One of the most important technologies that need to be developed, in addition to space ships, will be the human habitats. They should offer humans protection from the harsh conditions of the different environments. In addition, they should be able to have an option to refine resources and export them back to Earth.
The most important mission for the habitats is to keep the settlers alive, reliably. Habitat should be able to provide all the necessary resources, such as water, oxygen, food and warmth. Currently, we already have most of the technology required for the habitats. We have nuclear submarines and space stations, that are able to keep humans alive for long periods of time.
In addition to the necessary requirements, habitats should be able to provide other things, also. One of the most important things is to be able to produce food inside the habitats. In addition, factories, research stations and other functions should be possible, to make the settlement financially valuable. Before these factors, though, we must keep our mind on keeping the settlers alive.
Types of Habitats
Surface habitats are the most traditional kind of habitat. There are multiple ways to build them. Probably the most inexpensive way would be to use modules, such as the ones used in space stations. Unfortunately, the capacity of the modules is quite limited and they probably wouldn’t offer enough protection from space radiation.
Surface habitats could be protected from radiation by covering them with a large amount of soil found on the foreign object. It would be possible to build a radiation shield by other methods, also, but covering them would probably be the most financially sound option.
The modular habitats could be brought from the Earth. The other option is to actually build them on-site, with the help of robots. Robots could arrive to the settlement before humans, and could build the habitats before the human colonizers would arrive. This way, resources of the habitable object could be used when building the colony.
Surface habitats would provide an inexpensive way for humans to colonize a planet. Modules could be added as needed, or the whole settlement could be moved if there’s a need for it. However, the space is quite limited in the surface habitats, and psychological problems caused by living in small spaces, for example, could be quite devastating for the colony.
Surface habitats could be built on a bigger scale, also. It would be possible to build large domes filled with breathable oxygen, in which habitats could be built. Finding the suitable materials for such domes could pose a problem. Building these domes, however, would offer a possibility to live in a foreign object in Earth-like conditions. Domes would have weather phenomena, clouds and plenty of room for humans, plants and even animals.
One possibility would be to build the habitats underground. In this option, robots would be sent to the surface before arrival of humans. Robots could manufacture the necessary drilling equipment on-site, or they could be brought completely from Earth. Robots could excavate large caves, and the walls and the roof would provide shelter from radiation, temperature and micrometeorites.
Currently, we do not have necessary technology to build underground habitats. As we already have necessary technology to build surface habitats, developing technology for underground habitats could be too expensive. Robots excavating the soil would face multitude of problems. Because it is likely that the distance between robots and the Earth is quite large, the robots should be able to build the habitats quite autonomously.
Underground habitats could be a good option for places, where temperatures are low and space radiation is a problem. For example, many moons might have an underground ocean, where temperatures could be bearable for humans. This would remove the need for too much insulation, and would also provide necessary shelter from radiation. Micrometeorites wouldn’t pose a problem for underground habitats, either.
Many objects that we would like to colonize have a thick atmosphere. Floating habitats have been suggested for colonizing Venus, but gas giants could also be settled by using floating habitats. The idea of floating habitats is based on a fact, that on a thick atmosphere, there is an area where the pressure of the atmosphere is about the equal that to sea level pressure on Earth. Floating habitat would be able to stay afloat in a thick atmosphere, using virtually no energy.
The problem of floating habitats is, that the resources of the planet can not be easily used. Building the habitats would be relatively easy, but going to the surface to excavate resources of Venus, for example, would still be impossible. Floating habitat on Venus could be used as a research station that could provide enough data for terraforming the planet eventually.
There are multiple ways to provide shelter for humans in foreign bodies. The proper way should be chosen according the properties of the object we are trying to colonize. In many cases, combining these methods could be useful. For example, on Mars, the initial habitats could be built on surface, and after that extended to a large underground network. None of the habitat types should be ignored, as some objects might require using one of them.