Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V10_2/V10_264.TXT

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Subject: SPACE Digest V10 #264

SPACE Digest                                     Volume 10 : Issue 264

Today's Topics:
           Re: Looking Down [was: Re: HST resoluti
            Re: deadliness of environments
         Re: Planetary Society - net address
           Re: Looking Down [was: Re: HST resoluti
         Re: Frequently asked SPACE questions
             More on Space Cable
         Re: Frequently asked SPACE questions
----------------------------------------------------------------------

Date: 18 Nov 89 19:42:00 GMT
From: tank!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!uxa.cso.uiuc.edu![e-mail]
Subject: Re: Looking Down [was: Re: HST resoluti


Just a second here.  I agree that the HST would have a resolution on
earth of ~6 inches, but dont DoD Spysats have a resolution of about
2 inches?  Why dont we just tell the DoD to point one of em at whatever
astronomers want to look at?  I'll admit this would probably be like
squeezing blood from a stone but even if we used some of the Fed's junk
in space (resoloution of 8 inches???) we could get good data.

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

Date: 19 Nov 89 01:45:29 GMT
From: mnetor!utzoo![e-mail]  (Henry Spencer)
Subject: Re: deadliness of environments

In article <191700030@trsvax> [e-mail] writes:
>I am curious to here what you consider "basic technology"...

Reasonably solid pressure vessels, thermal insulation, a food supply, plants
and equipment for simple air and water recycling, power, and sufficient
"make-up" supplies of air and water to tolerate some non-zero loss rate.  Not
trivial; not spectacularly hard either.

> In the wilds of
>Antartica, the "basic technology" necessary to conserve heat, obtain water,
>and breath is supplied to every human child by its mother. Food gathering
>is a bit more complicated, you generally have to locate a rock or a big
>stick.

In the wilds of Antarctica, the basic technology necessary to conserve heat,
obtain water, and obtain food is artificial, not natural.  The thin layer of
fine hair that humans have naturally is *not* sufficient protection
against cold there.  Indeed, it takes quite carefully-made clothing to avoid
serious problems.  (The Amundsen south-pole expedition -- by far the most
competently-run Antarctic expedition -- spent its first fall/winter/spring
in Antarctica doing almost nothing but testing and rebuilding equipment.
For example, they completely rebuilt their boots three or four times, as
the original designs were grossly inadequate... even though Amundsen based
his equipment on extensive experience in the Arctic.)  There is lots of
water there, all of it frozen, and fuel for melting it is as important as
food to continuing survival.  There is *no* natural food on the Antarctic
plateau, and you have to haul all of it with you.  Read about what happened
to the Scott expedition sometime:  starving, dehydrated (badly short of
fuel), exhausted, gasping for breath (much of the Antarctic plateau is
10,000 feet up, and they were pulling heavy sledges by hand), frostbitten,
debilitated by B-vitamin deficiencies, crippled by scurvy, groping through
subzero blizzards trying to find inadequately-marked supply caches, after
coming second to the pole despite far superior resources.  *That* is what
happens when you trust to nature to provide, instead of planning your
operations and equipment meticulously.

>Please don't underestimate the massive amount of infrastructure which will
>be necessary to produce a sustainable space colony.  EMphasis on the word
>sustainable.  Projects such as Biosphere II in Arizona are but a modest
>step in the general direction towards self-sufficient artificial
>ecosystems.

Biosphere II, while a fascinating experiment, is trying to maintain a
completely self-sufficient ecosystem without material flow in or out.
I agree that with our current technology, you can't keep a lunar colony
going with no outside inputs.  So what?  No human community today operates
that way, not even the "self-sufficient" ones in primitive areas.  Many
problems get lots easier if you're willing to assume a steady flow of
raw materials in and waste out, plus occasional shipments of equipment,
parts, and scarce materials from outside.  Agreed, we're not talking about
places where humans can survive with hands and teeth; it will take brains,
tools, and materials.

>Space is not a panacea.  When "we" get there, "we" will be the same
>squabling lot of ego-centric beings that we are now. With life support
>sytems on which all of "our" lives depend on, government will become more
>stringent, not less. Responsibility of the individual to the whole will
>increase, not decrease.  The "throw away" society will perish or its
>members will fade away.

