Space habitat

Space habitat

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A space habitat is a space station
Space station
A space station is a spacecraft capable of supporting a crew which is designed to remain in space for an extended period of time, and to which other spacecraft can dock. A space station is distinguished from other spacecraft used for human spaceflight by its lack of major propulsion or landing...

 intended as a permanent settlement
Space colonization
Space colonization is the concept of permanent human habitation outside of Earth. Although hypothetical at the present time, there are many proposals and speculations about the first space colony...

rather than as a simple waystation or other specialized facility. No space habitats have yet been constructed, but many design proposals have been made with varying degrees of realism by both engineers and science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 authors.

History



About 1970, near the end of Project Apollo
Project Apollo
The Apollo program was the spaceflight effort carried out by the United States' National Aeronautics and Space Administration , that landed the first humans on Earth's Moon. Conceived during the Presidency of Dwight D. Eisenhower, Apollo began in earnest after President John F...

, Gerard K. O'Neill, an experimental physicist, was looking for a topic to tempt his physics students, most of whom were freshmen in Engineering. He hit upon the creative idea of assigning them feasibility calculations for large space habitats. To his surprise, the habitats seemed to be feasible even in very large sizes: cylinders five miles (8 km) in diameter and twenty miles (34 km) long, even if made from ordinary materials such as steel and glass. Also, the students solved problems such as radiation protection from cosmic rays (almost free in the larger sizes), getting naturalistic sun angles, provision of power, realistic pest-free farming and orbital attitude control without reaction motors. O'Neill published an article about these colony proposals in Physics Today
Physics Today
Physics Today, created in 1948, is the membership journal of the American Institute of Physics. It is provided to 130,000 members of twelve physics societies, including the American Physical Society...

in 1974. (See the above illustration of such a colony, a classic "O'Neill Colony"). The article was expanded in his 1976 book The High Frontier: Human Colonies in Space
The High Frontier: Human Colonies in Space
The High Frontier: Human Colonies in Space is a 1976 book by Gerard K. O'Neill, a road map for what the United States might do in outer space after the Apollo program, the drive to place a man on the Moon. It envisions large manned habitats in the Earth-Moon system, especially near stable...

.

The result motivated NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 to sponsor a couple of summer workshops led by Dr. O'Neill. Several designs were studied, some in depth, with sizes ranging from 1,000 to 10,000,000 people.

At the time, colonization was definitely seen as an end in itself. The basic proposal by O'Neill had an example of a payback scheme: construction of solar power satellites from lunar materials. O'Neill's intention was not to build solar power satellites as such, but rather to give an existence proof that orbital manufacturing from lunar materials could generate profits. He, and other participants, presumed that once such manufacturing facilities were on-line, many profitable uses for them would be found, and the colony would become self-supporting, and begin to build other colonies as well.

The proposals and studies generated a notable groundswell of public interest. One effect of this expansion was the founding of the L5 Society
L5 Society
The L5 Society was founded in 1975 by Carolyn and Keith Henson to promote the space colony ideas of Dr Gerard K. O'Neill.The name comes from the and Lagrangian points in the Earth-Moon system proposed as locations for the huge rotating space habitats that Dr O'Neill envisioned...

 in the U.S., a group of enthusiasts that desired to build and live in such colonies. The group was named after the space-colony orbit which was then believed to be the most profitable, a kidney-shaped orbit around either of Earth's lunar Lagrange points 5 or 4.


In this era, Dr. O'Neill also founded the quieter, and more targeted Space Studies Institute
Space Studies Institute
Space Studies Institute is a non-profit organization that was founded in 1977 by the late Princeton University Professor Dr. Gerard K. O'Neill. The stated mission is to "open the energy and material resources of space for human benefit within our lifetime"...

