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Encyclopedia > Space colonization
Artist's conception of a space habitat called the Stanford torus, by Don Davis

Current NASA chief Michael Griffin has identified space colonization as the ultimate goal of current spaceflight programs, saying: This article is about the American space agency. ... Michael Griffin can refer to: Michael A. W. Griffin, links to Griffin Genealogy pre Norman Conquest. ...

 “ ...the goal isn't just scientific exploration... it's also about extending the range of human habitat out from Earth into the solar system as we go forward in time. . . . In the long run a single-planet species will not survive... If we humans want to survive for hundreds of thousands or millions of years, we must ultimately populate other planets. Now, today the technology is such that this is barely conceivable. We're in the infancy of it... I'm talking about that one day, I don't know when that day is, but there will be more human beings who live off the Earth than on it. We may well have people living on the moon. We may have people living on the moons of Jupiter and other planets. We may have people making habitats on asteroids... I know that humans will colonize the solar system and one day go beyond. ” —Michael D. Griffin[1] Dr. Michael D. Griffin Dr. Michael Douglas Griffin (born November 1, 1949 in Aberdeen, Maryland) has been the Administrator of NASA since April 13, 2005. ...
 Space colonization Outer solar system Lagrange Point Colonization is the colonization of the five equilibrim points in the orbit of a planet or moon around its primary, called Lagrange points. ... Mercury Mercury has been suggested as one possible target for space colonization of the inner solar system, along with Mars, Venus, the Moon and the asteroid belt. ... Venus The colonization of Venus, Earths nearest planetary neighbour, has been a subject of much speculation and many works of science fiction since before and after the dawn of spaceflight. ... â€œLunar outpostâ€ redirects here. ... Mars Mars is the focus of much speculation and serious study about possible human colonization. ... It has been suggested that this article or section be merged with Colonization of the asteroids. ... It has been suggested that Colonization of Ceres be merged into this article or section. ... Some of the moons of the outer planets of the solar system are large enough to be suitable places for colonization. ... Jupiter Saturn Trans-Neptunian Objects This box: view • talk • edit

Artists conception of a space habitat called the Stanford torus, by Don Davis Space colonization, also called space settlement and space humanization, is the hypothetical permanent autonomous (self-sufficient) human habitation of locations outside Earth. ... The Artemis Project designed a plan to colonize Europa. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Saturns moon Titan in natural color. ... Freeman Dyson has proposed that Trans-Neptunian Objects, rather than planets, are the major potential habitat of life in space. ...

Building colonies in space will require access to space, people, food, construction materials, energy, transportation, communications, life support, simulated gravity (using steady circular rotation), entertainment, and radiation protection. Colonies will presumably be situated to help fulfill those requirements. Communication is a process that allows organisms to exchange information by several methods. ... In human spaceflight, the life support system is a group of devices that allow a human being to survive in outer space. ... Artificial gravity is a simulation of gravity in outer space or free-fall. ... Radiation as used in physics, is energy in the form of waves or moving subatomic particles. ...

### Materials

Colonies on the Moon and Mars could use local materials, although the Moon is deficient in volatiles (principally hydrogen, and nitrogen) but possesses a great deal of oxygen, silicon, and metals such as iron, aluminum and titanium. Launching materials from Earth is very expensive, so bulk materials could come from the Moon or Near-Earth Objects (NEOs - asteroids and comets with orbits near Earth), Phobos, or Deimos where gravitational forces are much less, there is no atmosphere, and there is no biosphere to damage. Many NEOs contain substantial amounts of metals, oxygen, hydrogen and carbon. Certain NEOs may also contain some nitrogen. ISRU Reverse Water Gas Shift Testbed (NASA KSC). ... Volatility in physics is a measure of the speed at which a chemical element or chemical compound evaporates. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... Not to be confused with Silicone. ... This article is about metallic materials. ... For other uses, see Iron (disambiguation). ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ... General Name, symbol, number titanium, Ti, 22 Chemical series transition metals Group, period, block 4, 4, d Appearance silvery metallic Standard atomic weight 47. ... Near-Earth objects (NEO) are asteroids, comets and large meteoroids whose orbit intersects Earths orbit and which may therefore pose a collision danger. ... 253 Mathilde, a C-type asteroid. ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... Phobos (IPA: or [ËˆfoÊŠ.bÉ™s]) (systematic designation: ) is the larger and closer of Mars two moons (the other being Deimos). ... Deimos (IPA or ; Greek Î”ÎµÎ¯Î¼Î¿Ï‚: Dread), is the smaller and outermost of Marsâ€™ two moons, named after Deimos from Greek Mythology. ... For other uses, see Atmosphere (disambiguation). ...

Further out, Jupiter's Trojan asteroids are thought to be high in water ice and probably other volatiles[1]. Some of the moons of the outer planets of the solar system are large enough to be suitable places for colonization. ...

### Energy

Solar energy in orbit is abundant, reliable, and is commonly used to power satellites today. There is no night in space, and no clouds or atmosphere to block sunlight. The solar energy available, in watts per square meter, at any distance, d, from the Sun can be calculated by the formula E = 1366/d², where d is measured in astronomical units. Solar power from a parabolic reflector. ... The astronomical unit (AU or au or a. ...

Particularly in the weightless conditions of space, sunlight can be used directly, using large solar ovens made of lightweight metallic foil so as to generate thousands of degrees of heat at no cost; or reflected onto crops to enable photosynthesis to proceed. solar oven A solar oven or solar furnace is a way of harnessing the suns power to cook food. ... The leaf is the primary site of photosynthesis in plants. ...

Large structures would be needed to convert sunlight into significant amounts of electrical power for settlers' use. In highly electrified nations on Earth, per-capita electrical consumption can average 1 kilowatt/person (or roughly 10 megawatt-hours per person per year.[2]) The watt-hour (symbol WÂ·h) is a unit of energy. ...

