"Kaido Kert" wrote in message
...

But selling a better future for people or their children,

NASA's been flying the Spinoffs flag for decades. People stopped believing
them years ago.

I once witnessed a speech made by the guy who invented teh high-pressure
turbopumps used in SSMEs. The guy was blatantly pimping for NASA, adn one of
the "future uses" he claimed for the shuttle was to act as "ambulances" to
take critically ill people to orbiting space hospitals. When I asked him
just how many critically ill people would survive the actual launch, he
replied that that was a myth, the shuttle was way smoother than Apollo, in
fact it pulled fewer Gs than a rollercoaster. To which I replied "okay, how
many critically ill people would survive a roller coaster ride?" Never got
an answer to that one...

either through
potential for clean energy sources from space ( SPS) ,

Bull****. utter bilge. SPS as a ground-based power supply is a massive
boondoggle.

Even the proponents of solar power satellites (or Space Solar Power, for
those trying to evade the subject) eventually have to admit that the launch
and operations costs of SPS are prohibitive, and always will be so as long
as we're stuck using chemical rockets.

To give you some idea: a single SPS would have to be roughly 20-25 square
miles. Has to be, no way to build 'em smaller and still beam enough power
down to Earth to mean anything.

Question: how do you send up enough material into GEO to build that first
SPS? Well, the current idea is to use "millions" (direct quote from several
SPS proponents) of individual modules, each of which is 500-600 feet across
when fully deployed. They get launched individually, then use something like
a solar-to-ion drive (similar to Deep Sace 1) to propel tehmselves into GEO,
where they attach themselves automatically to their fellow modules.
Eventually, the entire SPS is constructed and away we go.

Sounds like a plan, right? Wrong. Each "module" would be "very compact" and
"lightweight", of course. Powersat.com's plan seems to be fairly
representative of the general scheme. It calls for each module to stow into
a 36'x21' launch configuration. (which is too wide to fit in the shuttle
bay, btw, so you have to send it up on its own ELV).

Getting accurate, consistent numbers out of SPS studies is challenging at
best. Powersat.com claims that each module would deploy to be about 600 feet
across, in which case you would need about 2000 to form the entire receiver
(that's totally ignoring the transmitter, which itself is humongous, or the
rectenna on the ground). That's *two thousand* separate boosters just to get
the solar cells on orbit. And since their sales pitch claims that the SPS
would comprise "millions" of individual modules, I'm assuming that the
600x600 configuration is just to propel itself into GEO, at which point it
discards most of its mass.

So at bare minimum, you'd need several thousand launchers just to get the
space-based components for *one* SPS (which would only supply enough power
for *one* large city) into space.

Anybody out there think it's remotely feasible for anybody on Earth to
assemble, check out, and launch a couple thousand boosters within a 5-10
year span? Didn't think so.

Second, there's teh economics of SPS. Frankly, they suck. Even the
proponents of SPS admit that. An SPS would have startup costs roughly 150%
of a similar terrestrial power plant. And then, *maybe*, after 15-25 years
they could get the retail price of the electricity down to 7-10 cents per
kWH. But terrestrial power is currently about 5-6 cents. So *at best*, after
decades of development and improvement, the power from an SPS would be
40-60% more expensive than from a coal-fired or nuke plant. At *best*.

One of life's little ironies is that some of the more prominent space
advocates who criticize NASA because they way overhyped the performance and
profitability of the Shuttle are making *exactly* the same kind of utter
bull**** claims about SPS, and have been doing so for *exactly* the same
length of time that NASA has been bull****ting about the shuttle.

Funny, that...

--
Terrell Miller


"Very often, a 'free' feestock will still lead to a very expensive system.
One that is quite likely noncompetitive"
- Don Lancaster