A pair of O'Neill cylinders

Interior of a Torus (doughnut-shaped) station

A space habitat, also called space colony or orbital colony, is a space station intended as a permanent settlement rather than as a simple waystation or other specialized facility. It would be a "city" in space, where people would live, work and raise families. No space habitats have yet been constructed, but many design proposals have been made with varying degrees of realism by both science fiction authors and engineers. Image File history File links Download high-resolution version (1896x1388, 749 KB) [edit] ファイルの概要 NASA Ames Research Center space colony image http://lifesci3. ... Image File history File links Download high-resolution version (1896x1388, 749 KB) [edit] ファイルの概要 NASA Ames Research Center space colony image http://lifesci3. ... Painting of a space colony design by Donald E. Davis for NASA; see http://www. ... Painting of a space colony design by Donald E. Davis for NASA; see http://www. ... The space station Mir A space station is an artificial structure designed for humans to live in outer space. ... Artists conception of a space habitat called the Stanford torus, by Don Davis Space colonization, also called space settlement and space humanization, is the possible permanent autonomous (self-sufficient) human habitation of locations outside Earth. ... Science fiction is a form of speculative fiction principally dealing with the impact of imagined science and technology, or both, upon society and persons as individuals. ... Look up engineer in Wiktionary, the free dictionary. ...

History

About 1970, near the end of Project Apollo, Gerard K. O'Neill, an experimental physicist, was looking for a topic to tempt his freshman 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) wide 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. He published an article about these colony proposals in Physics Today in 1974. (See the above illustration of such a colony, a classic "O'Neill Colony"). The article was expanded in the book High Frontier. Apollo CSM in lunar orbit. ... Gerard Kitchen ONeill (1927 - 1992) was a U.S. physicist and space pioneer. ...

The result motivated NASA to sponsor a couple of summer workshops led by Dr. O'Neill.^[1][2] Several designs were studied, some in depth, with sizes ranging from 1,000 to 10,000,000 people. Attempts were made to make the habitats as self-supporting as possible, but all of the designs relied on regular shipments from Earth or the Moon, notably for raw materials and volatiles. Closed ecologies and aggressive recycling should dramatically reduce this reliance. Recent research has increased the probability of finding frozen water in deep craters on the moon's south pole, and found that certain asteroids contain significant amounts of volatiles such as water and ammonia. Therefore, space habitats could rely less on Earth than these original studies indicated. NASA logo Listen to this article · (info) This audio file was created from an article revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... An asteroid is a predominantly rocky body that orbits around its star. ...

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. A solar power satellite, or SPS, is a proposed satellite built in high Earth orbit that uses microwave power transmission to beam solar power to a very large antenna on Earth where it can be used in place of conventional power sources. ...

The proposals and studies generated a notable groundswell of public interest. One of the most interesting public effects was the founding of the L5 Society 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. The original L5 Society logo, currently located at the L5 News archive on the World Wide Web The L5 Society was founded in 1975 by Carolyn and Keith Henson to promote the space colony ideas of Dr. Gerard K. ONeill. ... In celestial mechanics, the Lagrangian points, (also Lagrange point, L-point, or libration point) are the five stationary solutions of the circular restricted three-body problem. ...

In this era, Dr. O'Neill also founded the quieter, and more targeted Space Studies Institute, 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, the essential technology to be used to economically move ores from the moon to space colony orbits. Cover of procedings for 7th Space Manufacturing conference. ... A mass driver for lunar launch (artists conception) A mass driver or electromagnetic catapult is a method of spacecraft propulsion that would use a linear motor to accelerate payloads up to high speeds. ...

The L5 Society later became the National Space Society, and former members started a number of related efforts, including the Artemis Project, and the Mars Society. As well, some former L5 Society members seem to be active in radical engineering groups such as the Extropian Institute. A number of prominent modern space engineers and rocket scientists trace their motivation to this era. National Space Society logo The National Space Society (NSS) is an international nonprofit 501(c)(3), educational, and scientific organization specializing in space advocacy. ... The Moon Society logo The Moon Society is a space advocacy organization, founded in 2000, and dedicated to promoting large-scale human exploration, research, and settlement of the Moon. ... Mars Society logo. ... This article or section does not cite its references or sources. ...

The space habitats have inspired a large number of fictional societies in Science Fiction. Some of the most popular and recognizable are the Japanese Gundam universe, and Babylon 5. Science fiction is a form of speculative fiction principally dealing with the impact of imagined science and technology, or both, upon society and persons as individuals. ... Gundam ) is one of the longest running series of anime featuring giant robots or mecha. ... Babylon 5 is an epic science fiction television series created, produced, and largely written by J. Michael Straczynski. ...

Motivation

There are several prominent reasons for space colonization: security, profits, energy and raw materials. Artists conception of a space habitat called the Stanford torus, by Don Davis Space colonization, also called space settlement and space humanization, is the possible permanent autonomous (self-sufficient) human habitation of locations outside Earth. ...

