[ExI] Why no space colonies or lunar bases? was Mooon.

Keith Henson hkeithhenson at gmail.com
Fri Jul 22 21:39:56 UTC 2011


On Wed, Jul 20, 2011 at 4:24 PM,  Damien Broderick <thespike at satx.rr.com> wrote:

> And here we are on the 42nd anniversary of the first Moon landing. Two
> generations later, just about. No Luna City. Not even a Luna Hovel. Sigh.

Freeman Dyson explained why in 1979.  I talked him (and the
publishers) into letting the L5 News print a chapter from _Disturbing
the Universe._  You can read it here:

http://www.nss.org/settlement/L5news/L5news/L5news7908.pdf

The bottom line is that transport into space is 10,000 times too
expensive for space to be colonized.

That's largely due to the small payload fraction, which in turn is a
direct consequence of an exhaust velocity which is half the delta V
needed to reach earth orbit.

Chemical fuels just won't do it.

But in recent years other ways have opened up, relatively low cost,
high efficiency, solid state laser diodes and low cost microwave
generators.  It's not entirely clear how to best exploit such beamed
energy sources, but they both offer exhaust velocity up in the same
range as the 9 km/s needed to get into orbit.

It's still too expensive for self funded space colonies, but if this
works out, it will only be 2 orders of magnitude too expensive rather
than 4.

Keith



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