How to Colonize an Asteroid

Asteroid Composition and Classification

Since the protoplanets which make up the bulk of the asteroids we see today were formed over a wide range of distances from the sun, their compositions vary greatly. The distribution of materials throughout the range of the asteroids is not even, due to orbital perturbations (say "they are stirred up") caused by Jupiter and Mars (and to a lesser extent by all of the other planets in the solar system). Collisions between asteroids are (or were) common, and this causes individual asteroids to be shot further into or out of the solar system, but a fair amount of the original distribution of materials still exists.

Scientists and Astronomers have developed a classification scale which gives asteroids a letter designation which indicates the type of material from which it is composed. There are over 50 distinct types {R.33.88},{R. 45}but this list contains only the most common.

**Asteroid Classes**
Class C	Carbonaceous	Includes about 75% of all asteroids. Consist of very dark material, mostly carbon, but contains organic matter, water soluable salts, magnetite and clay.
Subclass CI	C. Ivuna
Subclass CK	C. Karoonda
Subclass CM	C. Mighei
Subclass CV	C. Vigarano
Subclass CO	C. Ornans
Subclass CR	C. Renazzo
Class S	Silicacaceous	Includes about 17% of all asteroids. Metallic Iron and Magnesium silicates.
Class M	Metallic	Includes about 8% of all asteroids. Mostly Nickle or Nickle & Iron Mixtures

In addition to classification by their composition, asteroids are also classified as to their locations.

Centaur Asteroids - The farthest out, located between the orbits of Saturn and Uranus. Most of these objects are probably dormant comets from the Kuiper Belt which have been pulled in by the gravity of the outer planets.

Trojan Asteroids - Located in the gravitational Lagrange points 60 degrees ahead of and behind Jupiter. These asteroids were probably once part of the main belt, but have been swept from their orbits by the gravity of Jupiter.

Main Belt Asteroids - Most of the know asteroids are in bands between Mars and Jupiter. There are many distinct bands because the gravity of the Jupiter and the other planets tends to sweep certain areas of the asteroid belt clean. These are called "Kirkwood" gaps.

Near Earth Asteroids (NEO's) - There are a great number of asteroids which come close to earth, within 1.3 Astronomical Units (AU - the distance from the earth to the sun), and their classification is further broken down into three sub categories:

Amor Asteroids - 1.017 to 1.3 AU's - Stay Outside the orbit of earth, but inside the orbit of Mars. (These are probably the best choice of locations for our asteroid colony as they are in a great location to support missions to the outer solar system, but are close enough to the sun to receive a lot of energy).
Apollo Asteroids - 1.0 to 1.017 AU's - Basically follow the same orbit as earth - sometimes passing closer to the earth than does our own moon. Most of the Apollo asteroids require less energy to reach in a rocket than does our own moon.
Aten Asteroids - 0.983 to 1.0 AU's - Between earth and Venus, but sometimes cross the orbit of earth.

Asteroid Composition and Classification

© 2000, Robert Lyon Richards