Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V09_5/V9_539.TXT

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Subject: SPACE Digest V9 #539

SPACE Digest                                      Volume 9 : Issue 539

Today's Topics:
          Re:  Vaguely space related queries
             Re: new space goals
             Re: new space goals
               Re: SPACE Digest V9 #529
           Re: Re: Space station computers
----------------------------------------------------------------------

Date:     Mon, 3 Jul 89 14:46 EST
From: <[e-mail]>
Subject:  Re:  Vaguely space related queries

Will Martin asked several questions, which got various responses, some
of which were rather dubious attempts at physics.

>1) Regarding X-ray astronomy -- the X-ray detectors must be placed into space,
> [ stuff deleted about atmosphere X-ray absorption ]

Henry Spencer, among others, gave the correct answer.  The
atmosphere is actually opaque at all but visible wavelengths (plus a few
others).  The penetrability of ANY type of radiation has little to do
with the density of the matter by itself, but rather with ALL of the
properties of the matter, of which density is only one.

>2) Regarding elementary particles -- one of their characteristics is called
>"spin". Is this REALLY "spin" the way a top or gyroscope spins -- that is,
> [ stuff deleted about what spin is and possible changes ]

Here there was some misinformation.  Spin is NOT angular momentum!!
Rather, it is a purely quantum mechanical phenomenum (like the quantites
of colour you mention above).  People mistakenly think that it is an
angular momentum because of its mathematical properties.  In the
mathematics of quantum mechanics, spin transforms and has operators that
are identical to the normal angular momentum operator, though with its
own unique eigenvalues (values that it can take on in particular
physical situations).  It does come in a particular quantum value,
and cannot be reduced.  In fact, spin is an intrinsic feature of any
particle, just like mass and electrical charge.  You can never
change the magnitude of the spin of a particle, just its `direction'.
(Another example of using macroscopic terms for unrelated microscopic
processes.)

>3) The 11-year (or so) Solar Cycle -- I realize the duration of this cycle
> [ stuff deleted about causes of the cycle ]

My knowledge is thin here, though I do know that the physics of the
solar surface and how the surface interacts with the interior is not
known well at all.  This is due to the fact that the surface is
turbulent and chaotic, as well as the fact that all solar models are
generally spherical, with some tweaking to account for rotation.
More than this, I cannot tell you.

>4) Black hole temperature -- Are medium-sized black holes hot or cold? I have
> [ stuff deleted about black hole radiation, etc ]

Here there were a few mistaken answers.  The surface area of a black hole
is proportional to its ENTROPY, and INVERSELY proportional to its
TEMPERATURE.  Thus a small black hole is hotter than a large black hole.
In fact, small black holes can `evaporate' and disappear from the universe
because of the high rate of energy loss (that's how we define
temperature in the first place - equivalent black bodies, and so on).
If you want more information (I just ran dry), read stuff by Hawkings,
Wheeler, or Israel.  They know what they are talking about.  A good
place to look would be back issues of Scientific American.  Sorry, no
dates from me.

>5) Neutronium and similar compressed matter -- is there any theoretical
>way to keep compressed matter (the stuff that makes up white dwarfs and
>neutron stars) compressed if a chunk of it could be brought away from
>the intense gravity field of those bodies? Of would it expand
>uncontrollably as the piece moves into regions of lower gravity? If it
>could be kept compressed, what would it look like? I envision it as
>looking something like lead, but that is just some sort of unreasoning
>gut feel, not based on science. Would it actually be a perfect mirror?
>If you touched this stuff, what would it feel like? I have an idea that
>wouldn't be wise, but I'm not sure just what would happen to your finger...
>Would it be a perfect conductor of heat and electricity, or a perfect
>insulator? [I lean toward the latter -- electrons couldn't migrate
>through it...]

Neutronium is the popular name given to the neutron matter state as
present in the cores of neutron stars (NOT white dwarfs - they are a
mixture of electrons, protons, and heavier elements!).  It is produced
by the intense gravitational pressures, exerts a force that stops the
neutron star from collapsing, and is extremely relativistic.
This matter cannot exist outside of the neutron stars, unless something
else can be found to hold it together (something with, say, a pressure of
10^20 atmospheres or so - being off a few orders of magnitude here
doesn't mean very much).

