Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v16_6/v16no688.txt

Internet Message Format | 1993-07-13 | 33KB

Date: Sun,  6 Jun 93 05:05:19
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #688
To: Space Digest Readers
Precedence: bulk


Space Digest                Sun,  6 Jun 93       Volume 16 : Issue 688

Today's Topics:
               1992 NASA Authorization Budget- shuttle
                  Big Rock Can Hit Earth in Yr 2000
                  Case for Mars (Was: Re: Moon Base)
                            DC-X neighbor
        Fortran Compiler Recommendation(s) for DOS/Windows 3.1
                  Hey Sherz! (For real!) Cost of LEO
              Hey Sherz! (For real!) Cost of LEO  (Long)
                             mass drivers
                          Moon Base (6 msgs)
                        reducing launch costs
                    Refs, please (was: Moon Base)
 Self-replicating gadgets (was Re: Moon vs. asteroids, Mars, comets)
             Why are SSTO up-front costs rising? (2 msgs)

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
    "Subscribe Space <your name>" to one of these addresses: listserv@uga
    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 5 Jun 1993 15:28:03 -0400
From: Pat <[e-mail]>
Subject: 1992 NASA Authorization Budget- shuttle
Newsgroups: sci.space

Matt asks if i am in the pay of a foreign government.

No.  I am merely pointing out,  that  Autos, energy, textiles....
all have clamored for Government funding, help, protection,import taxes,....

Aero-space  is heavily US govt influenced.  and as such is subject to
other sectors making equivalent demands for those dollars.

I personally wish we were pre-eminent in all these technologies,
and I blame the Harvard Business SChool and the Reagan administration
for a lot of the problems.   But in the Now,  there are huge
budget Deficits, and economic recession.  Many mouths at a small trough.
Aero-space needs to fight among the crowd, or start increasing value
returned, Politically, Economically or Technically.

pat

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

Date: Sat, 5 Jun 1993 18:43:18 GMT
From: "Julian V. Noble" <[e-mail]>
Subject: Big Rock Can Hit Earth in Yr 2000
Newsgroups: sci.space,talk.environment,sci.physics,sci.astro

[e-mail]  writes:
> [e-mail] (Peter Newman) writes:
>
> >Is it true that the name of this object, Toutatis, is a pun based on
> >it being a contact binary, i.e. "two taties" (potatoes)...?  :-)
>
> Altogether now:
>
> Toutatis was a god worshipped by many Gaulic tribes as some
> sort of protector.
>
> --
>
> +-----------------------+---------------------------------------+
> |Phil Fraering          | "...drag them, kicking and screaming, |
> |[e-mail] | into the Century of the Fruitbat."    |
> +-----------------------+-Terry Pratchett, _Reaper Man_---------+
>

Re: Toutatis -- see Asterix, they are always swearing in the name of
this (ahem!) Toutelary deity.

--jvn

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

Date: Sat, 5 Jun 1993 22:30:15 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Case for Mars (Was: Re: Moon Base)
Newsgroups: sci.space

[e-mail] (Pat) writes:


>Well Dennis Newkirk is pretty good when he's producing one of his
>famous russian history articles.   And Coffman is quite good on
>Radio electronics and materials.   maybe we should get these
>3 to moderate sci.space.

I only see two names there. Obviously I can't count. Please help
me.

