[extropy-chat] Space elevator numbers III

[David Masten]

On Thu, 2007-02-15 at 17:13 -0500, Keith Henson wrote:
> Yep.  Prices have to come down to cents per kg from thousands of dollars a 
> gram.  But nobody has yet given a serious look at the iron process, which 
> looks like (if it works) would cost a few cents per kg to make nanotubes.

How well does the iron process do in terms of flaws in the fiber? The
last presentation I saw on carbon nanotubes was that this was the crux
of the problem.

> This puppy is sized at 2000 tons per day capacity to GEO, with the ability 
> to double that in 100 days.  The Saturn 5 could put maybe 50 tons in 
> GEO?  You thinking about 40 of those a *day*? 

Sure, the only why not is $$. If the rocket industry can deliver
reusable once-around launch vehicles (like the USAF is asking for), you
are looking at 10 tons/vehicle per mission to LEO, mission duration plus
turnaround at 4 hours, so 6 per day (3 shifts). Allow a few vehicles out
at any time for maintenance, so say 40 launchers. Probably 120 LEO-GEO
tugs. I think that puts the whole operation on par with an airline.
Launchers and tugs have a cost to build in line with airliners. So, the
capitalization required is doable, now. That leaves us with a practical
technology problem, which I would submit is much easier than the
practical technology problem(s) of a tether.

>  This thing runs on electric 
> power in the high 90 percent efficient.  Is there any way for rockets to do 
> that?

I have always been under the impression that electric motors are much
less efficient than chemical motors. Am I not recalling correctly, or
are you talking about a different efficiency rating, or something else?

Dave