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How's this for an idea? Building your own planet! You could use asteroids and comets for resources and an artificial magnetosphere for atmosphere retaintian. It would in effect be a space station with no hull.
Use what is abundant and build to last
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Do you mean take, say, all of the mass in the asteroid belt, and lump it together? I've had the idea. All of the mass in the asteroid belt would be about 1/100th the mass of the earth. You might get moon gravity, which isn't really enough.
-Josh
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Try the Oort cloud for material. With all the iron it could be possible to customize the gravity and it would be easy to make a custom atmosphere for scientific experiments.
Use what is abundant and build to last
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Try the Oort cloud for material. With all the iron it could be possible to customize the gravity and it would be easy to make a custom atmosphere for scientific experiments.
That means gathering many thousands if not millions of icy comets, seperated by tens or hundreds of billions of kilometers on vastly different orbits and coallescing them into a single much larger body. A project of mythic proportions. Why not just terraform an existing KBO like pluto, Eris or Sedna?
Also, why not simply mine the comets and use them to construct artificial habitats? This would allow far more earth-like conditions than living on a frozen ball of ice.
At this distance from the sun, some sort of artificial energy source would be neccesary for illumination and power in any event.
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Do you mean take, say, all of the mass in the asteroid belt, and lump it together? I've had the idea. All of the mass in the asteroid belt would be about 1/100th the mass of the earth. You might get moon gravity, which isn't really enough.
You need to adopt a more flexible interpretation of the word "Planet" You could make something about the size if not the mass of a planet with the materials in the asteroid belt, you'd just have to settle for it being hollow, if you want Earth gravity, you rotate the thing and use pseudo force pitting objects enertia against the inward centripetal acceleration of a curved floor.
The Earth has a radius of 6,378.14 km, so we can create a cylinder with that same radius. The surface area of a sphere of that diameter would be 4r^2*pi = 4*(6,378.14)^2*pi = 511,208,374.3 km^2
The surface area of a cylinder is simply the circumference of the circle times that cylinder's length, and since we already know the circumference to be 2r*pi = 2*(6,378.14)*pi = 40075.04 km we divide the area of the sphere above by the circumference to get the length of the cylinder as such 511,208,374.3 / 40075.04 = 12,756.28 km. So we end up with a cylinder that is 2*(6,378.14) = 12,756.28 km in diameter by 12,756.28 km long. Well what do you know The floor surface of a cylinder that is 12,756.28 km by 12,756.28 is equal to the surface of a sphere of that same diameter. If someone wishes to check my math, they may do so, it seems a strange coincidence that this should come about.
Acceleration of the floor area of a cylinder is given by a = (v^2)/r = 9.81m/sec^2 = (v^2)/6,378,140 m solve for v^2 = 9.81m/sec^2*6,378,140m = 62569553.4 m^3/sec^2 the square root of such comes out to 7,910.09 m/sec which is the tangential velocity of the floor of the cylinder. The circumference is as we remember 40,075,040 m if we convert to the same units, thus we have a period = 40,075,040 m / 7,910.09m/sec = 5,066.31 seconds which converts to a rotation rate of 1 hour, 24 minutes, and 26.31 seconds.
That is how you make a planet out of asteroid material, most of the area within the cylinder is empty vacuum. If the walls pointing inward from the floor were 125 km high, that should retain the atmosphere against the floor without need for enclosing the cylinder entirely. The cylinder is thus hollow. The remaining trick is how to get sunlight within. If you had a rectangular slab that was 12,506 km by 12,756.28 by 250 km in thickness, that should be plenty of room to create a hollographic image of the Sun radiating out parallel rays of sunshine towards half the cylinder while creating an image of a starfield visible from the other half. The image of the Sun will appear to rise from the North polar axis of the Cylinder and progress towards the South Polar axis with a changing slanting parallel rays over a roughly 25 hour day night cycle. On some portions of the cylinder, the sun will appear at an extreme angle at noon while at other parts it will appear directly overhead, thus we'd have climatic zones ranging from tropical to arctic conditions along the cylinder comparable to a spherical planet.