--

+-----------------------+---------------------------------------+
|Phil Fraering          | "...drag them, kicking and screaming, |
|[e-mail] | into the Century of the Fruitbat."    |
+-----------------------+-Terry Pratchett, _Reaper Man_---------+

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

Date: Sat, 5 Jun 1993 21:22:20 GMT
From: _Floor_ <[e-mail]>
Subject: DC-X neighbor
Newsgroups: sci.space

Three of my neighbors here in St. Louis work at McDonnell Douglas. I asked
two of them several months ago if they knew about the Delta Clipper project,
and they didn't. Today I'm talking to the third and he says he has to go
in to work today - so I ask him what he does. He works on software for
the DC-X!!! Anyone have any questions they'd like to ask a software
engineer for the program. He was telling me how he has to do some stuff
today with increasing the fuel pressure in the tanks, and also is working
on improving the speed of abort processes. Anyhow, another MD neighbor
was there at the time and said they now knew about it and would be glad
to give me their video from MD on it. Every 90 days MD puts out a video
giving an update on major projects to its employees. The June 93 one has
the DC-X rollout. My friend who works on the project was also telling me
that software simulations he did in that 8 hour period between the recent
firing tests permitted the team to go ahead so quickly with the second test.
Cool!

  _____    "But you can't really call that a dance. It's a walk." - Tony Banks
 /  ___\  ___  __ ___   ___      _____________   [e-mail]
 | / __  / _ \ | /   \ / _ \     |  physics  |   [e-mail]
 | \_\ \ | __/ |  /\ | | __/     |racquetball|   [e-mail]
 \_____/ \___/ |_| |_| \___/     | volleyball|   [e-mail]
 Gene Van Buren, Kzoo Crew(Floor), Washington U. in St. Lou - #1 in Volleyball

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

Date: Sat, 5 Jun 1993 20:01:01 GMT
From: Jon Noring <[e-mail]>
Subject: Fortran Compiler Recommendation(s) for DOS/Windows 3.1
Newsgroups: sci.math.num-analysis,sci.math.stat,sci.math,sci.misc,sci.optics,sci.physics,sci.space,sci.systems

Hello,

I'd like to get recommendations and experiences of those who routinely write
and compile number crunching Fortran programs on DOS platforms, that is,
engineers and scientists!

So, if you have some knowledge in this area, and would be willing to
share it with me, I'd appreciate the feedback.

I'm most interested in recommendations for the better Fortran compilers
available for DOS systems.  Are there any Fortran 90 compilers yet for DOS?
And, are there any good and relatively inexpensive mathematical subroutine
libraries?  Windows 3.1 compatibility?  32 bit operation?  Freeware or
shareware compilers, even if not the best?  Etc., etc.  Inquiring minds want
to KNOW.

Much thanks for your feedback.

***************************************************************
PLEASE E-MAIL YOUR REPLIES TO ME IF YOU CAN.  [e-mail]
***************************************************************


Jon Noring


--

Charter Member --->>>  INFJ Club.

If you're dying to know what INFJ means, be brave, e-mail me, I'll send info.
=============================================================================
| Jon Noring          | [e-mail]        |                          |
| JKN International   | IP    : 192.100.81.100   | FRED'S GOURMET CHOCOLATE |
| 1312 Carlton Place  | Phone : [phone]   | CHIPS - World's Best!    |
| Livermore, CA 94550 | V-Mail: [phone]   |                          |
=============================================================================
Who are you?  Read alt.psychology.personality!  That's where the action is.

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

Date: Sat, 5 Jun 1993 22:33:11 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Hey Sherz! (For real!) Cost of LEO
Newsgroups: sci.space

[e-mail] writes:

...
>>I'm sorry Dennis, I think your a very smart person but you don't even have
>>your BS degree yet. To call yourself an expert satellite systems engineer
>>is pushing it a bit. I fully expect that someday you will be an expert,
>>but not yet.
>>

>What the heck does a BS degree in Physics have to do with building satellites?

Although I think Dennis's figures about shuttle costs are wrong,
I'd have to say I agree with him here. He seems to know about
building satellites.

