Before Terra Nova can come to be, materials are needed for her construction, and for her inhabitants' basic life support - air, water, and food.
Getting these materials from Earth would prove very expensive. In terms of gravity, Earth is like a pit. It is very difficult and expensive to launch rockets from the Earth. Therefore, the bulk materials for Terra Nova should come mainly from the Moon and near-Earth asteroids. Their gravities are considerably less than Earth's, and you do not have to worry about polluting an atmosphere or biosphere like Earth's.
From the Moon we can acquire oxygen for an atmosphere, rocket fuel, and as a component of water. The metals needed to build the colony could also be obtained from the Moon. Aluminum and titanium, both good structural materials because of their strength and light weight, as well as iron and magnesium can be found in large enough quantities on the Moon. Silicon, a component of glass, is also found in ample supplies in the Moon's soil. The Apollo astronauts often found themselves slipping a lot because of all the silicon in the Moon's soil. This material could be used to make glass and solar cells. Although hydrogen is found on the Moon, it is present in very small quantities. The lunar soil contains about 0.01% hydrogen, so for every 10, 000 tons of soil processed, you would only get 1 ton of hydrogen. Hydrogen is very important because is it used as a rocket fuel, and more significantly, as a component of water. Luckily for space colonists, recent observations of the Moon have found what might be ice mixed into the soil. This would be great, because that way we would not have to import hydrogen from Earth, or even mix it with oxygen to make water.
In order to get materials from asteroids, they must be located near Earth. We can mine materials from near-Earth asteroids, or drag them from the asteroid belt to us. Otherwise, it would be very expensive to make lots of trips to that area. From the asteroids we can get metals, and perhaps even water if they happen to be burned out comets.
In order to extract the metals from the soil, the process of electrophoresis (mentioned earlier for the manufacture of zero-gravity drugs) could be used. If you insert electrodes into the soil and heat it to extreme temperatures, it will melt. Then electricity could flow between the electrodes and separate the soil's components. Different materials will collect at different electrodes at different times, so they can be thus gathered, and then stored.
Some of the best types of materials to use in the construction of any space structure are composite materials. Composite materials are made by bonding two materials together. One material acts as a glue that surrounds the fibers of the other material. NASA is currently using composite materials to construct the space stations because these materials do not react to heat or cold (one from the sun, the other from the vacuum of space), and therefore, do not expand or contract.
Unfortunately, the materials you can get from the Moon and the asteroids are not enough to sustain a space colony. Nitrogen, carbon, and some hydrogen would have to be imported from Earth at high costs. These would therefore become very precious resources.
In order for Terra Nova to produce artificial gravity (see "Human Element," "Emotional Needs"), the colony needs to have a circular shape which will enable it to spin. There are three options for circular habitats: the sphere, the cylinder, or the torus.
For Terra Nova, I chose to use the torus. This shape provides the most living space at a fixed distance from the axis. This "donut" shape also allows for maximum exterior views of space and earth. There is more surface area of walls in several tori than in one large cylinder.
I also chose to use this shape for more sentimental reasons. The wheel design for a space colony was first developed many years ago in 1950, by my favourite scientist and the person who first got men to the moon, Werner Von Braun. This design was also used in the movie 2001: A Space Odyssey in a scene called the ballet of the spaceships.
The size of my torus, or in the case of Terra Nova, my tori, is also an important factor. I have learned that an average human can tolerate 2-3 revolutions per minute without feeling ill, and the rare individual can only stand 1 revolution per minute. I have also learned that for a torus to produce 1 g of artificial gravity, and have a radius of 1km, it must rotate once every 63 seconds. So here I have found the perfect size for my colony. The inner ring and main living area of Terra Nova will have a diameter of 2km, and rotate once every 63 seconds. That way, any human can live there without being constantly nauseous and sick.
The two outer rings of Terra Nova will still rotate at the same rate as the inner ring, but they will be half its size. Because of this, the artificial gravity inside will only be half a g.
I have decided to make the hubs of all three rings each one tenth their size. That means the hub in the inner ring will be 200m in diameter, and the hubs in the two outer rings will be 100m in diameter. That will allow for zero-gravity conditions in all areas of these hubs. The connection spokes will be 20m in diameter to allow for transport of people, goods, and air from hub to ring, and hub to hub.
L5, the location of Terra Nova (See "Location"), is past the Van Allen Radiation belts, so solar radiation is the only worry for her inhabitants. However, it is still a serious worry. Cosmic rays and solar flares can cause lethal radiation in open space when unprotected by the Earth's atmosphere.