, which initially funded and constructed prototypes of much of the radically new hardware needed for a space colonization effort, as well as number of paper studies of feasibility. One of the early projects, for instance, was a series of functional prototypes of a mass driver
Mass driver
A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch which would use a linear motor to accelerate and catapult payloads up to high speeds. All existing and contemplated mass drivers use coils of wire energized by electricity to make electromagnets. Sequential...

, the essential technology to be used to move ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....

s economically from the Moon to space colony orbits.

The space habitats have inspired a large number of fictional societies in Science Fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

. Some of the most popular and recognizable are the Japanese Gundam
Gundam
The is a metaseries of anime created by Sunrise studios that features giant robots called "Mobile Suits" ; usually the protagonist's MS will carry the name Gundam....

 universe, and Babylon 5
Babylon 5
Babylon 5 is an American science fiction television series created, produced and largely written by J. Michael Straczynski. The show centers on a space station named Babylon 5: a focal point for politics, diplomacy, and conflict during the years 2257–2262...

.

Motivation


Several motivations for building space colonies
Space colonization
Space colonization is the concept of permanent human habitation outside of Earth. Although hypothetical at the present time, there are many proposals and speculations about the first space colony...

 have been proposed: survival, security, energy, raw materials and money.

Space habitats are immune to most of the natural disasters that plague the Earth, such as earthquakes, volcanoes, hurricanes, floods and tornadoes. A space habitat can be the passenger compartment of a large spacecraft for colonizing asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

s, moons, distant stars or other planets (see: Space and survival
Space and survival
Space and survival is the relationship between outer space and the long-term survival of the human species and civilization. Its investigation is justified by the fact that space colonization and space science could prevent many human extinction scenarios...

). Spreading our population out into multiple self-sufficient space habitats across the Solar System will increase our odds of survival, a possible ruin of the Earth's population as a whole not dooming all our species, any more.

Space is literally filled with light produced from the Sun. In Earth orbit, this amounts to 1400 watts of power per square meter. This energy can be used to produce electricity from solar cells
Photovoltaics
Photovoltaics is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material...

 or heat engine
Heat engine
In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work. It does this by bringing a working substance from a high temperature state to a lower temperature state. A heat "source" generates thermal energy that brings the working substance...

 based power stations, process ores, provide light for plants to grow and to warm space colonies, or to heat cold planets (Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

).

Most asteroids are a mixture of the aforementioned materials, virtually all stable elements on the periodic table
Periodic table
The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...

 can be found in the asteroids and comets and more importantly, because these bodies do not have substantial gravity wells, it is very easy to draw materials from them and haul them to a construction site.

There is estimated to be enough material in the main asteroid belt alone to build enough space habitats to equal the habitable surface area of 3,000 Earths.

Power generation


Colonies would have constant access to solar energy up to very large distances from the Sun. Weightlessness allows the construction of large flimsy structures such as mirrors for concentrating sunlight
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...

.

Resources


Space habitats may be supplied with resources from extraterrestrial places like Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

, asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

s, or the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 (in-situ resource utilization
In-Situ Resource Utilization
In space exploration, in-situ resource utilization describes the proposed use of resources found or manufactured on other astronomical objects to further the goals of a space mission....

 [ISRU]; see Asteroid mining
Asteroid mining
Asteroid mining refers to the possibility of exploiting raw materials from asteroids and planetoids in space, including near-Earth objects. Minerals and volatiles could be mined from an asteroid or spent comet to provide space construction material , to extract water and oxygen to sustain the lives...

). One could produce breathing oxygen, drinking water, and rocket fuel with the help of ISRU. It may become possible to manufacture solar panels from Lunar materials.

Population


Habitats may be constructed to give an immense total population capacity. Using the free-floating resources of the solar system, current estimates extend into the trillions.

Trade


Earth to space habitat trade would be easier than Earth to planetary colony trade, as colonies orbiting Earth will not have a gravity well to overcome to export to Earth, and a smaller gravity well to overcome to import from Earth.