Of course, you and I may know more about costing, but that's a
different field; you get your qualifications there by selling
your soul to Cthulhu... ;-)

--

+-----------------------+---------------------------------------+
|Phil Fraering          | "...drag them, kicking and screaming, |
|[e-mail] | into the Century of the Fruitbat."    |
+-----------------------+-Terry Pratchett, _Reaper Man_---------+

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

Date: 5 Jun 1993 15:23:33 -0400
From: Pat <[e-mail]>
Subject: Hey Sherz! (For real!) Cost of LEO  (Long)
Newsgroups: sci.space

I am somewhat pleased to realize that Dennis and Allen can go
Longer then fred and I even in our longest dialog.  Right fred?

Dennis says :

    GM Saturn...

    Dennis, I will read the article, but I think you may
    be reading too much into the "Write- OFF" of the SATURN
    R&D dollars, and Capital investment dollars.
    Saturn is at this point over 10 years old.  GM
    has probably depreciated this Investment against
    other Profits,  and now are merely conducting the final
    writedown.

    Trust Me dennis.  IF companies had to conduct enormous
    loss leading R&D,without a TRUE profit at the end of
    the road,  they'd be out of business. ATT Bell labs were
    the only organization that could just write off R&D dollars
    like a federal facility.

    The Japanese  ran for years without real profits, and now their
    companies are barefoot economically, and ready to totally
    unwind.  Despite all that wonderful capital gear they
    have,  they are on the bare ragged edge, because they
    lack financial depth.

    I think GM has merely conducted a final writedown of saturn
    because it is now over 10 years old.  and if you notice,
    their breakeven point is 300,000 units.


    Shuttle tile queries.

    I never read the Playboy article, on the shuttle, but i
    remmeber AvWeek letters to the editor where people were
    complaining about the total lack of margins in the STS.
    STS was the first booster, to fly without an unmanned test.
    and I remember the mission where they lost some tiles
    off the top.  There were many a sweaty brow around Johnson
    that week.

    It might have been interesting on the STS if they had
    built an expendable flight test vehicle,  that flew
    on a delta, and produced thermal data and tile engineering
    data.

    DC-N engine scaling.

    I guess we'll have to wait and see.  fortunately they do
    have some fall back positions.

    Allen.  Any idea if they will use the X vehicle after
    finishing flight test to test Plug nozzles?

pat

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

Date: Sat, 5 Jun 1993 22:19:55 GMT
From: Henry Spencer <[e-mail]>
Subject: mass drivers
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>... The hundreds of billions would not be for
>the construction of the mass driver anyway, they'd be for the massive
>infrastructure that would have to be developed on the Moon to achieve
>the capability to *build* a lunar mass driver. The thing would need to
>be on the scale of the SSC stretched out in a straight line...

Gary, have you *totally* ignored everything that has been learned about
mass-driver design since Gerry O'Neill and his people started looking
into it?  The idea that it would have to be many kilometers long is
simply obsolete, a relic of the days when 10 Gs was considered a very
high acceleration for such a thing.

At 10G, a mass driver capable of lunar escape velocity is 28km long (14km
to lunar escape, another 14km to declerate the buckets to rest again).
But 10G is a ridiculously *low* acceleration, which nobody would use for
a practical system.  SSI's first prototype mass driver, built out of the
MIT EE junkbox, demonstrated 30G.  A practical lunar system would almost
certainly run at 1000G or more, making it only a few hundred meters long.
--
Altruism is a fine motive, but if you   | Henry Spencer @ U of Toronto Zoology
want results, greed works much better.  |  [e-mail]  utzoo!henry

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

Date: Sat, 5 Jun 1993 16:24:48 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Moon Base
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Paul Dietz) writes:
>In article <[e-mail]> [e-mail] (Nick Janow) writes:
> > So, any arguments against the "cheap launcher, small LEO industrial modules"
> > gradual scenario?  Politics is, of course, the wild card.  :)
>
>Politics is among the least of the problems.  The significant problem
>is lack of market.  The heartfelt hope seems to be that materials
>processing/etc. types will spring out of the woodwork if launch costs

>are reduced, but skepticism is in order given past hype.  Of course,
>ET materials mostly suffer from the same viewgraph marketing.

