Mars vs Belt

Sander Vesik wrote:
Hop David wrote:


I see three stages:

1) The first asteroid colonists will simulate gravity by spinning two
small habs on the ends of a tether like a bolo.


broadly agreed - though I think 'hab' might be a bit big for the initial
versions, which probably be just two apartment sized 'things' at the ends
of a tether.


Does "hab" connote something large? I had in mind something like you
describe.



"stacked" tori have iirc quite a lot of drawbacks, I can't imagine wanting
more than 3-5 stacked.

What are the drawbacks?

Some of the advantages:

Smaller surface to volume ratio over time. (You could take down the
walls separating the tori and use material elsewhere)

As the torus lengthens you could have more open spaces. It would be less
cramped and more comfortable.

So I think step 3 will be:

3) peopel lkiving in the cluster of smaller tori build the
scaffolding of a large torus, fill out only 4-5 sections
and migrate from teh small tori to the large, continuing
to build it.

Of course, after some time you might get "tori building" toruses, with
the picture changing a lot.


Hop
http://clowder.net/hop/index.html

In article ,
Hop David wrote:

Minimal local "AI" (just enough to call for help when it hits trouble)
and remote guidance.
4 lunar distances is an extremely close fly by as NEAs go. Realtime
Teleoperation isn't possible.

Not realtime. Basically, look around, order the mining package to crawl
around a little, take seismic readings to find a good spot, and clamp
down. Work out a drilling plan from seismic readings, and set the mine
on autopilot. If the miner runs into something unexpected, stop and
contact home base for instructions.


Once you pick a place for the mine to clamp itself
down to the surface and start drilling, it be almost entirely automated.

Even drilling an ordinary well in nice earth conditions can be a pain in
the butt. (My brother-in-law has a broken drill bit that's been sitting
at the bottom of a hole for a few years. He still doesn't have his
windmill).

These mining packages will obviously have higher specifications and
backup parts. And there would be multiple ones in operation at any one
time. The odds are high some will fail, that has to be taken into
account. An atmosphere processor also has ways to fail, though I admit
it is an easier thing to engineer.


Drilling down to frozen volatiles, melting them and sending them up is a
much more complicated endeavor. How big is your drill bit? Is it's
diameter larger than the nuclear reactor you hope to send down?

A fully automated mission to do this would be very ambitious, in my opinion.

Anything of this sort will be "ambitious". I think it's possible to do
with current technology, though.


Land a few mines, set them up,

Would they be set up by humans? How long would it take? How long do you
think they could stay on an asteroid and still have an affordable return
to earth?

They could be set up remotely. Maybe a few weeks, to crawl to a stable
location and clamp down. They'd stay on the asteroid indefinitely, drill
a few holes, and be abandoned when they ran out of tanks to contain
volatiles or break down. Simple one-shot jobs, a half-dozen or so
scattered around the asteroid, so it's no big deal if something goes
wrong with some of them.


Dissipation can take awhile. Comets can outgas for a long time before
going extinct. When the Wilson Harrington comet stopped outgassing it
was lost and later discovered as asteroid 1979 VA. It is thought that
the dissipation leaves a tarry crust on the asteroid that insulates the
interior. Liquid pressurized pockets within a tarry shell are
conceivable during the asteroid's warmer times.

A hydrocarbon pitch or tar could hold liquid or semiliquid substances...


I'm talking about ices and hydrates in a stony-iron asteroid.

Volatiles would be less abundant and more difficult to get
from a stoney iron than a dead comet. And without volatiles
above earth's gravity well, delta v would be cost prohibitive
even if an asteroid is solid gold. You're going to need the delta v
first. That is why 1979 VA, Nereus and other possible dead comets are
more interesting.

A dead comet would be ideal for harvesting volatiles, and easier to
drill. However, I think its likely that most asteroids also contain a
fair amount of volatiles. Those with less will need to bring more gas
with them to blow stuff out of the hole.

--
Christopher James Huff
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG:
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