Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V09_2/V9_260.TXT

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Subject: SPACE Digest V9 #260

SPACE Digest                                      Volume 9 : Issue 260

Today's Topics:
               Re: the un/manned debate
              centrifugal forces
            Re: centrifugal forces
              Re: Re: Heavy Lift Vehicle
             Re: Space Resources
           Re: What ever happened to NERVA?
              Re: 1992 moon base
           Re: Manned vs unmanned space exploration
              Re: 1992 moon base
             Re: Synthetic Aperture Radar
----------------------------------------------------------------------

Date: 21 Feb 89 12:04:36 GMT
From: cs.utexas.edu!sm.unisys.com!csun!polyslo![e-mail]  (Dr. Dereference)
Subject: Re: the un/manned debate

I'd like to make one thing clear to those who are critisizing manned space R&D.
I am defending manned space R&D in general. I agree that NASA's program has
many problems, but by pointing those problems out you only attack the current
research program, not the importance of manned space R&D in general. Criticism
should be directed at that program, not the entire field of research.

In article <[e-mail]> [e-mail] (Nick Szabo) writes:
>John McKernan writes:
>>The basic premise in my posting is that manned space research is basic R&D.
>Then it should be funded as R&D, through the peer review of scientists.
>The manned program is not R&D.

Peer review applies to experiments, not entire fields of study. Peer review for
specific experiments in manned space is a good idea.
It is ridiculous to say that the entire field of manned space R&D is not R&D.
What do you think it is Nick? Please note that I am refering to manned R&D in
general, not NASA's current program.

>>It is wrong to try to catagorize some types of basic R&D as more important
>>than others.
>Then, how, pray tell, do you decide where to spend finite budgets?

The number of general fields where R&D is important (i.e. physics, chemistry,
superconductors, manned space, etc.) is fairly small. Less than 1% of GNP is
spent on this kind of R&D anyway, and because of its importance to the future
a minimum amount must be spent in each area.

>>That means that economic return on investment does not apply.
>The return in scientific knowledge, related to the dollars spent, most
>definitely *does* matter; this is the purpose of R&D.

The return from a specific experiment is what matters. You cannot attack an
entire catagory of R&D, only specific experiments.

>>Nick and Paul do state that it is unimportant now. This
>>is wrong because knowledge gained from basic R&D is valuble regardless (within
>>reason) of when it is learned.
>When is very important, if it means one has to spend billions of dollars
>on information that can be gained for much less in the future

As technology advances, the cost of a particular level of R&D decreases
continuously. But of course you do the R&D that can be financed now, otherwise
you wait forever. Do you think we should stop building particle accelerators
until room temperature superconducting wire costs 10 cents a meter?

>>Paul says that manned space won't be important for 40 years. I
>>don't think it's possible to predict technological advance with any accuracy
>>beyond 25 years, if that.
>The *time* is uncertain, but what we will need when we get there is pretty
>straightforward.  Our most expensive and essential need in space will be
>a large mining and industrial infrastructure to produce our air, water,
>food, structural materials, machines, etc. from the resources in space.
>To create this we must (1) discover the resources with an exhaustive search
>over a wide area of the solar system and (2) create the technology
>to process these materials in an environment of vacuum, low gravity and
>high labor cost.
>Unmanned exploration and basic R&D provide the two essential components.

While it is natural that R&D in one area is valuable in another, manned space
R&D (as I understand the term) is distinct from unmanned. Unmanned R&D will
not tell us everything we need to know to settle the solar system. One example
is your point (2) above. Mining and the construction of a residential and
industrial infrastructure are essentially manned activities. While it might be
possible to do these things entirely with robots, since the idea is to move
people into space such an extreme level of automation is not necessary.

>>I personally believe that manned space R&D should focus on reducing manned
>>launch costs before doing anything else.
>Launch costs are an important problem.  The problem of reducing manned and
>unmanned launch costs is similar; breakthroughs in the latter are usually
>breakthroughs in the former.

While both benefit from increased launch capabilities, manned space needs
inexpensive access to space for large amounts of mass much more than unmanned.
You can't miniaturize people. The focus of unmanned space today is launching
probes with the launchers we have now, not building new launchers.