Yes, this is a strong argument for starting small with minimal investment
and scaling as a market develops, or cutting your losses if one does
not. This is one of the major drawbacks of lunar bases. The necessary
*minimum* scale to approach economical production is too large for
the nascent market to absorb.

Gary

--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

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

Date: Sat, 5 Jun 1993 17:03:51 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Moon Base
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Nick Janow) writes:
>[e-mail] (Gary Coffman) writes:
>
>> Being early, but a continuing money loser, is not an advantage. Only if
>> Luna can be made to pay off should we go with bases and colonies.
>
>What if the lunar base loses money, but the value-added industries that it
>supports provide great returns for the governments that supported the lunar
>base?

Then it wouldn't lose money. It just gets part of it's cost per pound
roundabout through taxes. What I meant, and Paul touched on this, is
that if the base delivers product at below cost, someone has to be
paying the subsidy. In normal business, you can't sell below cost for
long. As long as the government is allowed to print money, they can,
but even then everyone pays via the debasement of the currency and
increased taxes. The lowest true cost producer sets the price floor.
If someone decides to start building and launching Sea Dragons,
you'll have no market for raw materials that cost over $10 a pound.
If Allen's hype is right, even DC will set the price floor at $400
a pound. A lunar base that covers it's actual costs can't approach
these prices. If the government funds it anyway, the costs are still
there, they're just recouped by reaching in another's pocket. That
isn't equitable, and it would be illegal if done by private companies.

>> Volume only works when it pushes past a cost barrier and begins to reap the
>> benefits of economies of scale. In that case you don't lose money on every
>> sale.
>That's for one specific business.  The situation is different when that one
>business is part of a larger business with many products and services.  It's
>okay to lose ten billion a year on a lunar base if you get twenty billion a
>year in taxes and economic activity driven by the space industry.

Normal accounting rules require that internal costs be passed through
to the ultimate product. Your example is artificial. All costs are always
charged against profit.

>> Lunar bases are like mass transit, an unwelcome, unwanted, money sink that
>> never goes away.
>
>Hey, mass transit is extremely welcome and appreciated in Vancouver.  The
>resistance to the "cars first" policies of other cities is part of what make
>it a desirable city to live in.  Expanding and improving mass transit is
>popular among the taxpayers.

It's not here, and if the producers were the majority of voters, it wouldn't
be popular anywhere. Subsidies distort markets, and they always ultimately
cost more than unsubsidized operations while inequitably distributing the
costs. Only 30% of working Americans are in jobs that produce wealth, the
rest are on the government dole either through government jobs or direct
handouts. I hear it's worse in Canada.

>> If we really want a healthy space economy, we've got to develop it on a
>> sound financial basis.
>
>In that case, we may as well ignore the moon/asteroid argument, because that
>will be decided by business people a long time from now.  A healthy space
>economy probably requires that the governments stay completely out of it.  :)

I basically agree with that. And I don't see private financing of lunar
bases as even a remote possibility. I do see ways that cometary water
recovery could be done by incremental investments suitable for private
ventures.

Gary
--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

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

Date: 5 Jun 93 22:27:55 GMT
From: Paul Dietz <[e-mail]>
Subject: Moon Base
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:

> That's why water from comets is so attractive. Extraction is simple,
> and can scale from small to large by bootstrapping. So the investment
> is never extreme at any given point in the development of the market.
> Water is the Holy Grail in space. It can be used as reaction mass
> in nuclear/steam, or even solar/steam, rockets. It can be electrolyzed
> with solar electricity to hydrogen and oxygen for more energetic
> rockets, or for breathing needs. ...


Let's not exaggerate here.  Yes, extracting water from a senile comet
is likely to be easier than extracting oxygen from lunar regolith.
But it is still nontrivial.  And the volatiles must be filtered and
purified before use in rockets.

