[ExI] Asteroidal mining was Nukes was less expensive energy

[Adrian Tymes]

On Mon, Sep 19, 2011 at 7:56 PM, Keith Henson <hkeithhenson at gmail.com> wrote:
> Have you ever worked the engineering numbers?  Dr. Eric Drexler and I
> have done some of them, as has Dr John Lewis of the University of
> Arizona.

Care to share them, then?

> Have you thought about how big these need to be?  I can make a case
> for one massing 50,000 tons, incorporating a 5-10 GW power satellite
> and manned by 500 people.  I expect this plant to make it's own mass
> in product (nickel) in around 50 days.  It's really not obvious to me
> how to scale it down or operate it with a few hours of delay in the
> control loop.

That seems excessive to me*, but let's take that as a starting point.  How
do the 500 people break down?  What are their tasks?  On what basis
do you say that each task requires that many people?  How is that 5-10
GW power budget, and 50 Kton mass budget, allocated?  How do you
figure that mass production rate?

* There are mines on Earth that operate with less than 25 employees.
Even accounting for oil platform style operations, life support technicians,
power plant technicians, and so on, a 20-fold increase in the minimum
possible staffing level suggests there may be unexamined ways to
optimize or scale down operations.

As to the delay - this is one of the reasons I favor gathering asteroids at
the Lagrange points or in lunar orbit.  (Not to mention, delta-v.  If you're
going to wind up using all or most of the asteroid's mass, then you're
eventually going to need to provide the delta-v to move it anyway.  Plus,
if the processing facility masses a significant fraction of any one asteroid,
then not moving the facility saves delta-v - making it possible to, say,
start by moving a small asteroid to the facility, and scale up by gathering
more small asteroids, then eventually start mining big ones worth
$billions.)

BTW, it is of note that, even on Earth, "fully automated" mines (as in,
no one on-site) are only recently becoming a reality.  See
http://www.theaustralian.com.au/business/mining-energy/rio-to-trial-automated-mining/story-e6frg9df-1111115351260

One might consider contracting development of the mining & processing
plant to Rio Tinto or similar.  Yes, it's in space, zero gravity, no air, and
so on - but the basic problems in designing, constructing, and operating
such a facility seem more similar to those of automated mines on Earth
than to, say, rockets.

> I am trying not to be snarkey because if you really have good idea on
> how to do this, I would like to help.

A "good idea" usually won't have the kind of advanced analysis you're
asking for, if it's really just an idea and not something with a lot of
money already invested (at which point, if you want to help, you apply
for employment with the entity).

If a version of this that you've worked on already does have that
analysis, OTOH, then deriving from that and seeing how to scale it
down might be useful.