, STS-1, Vostok 1 anniversaries
              Re: Fatal voltages
----------------------------------------------------------------------

Date: 21 Apr 90 01:45:49 GMT
From: [e-mail]  (LIS USER JS7A)
Subject: 890000 A ROBOTIC ASSISTANT FOR SPACE STATION FREEDOM


 IDNUM     03525372
 TYPE      Journal paper
 DATE      890000
 AUTHOR    McFalls, D.; Franke, E.
 TITLE     A robotic assistant for Space Station Freedom
 SOURCE    Robotics Today; vol.2, no.2; 1989; pp. 1-6
 SUBJECT   aerospace computer control; assembling; computerised materials
           handling; maintenance engineering; mobile robots; space vehicles;
           in-orbit construction; object retrieval; Extravehicular Activity
           Robotic Assistant; person retrieval; astronauts; robot language;
           Space Station; Freedom; prefabricated parts; highly autonomous
           free-flying robot; assembly; maintenance; EVA Retriever; EVAR;
           global positioning system
           Class codes: C3360L; C3390; C7460; C7420; C3320
 CODEN     ROTODJ
 ABSTRACT  The Space Station Freedom is to be constructed in orbit from
           prefabricated parts. The article describes a highly autonomous
           free-flying robot the Extravehicular Activity (EVA) Robotic
           Assistant, designed to perform tasks including assembly, maintenance
           and retrieval of objects and people. The last of these objectives is
           considered especially. The EVA Retriever (EVAR) must locate an
           object, move to it, grasp it, and return it to where it should be. A
           language for the robots is discussed. The EVAR uses a global
           positioning system
 MISCELLANEOUS
           Treatment: practical
           Robot. Today (USA)
           Abstract number(s):  C90006138
           ISSN: 0193-6913
           Refs: 8
               END OF DOCUMENT

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

Date:       Sun, 22 Apr 90 11:45:58 EST
From: [e-mail]
Subject:    re: Re SETI

I have to agree with Steve Nuchia, don't rule anything out.

A very good book which explores "an exotic combination" is
Dragon's Egg by Robert L. Forward (ISBN 0-345-31666-5 for paperback).
He also has a sequal called Starquake (which is even better).

Basically Dragon's Egg/Starquake explore the idea of humans
discovering life on a neutron star.

                  CP6-Mail: Michael Brown @CMR
                  NET-Mail: <[e-mail]>
Michael Brown   Snail-Mail: Service Informatique CMR, St-Jean, Que. J0J 1R0

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

Date: 21 Apr 90 04:43:02 GMT
From: zephyr.ens.tek.com!tektronix!percy!parsely!bucket!loop![e-mail]  (Keith Lofstrom)
Subject: Re: Fermi paradox

There is a stronger question implied by the Fermi paradox:  If they
are out there, and even if they have rules preventing local visits,
why don't we see their infrared emissions?  Why are there so many
high-quality energy sources (visible stars) compared to heat sources?

Surely an advanced civilization would be using most of the energy
from their local stars, perhaps even dismantling them. Unless there's
an efficient way to dump waste heat into a black hole, this would
make for some pretty spectacular infrared sources!

----

To add to all the other more plausible explanations, one
possibility is that "they" have access to much higher quality
resources than we see or know about, and we are living in the
cosmic trash heap!   Perhaps by the time a civilization in this
galaxy learns interstellar travel, they find out there are much
better places to live, and go elsewhere...


--
Keith Lofstrom    keithl@loop    tektronix!psueea!qiclab!loop!keithl
Launch Loop, P.O. Box 1538, Portland, Oregon 97207   (503)-628-3645

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

Date: 22 Apr 90 22:01:56 GMT
From: deimos.cis.ksu.edu!iowasp![e-mail]
Subject: Re: Dyson spheres?