John L. McKernan.                    Student, Computer Science, Cal Poly S.L.O.
-------------------------------------------------------------------------------
.signature currently under government sponsored basic research. Results
guaranteed to advance science, satisfy every special interest group, generate
2000 times the wealth expended, and show up the Russians expected REAL SOON NOW.

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

Date:         Tue, 21 Feb 89 17:05:02 EST
From: Eric Harnden <[e-mail]>
Subject:      centrifugal forces

     I'm not entirely sure that this is the place to be asking this
question, but I'm not subscribed to any other list that has engineers and
physicists around, so here it is, dumb though it may be..
     In short: does centrifugal force operate on a body inside of, but not
touching, a spinning, evacuated cylinder?
     Long form: I was re-reading 'Rendezvous With Rama', by Clarke. There is
a sequence in the book where a small bicycle-driven aeroplane flies down the
axis of Rama, a sixteen- by fifty-kilometer atmosphere-filled cylinder that
spins to provide artificial gravity. There is a warning at some point to
'not get too low' (far away from the axis), because then the gravity induced
by the centrifuge would become too great for the smaller craft to maneuver
effectively in. Now, this confused me. The only reason that I can think that
this would be so is that there is an atmosphere which is being centrifuged,
and that its' action will be transferred to the plane. If the cylinder were
evacuated, and the plane were not in physical contact with it, then would it
actually be sharing the cylinder's inertial frame of reference? The cylinder
would not actually be exerting any constraints on the plane's motion. This
also sort of brings up a more general question: does the whole idea of
artificial gravity via spinning require friction, or some other kind of force
transfer/constraint mechanism, in order to operate?

Eric Harnden (Ronin)

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

Date: 22 Feb 89 02:20:29 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: centrifugal forces

In article <Added.IY0SIUy00Ui34G=[e-mail]> [e-mail] (Eric Harnden) writes:
>     In short: does centrifugal force operate on a body inside of, but not
>touching, a spinning, evacuated cylinder?

Is the body moving in a circle around the cylinder's axis, as it would be
if it were part of the cylinder?  If so, yes.  If not, no.

>     Long form: I was re-reading 'Rendezvous With Rama', by Clarke. There is
>a sequence in the book where a small bicycle-driven aeroplane flies down the
>axis of Rama, a sixteen- by fifty-kilometer atmosphere-filled cylinder that
>spins to provide artificial gravity. There is a warning at some point to
>'not get too low' (far away from the axis), because then the gravity induced
>by the centrifuge would become too great for the smaller craft to maneuver
>effectively in. Now, this confused me. The only reason that I can think that
>this would be so is that there is an atmosphere which is being centrifuged,
>and that its' action will be transferred to the plane...

Precisely.  The atmosphere will be rotating with the cylinder, so an object
more or less at rest with respect to the atmosphere (i.e. moving slowly in
it) will share the cylinder's rotation.

>... This
>also sort of brings up a more general question: does the whole idea of
>artificial gravity via spinning require friction, or some other kind of force
>transfer/constraint mechanism, in order to operate?

Yes:  how else to constrain the object to move in a circle?
--
The Earth is our mother;       |     Henry Spencer at U of Toronto Zoology
our nine months are up.        | uunet!attcan!utzoo!henry [e-mail]

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

Date:    Fri, 17 Feb 89 15:48:52 PST
From: [e-mail]
Subject: Re: Re: Heavy Lift Vehicle
X-St-Vmsmail-To: JPLLSI::"[e-mail]"

>the entire SATURN 5 system (airframe, tanks, plumbing, electrical and the
>mighty F1's) COULD BE duplicated using the existing display units as models.
>
> Look for the startup costs to be just over $1 million. With the cost of
>finished S5-clones to run $800K per copy for the first 20, cheaper from
>20-50 (maybe a 10% cost roll-off), and cheaper yet from 50-100.
>
> ..anybody interested in starting a company? Got a "few" bucks and a little
>vision?  Rockwell just retired a bunch of Apollo-era M.E.s...and most of them
>are just sitting around bored with their retirements!
>--
>-Avatar-> (aka: Erik K. Sorgatz) KB6LUY           +-------------------------+

A MEASLEY MEGABUCK!?  I'd like to see 'em put THAT in those Publisher's
Clearing House Sweepstakes ads, right next to the luxury yacht and the
Rolls-Royce..."Ever dreamed of owning your own space ship?  Then enter
today!"...Yeah, sounds great!

