[extropy-chat] Space elevator numbers III

[Keith Henson]

At 01:01 PM 2/15/2007 -0800, Dave wrote:

snip

>Not to mention the materials science and economics.
>
>I'd place the odds of having a terrestrial tether system of any sort
>operational within the next 20 years at around one in a million.

If we never start, the odds are worse than that.

>Here is
>my reasoning: The mechanics of a really long tether requires near
>perfect carbon nanotube technology (or equivalent). The problem right
>now is getting the nanotubes with minimal inclusions, at a sufficient
>length, in large quantities. There are some real challenges here.

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.

>Then there is the economics: any advances in material sciences towards a
>tether are also advances toward cheaper rocket launch capability. As
>best as I can tell, tether systems are only marginally better

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

>than
>current, traditional launch systems, so any improvements to rocket
>launch vehicles make rockets better than tethers. My bet is on cheap
>rocket launch, which is why I started Masten Space Systems.

Ah, well, consider this.  If this project is done, there is going to be a 
*massive* need for rockets and ion tugs for a number of years to support 
orbital cleaning operations.

Keith