[extropy-chat] Space elevator numbers III

Keith Henson hkhenson at rogers.com
Fri Feb 16 15:16:34 UTC 2007

At 12:13 PM 2/16/2007 +0000, Giorgio wrote:

>I believe that something is extremely flawed on this entire concept.
>While I strongly agree that a space elevator could certainly be a benefit 
>in a long run strategy for space missions, I also believe that our 
>strategical approach to space development is wrong and that is the cause 
>of all the major setbacks that we have since the Apollo days.
>Our entire space strategy is based in sending,for now very limited 
>payloads at unaffordable costs from the bottom of a deep gravity well, The 
>earth, to other gravity wells, Moon or Mars .
>The new Vision plans, Orion and Ares are nothing more than a revised 
>Apollo and Saturn missions , fifty years later , putting aside all the 
>experience and knowhow that the shuttle and ISS, despite their basically 
>failure, has obtained.
>Let's suppose that we are a Kardashev 3 society.
>How would they approach the development of a new planetary system?
>They would be coming with a "mother ship" with all their knowhow aand 
>technology , they would utilize the most easily available materials for 
>their requirements (comets and asteroids without costly gravity wells) and 
>would deploy the required missions , first unmanned ,later , if possible, 
>manned to the most interesting bodies.
>We are not yet at Kardashev 1 level, we don't have a Mother ship and 
>everything must come from the bottom of a deep gravity well:
>So what it means all the above?
>it means that we could develop the same capability , changing our startegy 
>from the current earth-based  to a new space based approach.

I was one of the founders of the L5 Society.  You don't need to convince me 
of the value of extra terrestrial resources, but you might be interested in 
the history of why the space colony idea failed.  Freeman Dyson analyzed it 
in in _Disturbing the Unverse_.  He analyzed the Plymouth colony and the 
Mormon colonization of Utah.

The reason space colonies were not going to happen was that transport into 
space was *10,000* times to expensive for families to afford it.

*If* the space elevator is built and amortized for a massive SPS project, 
then transportation up to GEO depends mainly on energy cost.  A Gw day will 
lift 2000 tons, that's 24 million kwh.  At 5 cents a kwh, that 1.2 million 
dollars, and bus bar power from a rectenna might go as low as 1/5 of that.

If you figure a family of 4 plus household goods at 5 tons, it will cost 
them $15,000 for the lift to GEO, and might get down to $3000.  That's well 
inside Dyson's figure of 2 years of income.

>That can be done in the following phases:
>Phase 1-Rendez vous with a small ( 100 m ) water rich NEO asteroid
>  mine it and utilize its minerals to manufacture , automatically,


That's the key problem.  Nobody has any engineering experience with 
automatic manufacturing from dirt up.  I am (or was) a working engineer 
with wide experience and I wouldn't know where to start. If the Mars 
Society were to dump a package where they have their habitats and build 
even a small house without human labor input that would be an interesting 

I am a bit amused at the opposition to the space elevator from this 
group.  Perhaps it is to serious a proposal.  I don't want to live an 
energy poor lifestyle and if you think about it, I doubt you do either.

Keith Henson

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