Energy has been suggested as an eventual export item for space settlements, perhaps using wireless power transmission e.g. via microwave beams to send power to Earth or the Moon. This method has zero emissions, so would have significant benefits such as elimination of greenhouse gases and nuclear waste. Ground area required per watt would be less than conventional solar panels. Wireless energy transfer is wireless transfer of electromagnetic energy via electromagnetic induction. ... This article is about the type of Electromagnetic radiation. ... An artists depiction of a solar satellite, which could send energy wirelessly to a space vessel or planetary surface. ...

The Moon has nights of two Earth weeks in duration and Mars has night, dust, and is farther from the Sun, reducing solar energy available by a factor of about 1/2-1/3, and possibly making nuclear power more attractive on these bodies. Alternatively continuous energy could be beamed to the lunar surface from a solar power satellite at the Lagrange L-1 location. This article is about applications of nuclear fission reactors as power sources. ...

For both solar thermal and nuclear power generation in airless environments, such as the Moon and space, and to a lesser extent the very thin Martian atmosphere, one of the main difficulties is dispersing the inevitable heat generated. This requires fairly large radiator areas. Alternatively, the waste heat can be used to melt ice on the poles of a planet like Mars. The Carnot cycle is a particular thermodynamic cycle, modeled on the Carnot heat engine, studied by Nicolas LÃ©onard Sadi Carnot in the 1820s and expanded upon by Benoit Paul Ã‰mile Clapeyron in the 1830s and 40s. ...

### Transportation

#### Space Access

Transportation to orbit is often the limiting factor in space endeavors. Present-day launch costs are very high - \$3,000 to \$25,000 per kilogram from Earth to Low Earth Orbit (LEO)[citation needed]. To settle space, much cheaper launch vehicles are required, as well as a way to avoid serious damage to the atmosphere from the thousands, perhaps millions, of launches required. One possibility is air-breathing hypersonic air/spacecraft under development by NASA and other organizations, both public and private. There are also proposed projects such as building a space elevator or a mass driver. A low Earth orbit (LEO) is an orbit in which objects such as satellites are below intermediate circular orbit (ICO) and far below geostationary orbit, but typically around 350 - 1400 km above the Earths surface. ... Boeing X-43 at Mach 7 In aerodynamics, hypersonic speeds are speeds that are highly supersonic. ... A space elevator would consist of a cable anchored to the Earths surface, reaching into space. ... 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. ...

#### Cislunar and Solar System travel

Transportation of large quantities of materials from the Moon, Phobos, Deimos, and Near Earth asteroids to orbital settlement construction sites is likely to be necessary.

Transportation using off-Earth resources for propellant in relatively conventional rockets would be expected to massively reduce in-space transportation costs compared to the present day; propellant launched from the Earth is likely to be prohibitively expensive for space colonization, even with improved space access costs. ISRU Reverse Water Gas Shift Testbed (NASA KSC). ...

Other technologies such as tether propulsion, VASIMR, ion drives, solar thermal rockets, solar sails, magnetic sails, and nuclear thermal propulsion can all potentially help solve the problems of high transport cost once in space. Artists conception of satellite with a tether Tether propulsion uses long, strong strings (known as tethers) to change the orbits of spacecraft. ... VASIMR test bed The Variable specific impulse magnetoplasma rocket (VASIMR) is a hypothetical form of spacecraft propulsion that uses radio waves and magnetic fields to accelerate a propellant. ... An ion engine test An ion thruster is a type of spacecraft propulsion that uses beams of ions for propulsion. ... Solar thermal propulsion is a form of spacecraft propulsion that makes use of solar power to directly heat reaction mass, and therefore does not require an electrical generator as most other forms of solar-powered propulsion do. ... Solar sails (also called light sails or photon sails, especially when they use light sources other than the Sun) are a proposed form of spacecraft propulsion using large membrane mirrors. ... A magnetic sail or magsail is a proposed method of spacecraft propulsion. ... In a nuclear thermal rocket a working fluid, usually hydrogen, is heated in a high temperature nuclear reactor, and then expands through a rocket nozzle to create thrust. ...

For lunar materials, one well-studied possibility is to build electronic catapults to launch bulk materials to waiting settlements. Alternatively, Lunar space elevators might be employed. 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. ... A lunar space elevator (also called a moonstalk) is a proposed cable running from the surface of the Moon into space. ...

### Communication

Compared to the other requirements, communication is relatively easy for orbit and the Moon. A great proportion of current terrestrial communications already passes through satellites. Yet, as colonies further from the earth are considered, communication becomes more of a burden. Transmissions to and from Mars suffer from significant delays due to the speed of light and the greatly varying distance between conjunction and opposition - the lag will range between 7 and 44 minutes - making real-time communication impractical. Other means of communication that do not require live interaction such as e-mail and voice mail systems should pose no problem. For other uses, see Satellite (disambiguation). ... The speed of light in vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness.[1] It is the speed of all electromagnetic radiation, including visible light, in a vacuum. ... Wikipedia does not yet have an article with this exact name. ... Voicemail (or voice mail; abbreviated v-mail or vmail) is a specific application of an interactive voice response system. ...

### Life support

People need air, water, food, gravity and reasonable temperatures to survive for long periods. On Earth, a large complex biosphere provides these. In space settlements, a relatively small, closed ecological system must recycle or import all the nutrients without "crashing." For other uses, see Biosphere (disambiguation). ... An ecosphere Closed Ecological Systems (CES) are ecosystems that do not exchange matter with any part outside the system. ...

