Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_3/V13_337.TXT

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Subject: SPACE Digest V13 #337

SPACE Digest                                     Volume 13 : Issue 337

Today's Topics:
                Re: "Follies"
           What people will pay to move...
         Re: railguns and electro-magnetic launchers
         Re: railguns and electro-magnetic launchers
              Re: Space Profits
             Re: Project Iridium queries
     Iridium  (phone cells, not asteroid extinctions :-)

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

Date: 29 Mar 91 21:13:16 GMT
From: zephyr.ens.tek.com!tektronix!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: "Follies"

In article <[e-mail]> [e-mail] (Fraering Philip) writes:

>I'd like to call a truce on the subject of chemical launchers.

I second the notion.  Apology accepted on the "kill" flame, and I must
say I agree with everything you say here.



--
Nick Szabo            [e-mail]
"If you want oil, drill lots of wells" -- J. Paul Getty
The above opinions are my own and not related to those of any
organization I may be affiliated with.

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

Date: Sat, 30 Mar 91 15:13 GMT
From: AMON <[e-mail]>
Subject: What people will pay to move...


The numbers I've been hearing about what people will pay to move to space
seem  a bit absurd.

Anyone who has ever moved any reasonable distance knows that even a genuine
Earth bound move is quite costly. Probably more costly than some of the
numbers I've been hearing.

I personally financed my own move from Pittsburgh, USA to Belfast, North
Ireland a bit less than 2 years ago.

Moving costs:    about $7000
Travel costs:    about $ 800

But that was only the start, because there are other relocation costs, replacement of vehicle,
and such. I estimate the total cost to me was somewhere in the range of $12000.

Now, I may have been earning a bit above the "average" but still probably on
the low side for those who are probably interested in doing this since I
worked at a university and then with a startup company (attempt).

Add to this that the above cost was only for ONE person to relocate 3-4000 miles,
using current air, road and water transport...

Now obviously our intrepid relocatees in 2010 are not going to take their antique oak dresser along; but then again, information technology will make it
unnecessary to carry sevearl thousand pounds of old style information storage
and retrieval devices: books, records, file cabinets, magazines, bookshelves, stereos, and such.

With 2010 technology I would have radioed 3/4 of my belongings ahead of me, or
else paid for a few nextNeXT Optical Disks to carry in my luggage. The 3/4 figure may not hold for
everyone, but is ture for mylsef. I suspect it is true of many others who
read this net and are among those likely to go if such were possible.

Now I did not sell a house on one end and buy one on the other. I rented there and
I rent here. Why should I have to immediately buy a residence at a space settlement?

Now I did need to buy transport, and depending on the sort of settlement and location,
that equivalent might or might not be necessary at the settlement.

I don't agree with either the "government infrastructure" or the "group of families" models as being likely for a real settlement. Many of the early american
settlements were corporate ventures funded from comfortable offices in London.

In otherwords, folks, CAPITALISTS, out to get rich. The side effect was that
people got set up in the new world, and if they lived long enough, they thrived.
Now, if we look at the Utah and Mass. colony efforts, they were also joint stock
efforts in one manner of speaking or another.

The point about the multiplier was evidently missed by one responder. Unless
something drastic happens, the average wealth of a family disposed towards moving
astronomical distances will mostly by monotonic increasing with the year number.

I will also state that I have disagreements with absolute opinions on either of
the chemical/no chemical discussion. I am quite convinced that non-government
industrial purpose chemical rockets can be brought down to the sub $100/pound
costs. And I think efforts on this in the short term are quite reasonable.

I also think that rockets have no long term future. Maybe not even much of a mid term future.

I think Zubrin's Magsail is an example of the technology that will really open
the solar system.

EM launchers and such are the way to go for getting bulk materials off planet.

I don't see any good near term method of getting people off Earth, with nonchemical
propulsion. We are at least 30 years away from a viable anti-matter infrastructure, according to Dr. Forward, even though he doesn't see any serious technical
hurdles.

To summarize:
    1) People will pay more than has been suggested, and will be able
       to pay more as time goes on.
    2) The goods that must be brought along will decrease with time
       as more and more become "data" goods rather than physical goods.
    3) Chemical rockets can probably make major short term gains
        and will be the only way to get people up in the next
       10 or more.
    4) Chemical rockets will not be of much use beyond Earth orbit even
       in the near term.
    5) Chemical rockets will eventually be replaced even for Earth orbit,
       but only after significant investment and advances.