Initial capital outlay


Even the smallest of the habitat designs mentioned below is more massive than the total mass of all items ever launched by mankind into Earth orbit. Prerequisites to building habitats are either cheaper launch costs or a mining and manufacturing base on the Moon or other body having low delta-v
Delta-v
In astrodynamics a Δv or delta-v is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver....

 from the desired habitat location.

Internal life support systems


Air pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

, with normal partial pressures of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

, is a basic requirement of any space habitat. Basically, most space colony designs propose large, thin-walled pressure vessels. The required oxygen could be obtained from lunar rock. Nitrogen is most easily available from the Earth, but is also recycled nearly perfectly. Also, nitrogen in the form of ammonia may be obtainable from comets and the moons of outer planets. Nitrogen may also be available in unknown quantities on certain other bodies in the outer solar system. The air of a colony could be recycled in a number of ways. The most obvious method is to use photosynthetic
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

 garden
Gardening
Gardening is the practice of growing and cultivating plants. Ornamental plants are normally grown for their flowers, foliage, or overall appearance; useful plants are grown for consumption , for their dyes, or for medicinal or cosmetic use...

s, possibly via hydroponics
Hydroponics
Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk.Researchers discovered in the 18th...

 or forest gardening
Forest gardening
Forest gardening is a food production and agroforestry system based on woodland ecosystems, incorporating fruit and nut trees, shrubs, herbs, vines and perennial vegetables which have yields directly useful to humans...

. However, these do not remove certain industrial pollutants, such as volatile oils, and excess simple molecular gases. The standard method used on nuclear submarines, a similar form of closed environment, is to use a catalytic burner, which effectively removes most organics. Further protection might be provided by a small cryogenic distillation system which would gradually remove impurities such as mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

 vapor, and noble gases that cannot be catalytically burned.

Organic
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...

 materials for food production would also need to be provided. At first, most of these would have to be imported from the moon, asteroids, or the Earth. After that, recycling should reduce the need for imports. One proposed recycling method would start by burning the cryogenic distillate, plants, garbage and sewage with air in an electric arc, and distilling the result. The resulting carbon dioxide and water would be immediately usable in agriculture. The nitrates and salts in the ash could be dissolved in water and separated into pure minerals. Most of the nitrates, potassium and sodium salts would effectively recycle as fertilizers. Other minerals containing iron, nickel, and silicon could be chemically purified in batches and reused industrially. The small fraction of remaining materials, well below 0.01% by weight, could be processed into pure elements with zero-gravity mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...

, and added in appropriate amounts to the fertilizers and industrial stocks. This method's only current existence is a proof considered by NASA studies. It's likely that methods would be greatly refined as people began to actually live in space habitats.

Artificial gravity


Long-term on-orbit studies have proven that zero gravity weakens bones and muscles, and upsets calcium metabolism and immune systems. Most people have a continual stuffy nose or sinus problems, and a few people have dramatic, incurable motion sickness. Most colony designs would rotate in order to use inertia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

l forces to simulate gravity
Artificial gravity
Artificial gravity is the varying of apparent gravity via artificial means, particularly in space, but also on the Earth...

. NASA studies with chickens and plants have proven that this is an effective physiological substitute for gravity. Turning one's head rapidly in such an environment causes a "tilt" to be sensed as one's inner ears move at different rotational rates. Centrifuge studies show that people get motion-sick in habitats with a rotational radius of less than 100 metres, or with a rotation rate above 3 rotations per minute. However, the same studies and statistical inference indicate that almost all people should be able to live comfortably in habitats with a rotational radius larger than 500 meters and below 1 RPM. Experienced persons were not merely more resistant to motion sickness, but could also use the effect to determine "spinward" and "antispinward" directions in the centrifuges.

