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banquo's_bumble_puppy
2013-May-28, 05:34 PM
How many Earth analogue's could we build (if we had the technology) from the raw materials of the solar system? I'm referring specifically to the asteroids, moons, and comets; not any of the gas giants. This would also include the other rocky planets. Also, these planets would need to fit into the goldilocks zone. Can this number even be guessed at?

Noclevername
2013-May-30, 04:24 AM
If by analogue you mean Earth mass, one. Maybe one and a half with all the moons.

neilzero
2013-May-30, 05:00 AM
If Earth analog means a hollow sphere of unobtainium filled with high pressure hydrogen with a thin layer of soil and biosphere, two might be practical if we get little else but the hydrogen from gas giant planets, but perhaps 50 times the surface area of Earth would be practical = Saturn has less than one g gravity at the cloud tops so each of the artificial planets would be about the diameter of Saturn. Neil

JustAFriend
2013-May-30, 01:52 PM
Far better to build one of Larry Niven's Ringworlds than a planet...

eburacum45
2013-May-30, 02:46 PM
If Earth analog means a hollow sphere of unobtainium filled with high pressure hydrogen with a thin layer of soil and biosphere, two might be practical if we get little else but the hydrogen from gas giant planets, but perhaps 50 times the surface area of Earth would be practical = Saturn has less than one g gravity at the cloud tops so each of the artificial planets would be about the diameter of Saturn. Neil

This is an interesting idea, and might be doable without unobtainium. Paul Birch came up with the idea of the SupraJupiter, a shell contructed above a gas giant with people living on the outside. The shell is suspended magnetically by particles moving slightly faster than orbital speed.

See this .pdf about the concept
http://www.orionsarm.com/fm_store/SupramundanePlanets.pdf

Birch estimated that a SupraJupiter, with a surface area 316 x Earth, could be built from a single Galilean moon (but I'm a but doubtful that any single moon would contain enough magnetic material, so you might have to use a few).

eburacum45
2013-May-30, 02:58 PM
Alternately we could build a bubble filled with hydrogen and helium, with an outer skin of steel.
Here's Dani Eder talking about his Bubbleworld concept
http://yarchive.net/space/exotic/bubbleworld.html
A full sized Bubbleworld would need 3 times the mass of Earth, so you couldn't build it from the available moons and asteroids alone - but you could always disassemble the four terrestrial worlds in our system...

neilzero
2013-May-30, 06:32 PM
Thank you for the Paul Birch PDF = Way too much to grasp in one hour. It appears there are numerous possible approaches = it can be done by some means if not the first few attempts. The outer edge of the goldilocks zone is likely best, but it appears they can be built anywhere closer than Pluto and Sedna including much closer to the Sun than Mercury. Neil