In article <[e-mail]>, [e-mail] (Andrew Salamon) writes:
> So whats a dyson sphere?
>
> Magic in my Mind                     |   /Andrew/
> Music in my Heart                    |   soi-disant Bleydion op Rhys
> Laughter in my Soul                  |   [e-mail]
> And...A Sword in my Fist (sigh)      |


        A  "Dyson  Sphere" is the name associated with a concept  that
    Freeman  Dyson  (a  VERY eminent professor of Physics at Princeton
    University) suggested  some time ago dealing with the product of a
    very advanced civilization.  Dyson suggested that at some point in
    the advancement  of some civilizations,  they  would  develop  the
    ability to  transform all of the matter of their solar system into
    a very thin  layered  hollow sphere  centered  on  their star.  In
    this way  they could fully utilize the total stellar energy output
    as well as the maximum surface area on the interior of the sphere.
    Dyson  recognized that an Earth-based observer would  see  a  very
    bright infared source with no visible component.

        This concept  was  used by Larry Niven (in an economy mode!:))
    in the creation of his "RINGWORLD".  I highly recommend this story
    and the sequel "RINGWORLD ENGINEERS".

        Just in case you're interested, I am not related to him.  Just
    a  coincidence!   Every physics prof I've ever had asked the  same
    question on the first day of class.

    The penguin

--
Richard L. Dyson                Department of Physics & Astronomy
Graduate Research Assistant     University of Iowa
INTERNET: (1st choice)          [e-mail]
INTERNET: (2nd choice)          [e-mail]
SPAN DECnet:                    IOWASP::DYSON
Home: (319) 338--6117           Office: (319) 335--1864

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

Date: 22 Apr 90 23:07:30 GMT
From: portal!cup.portal.com![e-mail]
Subject: Re: voyager images on cd

Hmm, I came in on the middle of this conversation, but I'm fascinated by
the idea of obtaining Voyager imagery on CD!  What can anyone tell me about
this?  How do I get 'em?  What do I need, EXACTLY, to read 'em?  (I.e.,
are there some CD drives that will, and other drives that won't, read
them?  What file structure on the CD itself?)  What is the data format
of the images themselves?

My company is about to obtain some form of CD drive; how would I determine
whether the one we get would be able to read the images being discussed
here?  Once I can get a drive to read 'em, and know what the image for-
mat is on them, I can write software to convert 'em to what I can view...

Thanks in advance for any info; if you post here, please e-mail too, as
I find myself unable to keep up with the volume of this newgroup, try as
I might!  Thanks!

Chris Chiesa
Software Engineer
Light Valve Technology - A Kodak Company

[e-mail]

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

Date: 21 Apr 90 21:18:05 GMT
From: [e-mail]  (James Price Salsman)
Subject: Fwd: 890000 A ROBOTIC ASSISTANT FOR SPACE STATION FREEDOM


I thought this newsgroup might be interested in this reference.

 IDNUM     03525372
 TYPE      Journal paper
 DATE      890000
 AUTHOR    McFalls, D.; Franke, E.
 TITLE     A robotic assistant for Space Station Freedom
 SOURCE    Robotics Today; vol.2, no.2; 1989; pp. 1-6
 SUBJECT   aerospace computer control; assembling; computerised materials
           handling; maintenance engineering; mobile robots; space vehicles;
           in-orbit construction; object retrieval; Extravehicular Activity
           Robotic Assistant; person retrieval; astronauts; robot language;
           Space Station; Freedom; prefabricated parts; highly autonomous
           free-flying robot; assembly; maintenance; EVA Retriever; EVAR;
           global positioning system
           Class codes: C3360L; C3390; C7460; C7420; C3320
 CODEN     ROTODJ
 ABSTRACT  The Space Station Freedom is to be constructed in orbit from
           prefabricated parts. The article describes a highly autonomous
           free-flying robot the Extravehicular Activity (EVA) Robotic
           Assistant, designed to perform tasks including assembly, maintenance
           and retrieval of objects and people. The last of these objectives is
           considered especially. The EVA Retriever (EVAR) must locate an
           object, move to it, grasp it, and return it to where it should be. A
           language for the robots is discussed. The EVAR uses a global
           positioning system
 MISCELLANEOUS
           Treatment: practical
           Robot. Today (USA)
           Abstract number(s):  C90006138
           ISSN: 0193-6913
           Refs: 8