Protection from hostile external environment

  • Radiation
    Cosmic ray
    Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

    :
    Studies have shown that large space habitats could be effectively shielded from gamma ray
    Gamma ray
    Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...

    s by their structure and air and that these could in the case of large habitats substitute the wall of two meters of steel that would be needed without them. Smaller habitats could be shielded by stationary (nonrotating) bags of rock. Sunlight could be admitted indirectly via mirrors in radiation-proof louvres, which would function in the same manner as a periscope
    Periscope
    A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirrors at each end set parallel to each other at a 45-degree angle....

    . If the space habitat is located at L4 or L5, then its orbit will take it outside of the protection of the Earth's magnetosphere
    Magnetosphere
    A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...

     for approximately two-thirds of the time (as happens with the Moon), putting residents at risk of proton exposure from the solar wind
    Solar wind
    The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

    .
See Health threat from cosmic rays
Health threat from cosmic rays
The health threat from cosmic rays is the danger posed by galactic cosmic rays and solar energetic particles to astronauts on interplanetary missions.Galactic cosmic rays consist of high energy protons and other nuclei with extrasolar origin...


  • Heat rejection: The colony is in a vacuum, and therefore resembles a giant thermos bottle. The sunlight to radiated energy ratio can be reduced and controlled with large venetian blinds. Habitats also need a radiator
    Radiator
    Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics...

     to eliminate heat from absorbed sunlight and organisms. Very small habitats might have a central vane that rotates with the colony. In this design, convection
    Convection
    Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....

     would raise hot air "up" (toward the center), and cool air would fall down into the outer habitat. Some other designs would distribute coolants, such as chilled water from a central radiator.

  • Foreign objects: The habitat would need to withstand potential impacts from space debris
    Space debris
    Space debris, also known as orbital debris, space junk, and space waste, is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. These objects consist of everything from spent rocket stages and defunct satellites to erosion, explosion...

    , meteoroid
    Meteoroid
    A meteoroid is a sand- to boulder-sized particle of debris in the Solar System. The visible path of a meteoroid that enters Earth's atmosphere is called a meteor, or colloquially a shooting star or falling star. If a meteoroid reaches the ground and survives impact, then it is called a meteorite...

    s, dust, etc. Radar
    Radar
    Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

     will sweep the space around each habitat mapping the trajectory of debris and other man-made objects and allowing corrective actions to be taken to protect the habitat. Meteoroid strikes would pose a risk to a space habitat much stronger than they do to the Earth, unless there should be developed a method to avert them, because a space habitat does not possess a sheltering atmosphere.

Transportation and maneuvering

  • Orbital stationkeeping: The optimal habitat orbits are still debated, and so orbital stationkeeping
    Orbital stationkeeping
    In astrodynamics orbital station-keeping is a term used to describe the orbital maneuvers made by thruster burns that are needed to keep a spacecraft in a particular assigned orbit.For many Earth satellites the effects of the non-Keplerian forces, i.e...

     is probably a commercial issue. The lunar and orbits are now thought to be too far away from the moon and Earth. A more modern proposal is to use a two-to-one resonance orbit that alternately has a close, low-energy (cheap) approach to the moon, and then to the Earth. This provides quick, inexpensive access to both raw materials and the major market. Most colony designs plan to use electromagnetic tether propulsion, or mass driver
    Mass driver
    A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch which would use a linear motor to accelerate and catapult payloads up to high speeds. All existing and contemplated mass drivers use coils of wire energized by electricity to make electromagnets. Sequential...

    s used as rocket motors. The advantage of these is that they either use no reaction mass at all, or use cheap reaction mass.

  • Attitude control: Most mirror geometries require something on the habitat to be aimed at the sun and so attitude control is necessary. The original O'Neill design used the two cylinders as momentum wheel
    Momentum wheel
    A reaction wheel is a type of flywheel used primarily by spacecraft for attitude control without using fuel for rockets or other reaction devices....

    s to roll the colony, and pushed the sunward pivots together or apart to use precession
    Precession
    Precession is a change in the orientation of the rotation axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle is constant...

     to change their angle. Later designs rotated in the plane of their orbit, with their windows pointing at right angles to the sunlight, and used lightweight mirrors that could be steered with small electric motors to follow the sun.