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

Date: 30 Mar 91 15:46:39 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Re: railguns and electro-magnetic launchers

In article <[e-mail]> [e-mail] (Paul Blase) writes:
>
>If I do the math right, and if his figures are correct, with a bore
>length of 9 meters and a muzzle velocity of 2.4 kmps (kilometers per second)
>you get 320,000 meters/second^2.  A primary problem with railguns is keeping
>the projectile from turning into plasma on the way out.

I understand the primary problem is erosion of the rails.  I suspect
a railgun is not a desirable launcher for achieving high launch rates,
unless some way can be found to rapidly recondition the rails (say,
by making them with a liquid metal surface).  Other accelerator
concepts (coil guns, ram accelerators) have no sliding contact.

Small railguns accelerating 1 gram plastic cubes have achieved
accelerations approaching 10^7 m/s^2 (acceleration is limited by
disintegration of the projectile, among other things).  The maximum
acceleration should scale inversely with the linear dimensions of the
projectile, so a 1 kg plastic cube should, in principle, be able to
sustain 100,000 gees.  One can imagine accelerationg long, narrow
projectiles in discardable sabots to distribute the stress.

    Paul F. Dietz
    [e-mail]

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

Date: 30 Mar 91 14:52:02 GMT
From: att!pacbell.com!mips!samsung!news.cs.indiana.edu!msi.umn.edu!cs.umn.edu!ariel.unm.edu!triton.unm.edu![e-mail]  (John Prentice)
Subject: Re: railguns and electro-magnetic launchers

In article <[e-mail]> [e-mail] (Paul Blase) writes:
>to: [e-mail] (Craig DeForest)
>
>From "From Dreamworld to Realworld: ElectroMagnetic Guns", Terry L. Metzgar,
>Aerospace &  Defense Science, November/December 1990.
>
>If I do the math right, and if his figures are correct, with a bore
>length of 9 meters and a muzzle velocity of 2.4 kmps (kilometers per second)
>you get 320,000 meters/second^2.  A primary problem with railguns is keeping
>the projectile from turning into plasma on the way out.
>

This sounds familiar :-) .  So, you are getting about 32,000 g's,
assuming a constant acceleration (is this a good assumption?).  I don't
think you are anywhere close to energies to convert a solid to a plasma
(except perhaps on the skin of the projectile, though I may be
misinterpreting what you are saying here.), but you are most certainly
close to or beyond the material yield strength of most solid materials,
depending on how the projectile is actually accelerated (if it is being
pushed by a conductive plate for example, then a 1 kilogram projectile
of 1 cm**2 surface area is seeing 32 kilobars of pressure on its surface.
The yield strength of steel is about 15 kilobars.  In either case, it
sure rattling your electronics!

>BTW:
>"The speed at which chemical propellants can push a projectile is limited
>by the speed at which a gas expands.  For all practical purposes,
>conventional-gun-launched projectiles can't go much above 1.8 kmps."
>

Not quite true.  Two stage light gas guns routinely hit 7.5 km/sec
and some have shot sabot packages above 8.5 km/sec.  Sandia uses one
of these as the injector to a EM gun.  So the projectile is hypervelocity
before it even gets inside the EM gun.  However, your statement is
correct for guns using explosive propellants.

John
--
John K. Prentice    [e-mail] (Internet)
Dept. of Physics and Astronomy, University of New Mexico, Albuquerque, NM, USA
Computational Physics Group, Amparo Corporation, Albuquerque, NM, USA

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

Date: 28 Mar 91 17:40:46 GMT
From: rochester!uhura.cc.rochester.edu!ub!dsinc!unix.cis.pitt.edu!pitt!nss![e-mail]  (Paul Blase)
Subject: Re: Space Profits

to: [e-mail] (Philip Fraering)

(The PC was used as an example of a more-or-less world wide industrial
 standard)

 FP> If the IBM PC is one of your standards, perhaps we're better off
 FP> building custom machinery. :-)

I'm a Mac nut myself, but unfortunately most of our customers use PC's.
Seriously, it is amazing how ubiquitous the PC is, especially in
industrial control and data gathering applications.  There must be
a hundred different companies world wide that sell data collection boards
for it.

The PC does demonstrate a very important point, however, which
is that the best example of a technology does NOT always become the
standard, rather it is the item that gets to the most people first.
Another example is video tape.  In actuality, Betamax gives a superior
picture to VHS, however the companies that supported VHS managed to get
more pre-recorded tapes and better players on the market faster.  Something
to watch out for.