But seriously, that's only thousand bucks from a thousand investors, or
10,000 from 100, or whatever.  If this is true, it'd be a crime to let it
go undone.  Let's do it!

----
"Pave Paradise,                |         Dale M. Greer
     put up a parking lot."        |   Center for Space Sciences
        -- Joni Mitchell    | University of Texas at Dallas
                    | UTSPAN::UTADNX::UTD750::GREER

The opinions are my own, and may or may not reflect those of my employer.

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

Date: Tue, 21 Feb 89  17:17:13 EST
From: [e-mail]
      (Chip [e-mail])
Subject: Re: Space Resources

Uh..

From: cs.utexas.edu!sm.unisys.com!csun!polyslo![e-mail]
 (THE VIKING)

>I personally believe that manned space R&D should focus on reducing manned
>launch costs before doing anything else. I believe in this sense that virtually
>everybody in this group supports somekind of manned space R&D, with the
>exception of fanatics like Chip Olsen who don't support any R&D unless it is in
>their area of concern (ecology in Chip's case).

Ok, after rereading my article and the responses to it, I suppose I came
across as rather anti-space.  I strongly support manned and unmanned space
R&D, as long as it's done with some responsibility and with priorities
clearly set (and as long as those priorities are ones I agree with ;-) ).
Capture and mining of asteroids, settlement and exploitation of the moon
and Mars etc, deep-space probes like Voyager and Galileo, and the Hubble
Space Telescope are all things worth doing; the potential scientific and
material benefits to humanity far outweigh the costs.  It's all a question
of balance.

@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*@#$%&*
(    )  Chip Olson, 808-B McNamara, UMass, Amherst, MA 01003 [phone].
:\^^/:   "Why be difficult when with a bit of effort you can be impossible?"
(@::@)  Bitnet:     [e-mail]
 \\//   Internet:   [e-mail]
 (oo)   UUCP:       {blah!blah!blah}!mit-eddie![e-mail]
  ""

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

Date: 22 Feb 89 02:13:05 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: What ever happened to NERVA?

In article <[e-mail]> [e-mail] writes:
>I know for sure that prototypes of NERVA and Phoebus-2A were built and
>ground-tested, even if they were never flown. I wish I could know : why
>were these projects dropped ( I think they were, because I had never
>heard about them before ) ?  Was it because of technical difficulties,
>safety concerns, financial illness, political issues ( e.g. space-based
>nuclear weapons prhibition treaty ) ?  Or what else ?  ...

They were dropped because there was no mission for them, hence no reason
to continue spending money on them.  The missions, of course, had all
been cancelled or deferred in the previous rounds of budget cutting.
--
The Earth is our mother;       |     Henry Spencer at U of Toronto Zoology
our nine months are up.        | uunet!attcan!utzoo!henry [e-mail]

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

Date: 22 Feb 89 02:16:36 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!sq![e-mail]  (Mark Brader)
Subject: Re: 1992 moon base

> ... Sunlight on the moon is more
> reliable than on the earth, because the absence of atmospheric
> interference means the collectors get a full ~1450 W/m^2 whenever they
> face the sun perpendicularly. However, the long lunar night
> necessitates some form of power storage, building multiple collector
> arrays around the moon along with a large power grid, or orbiting
> arrays. ... A small nuke plant looks like a necessary starting seed.

I can think of one other option.  What about locating the first colony
precisely at one of the lunar poles?  There, the sun is always skimming
the horizon, but it's shining all the time... 655.7 hours per day!
And there's no problem of atmospheric attenuation is there is at the
poles of Earth.

To be exact, this is only true if the local horizon is truly level, or
if you build your solar collector on a sufficiently tall tower.  I don't
know how level the lunar terrain is in the polar areas, but if the pole
itself is unsuitable because of high ground, then the top of that high
ground itself might be suitable.

