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From: dietz@SLB-DOLL.CSNET (Paul Dietz)
Newsgroups: net.space
Subject: Re:  Contribution to 'scuttle the Shuttle' debate.
Message-ID: <8602131520.AA03002@s1-b.arpa>
Date: Thu, 13-Feb-86 07:29:06 EST
Article-I.D.: s1-b.8602131520.AA03002
Posted: Thu Feb 13 07:29:06 1986
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>(1) It wasn't NSA, it was OTA, that did the SPS study, and it showed that
>SPS would breakeven in 25 years.

I believe it was NAS (not NSA) that did the study.  Even under very
favorable assumptions (low interest rates, $10/lb to orbit launchers)
SPS was only just competitive.  NASA has no plan at all to make a $10/lb
to orbit launcher anytime soon (certainly not in 25 years).  Was that
breakeven point the PAYBACK time on the construction costs?

>(2) I had heard that story about Gold, but I'd hesitated to mention it:
>it seemed to much like ad hominem criticism "Gold is the nut that thinks
>that the earth's a large methane ball..."

The theory is certainly controversial, but that doesn't mean it's
wrong (do not take this as an endorsement of the theory).  See the
Feb. 86 issue of The Atlantic magazine for a (biased) review of Gold's
ideas.  Wrong or not, because of this (and because of the generally
poor reputation of SPS in the non-rabid-space-fan community) Gold
would, I think, disagree that SPS will be important in 20 years.

>(3) I would be very surprised if we could get 10^8 transistors on a (~)
>1 cm x 1 cm chip.  At 1 micron cmos, we can get about 5E5; to get to
>1E8, we'd need to go to about 10 nanometer feature size, with appropriate
>scaling on things like well size.   At that point, quantum effects start
>to really screw you.

The Japanese think they can push DRAM technology to at least 64 megabits
per chip, using smaller feature sizes, trenched capacitors and vertical
cells, and other tricks.  A review article on semiconductor trends in
Science a few years ago predicted a quarter billion transistors on a
chip by the end of the century.  That's less than 25 years away, so I'm
being conservative.

>(4) AI hasn't done appreciably better in the decade 1975-85, which saw
>a hundredfold increase in logic chip densities.  Why do you think that's
>going to change?

Where did I mention AI?

>(5) Manipulators aren't that light.  I'm not at all sure that
>human + life-support + fail-safe is all that much heavier than even a dumb
>teleoperator.

The arms are fairly light, and can be built of graphite composites (say)
for space applications.  In space the arms need not support large static
loads, giving further weight savings.  How much does the shuttle arm
weigh, for example?  I think you really must provide some justification
on this one.

>My argument is that there's a lot waiting for us in space, and there will be
>more in the future.  For that future, we SHOULD develop teleoperators of
>the sort you've mentioned, and of the sort of I've mentioned in messages to
>you.  We should also work, hard, on reducing costs to orbit: I agree that
>that's the primary task.  We should also develop an manned infrastructure in
>space so that we'll be able to do those things I've mentioned, whether the
>teleoperators are here or not.

In a world of unlimited resources, we could do this.  Resources are
restricted, we have to focus on the critical paths.  Putting men in
space now is not, in my opinion, on the critical path.

>  Hence the question
>is, do we get more for $8G of manned spaceflight or a much smaller amount
>of spending on other research?  I think the answer is clear.

What you mean "research"?  Money spent on manned spaceflight is (now)
operating costs, and doesn't produce much in the way of new scientific
or technical information.

>Your argument and Gold's is based on a false premise, anyway: namely, that
>there's some choice between manned and unmanned programs.

I'll remember that as I watch the TV pictures coming back from the NASA
Halley probe (whether such probes have been well directed is also
a good question; complex probes to the outer planets are probably not
needed for space exploitation anytime soon).

I don't believe in throwing money at space.  I believe in spending money
to achieve good solutions to well thought-out goals.  I don't think a
space station fits this description.  Research and development of
teleoperators would.