Aucbvax.4431
fa.space
utzoo!decvax!ucbvax!space
Thu Oct 15 11:03:09 1981
SPACE Digest V2 #15
>From OTA@S1-A Thu Oct 15 10:43:23 1981
SPACE Digest Volume 2 : Issue 15
Today's Topics:
SPS vs. Fusion - A response to REM
capital for SPS
Re: booze money
Budget cutting
SPS and radiation pressure
SPS continued
"When the Sun goes, we all go"?
Booze Budget
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Date: 14 Oct 1981 1158-PDT
From: Paul Dietz <DIETZ AT USC-ECL>
Subject: SPS vs. Fusion - A response to REM
To: space at MIT-MC
REM misses the point when we says that there are many ways to build
an SPS. What I was doing was this: look at the potential points of
vulnerability in each concept.
With solar sattelites, the big problem is not technical feasibility.
The big problem is that any low cost SPS is going to require
asteriodal or lunar material. We don't really know how hard it is to
build a full scale lunar materials processing plant. We have no
experience in extraterrestrial industry. We have never built a
factory that works in zero g or in a vacuum. We have never built a
factory that uses extraterrestrial materials. This is not to say that
we shouldn't build such factories. What I am saying is that we have
no idea how hard it is, or how much it will cost, or what the hidden
snags are. I suspect that the only way to find out is to go up and do
it. And this is very expensive.
With fusion, the problem is not building the plants after we're sure they
work. The problem is designing the plant in the first place. The problems
in fusion designs tend not to be common to all designs. Many that are common
have already been addressed in other types of power plants.
And for those who argue that the japanese or the russians will develope
SPS first: compare how much they are spending on fusion research to how
much they're spending on SPS research. The japanese are spending large
amounts of money on the tokamak idea. Their feeling is that they better
get a new energy source on line damn quick, before the oil gets expensive.
So, to reiterate, SPS's all share a common problem that may make them
uneconomical, or, may make them require too much start-up capital.
The whole SPS idea can be killed by a single bullet. Fusion does not
share this problem. The problems that fusion does have seem much more
amenable to quick technical solution.
We will get SPS if and when we get lunar or asteroidal materials - not
the other way around.
-------
------------------------------
Date: 14 Oct 1981 10:34:29-EDT
From: cjh at CCA-UNIX (Chip Hitchcock)
To: space at mit-mc
Subject: capital for SPS
Cc: rem at mit-mc
$1 million to establish a Lunar catapult? Dream on!$
And if it just throws dirt, how will the dirt be sorted out into
worthwhile metals? (That's probably safer to do on the moon than in
zero-G; the latest I've heard, the "traveling bucket" design has
been dropped, and capsules of refined material (with enough magnetic
metal to respond to the electric catapult) are what would be flung.)
------------------------------
Date: 14 Oct 1981 10:01:07-EDT
From: cjh at CCA-UNIX (Chip Hitchcock)
To: POURNE at MIT-MC
Subject: Re: booze money
Cc: space at MIT-AI
In response to your message of Wed Oct 14 03:46:08 1981:
Any suggestions as to how we bell that particular cat?
------------------------------
Date: 14 Oct 1981 0959-PDT
From: Tom Wadlow <TAW AT S1-A>
Subject: Budget cutting
To: space at MIT-MC
Several space advocacy groups, including the L-5 Society, are attempting
to approach Congress with proposals designed to reduce government red
tape involving spaceflight. The attitude of: ''Well, if you don't
intend to go, at least don't make it so bloody hard for us to go.''
is a much more productive one than another popular outlook: ''You are
all assholes for not going.''
The World Space Foundation has a proposal for an ''Earthport'', duty
free spaceport and industrial park that is being designed with some
of these problems in mind.
What is really needed is some production-line engineering to bring
down the cost of space travel. Jerry Pournelle mentioned recently
that a standard Shuttle pressure suit costs 14 megabucks. Clearly
a spacesuit is not as complex as the piece of a jet fighter that
14 megabucks will buy. A Shuttle has about the same number of parts
as a 747. But a Shuttle is built by large numbers of highly trained
craftsmen, each being a separate work unlike any other shuttle. A
747 is built on an assembly line, turned out by the dozens, and is
reliable as hell (especially compared to a Shuttle). If humanity's
move into space reaches its third generation, we can expect to
see those ticket to LEO base get a lot cheaper.