Note that no matter where you build your collector you want to pivot it
to follow the sun; at the pole it just happens that that pivoting is around
a vertical axis.  This might even make it easier; you don't have to worry
about the wind loading on the structure and can balance it on edge nicely.

Another advantage of a polar location is that it could both be in regular
contact with Earth, without needing in-space support, and yet be well
placed for visits to a part of the far side.  Hmm, I like this idea!
Anyone got a way to shoot it down?


Mark Brader, Toronto    "If the standard says that [things] depend on the
utzoo!sq!msb         phase of the moon, the programmer should be prepared
[e-mail]         to look out the window as necessary."  -- Chris Torek

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

Date: 21 Feb 89 12:39:57 GMT
From: cs.utexas.edu!sm.unisys.com!csun!polyslo![e-mail]  (Dr. Dereference)
Subject: Re: Manned vs unmanned space exploration

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (John McKernan) writes:
>>...I do believe that the space station is a mistake at this time. In fact I
>>agree with Henry Spencer that it would be best if we simply disbanded NASA
>>(with the exception of JPL) and turned it over to private industry with a
>>policy of payment on orbital delivery only...
>
>Unfortunately, this badly misrepresents my views:  I do not favor disbanding
>NASA or splitting it into pieces, although others have expressed that view.

I'm sorry, my statement was more extreme than I really intended. It was based
on Henry's statement that NASA should get out of the launch business entirely,
and turn it over to private industry on a payment after delivery to orbit
basis. I can't reference Henry's posting on that subject directly, it has
expired at my site. It's interesting to think about how little of NASA would
be left if all launch activities, the unmanned space program, and the space
station were removed. In my opinion the station is premature at current launch
costs, and I know some of Henry's postings have been critical of it, though I
can't say for sure whether he supports building the station now or not.

I do believe that at this time government is the only practical source of
funding for a robust manned space R&D program. So maybe reforming NASA is the
best solution, but NASA has gotten so bureaucratic that it would be difficult.

John L. McKernan.                    Student, Computer Science, Cal Poly S.L.O.
-------------------------------------------------------------------------------
.signature currently under government sponsored basic research. Results
guaranteed to advance science, satisfy every special interest group, generate
2000 times the wealth expended, and show up the Russians expected REAL SOON NOW.

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

Date: 20 Feb 89 18:30:10 GMT
From: phoenix![e-mail]  (Keith P. Mancus)
Subject: Re: 1992 moon base

>
>While earth-operated rovers may be slower, they could be operated around
>the clock (at least during the lunar day).  Earth-bound operators would be
>many times less expensive than lunar colonists.


    I fail to see why rovers couldn't be operated around the clock,
period.  Putting searchlights on them is no big deal.

--
------------------------------------------------------------------
-Keith Mancus <[e-mail]>  <- preferred
              <[e-mail]>

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

Date: 21 Feb 89 22:06:26 GMT
From: att!cbnewsl![e-mail]  (Stuart Warmink)
Subject: Re: Synthetic Aperture Radar

In article <[e-mail]> [e-mail] (Joe Dellinger) writes:
>
>    The question is, is there some way to CHEAPLY measure such
>ground motions (on the order of a meter or two) from space?

The measurements can also be performed the other way round: the reflector is already
in orbit around the Earth. A solid sphere of copper or so, covered with corner cube
reflectors for bouncing back a laserbeam. It is in a reasonably high orbit so as not
to be affected by air resistance too much, but being small and heavy that isn't a
big problem anyway.
It is especially usufull for comparative measurements, for instance continental drift.
I can't remember the name of the satellite, but I seem to remember that it has been
up there for many years now. Sorry about being so vague...

This puts the measurement equipment on the ground, which for one thing will make
it easier to maintain!  ;-)

--
------------------------------------------------------------------------------
"PENTAGON OFFICIALS ARE CONCERNED ABOUT  |  Stuart Warmink, Whippany, NJ, USA
AN ANTIMATTER SHORTAGE"  ("WHAT'S NEW")  |  att!groucho!sw, [e-mail]
-----------> My opinions are not necessarily those of my employer <-----------

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

End of SPACE Digest V9 #260
*******************