It actually turns out that neutron matter is a superconductor.  As
evidence for this, consider pulsars.  These are neutron stars with
high magnetic fields that are corotating with the star.  In other
words, the magnetic field and the matter are `frozen' together.  In
MHD (MagnetoHydroDynamic) theory, this means that the conductivity has
gone off to infinity.  In quantum theory, the neutron energy states are
all filled up, but the electron ones are empty, so that an electron can
do whatever it wants within the neutron matter.  In terms of heat
conduction, I would say that pure neutronium cannot conduct heat well for
the same reason - all of the neutron energy states are filled.  However,
I may be wrong on this last point.

Arnold Gill
Queen's University at Kingston
BITNET:  gill@qucdnast

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

Date: 3 Jul 89 17:08:00 GMT
From: apollo![e-mail]  (Steve Rehrauer)
Subject: Re: new space goals

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>... and Mars is not
>much harder than the Moon.  In some ways it's easier, because we have
>Phobos and Deimos as potential resources, and the Martian surface has
>useful supplies of things like water.
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Certainly not trying to dispute that, just curious: Have readily-accessible
sources of water on Mars been identified, or do you mean that, given the
presense in whatever amounts & form, accessing it is just a question of
engineering?  My impression from the most recent stuff I've read on the
subject was that there was conflicting data (or at least, conflicting
interpretations of it :).
--
>>> "Aaiiyeeeee!  Death from above!" <<<  | Steve Rehrauer
    Fone: [phone] x6168             | Apollo Computer, Inc.
    ARPA: [e-mail]             | (A subsidiary of Hewlett-Packard)
"Look, Max: 'Pressurized cheese in a can'.  Even _WE_ wouldn't eat that!"

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

Date: 3 Jul 89 21:26:15 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: new space goals

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Tom Neff) writes:
>>                                                           Mars is such
>>a mammoth project (much harder than the Moon)...
>
>Uh, why is it much harder?  Remember, going from Sputnik to Tranquillity
>required developing a lot of new technologies.  I see no comparable
>requirement for Mars orbit+surface bases.  ... [Improved technology]
>would be useful, but basically we have the technology we need.  The greater
>distances to Mars simply require bigger vehicles (for larger crews and
>more supplies); otherwise distance is just waiting time, and Mars is not
>much harder than the Moon.

Going to Tranquillity required that we invent manned spaceflight from
scratch and develop a bunch of new technologies.  We have what we need
to GET TO Mars, and back, safely, in a sort of Apollo Mark II.

What we do not have, and ain't even close to having, is the ability to
go there and stay.  To build anything there that would last.  We know
how to raid space like Leif Ericsson, now we must learn to build an
outpost there like Robinson Crusoe.

We could also do this on the moon, but Mars is sexier and has more to
teach us I believe.  And as Henry has pointed out, it's not that much
farther up the gravity well.

>                In some ways it's easier, because we have
>Phobos and Deimos as potential resources, and the Martian surface has
>useful supplies of things like water.

And you wanted to know what new technology we'd have to develop??  Be
honest, wonderful ANALOG fodder though it makes, nobody has ever run
anything industrial off Earth for any length of time.  It's hard enough
keeping a materials processing plant running right down here.  We'll
certainly do it some day, but not until humans have had the opportunity
to kick around on-site for a while and play with things.  To do that we
have to get them there, with Earth materials.

>We also have the immense advantage of the beginnings of a private space
>launch industry.  The clear number one problem for a major Mars effort
>is the high cost of launch to low Earth orbit.  The way to fix that is
>to say, *believably*, "starting in 1995, we will buy one million pounds
>a year of freight capacity to low orbit from the lowest qualified bidders,
>price not to exceed $500/lb, tested hardware required; development funding
>must be private, the Mars project will provide none".

