For other asteroid models, please go to Asteroids (theoretical models).
A rocky asteroid is an asteroid made of solid rock and with only limited (or no) water. In Solar System, such an asteroid should exist between the orbits of Mars and Venus.
General properties Edit
A rocky asteroid is made of solid rocks. It might contain silicates, metallic compounds (usually oxides) and other solid materials, even carbon compounds. At their distance to the Sun (or parent star), water would sublimate. Only if water is enclosed deep beneath the crust, it might remain captive. Close to the surface, water should slowly evaporate. Still, water ice might be present in holes (like craters), close to the poles, where light and heat from parent star cannot reach. If the rotation axis is too tilted, poles can be directly exposed to sunlight and the chance to find ice is very small.
Usually, asteroids rotate fast. If they rotate too fast, their surface might not be covered with regolith. Also, spaceships might find difficult to dock on a fast moving asteroid.
Asteroids lack of magnetic fields. Any construction will be directly exposed to solar winds and cosmic radiation.
Despite having only limited amounts of available water, asteroids have some major advantages for settlers. First of all, inside the asteroid, temperature is not oscillating like on the surface. This makes rocky asteroids good candidates for Internal paraterraforming. Another major advantage is that many asteroids are rich in metals and minerals. Mining in almost zero-G is more easy. Because of low gravity, ores can be lifted more easily from an asteroid than from a planet, to a refinery. Also, many industrial corporations might find more easy to build and manage their factories on an asteroid than on a planet. It is not only that their structures will face less gravity, but also that from an asteroid, cargo can be shipped more easily.
Another important advantage will be political consideration. It is expected that, once people will settle on Mars, Venus, the moons of Jupiter and of Saturn, they will prefer to be free from Earth authorities. It will be almost impossible for a future state to claim all asteroids. Many industrial corporations will benefit from celestial bodies ranked as neutral zones.
Being on a rocky asteroid, you are close to the inner planets of the Solar System. Shipping cargo to them is easy.
Industrial corporations on an asteroid will not need to fear of pollution, like they would on a terraformed planet.
Living on the surface of an asteroid can be dangerous. First of all, people, plants and equipment will be exposed to solar and cosmic radiation. The second problem is the lack of gravity, that will strongly affect settlers (see Future races for details). The third problem is the risk of impacts from micrometeorites.
A major problem is the lack of water and volatiles (carbon dioxide, nitrogen).
There are 3 ways to paraterraform a rocky asteroid.
Global paraterraforming requires the construction of a global shield, that will cover the entire surface. It is possible for an object that has a nearly spherical shape. However, many asteroids have elongated surfaces, even are composed of two lobes.
Once an asteroid is global paraterraformed, it can no longer be an industrial center. It becomes a residential asteroid. However, such celestial bodies can become important tourist destinations. In their low gravity, you can walk on water (since it takes too much for your body to sink). You can jump out of water, like a dolphin.
Low gravity can be used to help people with heart diseases. Also, people with extreme obesity can move to an asteroid, where they can still walk.
Local paraterraforming can be used both for irregular and spherical asteroids. In this case, settlers can have their own farms or parks, unaffected from the industrial areas. Because of limited founds, this is the kind of paraterraforming expected to appear first.
Internal paraterraforming means that all structures are done in cavities, inside the asteroid. This can result after a mining corporation has ceased operation. It is also possible that settlers will dig their own caverns.
In theory, it is cheaper to produce all food, air an water you need on an asteroid then to transport all the goods from a nearby planet. Without a protective shield, plants can suffer from solar radiation. Still, plants will grow more easy because they will not face strong gravity forces.
In a self-sufficient model, bacteria will decompose all what we, humans, leave behind. Also, plants will provide us with all the food and oxygen we need. The process needs to be well monitored. Bacteria can produce carbon dioxide and sulfur dioxide.
Water management is also crucial for the colony. All residual water needs to be treated and reused. Every chemical you use, will then come into your drinking water. Bacteria, used to decompose organic matter, can reach into tanks with drinkable water and infect everyone.
Diseases can spread much faster then on a planet, because of the closed ecosystem.
Tourism & resort Edit
Can an asteroid be a tourist attraction? Yes. In low gravity, you can walk on water or you can jump out of the water like a dolphin. In almost zero-G, you can even dance on the walls.
A paraterraformed asteroid can offer tourists a multitude of ecosystems. You can have a tropical beach at only 2 km from a glacier. For this, all what is required is to create a different greenhouse effect in each part.
Low gravity can be of great help for some severe medical problems. People with heart diseases will move more easily. Also, people with severe obesity will be able to walk and move.
Cosmic Bases Edit
Asteroids, as well as small satellites, can be used for creation of cosmic bases. For example, Phobos, one of Mars's satellites, can be used as a joint base for freight traffic from and towards the planet. In the same way, any of the outer, small satellites of Jupiter and Saturn can serve as a transit base for cargo.
When humans will start to terraform extrasolar planets, asteroids can play an important role. Fast but fragile interstellar spaceships will travel on safe routes from a star to another. These ships will need to be protected and landing on a planet might affect them. So, settlers would prefer to build one interstellar base on an asteroid in each solar system and use other vehicles to transport the goods to each planet and colony.