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What if we took a small ball of matter and heated it to the Sun's surface temperature through nuclear fission? I remember a story by Arthur C. Clarke in which he turned one of Mars's satellites into an artificial sun to heat up the surface of Mars. What if we wanted to do this in reality, say we had a nuclear core made up of critical mass Uranium, it is critical enough to be as hot as the interior of the Sun, and we surround this with a mantle of lighter nonfissionale material, such as iron for instance. The iron is heated to a plasma by the fissile core in the center. So how big would this artificial fissile Sun have to be to hold itself together? It would be some task to gather enough Uranium together to make a fissile core artificial sun. The gravity of the Sun would have to have a high enough escape velocity to prevent iron plasma heated to the surface temperature of the Sun from escaping. Or perhaps magnetic and electric fields could be used to contain this plasma. What do you think?
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To provide artificial sunlight illumination equivalent to a North European Country (i.e. UK, Netherlands, Denmark, etc.) would require a time averaged illumination of 100W/m2, or 100MW per square km. To provide illumination for an area of 10million square-km (equivalent to a dwarf planet like Pluto or Eris) would require a continuous power of 1million GW. If fission power were used, this would consume 1million tonnes of uranium or thorium per year. That’s a lot of uranium/thorium and these elements are relatively rare in the solar system.
A better alternative might be mega-fusion reactors. As the size of a fusion reactor increases, the ratio of surface area to volume declines in proportion to radius. A metal sphere 100km in diameter filled with hydrogen plasma would develop a natural temperature gradient, with relatively cool plasma at the edges and fusion-temperature plasma at its core. With such a large column density of hydrogen plasma, neutron radiation and x-rays would be attenuated before reaching the outer surface. The outer shell would be cooled using liquid sodium, which would transfer heat to a condensing vapour thermo-dynamic cycle generating electric power.
Power density is a problem. If the average temperature of the plasma is 10million K and pressure is 1bar, then plasma density is 0.001gram/m3. The reactor would need to be very large (100s of km in diameter) in order to achieve a sufficient column density to attenuate ionising radiation generated in its core. It might be easier to build the reactor and then build the planet on top of it.
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I readed somewhere, but I can't find the source now, that for "gravitational confinement fusion" fusing deuterium, a "star" of the (Earth's) lunar mass is enough?
From the other hand -- stellar natural light is abundant enough on intergalactic distances ( i.e. in the whole universe ), so using cheaper and simpler optics ( mirrors, lenses... ) enough of it to be concentrated on any habitat surface with the desired areal density...
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To provide artificial sunlight illumination equivalent to a North European Country (i.e. UK, Netherlands, Denmark, etc.) would require a time averaged illumination of 100W/m2, or 100MW per square km. To provide illumination for an area of 10million square-km (equivalent to a dwarf planet like Pluto or Eris) would require a continuous power of 1million GW. If fission power were used, this would consume 1million tonnes of uranium or thorium per year. That’s a lot of uranium/thorium and these elements are relatively rare in the solar system.
A better alternative might be mega-fusion reactors. As the size of a fusion reactor increases, the ratio of surface area to volume declines in proportion to radius. A metal sphere 100km in diameter filled with hydrogen plasma would develop a natural temperature gradient, with relatively cool plasma at the edges and fusion-temperature plasma at its core. With such a large column density of hydrogen plasma, neutron radiation and x-rays would be attenuated before reaching the outer surface. The outer shell would be cooled using liquid sodium, which would transfer heat to a condensing vapour thermo-dynamic cycle generating electric power.
Power density is a problem. If the average temperature of the plasma is 10million K and pressure is 1bar, then plasma density is 0.001gram/m3. The reactor would need to be very large (100s of km in diameter) in order to achieve a sufficient column density to attenuate ionising radiation generated in its core. It might be easier to build the reactor and then build the planet on top of it.
the trick would be in confining a ball of plasma 100 km in diameter with magnetic and electric fields, without destroying the thermonuclear reactor with these temperatures.
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I readed somewhere, but I can't find the source now, that for "gravitational confinement fusion" fusing deuterium, a "star" of the (Earth's) lunar mass is enough?
From the other hand -- stellar natural light is abundant enough on intergalactic distances ( i.e. in the whole universe ), so using cheaper and simpler optics ( mirrors, lenses... ) enough of it to be concentrated on any habitat surface with the desired areal density...
The Earth has a core with a temperature that if we could see it would glow.
From Wikipedia, the free encyclopedia
The internal structure of Earth
Earth's inner core is Earth's innermost part and is a primarily solid ball with a radius of about 1,220 km (760 mi), according to seismological studies.[1][2] (This is about 70% of the Moon's radius.) It is believed to consist primarily of an iron–nickel alloy and to be approximately the same temperature as the surface of the Sun: approximately 5700 K (5430 °C).[3]
http://en.wikipedia.org/wiki/Inner_core
It could be said that the Earth is sort of like a star than runs on fission. The main advantage of fission is that it doesn't require the temperatures and pressures found at the core of our Sun. So if we could heat the Moon to the temperature of Earth's core, it would glow like the Sun. the main problem is getting it to glow. Radio actives are scarce.
How far away is Triton from neptune? 220,500 miles.
How far away is the Moon from Earth? 238,855 miles
Similar distances.
How big is Neptune's moon Triton? Triton is approximately 2700km in diameter.
The Moon has a diameter of 2,159 miles (3,476 kilometers), 800 km larger.
Suppose we shined a laser on Triton causing it to low like the Sun. Much like the Solar powered laser to push of of Robert Forwards light sails to the stars, but what if we build such a laser near Mercury such that it shines on Triton to heat it to a temperature hotter than the sun to make up for its smaller size? Say on its back side. The hot plasma would carry over to the near side and make it glow like an artificial sun. That glow would in turn heat up Neptune.
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Tom,
Heating these moons to 6000 degrees celsium would simply evaporate them without trace...
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Antius wrote:To provide artificial sunlight illumination equivalent to a North European Country (i.e. UK, Netherlands, Denmark, etc.) would require a time averaged illumination of 100W/m2, or 100MW per square km. To provide illumination for an area of 10million square-km (equivalent to a dwarf planet like Pluto or Eris) would require a continuous power of 1million GW. If fission power were used, this would consume 1million tonnes of uranium or thorium per year. That’s a lot of uranium/thorium and these elements are relatively rare in the solar system.
A better alternative might be mega-fusion reactors. As the size of a fusion reactor increases, the ratio of surface area to volume declines in proportion to radius. A metal sphere 100km in diameter filled with hydrogen plasma would develop a natural temperature gradient, with relatively cool plasma at the edges and fusion-temperature plasma at its core. With such a large column density of hydrogen plasma, neutron radiation and x-rays would be attenuated before reaching the outer surface. The outer shell would be cooled using liquid sodium, which would transfer heat to a condensing vapour thermo-dynamic cycle generating electric power.
Power density is a problem. If the average temperature of the plasma is 10million K and pressure is 1bar, then plasma density is 0.001gram/m3. The reactor would need to be very large (100s of km in diameter) in order to achieve a sufficient column density to attenuate ionising radiation generated in its core. It might be easier to build the reactor and then build the planet on top of it.the trick would be in confining a ball of plasma 100 km in diameter with magnetic and electric fields, without destroying the thermonuclear reactor with these temperatures.
or: http://www.newmars.com/forums/viewtopic.php?id=7021 ( reminder )
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