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I was readng the "Terraforming Jupiter's Moons" thread when I came across noosfractals suggestion of using a smaller fresnel lens close to the sun to beam concentrated light to the moons of jupiter (to aid their habitability), instead of using a larger concentrator closer to the moon itself.
This made me think of using a mirror array (made up of many individually movable mirrors) on the surface of Mercury to achieve the same job. Of course, they will have to withstand those high surface temperatures, but this idea has the advantage that the mirror array can be constructed and supported on the surface and built from local materials. Perhaps each segment can be built on the cold side and transported around to the hot side when completed.
Has this idea been proposed before?
- Mike, Member of the [b][url=http://cleanslate.editboard.com]Clean Slate Society[/url][/b]
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Would other planets pass in front of the light and block it? If so how often? Everything's moving around pretty much in the same plane so it seems like this might be a problem.
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I think the planet most likely to get in the way is Mercury.
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You realize that since Jupiter is 778,330,000 km (5.20 AU) from the Sun it would be very difficult to aim. It would be much easier to put concentrator mirrors in orbit around the moons.
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Well, you could have two or more mirrors. One on Mercury to beam the concentrated light, and one in orbit, or held stationary by light pressure, around the planet itself. Maybe another one in orbit above mercury, or held by light pressure above the sun.
Here's another thought: Has anyone considered using the extreme temperature variation across the surface of Mercury to generate electricity?
- Mike, Member of the [b][url=http://cleanslate.editboard.com]Clean Slate Society[/url][/b]
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Well, you could have two or more mirrors. One on Mercury to beam the concentrated light, and one in orbit, or held stationary by light pressure, around the planet itself. Maybe another one in orbit above mercury, or held by light pressure above the sun.
But then you have to wonder if it is not just more efficient to build only the orbital mirror - perhaps with Mecurian resources.
Here's another thought: Has anyone considered using the extreme temperature variation across the surface of Mercury to generate electricity?
Sounds like a good idea. How would you go about it?
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Actually, yesterday I was reading about the effects of Libration (http://en.wikipedia.org/wiki/Libration), which makes the Terminator Zone (http://en.wikipedia.org/wiki/Terminator_%28solar%29) move around during the orbit of Mercury. This might make a Heat Engine (http://en.wikipedia.org/wiki/Heat_engine) on the surface difficult, but still possible. What I propose is some sort of fluid conduit between the hot and cold sides of Mercury, across the terminator zone, which transfers fluid energy to a generator. The advantage of locating such a heat engine on the surface of Mercury is that a huge heat-sink (the cold rocks on the dark side of Mercury) is available for conduction-based heat rejection. This is opposed to using radiation-based heat rejection available in the vacuum of space, which is extremely slow.
On a related, but somewhat macabre, note; I read somewhere that a human body, if ejected into the vacuum of space, would actually stay warm for hours (i.e. not instantly freeze to death). Rather, one would die of asphyxiation, independant of any other cause. Heat rejection via pure radiation is apparently very slow.
- Mike, Member of the [b][url=http://cleanslate.editboard.com]Clean Slate Society[/url][/b]
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Actually, yesterday I was reading about the effects of Libration (http://en.wikipedia.org/wiki/Libration), which makes the Terminator Zone (http://en.wikipedia.org/wiki/Terminator_%28solar%29) move around during the orbit of Mercury. This might make a Heat Engine (http://en.wikipedia.org/wiki/Heat_engine) on the surface difficult, but still possible. What I propose is some sort of fluid conduit between the hot and cold sides of Mercury, across the terminator zone, which transfers fluid energy to a generator. The advantage of locating such a heat engine on the surface of Mercury is that a huge heat-sink (the cold rocks on the dark side of Mercury) is available for conduction-based heat rejection. This is opposed to using radiation-based heat rejection available in the vacuum of space, which is extremely slow.
On a related, but somewhat macabre, note; I read somewhere that a human body, if ejected into the vacuum of space, would actually stay warm for hours (i.e. not instantly freeze to death). Rather, one would die of asphyxiation, independant of any other cause. Heat rejection via pure radiation is apparently very slow.
'Geothermal' might be an effective energy source for a Mercury base. The day side of Mercury is +400C, the night side -170C. That gives an average rock temperature (just a few metres beneath the surface) of 230C. The only difficulty as far as I can see is that a substantial heat exchanger would be needed for heat rejection, given the vacuum conditions on Mercury's surfcae.
A similar Seleno-thermal heat engine could be set up on the moon to provide power during the long lunar night, given that ambient surface night-time temperature are -100C and average subsurface rock temperatures approximately -20C. The downside again, is the sheer size of the heat rejection radiator that would be needed at such a low heat rejection temperature
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This made me think of using a mirror array (made up of many individually movable mirrors) on the surface of Mercury to achieve the same job [focusing heat on Jupitor's moons]. ...
Perhaps each segment can be built on the cold side and transported around to the hot side when completed.
Hi all, Michael.
The mirrors will be sending the light typically 930 million km. To create a mirror with a focal length with this precision will require the reflecting surface to be optically smooth at the sub-atomic level. These giant mirrors will have to flex to keep the moons in focus. They will have to adjust for the heat causing them to expand and change the focal length, etc. I don't see it being physically possible.
Mercury does not have a cold and hot side. It rotates 3 time every two orbits.
Warm regards, Rick.
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Split this thread because it went offtopic, the discussion about terraforming Neptune is under Terraforming Neptune
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An idea for Mercury ,besides terraformation for Jupiter, could be to construct a massive array of solar panels across the face of mercury. This could provide a solution to part of the alternative energy problem. Unfortunately the cost would be high and maintenance would probably be required often. Still it's an Idea. Any thoughts?
-"you watch the sunset, and I watch the night rise"
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