[extropy-chat] Space elevator numbers III

[Keith Henson]

At 02:11 PM 2/16/2007 +0000, Giorgio wrote:
>If robotics systems are still unavailable and sophidticated enough we wil 
>need a manned mision but that means higher costs and payloads
>Still is much less expensive to reach a NEO than the Moon, being a gravity 
>well

What's important is not the depth of the gravity well, but the cost 
(largely energy) to get out of it.  If you can get the efficiency high 
(which a mechanical space elevator does) and get the cost of energy low, 
gravity wells are not a problem.  As a matter of fact, if you are dropping 
more mass down the well than you are taking out, the system produces excess 
energy.

>We have all what we need at reachable lenght, we only need to grab it 
>forgetting, fo the time bieng,me being, the Moon and Mras , both gravity 
>wells and science fiction myths.
>we can reach them later with an affordable possibility to come back and to 
>develop a space economy but we must first build a space transportation 
>system with in situ materials

All that junk around the earth is "in situ" and we need it for the 
counterweight.  Certainly having this much infrastructure in GEO would make 
going after the other goodies the solar system has to offer much less 
expensive.

I don't *know* that this project is possible even in the engineering sense 
much less the business sense.  The main problem is the cable, this pulley 
design can use considerably lower strength cable than the magic 63 Gpa and 
still use mechanical power.  (how many pulley stages depends sensitively on 
the cable strength.)

Someone have a web site they could hang a 240k jpg on?

Keith