The closest terrestrial analogue to space life support is possibly that of Nuclear submarines. Nuclear submarines use mechanical life support systems to support humans for months without surfacing, and this same basic technology could presumably be employed for space use. However, nuclear submarines run "open loop" and typically dump carbon dioxide overboard, although they recycle oxygen. Recycling of the carbon dioxide has been approached in the literature using the Sabatier process or the Bosch reaction. USS Los Angeles A submarine is a specialized watercraft that can operate underwater. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... The Sabatier process involves the reaction of hydrogen with carbon dioxide at elevated temperatures and pressures in the presence of a nickel catalyst to produce methane and water. ... The Bosch reaction is a chemical reaction between carbon dioxide and hydrogen that produces elemental carbon (graphite), water and heat. ...

Alternatively, and more attractive to many, the Biosphere 2 project in Arizona has shown that a complex, small, enclosed, man-made biosphere can support eight people for at least a year, although there were many problems. A year or so into the two-year mission oxygen had to be replenished, which strongly suggests that they achieved atmospheric closure. Biosphere 2 Biosphere 2 is a 3. ... Official language(s) English Spoken language(s) English 74. ...

The relationship between organisms, their habitat and the non-Earth environment can be:

Note that plant based life support systems are very inefficient in their use of energy; about 1-3% energetic efficiency is common[citation needed]. This means that 97-99% of the light energy provided to the plant ends up as heat and needs to be dissipated somehow to avoid overheating the habitat. The biosphere is that part of a planet earths outer shell&#8212;including air, land, and water&#8212;within which life occurs, and which biotic processes in turn alter or transform. ... Biosphere 2 Biosphere 2 is a 3. ... In human spaceflight, the life support system is a group of devices that allow a human being to survive in outer space. ... Artists conception of a terraformed Mars in four stages of development. ... Kenyans examining insect-resistant transgenic Bt corn. ... Posthuman Future, an illustration by Michael Gibbs for The Chronicle of Higher Educations look at how biotechnology will change the human experience, has become one of the secular icons representing transhumanism. ... For other uses, see Cyborg (disambiguation). ...

A combination of the above technologies is also possible.

Cosmic rays and solar flares create a lethal radiation environment in space. In Earth orbit, the Van Allen belts make living above the Earth's atmosphere difficult. To protect life, settlements must be surrounded by sufficient mass to absorb most incoming radiation. Somewhere around 5-10 tons of material per square meter of surface area is required. This can be achieved cheaply with leftover material (slag) from processing lunar soil and asteroids into oxygen, metals, and other useful materials, however it represents a significant obstacle to maneuvering vessels with such massive bulk. Inertia would necessitate powerful thrusters to start or stop rotation. Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ... A Solar Flare and CME, courtesy NASA A solar flare is a violent explosion in the Suns atmosphere with an energy equivalent to a billion megatons, traveling normally at about 1 million km per hour (about 0. ... Radiation as used in physics, is energy in the form of waves or moving subatomic particles. ... Van Allen belts The Van Allen radiation belt is a torus of energetic charged particles around Earth, trapped by Earths magnetic field. ...

### Self-replication

Self-replication is an optional attribute, but many think it the ultimate goal because it allows a much more rapid increase in colonies, while eliminating costs to and dependence on Earth. It could be argued that the establishment of such a colony would be Earth's first act of self-replication (see Gaia spore). Intermediate goals include colonies that expect only information from Earth (science, engineering, entertainment, etc.) and colonies that just require periodic supply of light weight objects, such as integrated circuits, medicines, genetic material and perhaps some tools. This article is about Earth as a planet. ... Self-replication is the process by which some things make copies of themselves. ... The study of planetary habitability is partly based upon extrapolation from knowledge of the Earths conditions, as the Earth is the only planet currently known to harbor life. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... For the chemical substances known as medicines, see medication. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ...

See also: von Neumann probe, clanking replicator, Molecular nanotechnology A von Neumann probe is a specific example of a hypothetical concept based on the work of Hungarian-born American mathematician and physicist John von Neumann. ... A clanking replicator is an artificial self-replicating system that relies on conventional large-scale technology and automation. ... Molecular nanotechnology (MNT) is the concept of engineering functional mechanical systems at the molecular scale. ...

### Population size

In 2002, the anthropologist John H. Moore estimated that a population of 150–180 would allow normal reproduction for 60 to 80 generations—equivalent to 2000 years. Also see: 2002 (number). ... Anthropology (from Greek: á¼€Î½Î¸ÏÏ‰Ï€Î¿Ï‚, anthropos, human being; and Î»ÏŒÎ³Î¿Ï‚, logos, knowledge) is the study of humanity. ... Dr. John H. Moore is a professor of anthropology at the University of Florida in Gainesville, Florida. ...

A much smaller initial population of as little as two female humans should be viable as long as human embryos are available from Earth. Use of a sperm bank from Earth also allows a smaller starting base with negligible inbreeding. For other uses, see Embryo (disambiguation). ... A sperm bank is a facility that collects and stores human sperm from donors, primarily for the purposes of artificial insemination. ... It has been suggested that inbreeding depression be merged into this article or section. ...

Researchers in conservation biology have tended to adopt the "50/500" rule of thumb initially advanced by Franklin and Soule. This rule says a short-term effective population size (Ne) of 50 is needed to prevent an unacceptable rate of inbreeding, while a long‐term Ne of 500 is required to maintain overall genetic variability. The Ne = 50 prescription corresponds to an inbreeding rate of 1% per generation, approximately half the maximum rate tolerated by domestic animal breeders. The Ne = 500 value attempts to balance the rate of gain in genetic variation due to mutation with the rate of loss due to genetic drift. In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ...

Effective population size Ne depends on the number of males Nm and females Nf in the population according to the formula:

$N_e = frac{4 times N_m times N_f} {N_m + N_f}$

## Location

Location is a frequent point of contention between space colonization advocates. Space advocacy is a political position that favors the exploration, utilization, and colonization of outer space. ...