:James

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

Date: 22 Apr 90 18:20:12 GMT
From: shelby!portia![e-mail]  (Carl Gooch)
Subject: Re: Aerobrake Vehicles

In article <[e-mail]> [e-mail] (Jay Lewis Nestle) writes:
>I am interested in doing possible graduate work on aerobrake
>and reentry vehicle design, test, and simulation.
>    Has anyone done any reentry vehicle modelling or analysis in wind
>tunnels of this type?  If so which design criteria (i.e. Reynolds,
>Froude, etc.) did you use and why?

I haven't actually done any design work in this area, but I've taking more than
enough aerothermodynamics courses to know that Mach and Reynolds numbers, while
important for re-entry simulations and experiments, are not necessarily the
most important.  At re-entry speeds (and this goes at least double for Earth-
Mars or Mars-Earth trajectories), the heating behind a shock wave causes air
to react.  Your average reacting air model includes quite a few chemical
species:  N2, O2, NO, N, O, N+, O+, NO+, e-, and maybe some tri-atomic species
too.  There will be maybe as many as 40 or 50 chemical reactions to calculate.
That's for the Earth's atmosphere.  For Mars you start with basically an N2/CO2
atmosphere and the chemistry is worse; CO2 reacts to form the most astounding
things!  All of this chemistry nonsense is not intrinsically difficult to
program, although it's tedious; the big problem is that at very high
temperatures the reaction rates are questionable.  Other factors which are
neglected:
   Radiation is (at least almost) universally calculated as an afterthought,
     which is okay for moderate temps, but not for 25 km/sec re-entry.
   The flow is always treated as weakly ionized because of the huge problems
     which otherwise inevitably occur in you chemistry model.

So, having said all of those encouraging words about state-of-the-art
simulations, what about experiments?  Well, the three most important non-dimen-
sional parameters are Mach, Reynolds, and Damkoehler numbers.  (Damkoehler # is
a ratio of characteristic flow time to characteristic chemical reaction time.)
Getting all three of these to match in an experimental facility is next to
impossible.  Shock tunnels can get Damkoehler number right, and Reynolds
number is just a matter of model scaling, but to get high enough Mach numbers
you have to expand the flow so much that the freestream conditions are way off
chemically.  A ballistic range (boo! hiss! shout the wind tunnel people) can
get everything except Damkoehler number, which is a bitch to match in a
ballistic range because of the small size of the models.

   I guess the short answer to your question is that lots of people are working
on this problem, but that there are strict limitations on the accuracy of their
results which are completely unrelated to the accuracy of their coding/experi
-mental technique.

>Also if there is any information out there concerning other schools or
>companies that do this sort of research work please let me know.  Thanks in
>advance!  Jay.

   May I, as a humble grad student, humbly mention that Stanford Aero/Astro and
ME departments, in conjunction with NASA-Ames and their All-Cray Orchestra are
doing lots and lots of things in this area.   We play with numerical models and
solution techniques on the one hand and some great experimental toys on the
other.  No ballistic range at the moment, alas.   (The last sentence is brought
to you by Acme Asbestos Keyboards and Monitors, Inc.)

   If you have any questions about your project or about grad school, Jay,
send me e-mail and I'll see what I can do to help.





--
Carl Gooch                       [e-mail]
Disclaimer:  You think Stanford actually agrees with this?  Hah!  If they want
             my opinions and theirs to match they should pay me enough to
             agree with them!

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

Date: Sun, 22 Apr 90 22:42 CST
From: The Angry Young Man <[e-mail]>
Subject: I would like to join

I would like to join this mailing list if possible.
                    Thanks,
                        Juan Cabanela
                        [e-mail]

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

Date: 22 Apr 90 17:44:54 GMT
From: psuvm![e-mail]
Subject: Re: Decompression and 2001

In article <[e-mail]>, [e-mail] (Dan Tilque) says:
>By a not so amazing coincidence, this was also a Clarke story.  It was
>written back in the 50's, I think.  Unfortunately, I can't remember the
>name but the plot goes like this:
>
The Clarke story in question was "Take a Deep Breath," and I don't know about
      you guys, but I wouldn't try holding my breath in hard vacuum; I'd be
      afraid of breaking my jaw, and then losing the air anyway. I might try
      sticking my fingers in my ears, though.

