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.

"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)?

--
Nom=de=Plume

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.

On Fri, 25 Sep 2009 08:08:57 -0400, Tom Francis - SWSports
wrote:

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.

Not to be argumentative, but since the moon already has a surface area
far larger than 6 miles across, why isn't it being boosted out of
orbit as we speak ?

On Sep 25, 8:08*am, Tom Francis - SWSports
wrote:
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.

Tom:

Being somewhat familiar with lightsails but being too lazy to
calculate right now, something about the" 6 mile wide sail boosting
the moon out of orbit" thing didn't sound right. Here is the flaw.
The moon is already a light sail a couple thousand miles wide and it
does not get boosted out of orbit.

This says nothing about boosting smaller objects with large sails.
However, the thrust/sq km of sail is very low necessitating very small
payloads, really small, in order to get to any substantial fraction of
c (speed of light).

Another similar idea is called Mini-Magnetospheric Plasma Propulsion
or M2P2. It is a magnetic sail that interacts with the "solar wind"
of charged particles emanating from the sun. It uses a plasma
contained in a magnetic field to interact with solar protons. The
plasma gets "inflated" by injecting it into a mag field so it is miles
wide. Also low thrust.
One can increase the thrust of a lightsail by using high power lasers
pointing at it but even the best laser will diverge enough to have low
power density at astronomical distances. I have proposed to use
plasma lenses based on the M2P2 idea to re-focus said lasers on the
sail. These lenses would be miles in diameter and have extreme focal
lengths.

In my opinion, the 2nd best drive system for a prototype interstellar
probe would be something called Mini-Mag Orion that uses tiny fusion
explosions produced by laser driven inertial confinement. The plasma
from said explosions interacts with a mag field on spacecraft driving
it forward. Spacecraft would encounter fuel packets sent from solar
orbit that match its velocity so the spacecraft does not have to carry
the fuel. The fuel gets its speed from an accelerator in solar
orbit. It is called Orion after Freeman Dysons nuclear bomb driven
spaceship. I say it is second best because we currently cannot get
laser driven fusion done well.

Best near term drive system for an interstellar probe would be
something called a Nuclear Salt water Rocket where salts of uranium
dissolved in water are fed by nozzles to an area behind the rocket
where they reach critical mass forming a continuous nuke explosion
driving the rocket. Again, it gets its fuel from an accelerator in
solar orbit. I think this is more near term than the Mini Mag Orion
because it uses fission and does not rely on unknown technology. At
least this one uses water so is tangentially related to boats.

"Tom Francis - SWSports" wrote in
message ...
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.


Thanks for all the cool references... I was never a fan of Deep Sh*t 9, but
I'll see if I can find the episode.

I don't near enough about DaVinci... just not enough time to read, work, and
stay semi-current with the news. Maybe I should look more favorable to human
cloning. lol

I'm going to try and find the Astounding issue. Asimov is one of my favorite
authors, unless I'm in my trash novel reading cycle... you know Danielle
Steel. I know, I know...

--
Nom=de=Plume

"Wayne.B" wrote in message
...
On Fri, 25 Sep 2009 08:08:57 -0400, Tom Francis - SWSports
wrote:

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.

Not to be argumentative, but since the moon already has a surface area
far larger than 6 miles across, why isn't it being boosted out of
orbit as we speak ?


Reflectiveness? Gravity effect of the Earth? No idea... interesting
question.

For that matter, why isn't the Earth being boosted?

--
Nom=de=Plume

On Sep 25, 1:34*pm, "nom=de=plume" wrote:
"Wayne.B" wrote in message

...

On Fri, 25 Sep 2009 08:08:57 -0400, Tom Francis - SWSports
wrote:

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.

Not to be argumentative, but since the moon already has a surface area
far larger than 6 miles across, why isn't it being boosted out of
orbit as we speak ?

Reflectiveness? Gravity effect of the Earth? No idea... interesting
question.

For that matter, why isn't the Earth being boosted?

