Asteroid use

--- bill t wrote:
> > >
> > MW: This is pretty old news. Viking spacecraft
> back in
> > the 1970s found naturally radioactive isotopes of
> > uranium, thorium and potassium in the marsian soil
> in
> > proportions similar to those found in terrestrial
> > soils. But if you need an online reference, you
> might
> > want to check Britannica.com at the following URL:
>
> Bill: That porportions in terrestrial soil is in the
part
> per billion. You
> do know that don't you?

MW: Oh! I forgot. Humans don't mine uranium and
thorium on Earth :-). Carolina beach sands, by the
way, are almost 10% thorium.
>
> > MW: Hydrogen is lighter than carbon dioxide Bill
> and
> > hydogen derigibles have been proposed for Mars
> since
> > the 1960s even by Arthur C. Clarke. And although
> the
> > marsian atmosphere is thin, you can even design
> > aircraft for aerodynamic lift on Mars.
>
> Bill: Yes hydrogen is lighter than CO2. the lifting
power
> of a balloon is
> porportional to the pressure difference as well as
> the mass. To move a
> tonne on Mars you will need balloons half a
> kilometer in diameter.

MW: McKay wrote an interesting paper on this subject
back in 1985:

"Airships for Martian Surface Exploration," AAS
84-176, W. Mitchell Clapp, The Case for Mars II,
Christopher McKay, editor, 1985, pp. 489-496; paper
presented at the second Case for Mars Conference in
Boulder, Colorado, July 10-14, 1984.

Clapp, with Massachusetts Institute of Technology,
compares performance of balloons, airplanes, and
dirigibles on Mars and finds that a hybrid dirigible
deriving 15 percent of its lift from buoyancy and the
remainder from aerodynamic lift offers advantages over
fixed-winged aircraft using aerodynamic lift only and
balloons using buoyancy only. Clapp assumes for his
calculations that all three vehicles will use a
20-kilogram, 15-horsepower piston engine burning
hydrazine fuel and nitrogen tetroxide oxidizer. He
reports that, while the airplane is fastest (136 knots
versus 50 for the dirigible and 10 for
the balloon), the delta-shaped dirigible can lift more
payload than either of its rivals, yet is more compact
(38 meters across its largest dimension, compared to
42 meters for the airplane and 50 meters for the
balloon). Of the dirigible's weight, 17 percent can be
payload, compared to 4 percent for the airplane and
3.5 percent for the balloon. He finds that the
dirigible's horizontal top surfaces are large enough
to mount sufficient solar cells to drive its
propellers electrically, providing indefinite range.
Because no prepared runway is likely to be available
away from the Mars surface base, both the airplane and
the dirigible need vertical takeoff and landing (VTOL)
rocket motors - however, the dirigible's VTOL motors
use less fuel.
>
> > > MW: That would only be true if you purchased
> your
> > material for your solar pannel from one of my Mars
> > orbiting asteroid processing stations. But if your
> > getting your material from the Earth or the moon
> then
> > its going to be a lot more expensive.
>
> Bill: Your Mars colony doesn't exist. And I would be
> manufacturing my own
> turbo generators, and using a solar furnace to drive
> a regular rankine
> cycle electric generating system.
>
MW: Neither does your roving asteroid processing
station.
>
> > > Bill: Antarctica has all the resource for
> > constructing
> > > buildings and
> > > biodomes on earth, so why is everything shipped
> in
> > > pre-built? Because
> > > the industry required to go from mines to
> finished
> > > products requires
> > > large amount of physical effort, energy and
> > > machinery.
> > >
> > MW: No one wants to live in Antarctica. And
> Antarctica
> > is a natural wonder that shouldn't be exploited
> > anyway.
>
>Bill: I don't see many people lining up to living on
Mars
> either.
>
MW; A lot more folks would like to work on Mars for a
few years to make a fortune in the asteroid process
industry than to work on some lonely asteroid. And
Mars would even have tourist.

> >
> > MW: Living on an asteroid would be much more
> > deleterious to your health than livining on the
> > surface of Mars. I guarantee you that there would
> be
> > at least a hundred times as many people who would
> be
> > willing to work in the asteroid processing
> industry on
> > the surface of Mars than who would want to work
> in
> > that same industry on some lonely asteroid-- even
> as
> > large as Ceres. Your labor cost are going to be
> > extremely high.
> >
> Bill: You said the above three or four times now
without
> providing any
> proof.
>
MW: Lets see. How many science books, novels, and
movies have there been about going to Mars. If you're
not aware that there has always been a yerning by
people to visit Mars in human culture then I guess
you've been living in a hollowed asteroid :-).
> > >
> > MW: I'll sell you the material for your enterprise
> > from my marsian orbital asteroid processing
> factories
> > so you can keep your cost down.
>
>Bill: There won't be any enterprise on Mars unless
you
> start giving better
> reasons to start one.
>
MW; I've given you my reasons (in detail)-- over and
over again.
> > >
> > MW: Asteroids are the key to affordably producing
> > large O'neill type colonies. And the cheapest
> place to
> > process asteroids on a massive scale is in Mars
> > orbit. The next best place would probably be
> Ceres.
> > But once O'neill colonies are built with asteroid
> > processing plants of their own, these colonies
> will
> > dominate asteroid processing in the solar system.
> And
> > I suspect that this may begin to happen around
> 2050
> > after the first O'Neill colonies are built out of
> > asteroid materials processed in marsian orbit.
> >
> Bill: You still haven't convinced me that Mars is a
place
> worth going to. In
> fact you have given many reasons not to ever go
> there.
>
> Bill

MW: I don't have to. The hard facts speak for
themselves. But if you want to believe that
transporting humans around the solar system-- every
time you want to process a single asteroid-- is
cheaper than an unmanned machine that simply captures
an asteroid (and could get there at least ten times
faster than your roving manned factory) and delivers
it directly to an automated factory, then so be it. I
have no problem with that.

Marcel F.Williams
1/7/01