Re: ET: Scientific American article on GHZ

From: Mike Lorrey (
Date: Wed Oct 03 2001 - 10:51:34 MDT

"Robert J. Bradbury" wrote:
> The point about avoiding radiation due to impacts on the magnetosphere
> and possible loss of hydrogen does seem moderately important though.
> However, it looks like there may be a lot of "water worlds" out there
> and so one could argue that occasional magnetosphere disruptions could
> actually be a good thing since the H loss would likely eventually bring
> some of the ocean floor above sea level.

As opposed to the way we got it? I actually side more with the opinion
that large moons are absolutly necessary for ATC to get off planet. Not
only does stripping the normally thick lithosphere off with planetisimal
glancing impact improve the terrain, but it also improves access to the
technologically useful metals as well as rip enough protoplanetary
atmosphere off that life can evolve in the fluid water temperature

If moons were not so important, Venus would have beaten us in the
civilization game. Venus was once in a cool greenhouse stage earlier
than earth was, and if earth did not have its atmosphere and lithosphere
stripped by planetesimal impact and resultant sequestration of 98% of
its atmosphere, the Earth would be just like Venus right now.

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