[extropy-chat] Space elevator numbers IV

[Keith Henson]

A. Where do you put the anchor point?

It has to be on the equator for the most reasonable configurations.  The 
most storm free section along the equator is in the Western Pacific.  It 
happens that the US territorial limits come within a mile of the equator to 
the south of Baker Island.

http://en.wikipedia.org/wiki/Baker_Island

If the project was to be based legally in the US that might be important.

It could be attached anywhere on the equator.  The second one might be in 
Equator, Sumatra, or some location in Africa.  Having several as soon as 
possible is a *good idea.*  Even if you clean up all the manmade orbital 
junk, a flying rock is going to cut it sooner or later.

B.  What do use for the anchor point?

My suggestion is the aircraft carrier Enterprise.

Full out, its 8 reactors put out 210 Mw.  That's enough to bootstrap up 
most of the way to the 2000 ton per day level.  The Enterprise is to be 
retired about the time it would be needed for this project so getting the 
use of it isn't out of the question.

C.  How do you put up the bootstrap strand.

Well, *before* you do, you need to clean out most of the junk in lower 
orbits, *including* the space station and Hubble.  Ion engine tugs remotely 
operated seem like they would work.  There are something like 10,000 
pieces, most of them small.  Probably 200 tugs, most of them rather small 
would do the job in a few years.  (Small tugs would gather up the small 
chunks and when they had a large load, meet up with a larger tug.  It will 
be an interesting computational planning project.)

Since you need mass for the counterweight, you want to push it out to GEO 
rather than dump it into the atmosphere.

Once the big stuff is out of the way, you put up a few shuttle loads of 
nanotube string and push it to GEO.  Then deploy, stringing pulleys as 
needed.  Brad Edwards:

"proposes that a single hair-like 18 metric ton (20 short ton) 'seed' cable 
be deployed in the traditional way, giving a very lightweight elevator with 
very little lifting capacity.

"Then, progressively heavier cables would be pulled up from the ground 
along it, repeatedly strengthening it until the elevator reaches the 
required mass and strength. This is much the same technique used to build 
suspension bridges.

"Although 18 tonnes for a seed cable may sound like a lot, it would 
actually be very lightweight — the proposed average mass is about 0.2 
kilogram per kilometer. Conventional copper telephone wires running to 
consumer homes weigh about 4 kg/km."

http://en.wikipedia.org/wiki/Space_elevator