--- via Silver Xpress V2.26 [NR]
--
Paul Blase - via FidoNet node 1:129/104
UUCP: ...!pitt!nss!Paul.Blase
INTERNET: [e-mail]

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

Date: 30 Mar 91 08:46:18 GMT
From: ubc-cs!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Project Iridium queries

In article <[e-mail]> [e-mail] (Matthew Kwan) writes:
>Over the past couple of months I've heard a bit about Motorola's
>Project Iridium. Apparently it involves 77 orbiting satellites.
>
>Why 77? Does this ensure an even coverage of the Earth's surface,
>or a more concentrated coverage of "busy" areas like New York
>and other big cities?

They're in low orbit, not Clarke orbit like most current comsats, so a
lot of them are needed to make sure there is always one in line of sight.
The low orbit buys them a lot, keeping time lags down and making it
possible to get good performance with small satellites and small radios,
but it does mean that the radio horizon for a given satellite doesn't
cover half the Earth any more.

>Also, this network sounds like it will cut into a lot of national
>telecommunications monopolies. Who is going to handle the resulting
>political problems - Motorola or the US Government? Will the network
>be regulated by the US Government, or will it be free?

It will be an international network, and the political complications are
in the "mind-boggling" category.  I believe Motorola is hoping to pick
up international partners who will handle some of the political haggling
in their own neighborhoods, but US government politicking will undoubtedly
be needed for things like frequency allocation.

There is no such thing as a "free" network on this scale.  It will be
regulated by everyone you can think of.
--
"The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 are all true."  -D. Harrison|  [e-mail]  utzoo!henry

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

Date: 30 Mar 91 02:21:55 GMT
From: zephyr.ens.tek.com!tektronix!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Iridium  (phone cells, not asteroid extinctions :-)

In article <[e-mail]> [e-mail] (Doug McDonald) writes:
>
>[Wales Larrison writes]
>>  The hardest part of Iridium has
>>always been setting up an international consortium or organization
>>to fund and operate the constellation.
>
>"Lockheed" and "Motorola" are US companies. The biggest market for this
>thing would be in North America.

So far, the major investors are American (though I expect Japanese
business to get in on this at some point).  However, most of the North
American population is already covered by cellular, so most of the initial
market is international -- especially those countries that do not yet
have cellular service.

For each country in which it wishes to operate, Iridium needs to get a
frequency allocation.  Not only that, but the frequencies have to
match from country to country.  Not an easy task.

Of course, any country that doesn't give Iridium its frequency could
get shut out of international cellular service, so both sides have
cards to play.  Ironically enough, due to entrenched U.S.
communications interests, the U.S. could become one of those countries,
even though our companies are putting up the $$$!


>Whay bother? Just turn off the satellites off except over North America.

And lose tons of $$$.  I doubt Montana cowboys (& their saddle-mounted
phones :-) have enough to pay back the $2.something billion investment.
However, there are huge populations -- even large numbers of _wealthy_
people, despite being a small % of the total -- in India, China, Brazil,
Mexico, Iran, Indonesia, Thailand, Turkey, Eastern Europe, etc. that have
no cellular service.  Iridium can also usefully serve international
air and ocean lines.   At least initially, it cannot compete with existing
cellular service, and is not intended to.   The market for Iridium is
universally (well, globally :-) available cellular service, at a higher
cost.  How much higher depending on how many people sign on...the old
chicken & egg story.  If everybody signed on, it would actually be much
cheaper than the current local cell system, but nobody expects that to
happen anytime soon.

The way Iridium is deploying phone cell satellites can serve as a good
model for other marketers of advancing technology: search and scour the
globe for its optimum niche, and spread from there.  Another example of
this: I've been telling folks for years, the best market for solar
power satellites is Japan, since there you have the most people paying
the highest prices for electricity.  120 million people and a good chunk
of the planet's industry paying c. $.20/kwh.  Japan is even now considering
spending upwards of $50 billion on new nuclear plants -- you can image
how _that_ is going over in Nagasaki.  After the Rising Sun SPS is
perfected, we can start thinking about solving the energy crisis.  If
you can't win the small battles, you ain't gonna win the big ones, so take
Sun Tzu's advice and hit 'em where they ain't.  Look for the optimum
niche.


--
Nick Szabo            [e-mail]
"If you want oil, drill lots of wells" -- J. Paul Getty
The above opinions are my own and not related to those of any
organization I may be affiliated with.

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

End of SPACE Digest V13 #337
*******************