Iron outside = Iron inside

Hi Ron,

I must admit I found that a very interesting little list. It isn't
something you come across very often.

Best wishes, Andy.

rmenich@... wrote:

>
> Ian: NEVER MIND.
>
> I found http://chemicool.com/elements/ :
>
> Xenon, $1200/kg
> Oxygen, $3/kg
> Nitrogen, $4/kg
> Neon, $330/kg
> Hydrogen, $120/kg
> Helium, $52/kg
>
> Ron Menich
> ************************
>
> rmenich@...
To:
09/27/01 08:20 AM spacesettlers@yahoogroups.com
Please respond to cc:
spacesettlers Subject: Re: [spacesettlers]
Iron outside = Iron inside
>
> Ian Woollard wrote,
>
> "Also, Hall effect thrusters can run on less exotic propellents; i.e.
> cheaper. xenon is *very* expensive."
>
> How much does a kilogram of liquid xenon cost? How much more
> expensive is liquid xenon than, say, liquid oxygen?
>
> Ron Menich
>
> Ian Woollard
To:
spacesettlers@yahoogroups.com
09/26/01 09:45 PM cc:
Please respond to Subject: Re:
spacesettlers [spacesettlers] Iron outside = Iron
inside
>
> Al Globus wrote:
>
> > I would like to re-introduce a completely different approach to
> asteroid
> > mining to this group. See
> > http://www.nas.nasa.gov/~globus/papers/AsterAnts/paper.html. Basic
> idea:
> > find very small asteroids (~1 meter diameter) and return the whole
> thing
> > to Earth orbit. Use a large fleet of solar sail powered spacecraft
> to
> > get large amounts of returned mass. Using a large fleet gives you
> > economies of manufacturing scale and failure tolerance. Returning
> whole
> > asteroids avoids the uncertainties of rock mining.
>
> FWIW: I *really* like this idea, Al.
>
> The only comment I have is have you run the numbers with a low ISP
> ion drive instead of the sail? I'm think an ISP around ~1000
> seconds, but I don't know of any quite that low, Hall effect
> thrusters can go down to 1200 seconds; (but I'm not sure of the
> efficiency at that power). The idea of using a low ISP ion drive is
> that the thrust is much higher and you may even have enough power
> to run several drives in parallel; they'd use more propellent but
> not necessarily an impossible amount. Also, Hall effect thrusters
> can run on less exotic propellents; i.e. cheaper. xenon is *very*
> expensive.
>
> It might even be a project you could run in the very near term in a
> smaller way- with DS1 so successful, it would be a good time to
> raise it I think.
>
> --
> - Ian Woollard (ian.woollard@...)
>
> "Is a planetary surface the right place for an expanding
> technological civilization?"
> - Gerard O'Neill

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