From: spike66 (spike66@attbi.com)
Date: Fri Aug 23 2002 - 22:02:36 MDT
Robert J. Bradbury wrote:
>On Fri, 23 Aug 2002, spike66 wrote:
>
>>I did the calcs and confidently predict the probability of a space elevator
>>in the next 15 years at zero. The probability of a space elevator in 25
>>years at verrry near zero. Probability in 50 years, assuming no singularity
>>and optimistic assumptions regarding material science, ~20%.
>>
>
>Based on what assumptions? This statement is even more handwaving
>than I typically do.
>
You are right, Robert. I thought it over and would lower my estimate
in 50 years to no more than 10%. This is because I am estimating the
probability of our not needing Earthsats at that time, and furthermore
figuring out a way to get those that already exist out of the way.
The original calcs were on based on the required mass, assuming
we completely master the C-C bond so that we can make diamond
in any shape. We would need a mass driver on Mars for the source
of most of the carbon (way too much to lift all the way out of Earth's
relatively large gravity well, not enough total carbon available on
Luna.)
>>I derived the equation for the mass of a space cable about 10 years
>>ago and published them in an appendix of an engineering paper.
>>I should resurrect those. spike
>>
>
>Indeed you should spike so we can compare it with any numbers in
>the NIAC study papers.
>
Roger that. Robert I sent you the only copy I had of that paper
a couple years ago. Fortunately I presented that paper at a
conference and consequently 300 hard copies were made, which
I can find in the archives back at the office.
>Furthermore, if your collision numbers are realistic, we should
>be communicating them to the people promoting the development
>of this idea so we can stop spending money on the idea if its
>a complete boondoggle.
>
Roger that. I am curious how they deal with that aspect.
>Get thee up off thoust lazy butt and cook us up some beef!
>
>Robert
>
OK, but in the meantime, those still reading should attempt an estimate
themselves. That paper predated the internet, so I had some wild
guesses on the cumulative number of sats and their sizes. The space
station alone, even at its high-ish inclination, poses a significant
risk all
by itself. What say ye, Sir Robert? spike
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