We'll cope, as we do today in place like Los Angeles, and, I'd suspect,
Fort Worth where you are -- ever considered what happens to your
neighborhood if the city water system dies?  Communities dependent on
artificial life-support systems are nothing new.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 19 Nov 89 10:36:43 GMT
From: philmtl!philabs!ttidca![e-mail]  ( Avatar)
Subject: Re: Planetary Society - net address

In article <[e-mail]> [e-mail] (Andrew Kemp) writes:
+Can someone out there in netland please help me.
+
+I am a member of the Planetary Society, and have been for about 4 years.
+It is a very good society for space related issues, so I would recommend
+people join. Anyway, enough of the sales pitch and onto the reason for
+this news article :-)

 You'll grow tired of this after a while...price vs performance and all that!

+
+I am having a LOT of trouble with trying to renew my membership to the
+Planetary Society. They have sent me 3 reminders (and a letter informing
+me that my membership has expired) and I have replied to every one.
+

 Good luck! The same happened to me and I was appalled at their lack of real
organization regarding the resolution of such matters. They finally did cash
my check and then lost all record of it! What a hassle! Finally (read 5 months
a few dozen phone calls and 3 letters with xerox-copies of the cancelled check
later!) they resolved the problem. Then, when renewal time came again, I looked
at ALL the stuff they'd sent me over 2 years time...it's all TALK!

 I wrote their membership chairman a little note, stating flatout that I would
NOT renew my membership based primarily on the fact that I was disgusted with
their position as "NASA cheerleader squad", their lack of critical commentary
on the roots of the Challenger disaster, and their refusal to take an early
lead in recommending deregulation of launch vehicles and an endorsement of the
Non-NASA or commercial space ventures. He's phoned me a few times..to no real
avail. I won't contribute another penny to such a crowd. They are avoiding the
real issues and playing cheerleader, it's absurd!  You'd be best off to call
them, they don't have an email address that I know of...if you insist on
dumping your money into the 'good-ole-boys-network' why don't you just send
it to Huston Control with a note attached: "Dear Boys, buy some more beer and
talk about the glory days of Apollo..since that's all that's left of our
"Space Program"..good luck, A Devoted Space-Program Fan" ;-)
--
-Avatar-> (aka: Erik K. Sorgatz) KB6LUY           +-------------------------+
Citicorp(+)TTI                          *----------> panic trap; type = N+1 *
3100 Ocean Park Blvd.   [phone], ext. 2973 +-------------------------+
Santa Monica, CA  90405 {csun,philabs,randvax,trwrb}!ttidca!ttidcb!sorgatz **

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

Date: 19 Nov 89 16:56:44 GMT
From: cs.utexas.edu!samsung!aplcen!haven!uvaarpa!hudson!astsun.astro.Virginia.EDU![e-mail]  (Greg S. Hennessy)
Subject: Re: Looking Down [was: Re: HST resoluti

In article <[e-mail]> [e-mail] writes:
#
# Why dont we just tell the DoD to point one of em at whatever
#astronomers want to look at?  I'll admit this would probably be like
#squeezing blood from a stone but even if we used some of the Fed's junk
#in space (resoloution of 8 inches???) we could get good data.

The difference between the detectors that DoD wants and the detectors
that astronomers want differ like night and day.(That's a hint.)



-Greg Hennessy, University of Virginia
 USPS Mail:     Astronomy Department, Charlottesville, VA 22903-2475 USA
 Internet:      [e-mail]
 UUCP:        ...!uunet!virginia!gsh7w

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

Date: 19 Nov 89 15:51:20 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: Frequently asked SPACE questions

Well one thing's for sure, starting the FAQ list with that Saturn V stuff is
a mistake, unless we want to retitle it "Frequently Rekindled Threads" :-)

--
Psychoanalysis is the mental illness   \\\    Tom Neff
it purports to cure. -- Karl Kraus      \\\   [e-mail]

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

Date: 11/18/89 18:39:58
From: [e-mail]
Comment: CROSSNET mail via SMTP@INTERBIT
Return-Receipt-To: [e-mail]
Subject: More on Space Cable

Michel van Roozendaal(13 nov. 89 - SPACE digest Vol.10 #245) writes:
>In view of our applications a nice property in order to compare
>materials is the free breaking length in a 1-G environment. This is
>the length of a cable of a certain material when it will collapse
>under its own weight, without tapper/1G. Remember; the free breaking
>length of any material is infinite when we apply tapper.
>
>Let's list a few materials:
>
>Steel       37 km         Carbon     171 km
>Glass       76 "          Aramide    193 "
>Nylon       92 "          HP-PE      336 "