NASA designs


Designs proposed in NASA studies included:
  • Bernal sphere
    Bernal sphere
    A Bernal sphere is a type of space habitat intended as a long-term home for permanent residents, first proposed in 1929 by John Desmond Bernal....

    : "Island One", a spherical habitat for about 20,000 people.
  • Stanford torus
    Stanford torus
    The Stanford torus is a proposed design for a space habitat capable of housing 10,000 to 140,000 permanent residents.The Stanford Torus was proposed during the 1975 NASA Summer Study, conducted at Stanford University, with the purpose of speculating on designs for future space colonies...

    : A larger alternative to "Island One."
  • O'Neill cylinder: "Island Three" (pictured), the largest design.
  • Lewis One: A cylinder of radius 250m with a non rotating radiation shielding. The shielding protects the micro-gravity industrial space, too. The rotating part is 450m long and has several inner cylinders. Some of them are used for agriculture.
  • Kalpana One, revised: A short cylinder with 250 m radius and 325 m length. The radiation shielding is 10 t/m2 and rotates. It has several inner cylinders for agriculture and recreaction.
  • A "bola": a spacecraft or habitat connected by a cable to a counterweight
    Counterweight
    A counterweight is an equivalent counterbalancing weight that balances a load.-Uses:A counterweight is often used in traction lifts , cranes and funfair rides...

     or other habitat. This design has been proposed as a Mars ship, initial construction shack for a space habitat, and orbital hotel
    Transhab
    TransHab was a concept pursued by NASA to develop the technology for expandable habitats inflated by air in space. Specifically, TransHab was intended as a replacement for the already existing rigid International Space Station crew Habitation Module. When deflated, inflatable modules provide an...

    . It has a comfortably long and slow rotational radius for a relatively small station mass. Also, if some of the equipment can form the counter-weight, the equipment dedicated to artificial gravity is just a cable, and thus has a much smaller mass-fraction than in other designs. This makes it a tempting design for a deep-space ship. For a long-term habitation, however, radiation shielding must rotate with the habitat, and is extremely heavy, thus requiring a much stronger and heavier cable.
  • "Beaded habitats": This speculative design was also considered by the NASA studies, and found to have a roughly equivalent mass fraction of structure and therefore comparable costs. Small habitats would be mass-produced to standards that allow the habitats to interconnect. A single habitat can operate alone as a bola. However, further habitats can be attached, to grow into a "dumbbell" then a "bow-tie," then a ring, then a cylinder of "beads," and finally a framed array of cylinders. Each stage of growth shares more radiation shielding and capital equipment, increasing redundancy and safety while reducing the cost per person. This design was originally proposed by a professional architect because it can grow much like Earth-bound cities, with incremental individual investments, unlike designs that require large start-up investments. The main disadvantage is that the smaller versions use a large amount of structure to support the radiation shielding, which rotates with them. In large sizes, the shielding becomes economical, because it grows roughly as the square of the colony radius. The number of people, their habitats and the radiators to cool them grow roughly as the cube of the colony radius.
  • Nautilus-X
    Nautilus-X
    Nautilus-X is a multi-mission space exploration vehicle imagined by the Technology Applications Assessment Team by NASA....

     Multi-Mission Space Exploration Vehicle (MMSEV): this 2011 NASA proposal for a long-duration crewed space transport vehicle included an artificial gravity
    Artificial gravity
    Artificial gravity is the varying of apparent gravity via artificial means, particularly in space, but also on the Earth...

     space habitat intended to promote crew-health for a crew of up to six persons on missions of up to two years duration. The partial-g torus-ring
    Torus
    In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...

     centrifuge
    Centrifuge
    A centrifuge is a piece of equipment, generally driven by an electric motor , that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis...

     would utilize both standard metal-frame and inflatable
    Inflatable space habitat
    Inflatable habitats or expandable habitats are pressurized structures capable of supporting life in outer space whose internal volume increases after launch...

     spacecraft structures and would provide 0.11 to if built with the 40 feet (12.2 m) diameter option. , developing and assembling the NAUTILUS-X "would take at least five years and require two or three rocket launches. It would cost about $3.7 billion." NASA has released a short animation of NAUTILUS-X in space; the link is included in the External links section below.