Another point.  Water is nice, but it is hardly ideal as reaction
mass.  If you had your choice of a propellant for nuclear or solar
thermal rockets, hydrogen, methane, ammonia, hydrazine or methanol
would be superior -- ammonia would deliver an Isp more than twice as
high, for example, as the molecular weight of the exhaust is much
lower (it decomposes to nitrogen + hydrogen) and, being reducing, is
compatible with higher temperature materials.  If you are shipping
stuff up from earth, you can afford to ship up a better, if harder to
make, material, since making things down on earth is so easy.

This same argument applies to other potential ET resources.  Crude
lunar aluminum, say, is going to be competing against highly optimized
terrestrial alloys and composites.  Ditto for manufactured products --
turning those materials into useable forms is easier on earth.  The ET
materials are going to have to be not just a little cheaper, but
considerably cheaper to overcome this disadvantage.

    Paul F. Dietz
    [e-mail]

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

Date: Sat, 5 Jun 1993 22:22:13 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Moon Base
Newsgroups: sci.space

[e-mail] (Gary Coffman) writes:

>In article <[e-mail]> [e-mail] (Theodore F. Vaida ][) writes:
>>To throw in my own two cents worth in support of a lunar base...
>>... exactly how much delta-V would be needed to bring even the closest
>>approaching asteroids into earth orbit for those "cheap teleoperated
>>factories" that would be built in LEO?

>You don't bring the asteroid to LEO. You refine in situ and only ship
>the refined materials back to the factories. For comets, you boil off
>and capture the water, methane, carbon monoxide, and other volatiles
>in situ and return only the refined and separated materials, nominally
>as thermally shielded frozen pigs, a "tankless" method of transport.
>Simple foil sunshades are sufficient for thermal shielding against
>solar energy, and glass fibre between the pigs and the guidance
>thrusters.

>Best identified targets require <= 5 km/s delta-v. This can be achieved
>by low thrust long duration small engines, however, such as ion engines
>or small solar thermal engines. Large powerful rockets are not required
>since the gradient is gentle, and some of the volatiles can be used as
>reaction mass if desired.

Understatement of hte year.

The preprints I saw a while back showed water being used as reaction
mass and as tank walls (ice). With pessemistic assumptions about the
delta-v needed, the design ended up using >50% of the extracted volatiles
(assumed to be water) as reaction mass to enter an eccentric Earth orbit.


>Gary
>--
>Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
>Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
>534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
>Lawrenceville, GA 30244     |                     |
--

+-----------------------+---------------------------------------+
|Phil Fraering          | "...drag them, kicking and screaming, |
|[e-mail] | into the Century of the Fruitbat."    |
+-----------------------+-Terry Pratchett, _Reaper Man_---------+

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

Date: Sat, 5 Jun 1993 22:25:41 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Moon Base
Newsgroups: sci.space

Oops, I forgot something in the last post:

About the assumption in the preprint about the "mainly water"
bit... part of the reason I wanted a reference was to see if
anyone had worked out a good filtration system or pump... or
separation system, for that matter.

How scalable would _those_ be?


--

+-----------------------+---------------------------------------+
|Phil Fraering          | "...drag them, kicking and screaming, |
|[e-mail] | into the Century of the Fruitbat."    |
+-----------------------+-Terry Pratchett, _Reaper Man_---------+

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

Date: Sat, 5 Jun 1993 20:19:32 GMT
From: Nick Janow <[e-mail]>
Subject: Moon Base
Newsgroups: sci.space

[e-mail] (Jim Hart) writes:

> Do you know what the hell you are talking about?  No one has built factory
> machinery that recycles water and air like that, not to mention all the
> gooey crap machines use that is missing from the moon. Not even close.  Air
> pollution and wastewater are produced in huge volumes by just about any
> industry worthy of that title.

