Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V08/V8_352.TXT

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Date: Wed, 7 Sep 88 01:07:09 PDT
From: Ted Anderson <[e-mail]>
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Subject: SPACE Digest V8 #352

SPACE Digest                                      Volume 8 : Issue 352

Today's Topics:
                  plutonium
          RE: space exploitation/exploration
               Aerospikes/plug nozzles
               Space Station Future???
              Re: Why no aliens
              moon buggy as robot rover
                SKYLAB
                 yay!
              Re: Transmutation
                Re: Aegis, SDI
          Re: space exploitation/exploration
----------------------------------------------------------------------

Date:     Thu, 25 Aug 88  13:09:44 EDT
From: =3545*** <[e-mail]>
Subject:  plutonium

Someone wrote in suggesting that we dump plutonium into the sun and kill
two birds with one stone: getting dangerously radioactive stuff off of the Earth
and also once the plutonium was in the sun it would be ionized and therefore
be detected by an alien race (if they are equipped with a damn good s[ppectro-
meter).

I see two problems: one is that you'd have to decelarate your load of Pt by
the orbital speed of the Earth to have it drop into the sun, and that speed
is 18.5 miles per second, which is as far as I know a damn sight faster than
we can go right now. The second problem is that to be seen as an emission
line from several light years away you'd have to dump a lot (A LOT!!) of
the stuff into the sun. I haven't actually done the calculation (line
intensities are difficult to get) but I would think you're talking about
billions if not trillions of tons of plutonium.

If someone out there can do this calculation, I'd love to see it. I don't
trust my numbers all that well.  But I'm pretty sure we don't have enough plut
onium on the planet to be seen.
\
{Phil Plait/[e-mail]/UVa Astronomy Dept.}

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

Date: 25 Aug 88 15:11:00 GMT
From: apollo![e-mail]  (Peter Nelson)
Subject: RE: space exploitation/exploration


  from the mailbag today:

>   The libertarians are perfectly willing to put in their money if the government
> would let them.

   ...This in reference to my statements about building a colony in space.

 1.  What makes you think there are enough Libertarians in the whole
     country to come up with the kind of money it would take to put up
     a space-colony?  If there were a million Libertarians in the country
     and they *all* agreed that this was a worthwhile venture and they
     *all* agreed to put up a thousand dollars a year, this would only
     come to a paltry billion dollars, hardly adequate for the scale of
     the task.

     You need to interest serious investors and this requires a business
     plan and I don't see any serius motion in that direction.


 2.  How is the government stopping you?  Because they have a lock on the
     launch facilities?   It will be YEARS before you will need any launch
     facilities!!  If you want to have a self-sustaining colony in space
     there is an enormous amount of technology and science to be developed
     first.  How about experimenting with closed ecosystems?  I only know
     one major project about to startup for this and it only involves life-
     support for 8 people.   The government isn't stopping the Libertarians
     from doing this research on a larger scale.  It's not stopping them from
     developing the technology for hollowing out asteroids.  It's not stopping
     them from breeding special varieties of plants adapted for growth in
     space-colony conditions.  It's not stopping you from doing the engineering
     designs for the system.

     Talk, as I said before, is cheap.  So are excuses.

                                               --Peter Nelson

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

Date:     25-AUG-1988 14:32:27 GMT
From: [e-mail]
Subject:  Aerospikes/plug nozzles

>
> What is an aerospike?  What is meant by its being (or not being)
> "plugged"?
>

 The business end of a conventional rocket engine is a bell shaped nozzle. This
has some disadvantages, among which are the fact that (for best efficiency) it
should be narrow in dense atmosphere and wide in vacuum, and you can't
re-enter with it pointing forward because it won't be there when you've landed.
 Some company (can't remember which) started experimenting with ways round
this, and came up with the idea of turning the nozzle inside out, so you have
a thing shaped [ ABS(COS(X)), X=0,PI ] (ha! that solves the problem of no
graphics!) with a ring of fuel injectors round it. In atmosphere, the air
acts as the 'other side' of the pseudo-nozzle, making it narrow. In vacuum,
it's infinitely large.
 You still can't re-enter with this thing, but if you cut most of the spike off
to leave a thing shaped like [ MAX(.5,ABS(COS(X))), X=0,PI ] and then blow
a small jet of gas down through some holes in the flat bit, which is now
called a "plug", you can create a spike, hence "aerospike". If the plug is
made of suitably solid material, or covered with replaceable ablator, you can
use it as a heat-shield when you re-enter. It's also lighter than a spike.
 If you keep a small reserve of fuel on board, you can re-ignite your engine
and slow the craft down enough to soft-land without a parachute (a la LEM
descent stage). Because the engine is efficient you now have a small, 100%
re-usable VTOL spacecraft.
 That company made some research models in 1966, and declared the whole thing
viable. A man called Gary Hudson designed an aerospike-driven craft called
PHOENIX (presumably cos it lands in flames, then can be refueled and take off
from its own ashes) for which he needed $300M development. Nobody took it
on, so he set up the Pacific American Corporation, and started building
conventional engines to raise the money for PHOENIX. You may have heard of the
LIBERTY booster, which has just got a demonstration contract from the SDIO.
They're already bending metal for it, so hopefully it won't be too many years
before PHOENIX rises.
 For a better description of aerospikes, read Bono & Gatland's "Frontiers of
Space".