  • ISS
    ISS
    The ISS is the International Space Station.ISS may also refer to:* I See Stars, an American electronic rock band* ISS A/S, a Danish service company* Idea Star Singer, a Malayalam music reality show by Asianet TV...

     Centrifuge Demo: Also proposed in 2011 as a demonstration project preparatory to the final design of the larger torus centrifuge space habitat for the Multi-Mission Space Exploration Vehicle. The structure would have an outside diameter of 30 feet (9.1 m) with a 30 inches (76.2 cm) ring interior cross-section diameter and would provide 0.08 to partial gravity. This test and evaluation centrifuge would have the capability to become a Sleep Module for ISS crew.

Bubbleworld


The Bubbleworld or Inside/Outside concept was originated in 1964 by Dandridge M. Cole
Dandridge M. Cole
Dandridge MacFarlan Cole was an American aerospace engineer, futurist, lecturer, and author.-Parents and education:Cole was born February 19, 1921 in Sandusky, Ohio to Robert MacFarlan Cole III and Wertha Pendleton Cole, the daughter of bishop William Frederic Pendleton.He attended the Academy of...

 and Donald W. Cox in a nonfiction book, Islands in Space: The Challenge of the Planetoids.

The concept calls for drilling a tunnel through the longest axis of a large asteroid of iron or nickel-iron composition and filling it with a volatile
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

 substance, possibly water. A very large solar reflector would be constructed nearby, focusing solar heat onto the asteroid, first to weld and seal the tunnel ends, then more diffusely to slowly heat the entire outer surface. As the metal softens, the water inside expands and inflates the mass, while rotational forces help shape it into a cylindrical form. Once expanded and allowed to cool, it can be spun to produce artificial gravity, and the interior filled with soil, air and water. By creating a slight bulge in the middle of the cylinder, a ring-shaped lake can be made to form. Reflectors will allow sunlight to enter and to be directed where needed. Clearly, this method would require a significant human and industrial presence in space to be at all feasible.

The Bubbleworld concept was popularized by science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 author Larry Niven
Larry Niven
Laurence van Cott Niven / ˈlæri ˈnɪvən/ is an American science fiction author. His best-known work is Ringworld , which received Hugo, Locus, Ditmar, and Nebula awards. His work is primarily hard science fiction, using big science concepts and theoretical physics...

 in his fictional Known Space
Known Space
Known Space is the fictional setting of some dozen science fiction novels and several collections of short stories written by author Larry Niven. It has also in part been used as a shared universe in the Man-Kzin Wars spin-off anthologies sub-series....

 stories, describing such worlds as the primary habitats of the Belters
Belter (Niven)
In Larry Niven's fictional Known Space universe, a Belter refers to a resident of the Asteroid Belt around Sol, sometimes known as the Sol Belt to differentiate it from Alpha Centauri's Serpent Swarm....

, a civilization who had colonized the Asteroid Belt
Colonization of the asteroids
The asteroids have long been suggested as possible sites for human colonization. This idea is popular in science fiction. Asteroid mining, a proposed industrial process in which asteroids are mined for valuable materials, especially platinum group metals, may be automated or require a crew to...

.