The location of colonization can be:

### Planetary Locations

Some planetary colonization advocates cite the following potential locations:

#### Mars

Main article: Colonization of Mars

Mars is a frequent topic of discussion. Its overall surface area is similar to the dry land surface of Earth, it may have large water reserves, and has carbon (locked as carbon dioxide in the atmosphere). Mars Mars is the focus of much speculation and serious study about possible human colonization. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... For other uses, see Carbon (disambiguation). ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ...

Mars may have gone through similar geological and hydrological processes as Earth and contain valuable mineral ores, but this is debated. Equipment is available to extract in situ resources (water, air, etc.) from the Martian ground and atmosphere. There is a strong scientific interest in colonizing Mars due to the possibility that life could have existed on Mars at some point in its history, and may even still exist in some parts of the planet. This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... Hydrology is the study of the occurrence, distribution, and movement of water on, in, and above the earth. ... For other uses, see Mineral (disambiguation). ... An ore is a mineral deposit containing a metal or other valuable resource in economically viable concentrations. ... In situ is a Latin phrase meaning in the place. ...

However, its atmosphere is very thin (averaging 800 Pa or about 0.8% of Earth sea-level atmospheric pressure); so the pressure vessels necessary to support life are very similar to deep space structures. The climate of Mars is colder than Earth's. Its gravity is only around a third that of Earth; it is unknown whether this is sufficient to support human beings for long periods (all long term human experience to date has been at around Earth gravity or one-g). Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ... The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Youngs modulus and tensile strength). ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... Gravity is a force of attraction that acts between bodies that have mass. ...

The atmosphere is thin enough, when coupled with Mars' lack of magnetic field, that radiation is more intense on the surface, and protection from solar storms would require radiation shielding.

Mars is often the topic of discussion regarding terraforming to make the entire planet or at least large portions of it habitable. Artists conception of a terraformed Mars in four stages of development. ...

See also: Exploration of Mars, Martian terraforming Computer-generated image of one of the two Mars Exploration Rovers which touched down on Mars in 2004. ... Artists conception of a terraformed Mars in three stages of development. ...

#### Mercury

There is a suggestion that Mercury could be colonized using the same technology, approach and equipment that is used in colonization of the Moon. Such colonies would almost certainly be restricted to the polar regions due to the extreme daytime temperatures elsewhere on the planet. Mercury Mercury has been suggested as one possible target for space colonization of the inner solar system, along with Mars, Venus, the Moon and the asteroid belt. ...

#### Venus

Main article: Colonization of Venus

While the surface of Venus is far too hot and features atmospheric pressure at least 90 times that at sea level on Earth, its massive atmosphere offers a possible alternate location for colonization. At a height of approximately 50 km, the pressure is reduced to a few atmospheres, and the temperature would be between 40-100°C, depending on the height. This part of the atmosphere is probably within dense clouds which contain some sulfuric acid. Even these may have a certain benefit to colonization, as they present a possible source for the extraction of water. Venus The colonization of Venus, Earths nearest planetary neighbour, has been a subject of much speculation and many works of science fiction since before and after the dawn of spaceflight. ... Adjectives: Venusian or (rarely) Cytherean Atmosphere Surface pressure: 9. ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ... Standard atmosphere (symbol: atm) is a unit of pressure. ... R-phrases S-phrases , , , Flash point Non-flammable Related Compounds Related strong acids Selenic acid Hydrochloric acid Nitric acid Related compounds Hydrogen sulfide Sulfurous acid Peroxymonosulfuric acid Sulfur trioxide Oleum Supplementary data page Structure and properties n, Îµr, etc. ...

Artists conception of a terraformed Venus. ...

### Satellite locations

#### The Moon

Moon colony

Due to its proximity and relative familiarity, Earth's Moon is also frequently discussed as a target for colonization. It has the benefits of proximity to Earth and lower escape velocity, allowing for easier exchange of goods and services. A major drawback of the Moon is its low abundance of volatiles necessary for life such as hydrogen and carbon. Water ice deposits that may exist in some polar craters could serve as a source for these elements. An alternative solution is to bring hydrogen from NE asteroids and combine it with oxygen extracted from lunar rock. Image File history File links Mooncolony. ... Image File history File links Mooncolony. ... â€œLunar outpostâ€ redirects here. ... This article is about Earths moon. ... Space Shuttle Atlantis launches on mission STS-71. ... The word drawback can mean:- In general usage, a disadvantage. ... Volatiles are that group of compounds with low boiling points (see volatile) that are associated with a planets or moons crust and/or atmosphere. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... For other uses, see Carbon (disambiguation). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Tycho crater on Earths moon. ...

The moon's low surface gravity is also a concern (it is unknown whether 1/6g is sufficient to support human habitation for long periods - see microgravity). The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ... Astronauts on the International Space Station display an example of weightlessness Weightlessness is the experience (by people and objects) during freefall, of having no weight. ...

#### Europa, Callisto (or other Jovian moons)

The Artemis Project designed a plan to colonize Europa, one of Jupiter's moons. Scientists were to inhabit igloos and drill down into the Europan ice crust, exploring any sub-surface ocean. This plan also discusses possible use of "air pockets" for human inhabitation. The Artemis Project is a private venture to establish a permanent, self-supporting community on the Moon. ... Apparent magnitude: 5. ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Igloo An igloo (Inuit language: iglu, Inuktitut syllabics: áƒá’¡á“—, house, plural: iglooit or igluit), translated sometimes as snowhouse, is a shelter constructed from blocks of snow, generally in the form of a dome. ... Animated map exhibiting the worlds oceanic waters. ...

The Artemis Project designed a plan to colonize Europa. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Some of the moons of the outer planets of the solar system are large enough to be suitable places for colonization. ...