Space habitats are likely to be less affected by disasters that damage the Earth, such as overpopulation, or ocean strikes by large bolides (ie meteorites, etc). Although an individual habitat is probably less secure than Earth, many habitats together add substantially to human survivability. They provide opportunities for migration. The term bolide (from the Greek βολις, bolis, missile) can refer to either an extraterrestrial body that collides with the Earth, or to an exceptionally bright, fireball-like meteor regardless of whether it ultimately impacts the surface. ...

Space has most of the raw materials known, and large amounts of energy. It should be possible to make profits, if mining and manufacturing can just get off the ground.

For example, some proponents estimate that compared to Earth, a family or company might easily triple or quadruple their incomes. Costs might be lower as well. Proponents' estimates of the cost of space colony land work out to roughly $30,000 per acre ($7.50/m²) in 1995 USD, in large economical space colonies. While expensive for rural land, it is inexpensive for city land. The metre, or meter (US), is a measure of length. ... ISO 4217 Code USD User(s) the United States, the British Virgin Islands, East Timor, Ecuador, El Salvador, the Marshall Islands, Micronesia, Palau, Panama, Turks and Caicos Islands, and the insular areas of the United States Inflation 3. ...

As there exists a vast amount of material to build with in the solar system, and as a space habitat is out of planetary gravity wells, a vast population could live and work in space permanently. The Earth can be viewed as quite small, crowded and restrictive compared to outer space. see: overpopulation. Earth (IPA: , often referred to as the Earth, Terra, or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... Layers of Atmosphere - not to scale (NOAA) Outer space, also simply called space, refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. ... Map of countries by population —showing the population of the China and India in the billions. ...

Habitats outside the shadows of planets can use solar power 24 hours a day. Zero-g enables the creation of extremely large-yet-flimsy concentrating mirrors to gather this constant and abundant energy. As well, colonies are well outside the magnetosphere of Earth, and can employ nuclear power without fear of pollution. Solar power describes a number of methods of harnessing energy from the light of the sun. ... Schematic of Earths magnetosphere. ... A nuclear power station. ...

Advantages

Space habitats have a number of potential advantages over planet-based colonies:

1. Adjustable artificial gravity, via changing a colony's rotation speed. This is an important attribute if humans born and raised on the colonies are to be able to return to Earth, as it is expected that those born on low-gravity bodies (such as the Moon or Mars) would have insufficient skeletal strength to function effectively in Earth's higher gravity without significant habilitation.
2. Access to vast resources, including the material of the solar system's asteroids and the energy resources of the Sun.
3. Immense population capacity. Using the free-floating resources of the solar system, current estimates extend into the trillions^[3]
4. Easier trade with Earth, as colonies orbitting Earth will not have a gravity well to overcome to export to Earth, and a smaller gravity well to overcome to import from Earth.

Artificial gravity is a simulation of gravity in outer space or free-fall. ... Bulk composition of the Moons mantle and crust estimated, weight percent Oxygen 42. ... Note: This article contains special characters. ... Skeleton is also a winter sport: see skeleton (sport). ... The Sun is the star of our solar system. ...

Problems

Space habitats must solve a number of problems in order to maintain healthy normal human populations:

1. Air pressure with normal partial pressures of oxygen, carbon dioxide and nitrogen. Basically, most colony designs are large, thin-walled pressure vessels. Oxygen is available from lunar rock. Nitrogen is available from the Earth, an expensive source, but nitrogen is recycled nearly perfectly. Also, nitrogen is available from comets and Jupiter's moons in the form of ammonia. Nitrogen may also be available in unknown quantities on certain bodies in the outer solar system. The air can be recycled in a number of ways. The obvious method is to use photosynthetic gardens, possibly using hydroponics or forest gardening. However, these do not remove some industrial pollutants, such as volatile oils, and excess simple molecular gases. The standard method used on nuclear submarines is to use a catalytic burner, which effectively removes most organics. Further protection might be provided by a small cryogenic distillation system to gradually remove impurities such as mercury vapor, and noble gases that cannot be catalytically burned.
2. Organics for food. At first, most of these would have to be imported from the moon, asteroids, or the Earth. After that, recycling would 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 the farms. The nitrates and the salts in the ash would 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 spectrography, 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.
3. 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 centripetal forces to simulate gravity. 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 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.
4. Radiation. Space radiation has two distinct problems. One is that cosmic rays expose one to 80 millisieverts per year, well above the maximum safe occupational threshold of 50 mSv, and well above the healthy population maximum of 3 mSv. Another, separate issue is that solar flares occasionally emit very large amounts of soft x-rays, and energetic particles. When these events occur, they can exceed 4 sieverts, the lethal dose for half the population. The most interesting result of the studies was the discovery that large space habitats are effectively shielded by their structure and air, which easily exceeds the two meters of steel needed. Smaller habitats could be shielded by stationary (nonrotating) bags of rock. Sunlight could be admitted via mirrors in radiation-proof louvres.
5. 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 to eliminate heat from absorbed sunlight and organisms. Very small habitats might have a vane that rotates with the colony. In this design, convection would raise hot air "up", and cool air would fall down into the habitat. Some other designs would distribute coolants, such as chilled water from a central radiator. Because blinds and radiators might be a major expense, inexpensive habitats might be very warm.
6. Orbital stationkeeping. The optimal habitat orbits are still debated, and are probably a commercial issue. The lunar L4 and L5 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 drivers used as rocket motors. The advantage of these is that they either use no reaction mass at all, or use cheap reaction mass.
7. Attitude control. Most mirror geometries require something on the habitat to be aimed at the sun. The original O'Neill design used the two cylinders as momentum wheels to roll the colony, and pushed the sunward pivots together or apart to use precession 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.
8. Colliding foreign objects: space debris, meteorites, dust etc.

