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In page Space elevator:

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Rapidly spinning asteroids or moons could use cables to eject materials to convenient points, such as Earth orbits;[7] or conversely, to eject materials to send a portion of the mass of the asteroid or moon to Earth orbit or a Lagrangian point. Freeman Dyson, a physicist and mathematician, suggested[citation needed] using such smaller systems as power generators at points distant from the Sun where solar power is uneconomical.