As Gary did, you are making the mistake of assuming that present "designed
for Earth today" processes will be used directly in space.  No one has built
(that I know of) a factory that recycles volatiles as much as possible,
because that would be a bad economic decision.  Why spend a million dollars a
year extra in recycling water when your competitor spends only ten thousand a
year on large volumes of water which is used and dumped?  Industries dump
huge volumes of fluids and gasses because they haven't been charged for the
environmental costs of it.

The electronics industry used large quantities of CFCs for cleaning.  It was
more economical to waste it than to carefully contain and recycle it.  Now,
many of those companies are reclaiming and recycling most of it.  Others have
switched to processes which use alternative solvents, and processes which use
little or no solvents.

No one has developed the technology to refine aluminum with a closed-cycle
for volatiles because there's been no economic motivation to do so.  That
doesn't mean it's not possible.

What is "all the gooey crap machines use"?  Do you mean lubricants for
bearings, which can be replaced by magnetic bearings?  Do you mean cutting
fluids, which can certainly be recycled nearly 100% if you want to.  If you
mean plastic feedstocks, those might be replaced in many situations by new
designs or by new inorganic materials (foamed metals, ceramics, glasses).

> If we're going to delve into this kind of science fiction,...

Science fact.  Check the decreased use of CFCs in industry.  Check the
reduction in water consumption by the steel industry over the last few
decades. Check the decrease of fluid and gasseous waste in industries where
legislation has made pollution expensive.  Check the reductions of "black
liquor" dumped by pulp mills when new markets turned that waste product into
a useful chemical stock.

> As I
> suggested before, start delving into the industrial literature and learn
> what it takes to really do this stuff.

I read through Design News and various other publications, so I do have some
idea what's required, and what is possible.

--

[e-mail]

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

Date: Sat, 5 Jun 1993 22:05:07 GMT
From: Henry Spencer <[e-mail]>
Subject: reducing launch costs
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Jim Hart) writes:
>>The reason is that we are pretty sure we can reduce
>>the cost of launch mass from earth to on the order of tens of dollars
>>per pound, *if the market is large enough*.
>
>(1) Who is sure about this?  This nearly a factor of 1,000; most
>rocket engineers scoff at projections of DC-1 reducing costs by
>a factor of 10...

Which rocket engineers are you referring to?  Please be specific.  I think
the "rocket engineers" you are thinking of are the folks in charge of the
systems that DC-1 would render obsolete.  These people are hardly unbiased
sources on the subject.

The most impressive thing about recent events is that *everyone* who studies
the matter carefully concludes that SSTO is workable and would do what it
claims to do (although there is some dispute about how long it would take
to get it flying).  Note, for example, the Aerospace Corporation's favorable
report on the idea -- said to be the first time Aerospace has ever firmly
endorsed a concept they did not originate!

Particularly among the younger and less hidebound rocket engineers, there
are plenty who think launch costs could be reduced by a factor of ten by
much less radical changes than SSTO offers.  When the Commercial Space
Incentive Act (which proposed essentially that the government would pay
$500/lb for *anything* lifted into orbit -- note that current launch costs
are 5-10 times that) was being pushed, I know at least two of the "new"
launcher companies had firmly concluded that they could make a *bundle*
on that market... using straightforward developments of existing hardware.
It was the "old guard" firms who assured Congress, and anyone else who
would listen, that CSIA was pointless and would accomplish nothing because
nobody could lower costs that far.

>Can we really get to there from here by continuing to poor
>$billions per year into mature technology?

Depends on whether "mature technology" means "thirty-year-old launchers"
or "new concepts using off-the-shelf hardware".  There's nothing "mature"
about this technology; it's in a state of arrested infancy, frozen into
the state it assumed circa Sputnik 1... because very little new has been
tried since then.
--
Altruism is a fine motive, but if you   | Henry Spencer @ U of Toronto Zoology
want results, greed works much better.  |  [e-mail]  utzoo!henry

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

Date: Sat, 5 Jun 1993 22:17:01 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Refs, please (was: Moon Base)
Newsgroups: sci.space

[e-mail] (Gary Coffman) writes:

>In article <[e-mail]> [e-mail] (Paul Dietz) writes:
>>To avoid this problem, ET resources are either going to have to be
>>very simple to get (to minimize development cost) or something that
>>is expensive on earth (PGEs, say).