------------------------------
Date: 14 Oct 1981 01:37:27-PDT
From: E.jeffc at Berkeley
To: v.space@Berkeley, u:minsky@mit-ai
Subject: SPS and radiation pressure
While plausable, I'm not wholly satisfied that the problem has been
explained away. You were considering a two-body problem with the Earth
and the SPS as the bodies. However, the Sun must also be taken into
account, for the SPS is also in orbit about the Sun, and all of the
momentum from radition pressure will be wholly directed to pushing
the SPS away from the Sun. Unfortunately, I can't determine from
thinking alone whether this revives the problem or not. What is needed
is a computer simulation which will take all these factors into account.
Does anybody know of one? or does someone know how to do such a
simulation? I imagine that the moon would have to be taken into account
also. Anyway, even if the SPS is not blown away from the Earth, it
will still get knocked out of geosyncronous orbit, and I would hate
to see a high power energy beam wandering about the countryside.
------------------------------
Date: 14 October 1981 03:59-EDT
From: Jerry E. Pournelle <POURNE MIT-MC AT>
Subject: SPS continued
To: CSVAX.tuttle at UCB-C70
cc: "TO:" at MIT-MC, minsky at MIT-AI, CSVAX.space at UCB-C70,
e.jeffc at UCB-C70
You have pleaded for the validity of philosophical arguments,
and your prayer has been answered; but that doen't make bad
philosophy valid. Nor does re-inventing the wheel. I can well
believe you are "shocked" to discover that SPS might act as a
solar sail, but I assure you others have thought of it as well;
and long ago. As to the sheer volume of material, per kilowatt
SPS takes up about 1% of the mass of a dam to deliver the same
power. (Actually a 3-metere slice of the 1270 metere Grand
Coulee Dam would if put up as an SPS deliver the same power,
some 9 gigawatts.) If the sheer volume of material for SPS will
bankrupt us then we are bankrupted; for the entire US power
plant must be replaced over the next thirty years wqhether we
have growth or not; power plants don't last a lot longer than
thirty years.
And SPS is the SMALLEST system that would do that job.
It is expensive because the people to build it are expensive;
but of course the money is not "spent in space", there being no
one there to cash checks...
------------------------------
Date: 14 October 1981 18:48-EDT
From: Robert Elton Maas <REM MIT-MC AT>
Subject: "When the Sun goes, we all go"?
To: CSVAX.upstill at UCB-C70
cc: SPACE at MIT-MC
Forwarding info:
From: CSVAX.upstill at Berkeley
From menlo70!hao!woods Tue Oct 13 17:45:03 1981
To: menlo70!ucbvax!upstill
GREG (ucbvax!menlo70!hao!woods)
I certainly hope not!!! If this species has any desire to survive,
and any intelligence, it won't carefully arrange that when the Sun
dies we'll all kill ourselves. Within 100 years, unless we do
something stupid like have a nuclear war or like declare it
illegal to go into space, we'll have an awful lot of our population
(more than a thousand, probably more than a million, possibly more
than 1E9) living in space colonies. Within another 100 years we'll
have colonies orbiting not just the Earth/Moon system but freely
orbiting the Sun. We'll also have some probes out to other nearby
stars such as Alpha Centauri, Epsilon Eridani, Tau Ceti, Barnards Star.
Within 1000 years we'll have colonies living around some of these
other stars. Within 10,000 years we'll have populated all the
major stars in our local part of the galaxy. Within 100,000 years
we will have filled the whole Milky Way galaxy, not stuffed full,
more like the pioneers of North America have now "filled" the
whole continent, "from sea to shining sea", plenty of living space,
just no major areas remaining that are untouched by man. Within
10,000,000 years (less if we can exceed 0.1 c) we'll have
populated the Andromeda galaxy (M31) too. Within 500,000,000
years we'll have accomplished my goal of conquering the "final
frontier", the whole Virgo supercluster of galaxies. Then in
about 5,000,000,000 years, when the Sun burns itself out, the
people living on Earth and in colonies around the Sun will have
to move to some other star or perish. (Those who colonized
faster-burning stars like Sirius will have to move much much sooner.
I'd worry about them not the people of Earth/Sol.)
------------------------------
From: MINSKY@MIT-AI
Date: 10/15/81 00:15:12
Subject: Booze Budget
MINSKY@MIT-AI 10/15/81 00:15:12 Re: Booze Budget
To: SPACE at MIT-AI
Of course, if one were to consider the cost of booze, in
illness and automobile accident and injury -- the latter
might come to the order of 50,000 deaths and crippling injuries
which at a cost of, say, 500,000 each -- adds a few real,
non-taxable costs.
------------------------------
End of SPACE Digest
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