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How about a planet that could be terraformed, de terraformed, the terraformed by he next lot of trainee terraformers.
Use what is abundant and build to last
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How about a planet that could be terraformed, de terraformed, the terraformed by he next lot of trainee terraformers.
There are a limited number of planets within the Solar System that could be terraformed, you can however make more artificial planets of the type I described with less mass than you'd need to make a "natural" planet held together by gravity.
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How about a planet that could be terraformed, de terraformed, the terraformed by he next lot of trainee terraformers.
There are a limited number of planets within the Solar System that could be terraformed, you can however make more artificial planets of the type I described with less mass than you'd need to make a "natural" planet held together by gravity.
Building habitats from cometary material certainly appears far more efficient (in terms of total material needed) than attempting to terraform a comet.
In one respect a comet would be a much more useful starting material than an asteroid or lunar rock: it is rich with water, carbon and nitrogen. Having made some back of the envelope calculation for o'Neill type habitats, it very quickly became obvious to me that the bulk of the mass of the habitat was in the radiation shielding, the interior furnishings and the atmosphere. Only about 3% of the total mass was accounted for by actual structure. Water and cometary carbon provide much more of what we need for large Earth-like habitats.
Generally, smaller habitats provide a much more efficient utilisation of materials than very large ones.
One other thing: if the habitat is constructed within the Oort cloud or even the Kuiper belt, sunlight is likely to be far too weak to be useful as an energy source. Under this circumstance, an artificial energy source would be needed: probably fission/fusion. Given that we would no longer need to worry about how sunlight would permiate the internal geometry of the habitat, it would make more sense to create volumetric habitats, which do not waste large amounts of internal volume with 'empty' atmosphere. This dramatically reduces the size of a habitat needed to house a given number of people.
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I was thinking of recreating Earth's environment with all of its climatic variation. Seems to me that having the Cylindric curvature go North and South would be more important than having it go East and West. This would be for the benefit of migratory species that would tend to travel north and south, so you'd want to recreate the angles of sunlight from the equator to 90 degrees north and south. No it seems to be of benefit if the central light emmiting slab would be three times as long as it is wide. That is 38,268.84 km long and 12,506 km wide, that is just inside the upper atmosphere of this artificial planet. The slab would be attached to the atmospheric retaining walls and one can dock with the central axis and take and elevator 6,378.14 km down to the cylinder floor which would be covered with rock, soil, and water. There would basically be a wall to the "virtual East" and "virtual West". The "virtual East" would be the North end of the rotating cylinder while the virtual "West wall" would be the south end of the cylinder. Something like Carbon Nanotubes would be required to hold the entire structure together. The light emitting slab could furnish illumination through an array of light emmiting diodes, these would be powered by Solar energy of course, or perhaps nuclear energy if the intention is to build an "interstellar ark" that's as big as a planet, but less massive of course. If one wanted to eventually orbit Alpha Centauri A, one would accelerate this to about 1% of the speed of light and enjoy a nice leisurely cruise of 440 years Subjecting the whole world to accelerations no greater than a lunar tide on the ocean. One would occupy this world and really not care when it actually arrived at its destination just so long as it does so before the nuclear fuel that powers the life support, illumination, and propulsion runs out. I imagine that it would achieve a top velocity of 2% of the speed of light at the mid point of its journey, thus averaging 1% of the speed of light throughout.
That would be a maximum velocity of 6,000,000 m/sec, it would achieve this over 220 years of acceleration, thats 27,272.7 m/sec per year, which is 74.7 meters per second per day, which is 3.12 m/sec per hour, which is 0.0519 meters per second per minute, which is 8.65e-4 m/sec^2, this is 8.83e-5 g of Earths gravitational acceleration less than one ten thousanth of a g.
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The idea behind a planet that could be de-terraformed would be to teach terraformation.
Use what is abundant and build to last
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The idea behind a planet that could be de-terraformed would be to teach terraformation.