Hypothetical designs


In the 1990s, as the potential usefulness of carbon nanotube
Carbon nanotube
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material...

s as structural material became apparent, proposals were advanced for much larger habitats taking advantage of this material. The technology to produce nanotubes of the required length is not available, so these designs remain speculative.
  • Bishop ring
    Bishop Ring (habitat)
    A Bishop Ring is a type of hypothetical rotating space habitat originally proposed in 1997 by Forrest Bishop. As with other space habitat designs, the Bishop Ring would spin to produce artificial gravity by way of centrifugal force. The design differs from the classical designs produced in the...

    : A torus 1000 km in radius, 500 km in width, and with atmosphere retention walls 200 km in height. The design would be large enough that it could be "roofless", open to space on the inner rim.
  • McKendree cylinder
    McKendree cylinder
    A McKendree cylinder is a type of hypothetical rotating space habitat originally proposed at NASA's Turning Goals into Reality conference in 2000 by NASA engineer Tom McKendree. As with other space habitat designs, the cylinder would spin to produce artificial gravity by way of centrifugal force....

    : Paired cylinders in the same vein as the O'Neill cylinder/Island Three design, each 460 km in radius and 4600 km long (versus 3.2 km radius and 32 km long in the Island Three design).

Bigelow Commercial Space Station


The Bigelow Next-Generation Commercial Space Station was announced in mid-2010.
The initial build-out of the station is expected in 2014/2015, and will consist of two Sundancer
Sundancer
Sundancer is the proposed third prototype space habitat to be launched by Bigelow Aerospace and the first human-rated expandable module based on TransHab technology acquired from NASA...

 modules and one BA-330 module.
Bigelow has publicly shown space station design configurations with up to nine BA-300 modules containing 100000 cu ft (2,831.7 m³) of habitable space
Bigelow began to publicly refer to the initial configuration—two Sundancer
Sundancer
Sundancer is the proposed third prototype space habitat to be launched by Bigelow Aerospace and the first human-rated expandable module based on TransHab technology acquired from NASA...

 modules and one BA-330 module—as "Space Complex Alpha" in October 2010.

Bigelow recently announced that it has agreements with six sovereign state
Sovereign state
A sovereign state, or simply, state, is a state with a defined territory on which it exercises internal and external sovereignty, a permanent population, a government, and the capacity to enter into relations with other sovereign states. It is also normally understood to be a state which is neither...

s to utilize on-orbit facilities of the commercial space station: United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 and Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

.

See also



  • Generation ship
    Generation ship
    A generation ship is a hypothetical type of interstellar ark starship that travels across great distances between stars at a speed much slower than the speed of light...

  • Human outpost
    Human outpost
    Human outposts are artificially-created, controlled human habitats located in environments inhospitable for humans, such as on the ocean floor, in space or on another planet....

     (artificially created controlled human habitat)
  • Inflatable space habitat
    Inflatable space habitat
    Inflatable habitats or expandable habitats are pressurized structures capable of supporting life in outer space whose internal volume increases after launch...

  • Mars to Stay
    Mars to Stay
    Mars to Stay missions propose astronauts sent to Mars for the first time should stay there indefinitely, both to reduce cost and to ensure permanent settlement of Mars. Among many notable Mars to Stay advocates, former Apollo astronaut Buzz Aldrin has been particularly outspoken, suggesting in...

  • Space manufacturing
    Space manufacturing
    Space manufacturing is the production of manufactured goods in an environment outside a planetary atmosphere. Typically this includes conditions of microgravity and hard vacuum.Manufacturing in space has several potential advantages over Earth-based industry....

  • Space stations and habitats in popular culture
  • The Brick Moon
    The Brick Moon
    "The Brick Moon" is a short story by Edward Everett Hale, published serially in The Atlantic Monthly starting in 1869. It is a work of speculative fiction containing the first known depiction of an artificial satellite.- Synopsis :...

  • Transhab
    Transhab
    TransHab was a concept pursued by NASA to develop the technology for expandable habitats inflated by air in space. Specifically, TransHab was intended as a replacement for the already existing rigid International Space Station crew Habitation Module. When deflated, inflatable modules provide an...


External links