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#1
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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. |
#2
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"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 |
#3
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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. |
#4
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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 ? |
#5
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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. |
#6
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"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 |
#7
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"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 |
#8
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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. |
#9
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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. |
#10
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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. |
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