* Mike Salmon,                    Phone [phone] x2875      Time GMT+1   *
* Climatic Research Unit,         JANET [e-mail]865       BIX msalmon *
* University of East Anglia,     BITNET [e-mail]                 *
* Norwich, Norfolk,                ARPA [e-mail] *
* United Kingdom              Elsewhere [e-mail]         *
*  -  -  -  -  "How far can you comfortably spit a mail gateway?" -  -  -  -  *

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

Date:    Thu, 25 Aug 88 13:26:24 PDT
From: [e-mail] (Gary Palmer)
Subject: Space Station Future???
X-St-Vmsmail-To: SPACE,PALMER


I am considering applying for work at one of the contractors working
on the space station.  My specialty is Human Factors in computer
software design.  I have recognized a lack of information while trying
to determine how current politics and the elections will effect the
future of this project.

What I have found so far is the both Bush and Duke claim they will
keep the program at some level, but they don't say where cuts will
occur. One source tells me that they will eliminate the idea of it
being a constantly manned station.  This would increase the need for
powerful (I hate saying intelligent) computer control, which increases
the need for a highly functional interface etc...

If anyone out there has heard, or knows, anything about the future of
the space station please let me know.  If this is the wrong forum, I
appologize and need to be directed to the correct one.  I will be most
happy to summarize and post the results.

PLEASE send responses to me directly, do not burden the net.

Thankyou,
Gary Palmer
Science Applications International Corp.
[phone]
SPAN:     hbva::palmer
INTERNET: [e-mail]

Any necessary disclaimers apply!

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

Date:     MON AUG 29, 1988 10.30.15 EST
From: "Richard Mauren -  RAM9" <[e-mail]>
Subject:  Re: Why no aliens
To: "Richard Mauren" <[e-mail]>

     The reason for us not having had extraterrestial contact may be
simply that it is too dangerous.  Assuming that there is no feasible
reliable shield against nuclear devices(even if it got most of them the
radioactivity would be fierce) no "intelligent" intelligent life would
risk it.  Say beyond all hope--etc, there is life on mars.  They would
be stupid to contact us because it would be so easy for us to
annihilate the planet with nukes.

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

Date:     29-AUG-1988 11:51:20.85
From: [e-mail]
Subject:     moon buggy as robot rover
Reply-To: [e-mail]
Vaxnotes_Export:     MESCAL

I have a question concerning what seems to have been a missed opportunity in
the Apollo program.  The "moon buggy" lunar rover vehicle used on the last
few Apollo flights was, as I recall, used to take those nice videos of the
lunar module liftoffs.  Further, the camera was controlled from the ground
(I remember discussions of the fact that, when tracking the rising LM, the
earth-bound operator had to anticipate the camera motion to account for the
propogation delay).  These facts seem to imply that (a) there was a direct
video downlink from the rover to earth and (b) there was at least some kind
of data uplink for the camera controls.  Given this, it would seem that it
would have been a small matter to also permit ground control of the rover
itself.  This would have permitted the abandoned rover to be sent out on a
one-way camera safari over the hills and far away.

Why wasn't this done?  I can think of several possible reasons:
1) Nobody thought of it (hard to believe).
2) There wouldn't have been enough battery power left to get very far (but
   surely they must have planned a healthy reserve when the buggy was
   occupied).
3) There might have been difficulties tracking the earth with the dish on
   the back of the buggy (How was this handled during the normal use of the
   vehicle?).
4) Insufficient time/funds (I seem to remember that the whole rover vehicle
   project was something of an afterthought).

Anybody know the facts?

                -pete lucas ([e-mail])

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

Date: Mon, 29 Aug 88 14:50 N
From: "Rob A. Vingerhoeds / Ghent State University" <[e-mail]>
Subject: SKYLAB

On 16 Aug 88 Bob Gray wrote:
> Subject: Re: 95% vs. 99.9% reliability
> In article <[e-mail]> [e-mail] (Henry Spencer)
> writes:
> >As somebody wrote in Aviation Week a few months afterward (roughly, from
> >memory):  "If the same thing had happened to the Soviets, they would have
> >swept the debris off the launch pad, hoisted the next launcher onto the
> >pad, and started the countdown.
>
> Much more importantly, they don't scrap the old launch system
> until the new one is working reliably, and can do all that
> the old one could.
> Bob.

Yes, had NASA kept on using the Apollo, then not only would they be able to
use them now, while the Shuttle is out of service (by the way, is a firm
new launch date available yet?), but also would they have been able to save
Skylab in the late 1970's. Then they could have started from Skylab to
build the new Space Station.

Rob

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

Date: 25 Aug 88 17:45:41 GMT
From: aplcen!aplcomm!stdc.jhuapl.edu![e-mail]  (Jim Meritt)
Subject: yay!


