[ExI] The L5 Society ( was: EP and Peak oil.)

[hkhenson]

At 10:31 AM 4/10/2008, you wrote:
>"Keith Henson" <hkeithhenson at gmail.com>
>
> > I just finished working out the numbers for using 200 times reusable
> > rockets about twice the size of a Saturn V.  To my surprise the energy
> > payback works out to 15 days and it takes 3 power sats to provide the
> > propellants.
>
>That is a perfect example of a statistic

It's not a statistic.  I.e., it does not derive from statistical data.

>that may be true but is totally
>irrelevant; the fuel costs are a trivial aspect of the cost to get into
>geosynchronous orbit.

That's true at present, but in a mature system it would not be 
true.  Ask the airlines what part of their costs is fuel.

>Right now just the launch costs would be close
>to a trillion dollars per satellite,

Which is why it isn't being done.

>that's just to put it in the proper
>place, and that's not counting on the fact that then you've still got to
>actually build the thing.

Big they are, complicated they are not.

>You're going to have to figure out a way that
>is one hell of a lot cheaper than that and I don't see how ground
>launch from Earth can do it.

http://www.ilr.tu-berlin.de/koelle/Neptun/NEP2015.pdf

>And just how "reusable" is this giant rocket going to be? Are you going to
>carry a heavy heat shield all the way up to geosynchronous orbit and then
>carry it all the way back down to earth again?

I guess they carry 39 tons of water that provides the heat shield 
cooling while they are coming back down, but I really don't know.

>Maybe I just get paranoid
>when I hear the word "reusable"; the Space Shuttle was originally
>supposed to be reusable every 2 weeks but that turned into a joke.

It's not impossible.  A private rocket flew twice in ten days or so.

Keith