So as to be able to see what free breaking length is needed,
let us turn back to the equation given in my first intervention
(11/10/89 - Space Digest V.10 #235):
    Delta( Log(S) )  = p/s.g0.r0.(1 + x/2 - 3/2.x^(1/3) )
    where x = w^2.r0/g0 .
If one does not take into account the 'x' factor (which reduces the
strength needed by about 30%), this equation also says that the
section ratio equals 'e' (exponential one) when:
    s = p.r0.g0
In other words, the free breaking length is equal to Earth's (or
Moon's) radius in that case. Since that radius is around 6_400km,
the HP-PE material has only 1/20 of the corresponding resistance.
Or to turn it the other way around, if this material is used, the
section ratio will be e^20=485_165_195, which is much too large to
be useful.  On the other hand, if a material twice as strong is
invented, it will become e^10=22_026, which correspond to an
increase in diameter of e^5=148.4 : in that case, the space cable
can barely become a real thing, but quite a massive one.  And if yet
another two-fold gain is made, the ratio will be around 150, which
is almost nothing.  Now if the 30% bonus caused by Earth's rotation
is taken into account, figures are lower still: this time a 600km
breaking length will be enough. Start the research _now_!

Now for the Moon: the 'r0.g0' product is around 40 times less than
that of Earth, so that a cylindrical cable made of HP-PE will
sustain its own weight plus an additional payload. When do we start?
But the first question is: Is it useful?

Christofer Neufeld (14 Nov. 89 - Space Digest V.10 #249) writes:
>Bertrand MICHELET (13 Nov. 89 - Space Digest V.10 #246) writes:
>>Now my point was not only an Earth lift, but also a Moon one. That
>>one has several advantages.
>   Just a minor point. You can't anchor a lunar skyhook (where do
>you have to go for selenostationary orbit?).

Well, I have good news for you: there _is_ such thing as a
selenostationary orbit. Well, of course, seen from Earth, the Moon
dosen't seem to rotate much, since it shows is always the same side.
That simply means that the Moon's rotation equates its revolution
period of one turn per month. This is not much, but it is enough
to create a centrifuge force.

The problem with selenostationary orbit is that it is also
synchronized with Earth's revolution around the Moon (seen from the
Moon, of course), so that Earth's gravitational pull is constant.
The selenostationary orbit is therefore restricted to the five
Lagrange points. (Lagrange is a scientist born last century in some
obscure country you may not have heard of - mine.)  Two of these
points form an equilateral triangle with the Earth and the Moon, and
are a bit far for our purpose. The other three are unstable orbits
aligned on the Earth-Moon axis: as far as I remember, one is before
the Earth (useless, since the cable would have to cross the
earth...), another in between and the last one behind the Moon. The
orbits are unstable for free-fall satellisation, but the
selenostationary station being anchored makes it an entirely
different problem.

This is why the anchor point should be 'right in the middle' of the
Moon, either on our side or on the hidden one. In both cases, the
non-linearity of Earth's gravitational field adds a small second-
order bonus, so that the strength of the cable is a bit _under_ the
one given by my formula. (There is no correction for Earth's pull on
the moon orbit and the centrifuge effect caused by the Moon not
being centered on its center of rotation, since these two cancel out
- this is why the Moon is on a stable orbit.) Actually there is a
third-order bonus on Earth's side that is lost on the hidden one, so
that the best place is right in front of us. Furthermore, that place
is always under Sun- or Earth-light, which can be useful.  But this
dosen't prevent us from using the other point as well (telescopes
sites, for instance)

I like this idea of a cable lifted _up_ by its own weight, anyway.

                     Bertrand MICHELET
                     uDoc140 at FrOrs31 (BitNet)

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

Date: 19 Nov 89 20:48:42 GMT
From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!ists!yunexus!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Frequently asked SPACE questions

In article <[e-mail]> [e-mail] (David Schneider) writes:
>P.S.  During my brief fling as a student naval architect (sailboats), I was going
>to right all the wrongs I had encountered as a dock boy.  Run wiring through
>service alleys instead of "random path" point to point, for instance.
>I'm sure that Saturn V builders (as opposed to designers) had a similar
>laundry list.

Well, do remember that the builders and designers were, to a considerable
extent, the same people.  The first Saturns (of each model) were built at
Marshall, not at contractor plants, although contractor personnel were
heavily involved for the Saturn V in particular.

Marshall's manufacturing facilities were one of the first casualties of
the post-Apollo cutbacks.

I don't doubt David's point, though:  von Braun & Co. probably had a long
list of "things to revise if we ever get the chance".
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

End of SPACE Digest V10 #264
*******************