HDTenEightyP/NetNews huggingface dataset:
From: clarke@acme.ucf.edu (Thomas Clarke)
Subject: Re: averting doom
Organization: University of Central Florida
Date: Wed, 30 Dec 1992 21:36:04 GMT

In article <JMC.92Dec29211051@SAIL.Stanford.EDU> jmc@SAIL.Stanford.EDU (John  
McCarthy) writes:
> By the way, it seems to me that if the above idea is sound, it settles
> the question of the stability of the solar system - in the negative.
> Very likely an asteroid could be tamed over a sufficiently long time
> with as small an expenditure of delta-v as might be desired.  Once
> tamed it could be used with infinitesimal external force to expel a
> planet from the system.  This tells us that the current trajectory of
> the solar system is arbitarily close to one in which a planet is
> expelled.  Of course, the probability that a planet actually would be
> expelled by this mechanism in some particular finite time is extremely
> low, because maintaining the required sequence of encounters requires
> an improbable precision in the initial conditions.  I suppose a lower
> bound on the probability could be computed and from it an expected
> upper bound on the gravitational lifetime of the solar system could be
> obtained.

Hurray!  My Douglas Adamsian speculations were not totally hougwash :-)

More seriously, In the most recent Sci Am or Sky and Telescope 
(I was reading both last night and get confused) there is piece about
work by the group at MIT with the special purspose celestial 
mechanical computer (sorry for vagueness, but mags are at home)
concerning chaotic dynamics in the solar system.  The original work
is reported in a July issue of Science, but I missed the original.

The upshot is they simulated the solar system's dynamics for some 100
million years and made several runs after slightly (1 millimeter !)
perturbing the position of each planet.  The article showed a graph
of the expeonential (hence chaotic) divergence in the position of
Pluto for the 1 mm perturbation in Venus's position.  After 100 myear
Plutos position had changed by quite some million miles.

Hey, maybe Pluto would be better than Ceres.  Kick a periodic comet
so it ricochets of Pluto.  Pluto Ricochets off Neptune, then off Jupiter
and into the inner solar system where it becomes tame!

--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu
Newsgroups: sci.space
From: strider@clotho.acm.rpi.edu (Greg Moore)
Subject: Re: I thinI see our problem. (Was Re: Terminal Velocity of DCX? 
Organization: The Voice of Fate
Date: Thu, 24 Dec 1992 03:55:59 GMT

In article <ewright.725129915@convex.convex.com> ewright@convex.com (Edward V. Wright) writes:
>In <!jt240c@rpi.edu> strider@clotho.acm.rpi.edu (Greg Moore) writes:
>
>>	In reality it sounds more like you are talking about DC-10,
>>DC-12, etc.
>>	Unless you are saying that a 747 is the same plane as a DC-3
>>was.
>>	If your claims are about 50 years from now, or even 20
>>eyars from now, I'll buy them.  
>
>I think it would do you a world of good to go out to your local
>airport and look around.
>
	Are you stupid, or do you jsut like being argumentative?

>Do you have any idea how many DC-3s are still flying?  After 50
>years?
>
	I never claimed that DC-3's aren't flying.  What I am
claiming, is taht DC-3's aren't flying 400+ passengers on
trans-atlantic routes.  747's are.  And 747's came long
after the DC-3.
	To make it a little clearer, since you seem to want
to twist everything I say: DC-1 won't do everything.  It may
do a lot, and Joe Schmoe SpaceLines may be flying one in 2095,
but by 2095 I expect we'll have the space equilavent of the
747.

>And the 747, which you cite as an example of a modern airplane,
>is well over 20 years old!
>
	So? What's your point?

	Let me make my point clear:
"DC-1 will NOT be doing everything from satellite delivery to
satellite repair, to delivering cabbages, to lunar landing, to
fuel supplies, etc within the next 5 years. Perhaps not even
within the next 10.  But, it's follow-ons will do even more.
A DC-3 doesn't do everything. That's why we have the DC-9,
DC-10, L-1011, 747-100,200,300,400 etc."

>
From: roberts@cmr.ncsl.nist.gov (John Roberts)
Newsgroups: sci.space
Subject: Re: Aluminum as rocket fuel?
Date: 29 Dec 92 03:49:24 GMT
Article-I.D.: cs.C005BL.5D3.1
Distribution: sci
Organization: National Institute of Standards and Technology formerly National Bureau of Standards
X-Added: Forwarded by Space Digest
Original-Sender: isu@VACATION.VENARI.CS.CMU.EDU


-From: juan@hal.COM (John Thompson Reynolds)
-Subject: Aluminum as rocket fuel?
-Date: 28 Dec 92 14:36:43 GMT
-Organization: HaL Computer Systems, Inc.

