On Thu, 24 Sep 2009 22:19:31 -0700, "nom=de=plume"
wrote:

"Frogwatch" wrote in message
...
We officially have "water on the moon" so let's have some lunar
boating ideas. Only problem, it is basically some ice crystals mixed
with dust, not even good for ice boating. However, I still think that
lunar lava tubes might have lots of ice and other volatile materials.
Lava contains lots of dissolved water vapor. When it cools, the water
may come out of solution and freeze in the lava tube where there would
be no air movement to cause it to heat up. So, maybe kayaking with
runners on the bottom in lunar lava tubes. Could combine my three
interests, caves, boating and space.

I don't know about sailing on the moon, but how about just space sailing...
using solar sails from the engery of protons bouncing off. Nasa's been doing
some studies, but didn't this concept start with the Planet of the Apes book
published in 1963 (I actually read the book)?

Earlier than that - as early as 1913 ("light sail") and was based on a
"invention" by Leonardo DaVinci - he used a candle and reflected light
to move a paper mobile.

"Star Trek: Deep Space 9" did an episode in Season Three called
"Explorer", call it an homage to Thor Hyderdahl, where Commander Sisko
and his son Jake built a replica Bajoran vessel to prove that the
Bajorans had discovered interstellar travel before the Cadassians
which was powered by light pressure sails.

It's a sci-fi staple - I think every major sci-fi author has written
at least one light sail story. In the late '50s, "Astounding"
magazine devoted an entire issue to it including a novella by Issac
Asimov - I have a copy, but it's in storage so I can't point you to
the issue number.

The actual concept is called radiation pressure. I've done an
experiment with a wide aperature laser to move a piece of paper about
four feet back in the day. :)

Orders of magnitude in sail size. Larry Niven, a mathematician and
sci-fi author, developed a design for a light powered vessel in the
mid-70's. He estimated that a single sail, six miles across, could
boost an object the size of our moon out of orbit and complete one
grav of acceleration in ten years. Sails larger than that, the process
becomes quicker. Doing some simple math, one could accelerate an
object the size of a semi-tractor to light speed in less than a year
with a six mile wide light sail.

It's a fascinating subject that's for sure.