#### Phobos and Deimos

The moons of Mars may be an appealing target for space colonization. Low delta-v is needed to reach the Earth from Phobos and Deimos, allowing delivery of material to cislunar space, as well as transport around the Martian system. The moons themselves may be inhabited, with methods similar to those for asteroids. General In general physics delta-v is simply the change in velocity. ... Phobos (IPA: or [ËˆfoÊŠ.bÉ™s]) (systematic designation: ) is the larger and closer of Mars two moons (the other being Deimos). ... Deimos (IPA or ; Greek Î”ÎµÎ¯Î¼Î¿Ï‚: Dread), is the smaller and outermost of Marsâ€™ two moons, named after Deimos from Greek Mythology. ... Cislunar space (alternatively, cis-lunar space) is the volume within the Moons orbit, or a sphere formed by rotating that orbit. ...

#### Titan

Main article: Colonization of Titan

Titan has been suggested as an appealing target for colonization [3], because it is the only moon in our solar system to have a dense atmosphere and is rich in carbon-bearing compounds. [4] Saturns moon Titan in natural color. ... Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ...

### Free space locations

#### Space habitats

Main article: Space habitat

Free space locations in space would necessitate a space habitat, also called space colony and orbital colony, or a space station which would be intended as a permanent settlement rather than as a simple waystation or other specialized facility. They would be literal "cities" in space, where people would live and work and raise families. Many design proposals have been made with varying degrees of realism by both science fiction authors and engineers. A pair of ONeill 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. ... A pair of ONeill 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. ... The International Space Station in 2007 A space station is an artificial structure designed for humans to live in outer space. ... 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. ...

A space habitat would also serve as a proving ground for how well a generation ship could function as a long-term home for hundreds or thousands of people. Such a space habitat could be isolated from the rest of humanity for a century, but near enough to Earth for help. This would test if thousands of humans can survive a century on their own before sending them beyond the reach of any help. A generation ship is a hypothetical starship that travels across great distances between stars at a speed much slower than that of light (see interstellar travel). ... This article is about Earth as a planet. ...

#### Earth orbit

Compared to other locations, Earth orbit has substantial advantages and one major, but solvable, problem. Orbits close to Earth can be reached in hours, whereas the Moon is days away and trips to Mars take months. There is ample continuous solar power in high Earth orbits, whereas all planets lose sunlight at least half the time. Weightlessness makes construction of large colonies considerably easier than in a gravity environment. Astronauts have demonstrated moving multi-ton satellites by hand. 0g recreation is available on orbital colonies, but not on the Moon or Mars. Finally, the level of (pseudo-) gravity is controlled at any desired level by rotating an orbital colony. Thus, the main living areas can be kept at 1g, whereas the Moon has 1/6g and Mars 1/3g. It's not known what the minimum g-force is for ongoing health but 1g is known to ensure that children grow up with strong bones and muscles. Astronaut Bruce McCandless II using a manned maneuvering unit outside the U.S. Space Shuttle Challenger in 1984. ... The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ...

The main disadvantage of orbital colonies is lack of materials. These may be expensively imported from the Earth, or more cheaply from extraterrestrial sources, such as the Moon (which has ample metals, silicon, and oxygen), Near Earth Asteroids, which have all the materials needed (with the possible exception of nitrogen[citation needed]), comets, or elsewhere. Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earths orbit. ... Comet Hale-Bopp, showing a white dust tail and blue gas tail (February 1997) A comet is a small astronomical object similar to an asteroid but composed largely of ice. ...

#### Lagrange points

A contour plot of the effective potential (the Hill's Surfaces) of a two-body system (the Sun and Earth here), showing the five Lagrange points.

Another near-Earth possibility are the five Earth-Moon Lagrange points. Although they would generally also take a few days to reach with current technology, many of these points would have near-continuous solar power capability since their distance from Earth would result in only brief and infrequent eclipses of light from the Sun. Image File history File links Lagrange_points. ... Image File history File links Lagrange_points. ... In physics, a potential may refer to the scalar potential or to the vector potential. ... Sol redirects here. ... This article is about Earth as a planet. ... A contour plot of the effective potential (the Hills Surfaces) of a two-body system (the Sun and Earth here), showing the five Lagrange points. ...

The five Earth-Sun Lagrange points would totally eliminate eclipses, but only L1 and L2 would be reachable in a few days' time. The other three Earth-Sun points would require months to reach.

However, the fact that Lagrange points L4 and L5 tend to collect dust and debris, while L1-L3 require active station-keeping measures to maintain a stable position, make them somewhat less suitable places for habitation than was originally believed. 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). ...

#### Asteroids

It has been suggested that Colonization of Ceres be merged into this article or section. ...

##### Near Earth Asteroids

Many small asteroids in orbit around the Sun have the advantage that they pass closer than Earth's moon several times per decade. In between these close approaches to home, the asteroid may travel out to a furthest distance of some 350,000,000 kilometers from the Sun (its aphelion) and 500,000,000 kilometers from Earth. This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...

##### Main Belt Asteroids

Colonization of Asteroids would require Space habitats. The asteroid belt has significant overall material available, although it is thinly distributed as it covers a vast region of space. Unmanned supply craft should be practical with little technological advance, even crossing 1/2 billion kilometers of cold vacuum. The colonists would have a strong interest in assuring that their asteroid did not hit Earth or any other body of significant mass, but would have extreme difficulty in moving an asteroid of any size. The orbits of the Earth and most asteroids are very distant from each other in terms of delta-v and the asteroidal bodies have enormous momentum. Rockets or mass drivers can perhaps be installed on asteroids to direct their path into a safe course. For other uses, see Asteroid (disambiguation). ... General In general physics delta-v is simply the change in velocity. ... This article is about momentum in physics. ... 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. ...

