From: szabo@techbook.com (Nick Szabo)
Newsgroups: sci.space
Subject: Re: SPS feasibility
Date: 20 Aug 92 09:40:44 GMT
Article-I.D.: techbook.1992Aug20.094044.7554
Distribution: sci
Organization: TECHbooks --- Public Access UNIX --- (503) 644-8135

In article <Bsy0K5.MEF.1@cs.cmu.edu> 18084TM@msu.edu (Tom) writes:

>[SPS & launch cost]

The cheapest launch is still Ariane, $25,00/max. kg to GEO.  At 
100 kg/kw the cost of launching a 1-GW SPS is $2,500 billion at 
that rate, three orders of magnitude higher than Earthside 1-GW
plants for the launch costs alone.

>Even at $700.oo, we'd see
>remarkable increases in space activity, including, among other
>things, attempts to answer those questions at the heart of the SPS
>debate on this thread.

At even half today's cost, $12,000/kg to GEO, large-scale direct broadcast and 
mobile satellites in GEO become feasible, as well as a much greater 
climate monitoring and military observation & communications presence.  
These high-power satellites can eventually evolve into SPS, but a factor
of 1,000 is a much longer way to go than a factor of 2.

Tapping native resources -- comet or asteroid ices, Martian
CO2 and ices, regoliths, etc. -- for space propellant, construction and
raw materials will become economical sooner.  cf. especially my
ice-rocket proposal, which could be economical at half today's launch
costs if we find ice in the Apollos or Phobos/Deimos or with a
high-energy stage to Jupiter-family comets.

The main market will be materials substitution for current 
satellites -- the redesign of communications & observations
platforms made from mostly native products.  Once this kind of industry
is in space, tapping platinum from metal asteroid regoliths and 
alluvial gold ores on Mars (if they exist) becomes economical. The
largest market is probably microgravity and vacuum manufacturing using
native materials.  Those markets alone could give us $200 billion/year
in industry, fourteen times the current NASA budget and run by private
industry.  At some later point, with _very_ mature space industry, 
we can start building SPS from native materials captured into GEO and 
this could be quite competitive beamed to Earth.  But it must follow on a
series of intermediate evolutionary steps, each of which can generate
large amounts of revenue and space industrial capability in their own right.

>Serously, wouldn't a drop in launch costs by only a factor of ten imply,
>maybe even necessitate, a corresponding increase in space activity?
>How about a factor of 2?

I suspect that the ratio is on the opposite side, that a factor of 2
decrease in launch costs would bring a factor of 4 increase in space
industry.  We've more than tripled the comsat industry in the last
decade just from the very modest gains made by Ariane over Delta
and Atlas, combined with value/lb. advances in the communications 
payload itself.

>Imagine how cheap shuttle launches would
>be if the workers were paid comparably to Arabian oil workers. 

Imagine how expensive Saudi oil would be if the oilfield workers cost 
the same as astronauts, $10 million per hour.  :-(

>Sure, we'll continue designing and modelling, and finding
>cheaper ways to do it.  But oil is fundamentally limited.  It will become
>permanantly more expensive, possibly in our life-times.

Doubtful.  Oil prices have been at or near their all-time lows since 
the mid-1980s, so if there is any long-term price trend it is down, not up.

Saudi oil costs $3/barrel to pump.  But elsewhere is more expensive
so it sells for $20/barrel on the market.  If we can get a reasonably
export-tax-free market in Siberia, that oil could be pumped for less than
$10/barrel at least through 2030.  After that, there are many other
kinds of deposits (tar sands, etc.) as well as synfuels from coal,
natural gas, and/or biomass that could be tapped for less than
$40/barrel with today's technology, and probably less than $20/barrel
with 2030 technology.  Even $40/barrel would less than double the cost 
of gasoline at the pump (most of the retial cost is refining and taxes).  The 
major constraint on fossils is probably global warming from CO2, not supply.

>[The argument] seems more along the lines of "SPS will never be worth it." 

My argument is that there are many other kinds of space industries that
will be economical long before SPS, and they can provide us the money
and industrial capability to build SPS and habitats in space.  SPS may or
may not ever be competitive for Earthside power.  We should
concentrate on those intermediate industries, and start by working to
expand the industries we have now.


-- 
szabo@techbook.COM  Public Access User --- Not affiliated with TECHbooks
Public Access UNIX and Internet at (503) 644-8135 (1200/2400, N81)