Perilously close to special pleading here.  Henry is a Usenet treasure,
but David Copperfield's Mr. Dick was beloved too, and he couldn't seem
to keep King Charles's head from popping up in everything he did... :-)

We don't need commercial megaboosters to go to Mars.  We do need USG to
get out of the comsat business BY LAW and get back to exploring,
experimenting and blowing up Ivan like it's supposed to.  (My primary
objection to SDI is that it doesn't kill anybody.**  We pay these guys
to kill people, not build Maginot Modules.  Back to work sojer!)
Reaffirm the original NASA charter and insist it get back in the
business of exploring the solar system -- not trying to make a buck off
it or "establishing presence" or other Zen nonsense -- and you'll see
some action.

>                            General Dynamics,
>Martin Marietta, McDonnell Douglas, Arianespace, etc., will scream bloody
>murder, hire lobbyists, and start talking excitedly to Congressthings,
>because they simply can't do it.

Precisely the kind of catfight that kills missions.  QED.

>And cheap transport to low orbit makes the whole thing much easier and
>much less demanding, because it's no longer necessary to pare every gram
>off the project's hardware.

Paring grams off the hardware is where you learn.  Weight exigencies
are the soul of spinoff.  The trick is to structure the mission so that
staying there is something you DON'T give up.  Better to live three
years in a Mylar bubble than three nights in titanium.**

>>What we can do in 10 years simply doesn't last.  What we can do in 50
>>might.  I want to follow the Antarctica model - establish an
>>international scientific outpost in a distant, hostile environment.
>
>Why can't we get the hardware in place for that in 10 years?

Our track record supports my assertion better than your objection, I
think.  We can't get that hardware ready in 10 years because we can't do
ANYTHING in 10 years anymore.  The can-do technocracy that gave us
Vietnam and Apollo is ancient history.  It's suicidally futile to
predicate a Mars mission on JFK rising Arthur-like from the grave.  We
have to design something around the do-able.  While we don't have
Sputnik or Camelot to lean on anymore, we do have new dynamics like
international cooperation, plus the huge quantum leap in one fundamental
ability: to send back killer images from anywhere we visit.  Neptune
about to provide a fresh example it appears.  The early Moon race had
the support of the nation even though most Americans only "saw" it through
paragraphs in the newspaper.  What could Ogilvy & Mather do with the
Viking stuff and the JPL Mars Movie?  But I digress.

>                    [Apollo] developed -- but was
>never allowed to *use* -- most of the hardware needed for more permanent
>follow-ons.

It would be more accurate to say that some NASA and contractor groups
designed, but were not allowed to build or fly, follow-ons.  If Henry or
anyone else is aware of built, unflown hardware besides CSMs, LMs and
Saturn hardware, I would like to hear about it.

>        (Anyone who claims that Apollo was always meant to be a
>one-shot has never seen some of the work Apollo did on follow-ons to the
>early missions.  Apollo was strangled in infancy.)

I guess that depends on who is doing the "meaning."  Certainly by the
time the White House gave Lunar Orbit Rendezvous (LOR) the nod as the
mission strategy that would beat the Soviets and the JFK deadline
without busting the budget, things were "meant" to go pretty much as
they did.  No doubt there was a constituency within NASA for ambitious
followups, but the program as pitched, designed and built logically
culminated at Taurus Littrow.  (18 would have been nice, but not
revolutionary.)

Apollo was not strangled at birth, it was conceived in haste and
repented at leisure.**

>>By drawing the program out timewise, you provide an ongoing focus of
>>activity that *defines* a half century of endeavor...
>
>You also tell everyone involved with it now that they will be old or dead
>before they see results.

Old yes, dead maybe, proud definitely.  It also means your kids would
be doing something meaningful in space, which is more than we can tell
the men who built Apollo.

Also keep in mind it wouldn't be 50 years of silent drudgery capped by a
sudden extravaganza.  There would be intermediate projects of great
satisfaction.  A lovely Space Station (Prometheus!  Down with jingoism)
with an actual well-I'll-be-damned MISSION would be nice within Henry's
10 year time frame.  And since we can in fact place hardware out at Mars
quicker than 50 years, another intermediate goal is Phobos Station.  The
perfect observatory and it solves some of the problems with a free
floater, while yielding a scientific bonanza beyond comprehension if you
can actually bunk exogeologists on it.  All this without the fatal extra
gravity well to deal with.

