Colonization of the asteroid belt

The asteroids have long been suggested as possible sites for human colonization. This idea is popular in science fiction. Asteroid mining, a proposed industrial process in which asteroids are mined for valuable materials, especially platinum group metals, may be automated or require a crew to remain at the target asteroid.

Advantages

• Low gravity simplifies construction technologies (such as cranes) and reduces structural strength requirements
• Large number of possible sites, with over 300,000 asteroids identified to date
• Asteroids contain several chemical composition classes, including iron and carbonaceous, providing a variety of materials usable in building and fueling spacecraft and space habitats. The Trojan asteroids, in Jupiter's orbit may be primarily extinct comets.
• Some Earth-crossing asteroids require less energy (delta-V) to reach from Earth than the Moon.
• Material mined from asteroids could be a basis for a trade economy
• Low gravity significantly eases transportation of material from asteroids, goods among asteroids and transport of large amounts of mass or massive objects
• High surface/volume ratio enables effective exploration and exploitation of mineral resources and provides maximal portion of useful building ground on the surface and underground
• High vacuum and low gravity would facilitate the evolution of some hi-tech industries such as material engineering and physical electronics (crystal growth, epitaxy)
• Many asteroids (especially the extinct comet cores) contain large amounts (more than 5% of total composition) of volatiles and carbon, which are necessary for life support.
• Isaac Asimov pointed out the advantage of building cities inside hollowed out asteroids since the interior area in square miles of all the asteroids put together is a great deal more than that of the surface area of Earth (viewed as a series of cubes one mile (1.6 km) by one mile resting on the surface of Earth) and thus a large population could be accommodated in the asteroid belt.

Disadvantages

• Low gravity. Humans would have to adapt, or some form of artificial gravity would have to be implemented.
• Most asteroids are far from the Sun. The main asteroid belt is roughly 2 to 4 times further from the Sun than Earth. This means that the available solar energy (solar constant) is 4 to 16 times less, although building large reflectors to collect sunlight is possible in space.
• Many asteroids may merely be loose agglomerations of dust and rocks, which may be very difficult to use.
• Asteroids are vulnerable to Solar radiation, lacking similarities like Earth's ozone layer and magnetosphere (though some may have a magnetic field, they are bound to be considerably weaker by comparison). Shielding with several meters of asteroidal regolith is a trivial solution to this problem.
• Asteroids have no or very little atmosphere.
• Smaller objects may collide with the asteroid and cause significant damage.

Asteroids of special interest

Asteroid 243 Ida is over 53 km long. Its moon, Dactyl on the right

• (6178) 1986 DA is a potentially metallic near-Earth asteroid.
• 216 Kleopatra is a metallic main-belt asteroid.

Some C-type asteroids are likely carbonaceous chondrites, which are some tens of percent water by mass.

Asteroid colonies in science fiction

See Asteroids in fiction.

References

• David Gump, Space Enterprise: Beyond NASA, Praeger Publishers, 1990, ISBN 0-275-93314-8.
• Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets
• The Technical and Economic Feasibility of Mining the Near-Earth Asteroids, M. J. Sonter.
• Template:Wayback, IEEE Spectrum, August 2001.

See also

• Space colonization
• Solar System