The use of water pressure - the Captain Cook Memorial Jet in Lake Burley Griffin, Canberra. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... The outer solar system (as opposed to the outer planets) is that part of the Solar System which begins at roughly the orbit of Neptune and terminates at maximum orbit distance, approximately one Light Year from the sun in terms of orbital measurements. ... The leaf is the primary site of photosynthesis in plants. ... A gardener Gardening is the art of growing plants with the goal of crafting a purposeful landscape. ... {{[[Unreferenced}} [[Image:Hydroponic onions nasa. ... Forest gardening (also known as 3-Dimensional Gardening) is a food production and land management system based on replicating woodland edge ecosystems, substituting trees (such as fruit or nut trees), bushes, shrubs, herbs and vegetables which have yields directly useful to humankind. ... In chemistry and biology, catalysis (in Greek meaning to annul) is the acceleration of the rate of a chemical reaction by means of a substance, called a catalyst, that is itself unchanged chemically by the overall reaction. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery white Atomic mass 200. ... Organic chemistry is a specific discipline within the subject of chemistry. ... Artificial gravity is a simulation of gravity in outer space or free-fall. ... An object that moves in a circular path undergoes a continuous acceleration towards the center of the circle. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ... The sievert (symbol: Sv) is the SI derived unit of dose equivalent. ... A Solar Flare, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to tens of millions of hydrogen bombs. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... The sievert (symbol: Sv) is the SI derived unit of dose equivalent. ... This article is about electromagnetic radiation. ... Convection is the transfer of potential energy, for example heat, by currents within liquids and gases. ... In astrodynamics orbital stationkeeping is a term used to describe a particular set of orbital maneuvers used to keep a spacecraft in assigned orbit, either low earth orbit (LEO), or geostationary orbit (GEO). ... A contour plot of the effective potential of a two-body system (the Sun and Earth here), showing the five Lagrange points. ... Artists conception of satellite with a tether Tether propulsion uses long, strong strings (known as tethers) to change the orbits of spacecraft. ... A mass driver for lunar launch (artists conception) A mass driver or electromagnetic catapult is a method of spacecraft propulsion that would use a linear motor to accelerate payloads up to high speeds. ... In the context of spacecraft, attitude control is control of the angular position and rotation of the spacecraft, either relative to the object that it is orbiting, or relative to the celestial sphere. ... A momentum wheel is a type of flywheel used primarily by spacecraft to change their angular momentum without using fuel for rockets or other reaction devices. ... Precession refers to a change in the direction of the axis of a rotating object. ... Space debris or orbital debris, also called space junk and space waste, are the objects in orbit around Earth created by man that no longer serve any useful purpose. ...

Designs (solutions)

Designs proposed in NASA studies included:

• Bernal sphere - "Island One", a spherical habitat for about 20,000 people.
• Stanford torus - A smaller alternative to "Island One."
• O'Neill cylinder - "Island Three" (pictured), the largest design.
• Lewis One^[4]
• A "bolo," a spacecraft or habitat connected by a cable to a counterweight or other habitat. This design has been proposed as a Mars ship, initial construction shack for a space habitat, and orbital hotel. 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 bolo. 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.

A Bernal sphere is a type of space habitat intended as a long-term home for permanent residents, first proposed in 1929 by Dr. John Desmond Bernal. ... Artists conception of the interior of a Stanford torus The Stanford torus is a proposed design for a space habitat capable of housing approximately 10,000 permanent residents. ... A pair of ONeill cylinders The ONeill cylinder is a space habitat design proposed by Gerard K. ONeill in his book The High Frontier. ... This article or section does not cite its references or sources. ... A cut away view of a Transhab concept. ...

References

1. ^ 404 error. Retrieved on 2006-05-28.
2. ^ Ames Summer Study on Space Settlements and Industrialization Using Nonterrestial Materials (1977). Retrieved on 2006-05-28.
3. ^ O'Neill, Gerard K. The colonization of space, [1] (Physics Today, September 1974). Retrieved on 2006-10-15.
4. ^ Globus, Al. Lewis One Space Colony. Retrieved on 2006-05-28.

• NASA's table of contents for the studies See the "online books" about half-way down the page.

2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... May 28 is the 148th day of the year in the Gregorian calendar (149th in leap years). ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... May 28 is the 148th day of the year in the Gregorian calendar (149th in leap years). ... Physics Today magazine, created in 1948, is the flagship publication of The American Institute of Physics. ... 1974 (MCMLXXIV) was a common year starting on Tuesday. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... May 28 is the 148th day of the year in the Gregorian calendar (149th in leap years). ...

See also

• Space colonization
• Space manufacturing
• Transhab
• Orion's Arm