>That's why water from comets is so attractive. Extraction is simple,
>and can scale from small to large by bootstrapping.

This reminds me... I'd like to find a list of references to the
extraction technology involved. (I have references on most everything
else).

NOTE: This is because I'd like to _read_ them; I'm not trying to
start an argument... (certian individuals on this list have turned
"where are your references, and in BibTeX format, please" into a
euphemism for "you're bullsh}iitting"; and this isn't what I'm
--

+-----------------------+---------------------------------------+
|Phil Fraering          | "...drag them, kicking and screaming, |
|[e-mail] | into the Century of the Fruitbat."    |
+-----------------------+-Terry Pratchett, _Reaper Man_---------+

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

Date: Sat, 5 Jun 1993 22:05:57 GMT
From: "Phil G. Fraering" <[e-mail]>
Subject: Self-replicating gadgets (was Re: Moon vs. asteroids, Mars, comets)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:

   In article <[e-mail]>, [e-mail] (Steinn Sigurdsson) writes:
   > Actually we do know one way. You use self-replicating ~75kg
   > automatons, use them to build tools, for self-repair and maintenance
   > and programming of new units for building new factories.
   > Overhead is high but the system has been quite thoroughly
   > debugged and most of the R&D is sunk...

   Thoroughly debugged?  With all due respect, I think you exaggerate.
   Usenet incorporates quite a few of these and they have proven to be
   the most unreliable components of the system.

Yah, but in about another six years or so they'll be replaced with
other components that have been found to be more reliable and less
troublesome.

Death to vermin!

--

+-----------------------+---------------------------------------+
|Phil Fraering          | "...drag them, kicking and screaming, |
|[e-mail] | into the Century of the Fruitbat."    |
+-----------------------+-Terry Pratchett, _Reaper Man_---------+

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

Date: Sat, 5 Jun 1993 21:45:36 GMT
From: Henry Spencer <[e-mail]>
Subject: Why are SSTO up-front costs rising?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Matthew DeLuca) writes:
>>Please! What your saying is that since Shuttle failed every project
>>will fail...
>
>...yesterday, Allen, you were telling me that since NASA messed up on the
>Shuttle they can't possibly build a cost-effective replacement; how do you
>reconcile that with the statement above that there are no automatic
>failures?

He didn't say there are no automatic failures; what he criticized was the
notion that *any* such project is an automatic failure.

It is one thing to assert that such projects can never work.  It is quite
another to assert that the organization which produced the last failure
is fairly likely to produce another if it tries again.
--
Altruism is a fine motive, but if you   | Henry Spencer @ U of Toronto Zoology
want results, greed works much better.  |  [e-mail]  utzoo!henry

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

Date: 5 Jun 1993 18:26:11 -0400
From: Matthew DeLuca <[e-mail]>
Subject: Why are SSTO up-front costs rising?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:

>It is one thing to assert that such projects can never work.  It is quite
>another to assert that the organization which produced the last failure
>is fairly likely to produce another if it tries again.

Hmmm, I don't think this is true, either; Delta Clipper is being brought to
you by the same folks doing parts of the space station.  Is Delta Clipper
going to be a success, indicating that organizations can change?  Or will
it be a failure, indicating that once an organization sinks, it stays in the
mud forever?  Allen likes to assert both sides, depending on whether or not
it is one of his 'blessed' projects.
--
Matthew DeLuca
Georgia Institute of Technology, Atlanta Georgia, 30332
uucp:      ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!matthew
Internet: [e-mail]

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

End of Space Digest Volume 16 : Issue 688
------------------------------