On the colonization of space

From: Michael Capriola [mailto:capcartoonist@...]

"But there is speculation that mining near Earth asteroids could be the
first step. An iron-nickel asteroid of diameter 1 km or so could be worth 30
trillion dollars. Mine the near Earth asteroids, build factories in orbit
around the Earth, ship the goods planetside."

The M-class (metallic) types get all the glory but there are other
asteroid types that offer things we might need first, to create the
infrastructure to allow us to go after that incredible wealth. I posted this
to another list a while back. As you might gather from the context, the
discussion was about why some folks favour the NEOs over a return to Luna
for resources...
The NEOs offer resources the Moon doesn't have. A carbonaceous chondrite
asteroid (the most common variety) contains from 5% to 20% water: an easier
source of oxygen, as well as hydrogen that's not available on the Moon. The
total amount of volatile materials from the asteroid ranges from 20% to 40%,
including nitrogen: needed for creating viable atmospheres in habitats, as
well as for fertilizer. Lunar regolith, by comparison, contains between .01%
and .02%, some two *thousand* times less. The asteroidal material left over
after these volatiles are extracted is of considerable value itself. Using
autoreduction to extract the organic carbon from the magnetite will leave a
residue of about 30% ferrous metal alloy. Lunar regolith, by comparison, has
about 0.1% free metal. This time, the asteroid is *only* three hundred
times richer! Now, let's take what's left of our asteroid, and use
some of the water we already extracted to leach out a wide array of
water-soluble salts, rich in sodium, potassium, halogens, and sulphates.
These can be used to produce valuable industrial chemicals: acids, bases,
halogens, sulphur, etc. The residual `slag' left over after all this is a
dry silicate that's very similar to average Lunar regolith! That's right;
the stuff you throw away from asteroid mining is what you'd *start with*
mining the Moon. The slag could then be used for radiation shielding for
space habitats, and/or ablative material for aerobraking material to the
Earth's surface.

That's just what the CC asteroids offer. There are several other classes,
with a wide variety of resources that either aren't available on the Moon at
all, or are only available in small amounts, and are usually more difficult
to extract. The advantages of the micro-G and zero-G processing available
for asteroid mining, vs. the more conventional mining techniques that'd be
used on the Moon, are yet another reason I feel the NEOs are the better
choice.

Dave