#### Statites

Main article: Statite

Statites or "static satellites" employ solar sails to position themselves in orbits that gravity alone could not accomplish. Such a solar sail colony would be free to ride solar radiation pressure and travel off the ecliptic plane. Navigational computers with an advanced understanding of flocking behavior could organize several statite colonies into the beginnings of the true "swarm" concept of a Dyson sphere. A statite is a hypothetical type of artificial satellite that employs a solar sail to continuously modify its orbit in ways that gravity alone would not allow. ... Solar sails (also called light sails or photon sails, especially when they use light sources other than the Sun) are a proposed form of spacecraft propulsion using large membrane mirrors. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... Flocking is a common demonstration of emergence and emergent behavior, first simulated in 1986 by Craig Reynolds with his simulation program, Boids. ... A cut-away diagram of an idealized Dyson shellâ€”a variant on Dysons original conceptâ€”1 AU in radius. ...

## Outside the Solar system

Colonization of the entire Solar system would take hundreds or thousands of years. Looking beyond our solar system, there are billions of potential suns with possible colonization targets.

Physicist Stephen Hawking has said:[5][6] Stephen William Hawking, CH, CBE, FRS, FRSA, (born 8 January 1942) is a British theoretical physicist. ...

 “ The long-term survival of the human race is at risk as long as it is confined to a single planet. Sooner or later, disasters such as an asteroid collision or nuclear war could wipe us all out. But once we spread out into space and establish independent colonies, our future should be safe. There isn't anywhere like the Earth in the solar system, so we would have to go to another star. ”

### Starship

An interstellar colony ship would be similar to a space habitat, except with major propulsion capabilities and independent energy generation. A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is any method used to change the velocity of spacecraft and artificial satellites. ...

Concepts proposed both by scientists and in hard science fiction include: Hard science fiction is a category of science fiction characterized by an emphasis on scientific or technical detail, or on scientific accuracy, or on both. ...

A generation ship is a hypothetical starship that travels across great distances between stars at a speed much slower than that of light (see interstellar travel). ... One of the fictional ships called the Starship Enterprise from Star Trek, one of the most famous fictional starships. ... A sleeper ship is a hypothetical type of manned spaceship in which most or all of the crew spends the journey in some form of hibernation or suspended animation. ... One of the fictional ships called the Starship Enterprise from Star Trek, one of the most famous fictional starships. ... This article refers to the process of hibernation in biology. ... Suspended animation is the slowing of life processes by external means without termination. ... Embryo space colonization is an interstellar space colonization proposal that involves sending a robotic mission to a terrestrial planet (having a biosphere) that transports frozen early-stage embryos. ... One of the fictional ships called the Starship Enterprise from Star Trek, one of the most famous fictional starships. ... A generation ship is a hypothetical starship that travels across great distances between stars at a speed much slower than that of light (see interstellar travel). ... A sleeper ship is a hypothetical type of manned spaceship in which most or all of the crew spends the journey in some form of hibernation or suspended animation. ... For other uses, see Embryo (disambiguation). ... An extrasolar planet, or exoplanet, is a planet beyond the Solar System. ... One of the fictional ships called the Starship Enterprise from Star Trek, one of the most famous fictional starships. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... For other senses of this term, see antimatter (disambiguation). ... An artists conception of the NASA reference design for the Project Orion spacecraft powered by nuclear propulsion. ... Freeman John Dyson FRS (born December 15, 1923) is an English-born American theoretical physicist and mathematician, famous for his work in quantum mechanics, solid-state physics, nuclear weapons design and policy, and for his serious theorizing in futurism and science fiction concepts, including the search for extraterrestrial intelligence. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, in 1945 lifted nuclear fallout some 18 km (60,000 feet) above the epicenter. ... Solar sails (also called light sails or photon sails, especially when they use light sources other than the Sun) are a proposed form of spacecraft propulsion using large membrane mirrors. ... Time dilation is the phenomenon whereby an observer finds that anothers clock which is physically identical to their own is ticking at a slower rate as measured by their own clock. ...

### Example

The star Tau Ceti, about eleven light years away, has an abundance of cometary and asteroidal material in orbit around it. These materials could be used for the construction of space habitats for human settlement. Tau Ceti (Ï„ Cet / Ï„ Ceti) is a star commonly mentioned by science fiction authors since it is similar to the Sun in mass and spectral type in addition to being relatively close to us. ...

## Terrestrial analogues to space colonies

The most famous attempt to build an analogue to a self-sufficient colony is Biosphere 2, which attempted to duplicate Earth's biosphere. Biosphere 2 Biosphere 2 is a 3. ... This article is about Earth as a planet. ... For other uses, see Biosphere (disambiguation). ...

Many space agencies build testbeds for advanced life support systems, but these are designed for long duration human spaceflight, not permanent colonization. Space agency can refer to: NASA, the National Aeronautics and Space Administration Canadian Space Agency China National Space Administration Korea Aerospace Research Institute European Space Agency Iranian Space Agency Italian Space Agency Indian Space Research Organisation Japan Aerospace Exploration Agency Russian Aviation and Space Agency Soviet space program (historical) National... In human spaceflight, the life support system is a group of devices that allow a human being to survive in outer space. ... Edward White on a spacewalk during the Gemini 4 mission. ...

Remote research stations in inhospitable climates, such as the Amundsen-Scott South Pole Station or Devon Island Mars Arctic Research Station, can also provide some practice for off-world outpost construction and operation. The Mars Desert Research Station has a habitat for similar reasons, but the surrounding climate is not strictly inhospitable. The Amundsen-Scott South Pole Station is a U.S. research station at the South Pole, in Antarctica. ... Devon Island, Nunavut. ... The Flashline Mars Arctic Research Station (FMARS) is a project operated by the Mars Society in collaboration with NASAs Haughton-Mars Project, to conduct geological and microbiological exploration under conditions similar to those found on Mars, to develop field tactics based on those explorations, to test habitat design features... The Mars Desert Research Station (MDRS) is one of four planned simulated Mars habitats (or Mars Analogue Research Station) maintained by the Mars Society. ...