Terraforming is a multi-lifetime human project that is likley to challenge the budgets of major human institutions for centuries to come. The idea that we would de-terraform a planet that has been terraformed is ridiculous. It would be rather like building a skyscraper and then demolishing it afterwards, it isn't a practical proposition. The sort of training that people would need is basic atmospheric physics and chemistry, not something that you would need to de-terraform a planet to learn.
I know that these forums are spectulatory at best, but it would help if you thought your suggestions before you posted them.
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The idea behind a planet that could be de-terraformed would be to teach terraformation.
Terraforming is a multi-lifetime human project that is likley to challenge the budgets of major human institutions for centuries to come. The idea that we would de-terraform a planet that has been terraformed is ridiculous. It would be rather like building a skyscraper and then demolishing it afterwards, it isn't a practical proposition. The sort of training that people would need is basic atmospheric physics and chemistry, not something that you would need to de-terraform a planet to learn.
I know that these forums are spectulatory at best, but it would help if you thought your suggestions before you posted them.
As a thought experiment, which would be quicker to do, building a giant cylinder that recreates Earth's planetary environment such as I described above or terraforming Venus or Mars?
I think a 12,756.28 km by 12,756.28 km hollow cylinder with an Earthlike environment inside might be compedative with a project to terraform Venus. One could build it right in the middle of the asteroid belt where all the materials to construct it are available, it doesn't involve planetary masses, so it can be moved if desired. Venus on the other hand has almost the mass of the Earth, it would be very hard to change its rotation rate much less to move it to another part of the Solar System. I think Mars might be terraformed more easily than constructing this giant cylinder I mentioned, since all were talking about is thickening the Martian atmosphere and making it breathable.
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The idea behind a planet that could be de-terraformed would be to teach terraformation.
Terraforming is a multi-lifetime human project that is likley to challenge the budgets of major human institutions for centuries to come. The idea that we would de-terraform a planet that has been terraformed is ridiculous. It would be rather like building a skyscraper and then demolishing it afterwards, it isn't a practical proposition. The sort of training that people would need is basic atmospheric physics and chemistry, not something that you would need to de-terraform a planet to learn.
I know that these forums are spectulatory at best, but it would help if you thought your suggestions before you posted them.
As a thought experiment, which would be quicker to do, building a giant cylinder that recreates Earth's planetary environment such as I described above or terraforming Venus or Mars?
I think a 12,756.28 km by 12,756.28 km hollow cylinder with an Earthlike environment inside might be compedative with a project to terraform Venus. One could build it right in the middle of the asteroid belt where all the materials to construct it are available, it doesn't involve planetary masses, so it can be moved if desired. Venus on the other hand has almost the mass of the Earth, it would be very hard to change its rotation rate much less to move it to another part of the Solar System. I think Mars might be terraformed more easily than constructing this giant cylinder I mentioned, since all were talking about is thickening the Martian atmosphere and making it breathable.
Although large, your cyclinder would be quite easy to build. You simply produce a thin-foil 'substrate' which you inflate with a non-oxidising gas, and then build up the required wall thickness using vacuum plating.
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Still a massive construction project though, about on the scale of an L1 Sun shield to block sunlight from reaching Venus. We'd need to reinforce the walls with the same material we'd build a space elevator out of. Increasing the thickness of the strands of nanotubes would increase its strength, then we'd spin it up, an operation what would require less energy than spinning up Venus. The area inside the central rectangular slab, is about 250 km thick, there is enough space in their to house plenty of fusion reactors, and a powerful ion or plasma drive, that way this world could be moved to where it is desired. To make a starship out of it would require perhaps a reaction mass tank filled with hydrogen with a mass comparable with the main cylinder, and its contents. In this case it wouldn't matter whether the target system had any habitable planets or not, since we'd be bringing our own. It would take about 440 years to get there. I guess the main purpose would be to spread humanity out among the stars rather than having him fill up this Solar System and use up all the material within.
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