Re: More Space Elevator news

From: Stefan Dobrev (hot_esteban_at_hotmail.com)
Date: 07/13/04 

Date: 13 Jul 2004 06:15:41 -0700

schillin@spock.usc.edu (John Schilling) wrote in message news:<ccv5r7$69o$1@spock.usc.edu>...
> "Pete Lynn" <pete@peterlynnkites.com> writes:
I will add just a clueless comment by an outsider.
 
...
> >> The assumption that a space elevator will exist, and provide
> >> commercial transportation services to GEO, but that rockets will be
> >> providing *cheaper* transportation to LEO, that I'd bet seriously
> >> against, ever.
>
> >Work the numbers.
>
> OK. The energy requirement to lift a kilogram to GEO along a beanstalk
> is a hair over 48 megajoules/kilogram. Assuming 50% efficiency in the
> power beaming and 50% efficiency in the drive system, that's 53 kW-h/kg
> at the wall plug.
>
> Wholesale price of electricity in Brazil, one reasonable location for a
> beanstalk terminus, is $0.024/kW=h.
>
> A mature beanstalk launch industry will eventaully approach 53 * 0.024 * 3
> or $3.82/kg to GEO (based on energy cost and railroad type operation).
I think that with a mature beanstalk lauch industry you can build as
many SPSs as you want and the energy costs would tend to go sharply
down. Ultimately, the costs of beanstalk launch will be determined by
maintenance/operational issues, not by energy costs. Similarly, the
cost of the energy will be deterined by
maintenance/operational/transport issues, not by the cost of launching
that SPS.
That is FAR in the future, though.

> If GEO is accessible at $3.82/kg by beanstalk and LEO costs $20/kg by
> rocket, or for systems you and I might live to see $38.20/kg to GEO
> and $200/kg to LEO, who on Earth do you think is going to be paying
> the extra 423% for the LEO service and why?
Convenience? If it took 1 week travel to reach GEO with a ticket
costing $5, compared to, say, 2 hours (including check-in & all) to
LEO for $30, which one would you chose? If it is $5000 and $30000,
most people would choose beanstalk GEO. If it is $5 and $30, nobody
cares about 600%. Hey, it is just 25 bucks.

Stefan

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