>                            ... set your sights higher.  Mars is not that
>hard.

Prove it!  Let's go there and prove me wrong!

Mars is too easy?  Nice problem to have!**

>(The folks at Spar Aerospace are fond of pointing out that the question
>of who would build the arm finally came down to Canada vs. an unnamed US
>company.  Canada won.  The US company [Spar refuses to identify them!]
>went after, and got, the contract to build... the shuttle toilet.)

This is just the kind of thing that happens when you evaluate bids
by a process of elimination.  :-)

>>Let's see... Glavkosmos is to spaceflight as the USSR is to vodka?**  :-)

--

NOTE: Aphorisms marked ** are approved for use in .signatures, with
credit given of course! :-)

--
"My God, Thiokol, when do you     \\    Tom Neff
want me to launch -- next April?"  \\    uunet!bfmny0!tneff

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

Date: 4 Jul 89 00:49:51 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: SPACE Digest V9 #529

In article <[e-mail]> [e-mail] writes:
[about recovering LDEF, which I pointed out is an SDI fetish just now]
>True, but the information on the effects of long term exposure of
>electronics and materials to LEO are going to be very useful to other
>people as well ...
>      ... Assuming the data doesn't get classified.

A very nice assumption indeed.

If the data prove meaningful to SDI, look for a push to classify it.
Musn't threathen the vital potency of our precious Peace Shield.

I do hope I'm wrong though, it would be nice to have some public domain
data on how materials fare up there.
--
"My God, Thiokol, when do you     \\    Tom Neff
want me to launch -- next April?"  \\    uunet!bfmny0!tneff

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

Date: 4 Jul 89 04:52:55 GMT
From: shelby!portia![e-mail]  (Michael Brooks)
Subject: Re: Re: Space station computers

In <[e-mail]> (Bob Myers) writes:

>"He`s talking about LCDs and other flat-panel technologies." Persons
>asking such questions are invited to study LCD manufacturing
>technology...

 The basic idea was that LCD development is not at a stage now, nor
will it be likely available in 1998  for computer displays (sorry
Bob, I may have the exact quote wrong).

Well, this might be unfortunately true.  Before I went back to school (don`t
ask me why!) I helped build mil-spec developmental devices of this sort
for Hughes Aircraft.  These were designed to function as sources for
the Advanced Tactical Fighter`s headsup display, as well as to be
retrofitted into the newer aircraft.  Well, last time I checked the
project was lamely continuing, with only lukewarm top level support.
This is not because the folks doing it are incompetant---far from.

It`s because LCDs are tough to build for a high reliability environment,
and the best of these are coming from those who invest heavily in the
technology and its applied science.  Seiko Epson is currently building
acceptable commercial displays of small size (as are other Japanese
manufacturers).  I am happily employed part-time at Lawrence Livermore
National Labs, where I am part of a group trying to employ some novel
technology to get a new start in this area that Americans seem to have
given up on.  The optimistic forcast by S. Morozumi (head of the
Seiko Group) is to have is to have LCDs for HDTV in the mid-late `90s.
Unrealistic?  Don`t bet against the Japanese in this.  You can
probably bet against a US sponsored effort and make money.  IF such
displays do become available, they will probably be commercial and
not mil-spec`d (let alone space-spec`d), unless we license the
technology (from the Japanese) and build an appropriate version.

The sad part is that we here in the US will not likely build them for sale,
within the time frame mentioned, on our own.  They could conceivably
be built, but only by those who want them (perhaps exclusively for
mil-spec systems).  In the race for LCD technology we are far
behind, like that of other electronics items (256K DRAMS).

(maybe there`s hope, I could be wrong again! :-))
Mike Brooks/Stanford Electronics Labs/SU

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

End of SPACE Digest V9 #539
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