(Appropriate last name for such a question. :-)  :-)

-I've seen references in the past which suggest using Lunar O2 and Aluminum
-as rocket fuels.  Have there been any fairly detailed designs of how such
-a beast would be constructed?  Perhaps a hollow cylinder of packed Aluminum
-dust into which LOX is pumped?

Here's the only fairly solid reference I've come across. If you could
contact the company and post some information, the readers of sci.space
would be very grateful.

An aluminum-oxygen engine could potentially be very useful for launch from
the moon, since both materials are abundant there (and hydrogen is at best
very rare, and therefore valuable). I expect the specific impulse isn't too
great, but you don't need a very high specific impulse to escape from the
moon.

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

>From: freed@nss.FIDONET.ORG (Bev Freed)
Newsgroups: sci.space
Subject: Toward 2001 - 02 Dec
Date: 3 Dec 91 02:05:21 GMT
Organization: The NSS BBS, Pittsburgh PA (412) 366-5208

                            ***********
                            TOWARD 2001
                            ***********
                      Week of 2 December 1991
--------------------------------------------------------------------
This information is reproduced by permission of the Space Age 
Publishing Company.  All rights reserved.  Copyright December 2, 
1991...
====================================================================
                           * * * * * * *
+ Wickman Space and Propulsion
Sacramento CA
 
Lunar soil broken down into liquid oxygen and aluminum powder powers 
a new engine being developed by Wickman engineers. A subscale engine 
has been sucessfully tested for periods of up to 35 seconds at 
varying levels of thrust.
                           * * * * * * *
--------------------------------------------------------------------

John Roberts
roberts@cmr.ncsl.nist.gov
Newsgroups: sci.space
From: games@max.u.washington.edu
Subject: Re: Lunar Resource Mapper funding.
Organization: 
Date: Thu, 24 Dec 1992 21:42:26 GMT

Well, I for one, am going to send them some of MY money.

			John.

Newsgroups: sci.space
From: pgf@srl01.cacs.usl.edu ("Phil G. Fraering")
Subject: Breeders
X-Added: Forwarded by Space Digest
Organization: [via International Space University]
Original-Sender: isu@VACATION.VENARI.CS.CMU.EDU
Distribution: sci
Date: Tue, 22 Dec 1992 02:46:14 GMT

\Session's Answer was too flipant.  The reason the U.S. doesn't hav mre
/ooops have more breeder reactors is that the anti-nuke forces won a battle
\in the late seventies and President Jimmy Carter stopped the development
/of them.  The arguements given revolved around the proliferation of 
\Plutonium that the reactors "breed" and not on the safety of the 
/reactors.  The nuke power industry was trying to sell them as the answer
\to lmited supplies of nuclear fuel (o.k. expensive supplies) because they
/produce 5 lbs of fuel for every 4 they consume.  Unfortunately, the 
\plutonium is also a great nuke weapon resource.  

From what I've heard, it's the wrong isotope or mixed with such as
to be useless in constructing a nuclear bomb.

Of course, don't let that stop you from freezing in the dark,
yankee...
-- 
Phil Fraering
"...drag them, kicking and screaming, into the Century of the Fruitbat."
<<- Terry Pratchett, _Reaper Man_
PGP key available if and when I ever get around to compiling PGP...
Newsgroups: sci.space
From: jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins)
Subject: Re: Acceleration, cats...
Organization: University of Illinois at Urbana
Distribution: sci
Date: Wed, 23 Dec 1992 18:46:54 GMT

pgf@srl03.cacs.usl.edu ("Phil G. Fraering") writes:

>Anyone here seen that special they did on TV a while back, about
>how some cats have fallen from ten or twenty stories and sometimes
>survived (don't try this at home! don't try it with a cat! and especially,
>it doesn't work well with humans!)?

>What I want to know is, how the ability to fall from 100-150 feet
>up was _selected for_ by evolution. It implies that they went through
>a period of development where cats that could do that were outcompeting
>cats that weren't, to the extent that a large number of cats today can
>do it.

>Especially since this isn't something that can be done gradually:
>the adaptations don't help in falls of 30-60 feet, or much higher than
>somewhere around 100 feet (I think)...

I'm not a biologist or even a cat owner but what the hell.  This is better than
the Terminal Velocity thread.

Two things come to mind.  First, you can't blame everything on evolution.  The
apendix comes to mind.  Some things are around simply because they weren't
selected against.