## Literature

The literature for space colonization began in 1869 when Edward Everett Hale wrote about an inhabited artificial satellite.[7] Statue of Edward Everett Hale in Boston Public Garden, by Bela Pratt. ...

The Russian schoolmaster and physicist Konstantin Tsiolkovsky foresaw elements of the space community in his book Beyond Planet Earth written about 1900. Tsiolkovsky had his space travelers building greenhouses and raising crops in space.[8]. Konstantin Eduardovich Tsiolkovsky Konstantin Eduardovich Tsiolkovsky (ÐšÐ¾Ð½ÑÑ‚Ð°Ð½Ñ‚Ð¸Ð½ Ð­Ð´ÑƒÐ°Ñ€Ð´Ð¾Ð²Ð¸Ñ‡ Ð¦Ð¸Ð¾Ð»ÐºÐ¾Ð²ÑÐºÐ¸Ð¹, Konstanty CioÅ‚kowski) (September 5, 1857 new style â€“ September 19, 1935) was a Russian and Soviet rocket scientist and pioneer of cosmonautics who spent most of his life in a log house on the outskirts of the Russian town of Kaluga. ...

Others have also written about space colonies as Lasswitz in 1897 and Bernal, Oberth, Von Pirquet and Noordung in the 1920s. Wernher von Braun contributed his ideas in a 1952 Colliers article. In the 1950s and 1960s, Dandridge Cole and Krafft Ehricke published their ideas.[citation needed]

Another seminal book on the subject was the book The High Frontier: Human Colonies in Space by Gerard K. O'Neill[9] in 1977 which was followed the same year by Colonies in Space by T. A. Heppenheimer.[10] Gerard Kitchen ONeill (1927 - 1992) was a U.S. physicist and space pioneer. ...

M. Dyson wrote Home on the Moon; Living on a Space Frontier in 2003;[11] Paul Eckart wrote Lunar Base Handbook in 2006[12] and then Harrison Schmitt's Return to the Moon written in 2007.[13]

## Justification

Main article: Space and survival

In 2001, the space news website Space.com asked Freeman Dyson, J. Richard Gott and Sid Goldstein for reasons why some humans should live in space. Their respective answers were:[14] Space and survival is the relationship between space and the long-term survival of the human species and civilization. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... Space. ... Freeman John Dyson FRS (born December 15, 1923) is an English-born American theoretical physicist and mathematician, famous for his work in quantum mechanics, solid-state physics, nuclear weapons design and policy, and for his serious theorizing in futurism and science fiction concepts, including the search for extraterrestrial intelligence. ... J. Richard Gott is a professor of astrophysical sciences at Princeton University John Richard Gott III is especially well known for developing and advocating two cosmological theories with the flavour of science fiction: Time travel, and the Doomsday argument. ...

The scientist Paul Davies also supports the view that if a planetary catastrophe threatens the survival of the human species on Earth, a self-sufficient colony could "reverse-colonize" the Earth and restore human civilization. For the member of the National Assembly for Wales, see Paul Davies (Welsh politician). ... Central New York City. ...

The author and journalist William E. Burrows and the biochemist Robert Shapiro proposed a private project, the Alliance to Rescue Civilization, with the goal of establishing an off-Earth backup of human civilization.[16] The Alliance to Rescue Civilization is an organization devoted to the establishment an off-Earth backup of human civilization. ... For other uses of Backup, see Backup (disambiguation). ...

Another important reason used to justify Space is the effort to increase the knowledge and technological abilities of Humanity.

## Objections

There are some who object to the idea of colonizing space as being "too expensive and a waste of time". According to this view, there is nothing in space that we really need, adding that moving beyond the solar system is totally impractical in any "reasonable" time scale[citation needed]. This article is about the Solar System. ...

The argument to live together on the earth we have suggests that if even half the money of space exploration were spent for terrestrial betterment, there would be greater good for a greater number of people, at least in the short term. This argument assumes that money not spent on space would automatically go toward socially beneficial projects. It also assumes that space colonization is not itself a valuable goal (see Space and survival). Space and survival is the relationship between space and the long-term survival of the human species and civilization. ...

Some anti-space arguments have gone so far as to suggest that space colonization is a remnant of historical colonization, an idea which is said to be a lingering desire left over from a romanticized notion of the 'founding fathers' and the conquest of territory on Earth. As such, the argument goes, space exploration wins the hearts and minds of voters but does little else. It is even said by some that the objective of colonizing space adds fuel to the patriotic dogma of conquest, and thus reinforces negative national prejudice rather than helping to unify Earth[citation needed].

As an alternative or addendum for the future of the human race, many science fiction writers have focused on the realm of the 'inner-space', that is the (computer aided) exploration of the human mind and human consciousness.

## Counter arguments

The argument of need: The population of Earth continues to increase, while its carrying capacity and available resources do not. If the resources of space are opened to use and viable life-supporting habitats can be built, the Earth will no longer define the limitations of growth (see extraterrestrial population growth). The equilibrium maximum of the population of an organism is known as the ecosystems carrying capacity for that organism. ... Map of countries by population density (See List of countries by population density. ...

The argument of cost: Very many people greatly overestimate how much money is spent on space, and underestimate how much money is spent on defense or health care. For example, as of June 13, 2006, over \$320 billion has been allocated by the US Congress for the current war in Iraq, in comparison it only cost \$2 billion to create the Hubble Space Telescope, and NASA's yearly budget averages only about \$16 billion a year, in other words the money that has been spent on the Iraq war could have funded NASA for approximately 21 years. Each year, the United States Congress passes a Federal Budget detailing where federal tax money will be spent in the coming year. ...