Mike Williams
[e-mail]

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

Date: 22 Apr 90 04:19:22 GMT
From: hpfcso!hpfinote![e-mail]  (Doug Josephson)
Subject: Re: Apollo 13, STS-1, Vostok 1 anniversaries

In article <[e-mail]> [e-mail] (John A. Weeks III) writes:

>Duct Tape?  Why on earth did they have duct tape on the Apollo?
                 ^^^^^^^^ (hmmm, 'off earth' maybe? :^) )
>How much did this flight certified duct tape cost?  Did any of the
>LM's that landed on the moon carry duct tape?

Well, at least the Apollo 15 LM carried duct tape to the moon.  From "To Rule
The Night" by James Irwin (LMP on Apollo 15):

"We had rolls of the tape; we'd strip it off to make a kind of sticky
fielder's glove, and we'd use it to mend or reinforce things that were
damaged or broken.  In this new, curious, weightless world, it was a surface
that you could count on to hold things."

And later in the book, when Irwin is inspecting his backpack prior to a
lunar EVA:

"When I examined mine, I found a large-sized nick in the antenna.  We
reported it and ended up using that good gray tape to wrap and reinforce it
at the weak point so that it wouldn't break off."

It'd be interesting when somebody gets back to the Apollo 15 site to see if
that stuff is still sticky after exposure to the Moon's tropical climate
for years.  My money's on the tape!

LET'S SPRAY SOME RUSTOLEUM ON A HORIZONTAL SATURN V AND GO SEE!!!!

( Sorry - I think the altitude is affecting my brain today!  %^) )

Doug Josephson  [e-mail]  Fort Collins, CO  (4980' ASL, only
250000 more miles of elevation gain to go...)

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

Date: 23 Apr 90 00:23:33 GMT
From: cs.utexas.edu!texbell!nuchat![e-mail]  (Steve Nuchia)
Subject: Re: Fatal voltages

In article <[e-mail]> [e-mail] (Arnold G. Gill) writes:
>>the saddle in the 50% fatal voltage level curve, 50 Hz is closer.
>     You are going to have to explain this one to me a little bit better.  I

No problem.  I'm working from memory though.

>guess I was always under the mistaken impression that the dangers of
>electricity have a lot more to do with voltage and the amount of current that
>that voltage can pump through a person

The critical value, at low power level, is the current through the heart.
At high power levels it just cooks flesh, and you may die of shock even
if the current path doesn't involve the nervous system.  Shocks not involving
the heart can also cause convulsions, which may be dangerous in their
own right.

> (0.1A is supposedly the fatal current level)

A tenth of that through the torso will usually be fatal, less sometimes is.
Your skin has a DC resistance in the megohms when dry, but it is
rather thin.  Once inside the bulk resistance varies depending on
the tissue involved, but is rather low.  The skin resistance can be
broken down by puncture, charring, capacitive coupling, or just by
having enough voltage.

>  What effect can frequency have?

Frequency has an effect on how well the energy is coupled to you and
how much current is associated with your capacitance relative to ground.
At very high frequencies the skin effect (referring to the outer
portion of a conductor, not people-skin) causes most of the current
to flow near the surface of the body, avoiding the heart.  Neither
of these effects is significant in the 10-400 Hz region.  In that
region the important effect seems to be the match between the
frequency of the shock and the natural frequencies of the heart
heart's control "circuits".   It is a second-order effect, and
the curve I alluded to is rather shallow, and it moves around
depending on individual factors, but it is statistially significant.

If anybody happens to know of a good reference I'd appreciate
a pointer too.

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

End of SPACE Digest V11 #305
*******************