Re: New space settlement article

From: Mike Combs (mikecombs_at_nospam.com_chg_nospam_2_ti)
Date: 06/28/04 

Date: Mon, 28 Jun 2004 13:06:00 -0500

"Sander Vesik" <sander@haldjas.folklore.ee> wrote in message
news:1088112445.957295@haldjas.folklore.ee...
>
> Null hypothesis:
> to cost the same per kW/h generated, the energy cost of a solar panel
> and its support structure must be more than launching it from Moon
> and de-accelerating it to GEO/HEO orbit.
>
> as any location of moon gets light 50% of time, you need 2x more solar
panels
> to generate the same power. Assuming we only care about solar panels and
their
> support structure, if launching from moon and de-acceleration to GEO / HEO
> costs more in energy than just making a second panel, then you are better
off
> if you don't launch.

A bit more than 2x, since lunar surface arrays would not always be able to
point at the sun optimally, but that's nit-picking and I take your point.

> If lunar aluminium extraction is as efficent as that on earth, getting
> aluminium from Moon to the SPS location should not cost more than
16KWh/kg,
> assuming 100% less efficent, 32KWh/kg. and thats payload mass.

But there are other factors, such as the fact that if we do the ore
reduction and materials proceessing in HEO, we can have continuous
operation, due to continuous availability of solar power. Cheaper
electrical costs due to solar availabilty should factor into construction
costs as well.

> Exporting
> regolith (that is, doing teh smelting in earth orbit) is at least six
> times worse.

I assume you're saying this since it would be 6 times the material to
process. But consider that there will be all kinds of useful materials
coming out of the lunar ore, such as oxygen. Even the leftover slag will be
usefull as radiation shielding.

> If using aluminium based solids, consider propellant to payload fractions.

No, I'd be the first to agree that the plan wouldn't be practical with this
or any other variety of rocketry. It's only practical assuming EM launch
with capture at the L-2 point.

> Fine, but all teh materials for the mission are coming from moon. So why
not
> also build everything on moon and have the crew redezvous with their deep
space
> vehicle in moon orbit? Why spend all teh energy to move teh large ship (or
> materials and consumables for it) to earth orbit and then away again? Why
not
> move a small capsule with the crew instead?

Not all of the materials would come from the moon; some percentage would
come from the Earth. One would have to strike a balance based on the two
issues. I was thinking HEO only because I was thinking about utilizing
infrastructure which was already set up there for other purposes, such as
the construction of SPS and orbiting habitats. But if HEO is too far down
the gravity well in your opinion, then I'd recommend the Earth-moon L-1
point as the staging area. That's well out of both gravity wells, and one
can do a boost maneuver around the Earth on the way out.

> Fine - its hard to argue that there will never be such. Whetever it
arrives
> before or other industry on say Moon is another matter, one that is not
quite
> that clear.

I base my opinion on the sole studies that NASA ever did on industrial use
of space resources. They suggested that lunar surface industry would only
happen when there was a requirement for products whose end use was on the
lunar surface.

> This is not a good metric.

There are many unknowns, I agree. And I also agree with your call for
mammalian testing.

But unknowns are not reason for confidence, they're reason for being
conservative with one's assumptions. 

-- 
Regards,
Mike Combs
----------------------------------------------------------------------
We should ask, critically and with appeal to the numbers, whether the
best site for a growing advancing industrial society is Earth, the
Moon, Mars, some other planet, or somewhere else entirely.
Surprisingly, the answer will be inescapable - the best site is
"somewhere else entirely."
   Gerard O'Neill - "The High Frontier"

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