There are two methods of protecting Terra Nova from these rays - active shielding and passive shielding. Active shielding involves surrounding the colony with a magnetic field that would divert the rays, while passive shielding involves surrounding the colony with enough mass to absorb the rays. Since the latter is the more stable, more feasible and simpler of the two, I chose passive shielding to protect Terra Nova.
Terra Nova must be surrounded by enough mass to absorb most of the incoming radiation, protecting the people and other living things inside. An average human can survive a 0.5 rem (Roentgen equivalent man - unit dose of radiation describing its biological effect) per year dose of radiation. To achieve this, the shield must contain about 4.5 tons of material/mē. For a torus like the inner ring of Terra Nova, this would mean approximately 10 tons of shield.
The rings of Terra Nova can be surrounded by a covering of lunar slag several metres thick; the materials left over from processing lunar soil into metals, oxygen, and ore-smelting operations.
The slag cover would not be attached to the rings. (See Figure 1) It would completely cover them except for the approximately 40m of glass at the top of the colony, and the other 40m wide set of windows set lower down in the colony. (These measurements are smaller for the two outer rings) That way, the colony would not have to drag all that extra weight around on its 1rpm journey. That could cause structural stress and damage to the tori. The slag covering would remain stationary while the rest of the colony rotated. The engineering for maintaining an alignment between the shield and the torus would not in principle be difficult, but so far no one has tried it.
The glass in the colony could protect the people from radiation too if V-shaped pieces of aluminum were placed in it. (See Figure 2) The radiation would have to bounce off all the angles in the aluminum in the glass. That would reduce the radiation's strength immensely.
Communication between Terra Nova, Earth, and the Moon is one of the relatively simple aspects of designing and constructing a space colony. Much of Earth's communication today is already done using satellites and satellite dishes, so communication with Terra Nova should not be too much of a problem. However, communications is still vitally important, and should be one of the first things put up when building a space colony.
Terra Nova's communications systems would consist of two main satellite dishes. The larger, principal one would be Terra Nova's communication satellite with her Earth headquarters. It would be located on the unmoving shield of her inner ring, and always point towards Earth. This satellite dish would have at least one auxiliary system. The second major satellite dish would be Terra Nova's communication link with the Moon. It would be located 90 from the Earth dish on the shield of the inner ring, and it too would constantly be fixed towards its target 60 away, the Moon. Like any good communication system, it would have at least one back-up system. It could be used to transmit information about incoming materials, shipments, and shuttles from the Moon.
There would also be satellite communication within Terra Nova. She would need contact with the maintenance people on her solar panels, SPS, and emergency habitats. Communications inside Terra Nova could be similar to that within a building on Earth, including telephones that could connect you with other people on board.
Determining a power source is another of the first things to do when building a space colony. The best power source with which to fuel Terra Nova is the cheap, reliable, abundant, and already usable solar energy.
Terra Nova would simply need to have large areas of solar panels attached to her. These would supply the colony with energy, and store energy in batteries for the two times a month when she would pass behind Earth's shadow.
Terra Nova's solar panels would be located on the edges of the colony. She would have two areas of panels sticking out from the hub of both the smaller rings. These panels would each measure 400m by 800m, or more if necessary, and be rotatable to achieve the best angle for receiving sunlight. The reason two areas of panels are needed is for security. If one of the solar panels were to break down for any reason, the other panel could still provide the colony with energy. As with anything, having auxiliary systems is always a good idea. This way you can also get more energy than with simply one area of panels.
Photovoltaic, or solar panels can convert sunlight into an electrical current. Most solar panels today have an efficiency rate of 10%. The total energy received by the light of the sun per area and time is known as the solar constant. Since the solar constant is about 1.365 kW per mē in Earth orbit, Terra Nova's panels could receive vast amounts of energy in just one day. If my calculations are correct, and if the solar panels have an efficiency of about 10%, she could get about 226 440 GJ of energy per month. That is equal to getting 174.72 MW. Since the average person consumes 4 GJ of energy a month, Terra Nova would have enough energy for 56 610 people, 5 times her population. The rest of the energy would be used by the colony's agricultural and space industries, as well as the colony itself.
Overall, light from the sun is the best power source for any spacecraft or colony. It is already being used in space stations today. Also, it is free, and it will be there 99% of the time. The only disadvantage of using solar panels is their cost. Right now, they can be very expensive to buy and ship. However, after initially being imported from Earth, they can be manufactured right on Terra Nova by shipments of silicon sent from the Moon.
