Unify:Colonize space
From Arcthon
Space colonization is autonomous (self-sufficient) human habitation outside of Earth. It is a long-term goal of national space programs.
The first space colony may be on the Moon, or on Mars. Ample quantities of all the necessary materials, such as solar energy and water, are on the Moon, Mars, or near Earth asteroids.
The NASA Lunar outpost, providing a permanent human presence on the moon, is at the planning stage. There is an ongoing development of technologies that may be used in future space colonization projects.
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Method
Building colonies in space would require access to water, food, space, people, construction materials, energy, transportation, communications, life support, simulated gravity, and radiation protection. It is likely the colonies would be located by proximity to such resources. The practice of space architecture seeks to transform spaceflight from a heroic test of human endurance to a normality within the bounds of comfortable experience.
Materials
Colonies on the Moon, Mars, or asteroids could extract local materials. The Moon is deficient in some volatiles (principally nitrogen), but has vast quantities of hydrogen (most notably in the form of water ice deposits buried beneath soil in the permanently shadowed craters) and helium-3 (deposited into the regolith by the solar wind). It also has industrially significant oxygen, silicon, and metals such as iron, aluminum, and titanium.
Launching materials from Earth is expensive, so bulk materials could come from the Moon, a Near-Earth Object (NEO—an asteroid or comet with an orbit near Earth), Phobos, or Deimosm where gravitational forces are much smaller, there is no atmosphere, and there is no biosphere to damage. Many NEOs contain substantial amounts of metals, oxygen, hydrogen, and carbon. Certain NEOs may contain nitrogen.
Farther out, Jupiter's Trojan asteroids are thought to be high in water ice and probably other volatiles.
Energy
Solar energy in orbit is abundant, reliable, and is commonly used to power satellites today. There is no night in space, and no clouds or atmosphere to block sunlight. The solar energy available, in watts per square meter, at any distance, d, from the Sun can be calculated by the formula E = 1367 W/d², where d is measured in astronomical units.
Particularly in the weightless conditions of space, sunlight can be used directly, using large solar ovens made of lightweight metallic foil so as to generate thousands of degrees of heat; or reflected onto crops to enable photosynthesis to proceed.
Large structures would be needed to convert sunlight into significant amounts of electrical power for settlers' use. In highly electrified nations on Earth, electrical consumption can average 1 kilowatt/person (or roughly 10 megawatt-hours per person per year).
Energy may be an eventual export item for space settlements, perhaps using wireless power transmission e.g. via microwave beams to send power to Earth or the Moon. This method has zero emissions, so would have significant benefits such as elimination of greenhouse gases and nuclear waste. Ground area required per watt would be less than conventional solar panels.
The Moon has nights of two Earth weeks in duration and Mars has night, dust, and is farther from the Sun, reducing solar energy available by a factor of about ½-⅔, and possibly making nuclear power more attractive on these bodies. Alternatively, energy could be transmitted to the lunar and martian surfaces from a solar power satellite.
For both solar thermal and nuclear power generation in airless environments, such as the Moon and space, and to a lesser extent the very thin Martian atmosphere, one of the main difficulties is dispersing the inevitable heat generated. This requires fairly large radiator areas.