Second, cats being hunters and able to climb trees, they must have had some
way of getting down before they invented firemen.  Jumping sounds like a 
possibility.  I believe that the constraint on hights is not so much a question
of shock absorbing ability but one of coordination.  The test I believe you are
refering to was studying just why it is that "cats always land on their feet."
If you toss one of the second story window they don't have time to twist into
the right position.  A higher fall may sound more dangerous but it gives the
cat time to get into landing position.  Thus it's actually safer.

One of these days, cats will have to adapt to space so maybe there is some
value to this post.  Probably not.


-- 
Josh Hopkins                                          jbh55289@uxa.cso.uiuc.edu
                        Ho^3     !=L
From: dietz@cs.rochester.edu (Paul Dietz)
Newsgroups: sci.space
Subject: The Appendix? (Re: Acceleration, cats...)
Date: 23 Dec 92 18:55:47 GMT
Followup-To: sci.med
Distribution: sci
Organization: University of Rochester

In article <Bzq6u7.6AB@news.cso.uiuc.edu> jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes:

> Two things come to mind.  First, you can't blame everything on
> evolution.  The appendix comes to mind.  Some things are around simply
> because they weren't selected against.

Actually, I was under the impression the appendix was thought
to have some role in the immune system (say, for acting against
GI infections).  Given that appendicitis can be lethal, evolution
*should* have gotten rid of it unless it had some compensating
benefit.

(Note followup.)

	Paul F. Dietz
	dietz@cs.rochester.edu
Xref: sparky sci.space:18110 sci.astro:13384 alt.sci.planetary:433
From: dbc@ecs.soton.ac.uk (Bryan Carpenter)
Newsgroups: sci.space,sci.astro,alt.sci.planetary
Subject: Re: Galileo's Atmospheric Probe Passes Health Checks
Keywords: Galileo, Jupiter, Ames, JPL
Date: 23 Dec 92 16:10:41 GMT

In <1992Dec15.170442.1866@elroy.jpl.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes:

>...
>New York in 90 seconds.  Deceleration to about Mach 1 -- the speed
>of sound -- will take just a few minutes, causing a buildup of heat
>so intense it will be like flying through a nuclear explosion.
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>...

>     Its incandescent shock wave will be as bright as the sun and
                                          ^^^^^^^^^^^^^^^^^^^^
>reach temperatures up to 28,000 degrees Fahrenheit.  After entry,
>...

I wonder if there is any quantative meaning to these statements.
Or did someone get a bit carried away with the superlatives?

Bryan
Newsgroups: sci.space
From: 18084TM@msu.edu (Tom)
Subject: Breeder reactors
X-Added: Forwarded by Space Digest
Organization: [via International Space University]
Original-Sender: isu@VACATION.VENARI.CS.CMU.EDU
Distribution: sci
Date: Mon, 21 Dec 1992 17:32:48 GMT


Brenda asks;
>>Speaking of breeder reactors, why doesn't the U.S. have more of
>>them?

Zack sez:
>Because they're too damn dangerous.

How do you figure?  Is this just blind fear?

Three Mile Island realeased as much radiation, during it's operation
as your average American recieves in a lifetime of X-rays.  That's
a total, not a per-capita, and most of it radiated onto things that
left no damage at all, like air, or water, or asphalt, or Jane Fonda :-)

Chernobyl was simply badly designed.  In an effort to make changing
the fuel rods easier, they built the whole thing with this nifty
removable cement ceiling.  Of course, if the pressure within the
core was to get too hign for some reason...

Are these the reasons you fear the things made by humans?  You judge
by the hype and mistakes?  You must have quite contradictory feelings
about the Shuttle ;-)

-Tommy Mac
------------------------------===========================================
Tom McWilliams               |Is Faith a short '  `      '   *.;     +%
18084tm@ibm.cl.msu.edu       |cut for attaining    +    .      '
(517) 355-2178 -or- 353-2986 |  . knowledge? ;"'       ,'    .   '     .
a scrub Astronomy undergrad  |      *     ,    or is it just  .       .
at Michigan State University |   ';   '        * a short-circuit?   ,
------------------------------===========================================
Newsgroups: sci.space
From: roberts@cmr.ncsl.nist.gov (John Roberts)
Subject: Re: Acceleration, cats
X-Added: Forwarded by Space Digest
Organization: National Institute of Standards and Technology formerly National Bureau of Standards
Original-Sender: isu@VACATION.VENARI.CS.CMU.EDU
Distribution: sci
Date: Thu, 24 Dec 1992 03:39:45 GMT


-From: gbt@cray.com (Greg Titus)
-Subject: Re: Acceleration, cats...
-Date: 23 Dec 92 20:27:45 GMT
-Organization: Cray Research, Inc.