The argument of Nationalism: Space proponents counter this argument by pointing out that humanity as a whole has been exploring and expanding into new territory since long before Europe's colonial age, going back into prehistory (the nationalist argument also ignores multinational cooperative space efforts); that seeing the Earth as a single, discrete object instills a powerful sense of the unity and connectedness of the human environment and of the immateriality of political borders; and that in practice, international collaboration in space has shown its value as a unifying and cooperative endeavor.[16]

The argument of 'Inner Space': This form of exploration need not be exclusive to space colonization, as exemplified for example by Transhumanist philosophies.

Space advocacy organizations: Space advocacy is a political position that favors the exploration, utilization, and colonization of outer space. ...

## In fiction

Although established space colonies are a stock element in science fiction stories, fictional works that explore the themes, social or practical, of the settlement and occupation of a habitable world are much rarer. The following list is restricted to works dealing primarily with the initial stages of colonization.

### Written works

Coyote (2002) is science fiction author Allen Steeleâ€™s novel of interstellar exploration and settlement. ... Allen Mulherin Steele, Jr. ... Farmer In The Sky is a 1950 science fiction novel by Robert A. Heinlein about a boy who emigrates to Jupiters moon Ganymede, which is in the process of being terraformed, and who creates a farm out of gravel. ... Robert Anson Heinlein (July 7, 1907 â€“ May 8, 1988) was one of the most popular, influential, and controversial authors of hard science fiction. ... The Martian Chronicles is a 1950 science fiction novel by Ray Bradbury that chronicles the colonization of Mars by humans fleeing from a troubled Earth, and the conflict between aboriginal Martians and the new colonists. ... Ray Douglas Bradbury (born August 22, 1920) is an American literary, fantasy, horror, science fiction, and mystery writer best known for The Martian Chronicles, a 1950 book which has been described both as a short story collection and a novel, and his 1953 dystopian novel Fahrenheit 451, is widely considered... The Mars trilogy is a series of award-winning science fiction novels by Kim Stanley Robinson, chronicling the settlement and terraforming of the planet Mars. ... For the late American actress, see Kim Stanley. ...

### Games

• Alien Legacy (1994), computer game. Player has to manage new colonies on the planets of Beta Caeli.
• Ascendancy (1995), computer game. Player tries to grow a colony into a spacefaring civilization.
• Outpost (1994), computer game. Player plans and manages a colony on another planet.
• Outpost 2 (1997), computer game. Player manages a colony on the fictional planet of New Terra.
• Sid Meier's Alpha Centauri (1999), computer game. Player tries to expand a human colony on Alpha Centauri.
• Starfarers of Catan (1999), tabletop game. Player manages trade and colonization in the fictional planetary system of Catan.

This article or section does not cite its references or sources. ... // Ascendancy is a 4X science fiction turn-based strategy computer game for DOS. It was released in 1995 by The Logic Factory. ... Outpost is a video game developed by Dynamix and published by Sierra On-Line. ... Outpost 2 is a real-time strategy computer game developed by Dynamix, released in 1997 by Sierra Entertainment. ... â€œSMACâ€ redirects here. ... Starfarers of Catan is a multiplayer board game loosely based on the Settlers of Catan series of games. ...

### Comics

2001 Nights is a manga series published in the early 1990s by Yukinobu Hoshino. ... Yukinobu Hoshino (æ˜Ÿé‡Ž ä¹‹å®£; Hoshino Yukinobu; January 29, 1954 - ) is a Japanese mangaka. ...

### Television

• Earth 2 (1994-1995), television series. A refugee group travels to and tries to colonize a distant Earth-like planet.
• Mobile Suit Gundam (1979-1980), animated television series. The series as well as its sequels and spin-offs mostly revolve around the conflicts between the Earth and the space colonies.

Earth 2 is a short-lived science fiction television series which aired on NBC from November 6, 1994 to June 4, 1995. ... Mobile Suit Gundam ) is a televised anime series, created by Sunrise. ...

## References

1. ^ "NASA's Griffin: 'Humans Will Colonize the Solar System'", Washington Post, September 25, 2005, pp. B07.
2. ^ http://www.unescap.org/esd/energy/information/ElectricPower/1999-2000/access.htm
3. ^ Robert Zubrin, Entering Space: Creating a Spacefaring Civilization, section: Titan, pp. 163-166, Tarcher/Putnam, 1999, ISBN 978-1-58542-036-0
4. ^ NASA page: News-Features-the Story of Saturn saturn.jpl.nasa.gov. Retrieved 8 January 2007.
5. ^ Move to new planet, says Hawking (2006).
6. ^ Mankind must colonise other planets to survive, says Hawking (2006).
7. ^ E. E. Hale. The Brick Moon. Atlantic Monthly, Vol. 24, 1869.
8. ^ K. E. Tsiolkovsky. Beyond Planet Earth. Trans. by Kenneth Syers. Oxford, 1960
9. ^ G. K. O'Neill. The High Frontier: Human Colonies in Space. Morrow, 1977.
10. ^ T. A. Heppenheimer. Colonies in Space. Stackpole Books, 1977
11. ^ Marianne J. Dyson: Living on a Space Frontier. National Geographic, 2003
12. ^ Paul Eckart. Lunar Base Handbook. McGraw-Hill, 2006
14. ^ Britt, Robert Roy. "The Top 3 Reasons to Colonize Space", Space.com, 08 October 2001.
15. ^ Halle, Louis J. (Summer 1980). "A Hopeful Future for Mankind". Foreign Affairs.
16. ^ Life After Earth: Imagining Survival Beyond This Terra Firma. New York Times.
17. ^ http://space.alglobus.net/
18. ^ http://www.space-settlement-institute.org
19. ^ http://www.seds.org/
20. ^ http://www.foresight.org/challenges/space.html

is the 8th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... The Brick Moon is a short story by Edward Everett Hale, published serially in The Atlantic Monthly starting in 1869. ...

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