We finally got something up there!

2 TRANSIT (navy navigation satellites) just made it up from Vandenberg AFB
to 600 mile orbits!!


Disclaimer: Individuals have opinions, organizations have policy.
            Therefore, these opinions are mine and not any organizations!
Q.E.D.
[e-mail] 128.244.65.5  (James W. Meritt)

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

Date: 25 Aug 88 19:03:00 GMT
From: aplcen!aplcomm!stdc.jhuapl.edu![e-mail]  (Jim Meritt)
Subject: Re: Transmutation

In article <[e-mail]> [e-mail] (Knudsen) writes:
}In article <[e-mail]>, [e-mail] (Steve Willner P-316 x57123) writes:
}
}> Speculating on the economics of advanced societies is a dubious
}> proposition, but it seems to me that transmutation would be
}> economically more attractive because of the shorter payback period
}> and thus the lower cost of capital equipment.  In fact, I would turn
}
}Unless I'm missing something, we should be able to transmute
}small quantities of elements with current technology.

Guess what - current technology allows large-scale transmutation!
There is no such thing as "natural" plutonium.

Well, maybe a pound or two, but not enough to go out and mine.
ALL of the stuff in our bombs and such is the result of transmutation.



Disclaimer: Individuals have opinions, organizations have policy.
            Therefore, these opinions are mine and not any organizations!
Q.E.D.
[e-mail] 128.244.65.5  (James W. Meritt)

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

Date: 25 Aug 88 07:55:42 GMT
From: tektronix!reed![e-mail]  (P Douglas Reeder)
Subject: Re: Aegis, SDI

I think the groups most likely to smuggle an atomic weapon into the US
are countries along the lines of Lybia and Iran, or terrorists backed by them.
Who sent tthe bomb might be hard to prove.

--
Doug Reeder                           USENET: ...!tektronix!reed!douglas
10 Cyclopedia Square             from BITNET: [e-mail]
Terminus City                     from  ARPA: tektronix!reed!douglas@berkley
Terminus,The Foundation               Box 502 Reed College,Portland,OR 97202

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

Date: 25 Aug 88 22:30:09 GMT
From: l.cc.purdue.edu![e-mail]  (Herman Rubin)
Subject: Re: space exploitation/exploration

In article <[e-mail]>, [e-mail] (Peter Nelson) writes:
>
>   from the mailbag today:
>
> >   The libertarians are perfectly willing to put in their money if the government
> > would let them.
>
>    ...This in reference to my statements about building a colony in space.
>
>  1.  What makes you think there are enough Libertarians in the whole
>      country to come up with the kind of money it would take to put up
>      a space-colony?  If there were a million Libertarians in the country
>      and they *all* agreed that this was a worthwhile venture and they
>      *all* agreed to put up a thousand dollars a year, this would only
>      come to a paltry billion dollars, hardly adequate for the scale of
>      the task.

A lot of people would support the space program besides Libertarians.  Many
people believe in space in the near future.  Possibly there are 50 million
Americans who believe in space, and how many in the rest of the world.  I
would not be surprised to get 20 million putting up 5-10 thousand a year,
hardly chicken feed.

>      You need to interest serious investors and this requires a business
>      plan and I don't see any serius motion in that direction.

I believe it will be possible to interest investors.

>  2.  How is the government stopping you?  Because they have a lock on the
>      launch facilities?   It will be YEARS before you will need any launch
>      facilities!!  If you want to have a self-sustaining colony in space
>      there is an enormous amount of technology and science to be developed
>      first.  How about experimenting with closed ecosystems?  I only know
>      one major project about to startup for this and it only involves life-
>      support for 8 people.   The government isn't stopping the Libertarians
>      from doing this research on a larger scale.  It's not stopping them from
>      developing the technology for hollowing out asteroids.  It's not stopping
>      them from breeding special varieties of plants adapted for growth in
>      space-colony conditions.  It's not stopping you from doing the engineering
>      designs for the system.

The non-theoretical work must be done in space.  It is much harder to build
a closed ecosystem on earth with all of the external pollutants and inter-
ferences, including gravity, than in space.  How can one possibly develop
the technology for hollowing out asteroids when you are operating under one
g and the waste disposal problem is totally different?  I suspect that 0 g
construction techniques will look nothing like what can be done on earth.

How can one breed plants which will thrive in space-colony situations on earth?
No one knows the effects of weightlessness on plants for any lenght of time.
Only materials research is possible on earth, and not too much of that.

So we have to get out in space to do the development.  The problem is not that
the government controls all of the existing launch facilities.  The problem is
that _the government restricts the launching by Americans_.  The best the
government can do for man in space is to desocialize the American space effort
by removing its restrictions, and in addition to declare space to be free of
usurpation by earth governments and to prepare to back its citizens.

If the government does this, the investment will come.  If it sits on private
space development which the bureaucrats find objectionable, right now there is
no place to make the investments.
--
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907
Phone: [phone]
[e-mail] (Internet, bitnet, UUCP)

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

End of SPACE Digest V8 #352
*******************