--
Nom=de=Plume

Both (earth and moon) are being "boosted" by solar pressure,
effectively reducing the gravity of the sun by a tiny tiny amount.
Put your small payload in circular orbit about the sun WITHOUT the
sail and it goes happily about the sun. Unfurl your sail and suddenly
the orbit is perturbed a tiny amount due to the force on the sail.
Near the sun, assume the force due to sunlight is constant (it really
drops as 1/r^2) so your change in velocity of sail is then: v=t*F/m
where t is time your sail is unfurled, m is mass of sail + payload and
F is force due to sunlight. After some time, furl your sail and you
settle into a new orbit.

On Sep 25, 2:13*pm, Frogwatch wrote:
On Sep 25, 1:34*pm, "nom=de=plume" wrote:



"Wayne.B" wrote in message

.. .

On Fri, 25 Sep 2009 08:08:57 -0400, Tom Francis - SWSports
wrote:

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.

Not to be argumentative, but since the moon already has a surface area
far larger than 6 miles across, why isn't it being boosted out of
orbit as we speak ?

Reflectiveness? Gravity effect of the Earth? No idea... interesting
question.

For that matter, why isn't the Earth being boosted?

--
Nom=de=Plume

Both (earth and moon) are being "boosted" by solar pressure,
effectively reducing the gravity of the sun by a tiny tiny amount.
Put your small payload in circular orbit about the sun WITHOUT the
sail and it goes happily about the sun. *Unfurl your sail and suddenly
the orbit is perturbed a tiny amount due to the force on the sail.
Near the sun, assume the force due to sunlight is constant (it really
drops as 1/r^2) so your change in velocity of sail is then: *v=t*F/m
where t is time your sail is unfurled, m is mass of sail + payload and
F is force due to sunlight. *After some time, furl your sail and you
settle into a new orbit.

Whether or not you escape from the sun and then go on to build up more
speed depends on the ratio of the force of the sun to the force due to
gravity and as both of these vary as 1/r^2, then this depends on the
size of the sail. Basically, at any distance you need a sail large
enough to outweigh gravity in order to escape from the sun, otherwise
you just change your orbit but stay in orbit about the sun.

On Sep 25, 2:31*pm, Frogwatch wrote:
On Sep 25, 2:13*pm, Frogwatch wrote:



On Sep 25, 1:34*pm, "nom=de=plume" wrote:

"Wayne.B" wrote in message

.. .

On Fri, 25 Sep 2009 08:08:57 -0400, Tom Francis - SWSports
wrote:

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.

Not to be argumentative, but since the moon already has a surface area
far larger than 6 miles across, why isn't it being boosted out of
orbit as we speak ?

Reflectiveness? Gravity effect of the Earth? No idea... interesting
question.

For that matter, why isn't the Earth being boosted?

--
Nom=de=Plume

Both (earth and moon) are being "boosted" by solar pressure,
effectively reducing the gravity of the sun by a tiny tiny amount.
Put your small payload in circular orbit about the sun WITHOUT the
sail and it goes happily about the sun. *Unfurl your sail and suddenly
the orbit is perturbed a tiny amount due to the force on the sail.
Near the sun, assume the force due to sunlight is constant (it really
drops as 1/r^2) so your change in velocity of sail is then: *v=t*F/m
where t is time your sail is unfurled, m is mass of sail + payload and
F is force due to sunlight. *After some time, furl your sail and you
settle into a new orbit.

Whether or not you escape from the sun and then go on to build up more
speed depends on the ratio of the force of the sun to the force due to
gravity and as both of these vary as 1/r^2, then this depends on the
size of the sail. *Basically, at any distance you need a sail large
enough to outweigh gravity in order to escape from the sun, otherwise
you just change your orbit but stay in orbit about the sun.

More "Waaaaay too much information":
It turns out that a perfectly reflective (shiny) surface gets twice
the boost from sunlight that a perfectly absorbing (black) surface
does simply due to conservation of momentum.

Nothing worse than a physicist with time on his hands.