-In article <Bzq6u7.6AB@news.cso.uiuc.edu> jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes:
->pgf@srl03.cacs.usl.edu ("Phil G. Fraering") writes:
->
->>... some cats have fallen from ten or twenty stories and sometimes
->>survived ...
->
->>What I want to know is, how the ability to fall from 100-150 feet
->>up was _selected for_ by evolution. It implies that they went through
->>a period of development where cats that could do that were outcompeting
->>cats that weren't, to the extent that a large number of cats today can
->>do it.

-It turns out that cats have a particular muscular/skeletal arrangement
-they go into when they enter free fall, which is designed to maximize
-the shock absorbance of the whole cat and minimize damage to any
-particular part of it.  However, this mode does not work all the way
-up to feline terminal velocity, with the result that as fall height
-increases past 10 or 15 feet, cats experience more and more damage
-upon landing.  Above 30 or 40 feet, they are usually very badly
-injured.  However, the tensed-up shock absorbing mode does not last
-very long.  If no landing occurs, then the cat begins relaxing, with
-the result that a cat falling from 80 to 100 feet lands as a blob, and
-often has very minor injuries.

I've read that small children often survive long falls with surprisingly
little injury. It was speculated that they may be more likely to relax
than adults.

John Roberts
roberts@cmr.ncsl.nist.gov

Newsgroups: sci.space
From: strider@clotho.acm.rpi.edu (Greg Moore)
Subject: Re: Terminal Velocity of DCX? (was Re: Shuttle ...)
Organization: The Voice of Fate
Date: Tue, 22 Dec 1992 06:24:01 GMT

In article <ewright.724698268@convex.convex.com> ewright@convex.com (Edward V. Wright) writes:
>
>>The average total cost of a shuttle mission is a little over $500 million 
>>not a billion+.
>
>Only if you learned math from the "Hitchhiker's Guide."
>
	Do you think it is possible for you to reply to a person's posting
without being insulting or condescending?

>Divide the amount of money NASA spends on the Space Shuttle program
>every year by six flights per year.
>
	Right, except last year they fley 8 times.  This year they
have 7 planned.
From: 0004244402@mcimail.com (Karl Dishaw)
Newsgroups: sci.space
Subject: Aluminum as Rocket Fuel?
Date: 3 Jan 93 20:28:44 GMT
Article-I.D.: cs.C0AoxB.91z.1
Distribution: sci
Organization: [via International Space University]
X-Added: Forwarded by Space Digest
Original-Sender: isu@VACATION.VENARI.CS.CMU.EDU

>george william herbert writes:
>aluminum is the wrong fuel to use if it's an earth based application.

Most discussion has centered on an Al rocket being used for exporting 
Lunar material, probably as a second stage to a mass driver or laser 
launcher.  A mass driver would need a rocket on its payload anyway for 
orbit circularization and course corrections.  Aluminum is the most 
energetic of the common lunar materials (runner-ups Si, Ti, Fe, Mg, Ca).

>Bruce Dunn writes:
>When the
>aluminum is melted in the tank, the fuel line, valve, and injector will all
>be heated to above the melting point of aluminum.

I'd hate to see the performance hit from carrying a heater that 
powerful.  Wouldn't it make more sense to pump the aluminum onto the 
rocket as a liquid and only have a heater powerful enough to offset 
cooling?


Karl
sold my soul to Uncle Sam . . . now marked down for resale.
Organization: Queen's University at Kingston
Date: Sat, 2 Jan 1993 20:42:40 EST
From: Graydon <SAUNDRSG@QUCDN.QueensU.CA>
Newsgroups: sci.space
Subject: Re: Justification for the Space Program
 <1992Dec28.223226.12849@aio.jsc.nasa.gov>

A functioning economy (a whole one - heavy manufacturing, food growing,
service sector, the whole nine yards) on the Moon is in a what military
position with respect to the earth?

Sounds like a justification to me....

Graydon
Newsgroups: sci.space
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Saturn lift capabilities
Date: Wed, 30 Dec 1992 20:58:02 GMT
Organization: U of Toronto Zoology

In article <1hsighINNich@mirror.digex.com> prb@access.digex.com (Pat) writes:
>	Given the opinion of the science community on ASTP,
>	why didn't we have the  ASTP mission meet at Skylab? ...
>	Was skylabs orbit too low in inclination for them to hit it?

