From: vince@offshore.ai (Vincent Cate)
Newsgroups: sci.space.tech
Subject: Re: Incoming!!!
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cray74@hotmail.com (Mike Miller) wrote in message news:<5dcb47db.0405050742.1240f1a7@posting.google.com>...
> vince@offshore.ai (Vincent Cate) wrote in message news:<9186edb5.0404290713.cdced66@posting.google.com>...
> > With a rotating tether exchanging the momentum of raw materials
> > coming down with finished products going up, it would not be
> > all that costly to bring them down. 
> 
> That's one reason I'm trying to avoid rotating tethers: in the
> scenario I'm working with, there's not a lot coming back up, where "a
> lot" is defined as "enough to balance the momentum of kilotons and
> megatons of metal going down."

I doubt your scenario would ever happen for long in the real world.
With a rotating tether and plenty of metal going down, the cost
to get into orbit would be near the cost of operating a reusable 
suborbital rocket.  This should be very small, like $10/lb.
Today people are paying like $2,000/lb to get to orbit.
At $10/lb I think you would see solar power stations being
built and people colonizing the moon/orbit/asteroids in large 
numbers.  You would have megatons of traffic going up.  At $10/lb,
megatons of traffic would only be a market of tens of billions.  
The current launch market is multiple billions already. 

Also, some of this up traffic would be wanting to buy metal
and shielding mass in orbit.  So you would be growing the 
orbital market for the asteroid products.  So a wise asteroid
miner would be cooperative with the tether folks.  As the
orbital market grows you may not need to send as much down.

However, there could be a ramp up time where the up demand was less,
so it would be good to have another reentry method,
like foamed metal.

  -- Vince