Space HabitatA Space Habitat, also called a Space Colony or Orbital Colony, is a space station that is a permanent installation rather than an orbital relay or other specialised facility. It could be a 'city' in space, where a population could live, work and raise families. No space habitat has yet been built, but many concepts have been developed with varying degrees of realism by both engineers and science fiction writers.
Considerations of building space habitats, whether in reality or in fiction, have survived as far back as the second half of the 19th century. For example, The Brick Moon, a fictional story by Edward Everett Hale from 1869, deals with such an idea. In 1903, Russian inventor Konstantin Tsiolkovsky speculated in Beyond Planet Earth about rotating cylindrical space habitats whose plants receive light from the sun to enable photosynthesis in space. In the 1920s, British naturalist John Desmond Bernal also speculated about giant space habitats. The US space engineer, futurist and author Dandridge M. Cole (1921-1965) also speculated about space habitats in various magazine articles and books in the late 1950s and 1960s. Most notably, in his 1964 book Islands in Space: The Challenge Of The Planetoids, he described the idea of hollowing out asteroids, putting them into rotation and then using them as settlements.
For the moment, the creation of permanent habitats in space is fiction. At this time, one could argue, there are no objective reasons that could motivate the creation of permanent habitats in space:
- Research Research work (biology) is satisfied with more or less long but temporary stays.
- Industry Experiments carried out in space stations have not confirmed the interest of space factories benefiting from microgravity.
- Population Growth No population growth justifies the creation of a space habitat, even if we speculate on considerable progress in the necessary techniques and a significant reduction in launch costs.
- Catastrophes No threat from space (asteroid prediction...) has generated a technological and financial effort that would allow the necessary know-how to emerge.
Proponents of space habitats cited various reasons for designing and building such facilities. Reasons for building space habitats include:
- Exploration Space Habitats could support space exploration as part of human spaceflight and space colonisation. Other use cases were also cited:
- Catastrophes In the event of a catastrophe on Earth, either stemming from natural events (such as volcanic eruptions, asteroid impacts or dramatic weather events) or caused by humans (e.g. wars, mismanagement, etc.), such habitats could enable survival of human civilisation and the biosphere.
- Space Mining Near-Earth space theoretically offers the possibility of mining existing raw materials on asteroids, for example, in order to use them in space projects. Space travel would thus no longer be dependent on earthly resources and their cost-intensive transport into space. It could also prevent the already scarce resources in ecosystems of indigenous peoples from being further destroyed.
- Population Growth Furthermore, it would help humanity on Earth to reduce population pressure and, associated with this, an increasing industrial burden, also from the point of view of environmental pollution.
Advantages of Space Habitats
- Access to solar energy: In near-Earth space, a large amount of light coming from the Sun is available as sunshine, which space habitats could use to generate energy. In space, the undamped radiant power, the (solar constant) E0, is 1,367 watts per square metre. This radiant power could be used to generate electricity with solar cells or heat engine-based power plants, which could be used, for example, to process ores, provide light for plant growth, and have the potential to heat space habitats.
- Location outside the gravitational field: Trade and transport of goods between Earth and space would be easier to conduct than that between Earth and other planets, since habitats orbiting Earth would not have to overcome a gravitational field to export goods to Earth or would only have to overcome a smaller gravitational field to import them from Earth to the habitat in return.
- In-situ resource utilisation: Resource utilisation, also known as asteroid mining or in English in-situ resource utilisation ISRU, would allow space habitats to obtain resources from extraterrestrial locations such as the Moon, Mars or asteroids. In situ resource utilisation would make it possible to produce breathing oxygen, drinking water, rocket fuel as well as solar panels from lunar materials.
- Asteroids and other small bodies: In the case that asteroids have mineable materials, since such small bodies have hardly any significant gravitational fields, they could be more easily transported from their surfaces for further processing. Their low gravitational field, due to a low delta v, would require much less energy to escape the gravitational pull of an asteroid than is the case with larger objects such as planets. While it is very optimistically believed that there are enough raw materials in the main asteroid belt alone to build as many space habitats with them as are equivalent to a habitable area of 3,000 Earths, estimates from other studies suggest a much smaller number of mineable asteroids.
- Population: a 1974 estimate indicated that mining all the raw materials in the main asteroid belt would allow the construction of habitats and thus achieve an immense total population capacity. Using the resources freely available throughout the solar system, this population supply estimate went into the trillions.
- Weightlessness as a recreational opportunity: if a habitat around its axis of rotation included a large area of no gravity, various zero-G sports would be possible, including swimming, hang gliding and the use of muscle-powered aircraft.
- Passenger space: a space habitat could also be used as the passenger space of a large spacecraft for colonising moons, planets and asteroids. It is also conceivable that a habitat could be used as a generational spaceship, allowing people to travel to other planets or distant stars. The British nuclear physicist Leslie R. Shepherd (1918-2012) described a generational spaceship in 1952, comparing it to a small planet where many people could live.
Problems and Solutions
- Radiation: cosmic rays are a definite danger to human life outside a planetary atmosphere, gamma rays are the main danger because they are very penetrating (1 cm of lead or 6 cm of concrete are needed to reduce their intensity by half) and bringing such quantities of heavy materials into orbit is a major technical problem.
- Self-sufficiency: an orbital habitat means an environment that will have to evolve in a virtual vacuum. As a result, all organic content will have to be recycled sparingly. In terms of food, hydroponics combined with GMOs could provide sufficient production to be viable. Water and air will also have to be continuously recycled. This also means that the entire survival system will be based on a very precise balance that must not be disturbed: population growth or loss of matter in space must be avoided at all costs.
- Metabolic weakening: if humans are no longer subject to gravitational acceleration (9.81 m/s2 for the Earth), their bone and muscle mass will gradually decrease. This effect was observed as early as the first space voyages, when scientists subjected astronauts to a battery of tests to establish their health. To remedy this problem, it is necessary either to include several hours of sport and physical exercise, or to maintain an artificial gravity similar to that of the Earth (by accelerating/decelerating or via a centrifuge model (see Tore from Stanford).
- Psychological impact: confinement in small spaces, proximity to others and the absence of normal cycles (day/night, seasons...) have effects that are not yet fully established in the long term. Simple means can create the illusion of days and nights (light intensity and wavelength) but claustrophobia, paranoia, apathy and other mental disorders are likely to occur. Experiments that tend to have people living together in a confined space all show these kinds of deviations in varying stages of danger.
Have a look at our dedicated page on Space Habitat Concepts.
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