No, the inclination was pretty much compatible... but Skylab's orbit was
simply too high for a standard Soyuz to reach.  Having a Soyuz dock to
Skylab (while a US crew was there!) was one of the ideas discussed early
on in the planning for what became ASTP, but it didn't seem feasible,
for altitude and other reasons.
-- 
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  henry@zoo.toronto.edu  utzoo!henry
Newsgroups: sci.space
From: mmarolda@NeoSoft.com (Mike Marolda)
Subject: Re: Moon Dust For Sale
Organization: Neosoft Communications
Date: Thu, 31 Dec 1992 00:35:16 GMT

In article <1992Dec30.175447.5258@news.arc.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes:
>Superior Galleries in Beverly Hills, California is having an auction
>of space memorabilia on January 11, 1993.  One item of particular interest
>is a 2 inch piece of transparent tape which has some Moon dust on it.  This is
>the first time that Moon dust is being offered for sale.   The Moon dust
>was collected by a NASA technician from the spacesuit of astronaut Dave Scott
>after his Apollo 15 trip to the Moon in July, 1971.  It is guarantteed
>to be genuine by Superior Galleries and is expected to be sold
>in the price range of $75,000 to $100,000.  For more information on the
>Moon dust or the auction, you can contact Superior Galleries at
>(800) 421-0754 or (310) 203-9855.

The ironic (and sad) thing is that by bidding, one is gambling that we will
never return to the moon and that the value will increase due to the scarcity
of the product.


Mike Marolda  (mmarolda@neosoft.com)


-- 
Newsgroups: sci.space
From: strider@clotho.acm.rpi.edu (Greg Moore)
Subject: Stupid Shut Cost arguements (was Re: Terminal Velocity of DCX?
Organization: The Voice of Fate
Date: Wed, 23 Dec 1992 04:03:15 GMT

In article <1992Dec22.160715.28828@iti.org> aws@iti.org (Allen W. Sherzer) writes:
>
>This number does not include NASA overhead, amortization of the orbiter,
>amortization of Shuttle development costs, and a host of other costs. Adding
>those in puts the cost at well over a billion per flight. Hell, interest
>costs on development alone adds over a quarter billion per flight (BTW,
>this interest is not a sunk cost since it is part of the national debt and
>we are paying for it even now).
>
	I thought you said that McDac or SDIO was going to treat
development costs of DC-1 as sunk costs.  Or is that just DC-X (in
which case, what exactly does that mean?).  If this is teh case, than
you have to treat the shuttle development costs as sunk costs.
As for amortization of the orbiter, the same rule applies to that
as any aircraft or spacecraft, including, DC-1.  The more you
fly it, the less this matter.  Right now, if you stopped all flights,
you could argue this cost (excluding interest) is about $150 million
a flight. (10 flights/orbiter, $1.5 Billion per orbiter).  This
number will shrink.
	As for interest based on the national debt, that's a slippery
one what I won't touch.  One question I have though, will you treat
any government financing for DC-X,Y the same way, i.e. consider
interested on national debt?)

>  Allen
>-- 
>+---------------------------------------------------------------------------+
>| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
>|  aws@iti.org     |  nothing undone"                                       |
>+----------------------123 DAYS TO FIRST FLIGHT OF DCX----------------------+


Newsgroups: sci.space
From: Nick_Janow@mindlink.bc.ca (Nick Janow)
Subject: Re: Aluminum as rocket fuel?
Organization: MIND LINK! - British Columbia, Canada
Date: Thu, 31 Dec 1992 07:38:24 GMT

Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes:

> Using molten aluminum will give a higher Isp than aluminum metal.  Major
> problems will be pumping, and how to keep the aluminum from freezing in
> pipes and injectors when the motor is shut off.

Pumping is simple, since aluminum is highly conductive.  Just use
electromagnetic fields to thrust it through a pipe.  There's no moving parts
to worry about.  I think this is being used in sodium reactor research, so it
isn't an untested technology.

Keeping the aluminum molten should be easy too...for a rocket that only
operates in a vacuum.  Since the main reason to use aluminum/oxygen is that
it is easily available from the moon, that's not a bad limitation.

Pipes and tanks could be polished on the outside to reduce radiation loss,
and structural supports could be made of insulating materials, and heated if
necessary.  If the tanks and pipes were non-conductive (perhaps fibre
reinforced ceramics, inductive heating could heat the aluminum directly.
Actually, there's not need to get fancy: inductively heat the pipe and tank
walls, and heat the aluminum by conduction.  Of course, simple resistance
heating might be simpler and more efficient.

It sounds like a great design for a lunar "space truck", for a future lunar
colony.  :)


Now, what about the nozzle problems....

--

Nick_Janow@mindlink.bc.ca
Newsgroups: sci.space