[ExI] Gold

[Keith Henson]

On Fri, May 24, 2013 at 5:00 AM,  Eugen Leitl <eugen at leitl.org> wrote:

> Space is expensive. Space is really, really expensive.
> It costs about 0.4 MUSD/kg of payload to Moon and
> back, 0.5 MUSD/kg for Mars.

There is reason for travel into space to always be expensive, but
nothing like it is now.  The energy cost for going to GEO on a moving
cable space elevator is 14.75 kWh/kg.  At ten cents a kWh, that's
$1.475 per kg, at two cents it's 30 cents a kg.

I can make a case with a Skylon derived vehicle and laser propulsion
to get the cost to GEO well under $100/kg.  That's low enough that
power satellites can be used to make power at 2 cents per kWh using
materials from earth.

In such an environment the power satellites will eventually be using
1-10 million tons per year.  I have my doubts that that more than a
few million tons per year can be lifted off earth, even with
propulsion lasers, without having nasty environmental consequences.
That will drive the use of ETR, asteroids or lunar materials or both.

In the long run it becomes possible to mine asteroids for gold and
platinum group metals.  I ran very rough analysis of how to do it
here:

http://www.htyp.org/Mining_Asteroids

Keith