Construction and extraterrestrial habitats | Construpedia

Construction and extraterrestrial habitats

Introduction

Space colonization refers to the human settlement or colonization of outer space or astronomical objects. In a broad sense, the term encompasses any form of permanent human presence in space, such as space habitats or extraterrestrial settlements.[2] This process may include the occupation or exploitation of resources, such as space mining.

International legislation, particularly the 1967 Outer Space Treaty, prohibits territorial claims in space, considering it a "Common Heritage of Humanity"). "Space habitat (facility) (not yet drafted)", nor have any extraterrestrial territories or properties been officially claimed. Although there are no concrete government plans to establish space colonies, various proposals, designs and speculations have arisen over time, driven by advocates) of space colonization. The private company SpaceX leads the most notable efforts for the colonization of Mars, although its advances are mainly focused on launch and landing systems.[5].

Space colonization raises complex sociopolitical questions. Among the arguments in favor are the survival of humanity and life "independent of the Earth by turning humans into a multiplanetary species"),[6] guaranteeing its continuity in the face of planetary disasters (natural or anthropogenic) and the commercial use of space, which could reduce terrestrial exploitation through access to extraterrestrial resources.[7] However, critics point out that the commodification of space could perpetuate problems such as environmental degradation, economic inequality and war conflicts, prioritizing interests of the powerful to the detriment of addressing urgent social and environmental problems.[8][9][10].

The construction of extraterrestrial settlements requires overcoming enormous technological, economic and social challenges. Space settlements are usually designed to satisfy almost all, or all, the needs of a larger number of human beings. Space environments are extremely hostile to human life and difficult to access for maintenance and supply. This calls for significant advances in technologies such as "controlled ecological life support systems" and the reduction of the high costs of orbital spaceflight, which currently hover around $1,400 per kg to low Earth orbit with SpaceX's Falcon Heavy. However, advances in reusable launch systems could reduce these costs dramatically, potentially reaching $20 per kg,[11] in addition to the creation of automated manufacturing and construction techniques.

Definition

Construction and extraterrestrial habitats

Introduction

History

In the first half of the century, John Wilkins proposed in his work A Discourse Concerning a New Planet that future explorers, such as Francis Drake or Christopher Columbus, could reach the Moon and establish human settlements.[22] The first known work on space colonization was the 1869 story The Brick Moon, by Edward Everett Hale, which describes an inhabited artificial satellite.[23] In 1897, Kurd Lasswitz also explored the concept of space colonies. Russian space science pioneer Konstantin Tsiolkovsky anticipated elements of a space community in his book Beyond Planet Earth, written around 1900. Tsiolkovsky envisioned space travelers building greenhouses and growing food in space.[24] In addition, he believed that space exploration would perfect humanity, leading to immortality and peace.[25]

In 1902, Cecil Rhodes spoke about «those stars that are seen at night, those immense worlds that we will never be able to reach» and added: «I would annex the planets if I could; I often think about it. It saddens me to see them so clear and so far away».[26] In the 1920s, thinkers such as John Desmond Bernal, Hermann Oberth, Guido von Pirquet and Herman Noordung further developed the idea of space colonization. In 1952, Wernher von Braun popularized his proposals in an article in the magazine Colliers. During the 1950s and 1960s, Dandridge M. Cole[27] also contributed his ideas.

With the beginning of orbital spaceflight in the 1950s, colonialism remained a relevant international project, which made it easier for the United States to advance its space program), presenting space as a *new frontier "New frontier (United States)").[8] However, the rise of decolonization gave rise to numerous independent countries that demanded an anti-colonial stance and the regulation of space activities within the framework of international space law. Territorial grabs and an arms race in space grew, even among space-capable nations.[4] This led to the drafting of international space laws, beginning with the Outer Space Treaty of 1967, which declared space as a common heritage of humanity and made provisions for its regulation and shared use.

The emergence of geostationary satellites raised the problem of limited resources in space. In the 1960s, the international community agreed to regulate the assignment of positions in the geostationary orbit (GEO) through the International Telecommunication Union (ITU). Currently, any entity wishing to launch a satellite to GEO must request an orbital position from the ITU.[28] In 1976, a group of equatorial countries, all former colonies of colonial empires and without their own space capabilities, signed the Bogotá Declaration. This declaration stated that the geostationary orbit is a limited natural resource that belongs to the equatorial countries located directly below, which is why they do not consider it part of outer space, the common good of humanity, challenging the domination of space nations by considering it an imperialist practice.[29][30][3].

In the 1970s, authors such as Gerard K. O'Neill, with The High Frontier: Human Colonies in Space,[31] and T. A. Heppenheimer, with Colonies in Space,[32] continued to develop concepts of space colonization. In 1975, the first joint international space mission, between the American Apollo spacecraft and the Soviet Soyuz spacecraft, marked a milestone in the detente policy, with the spacecraft docking in Earth orbit for almost two days.[33] In 1977, the Saliut 6 station became the first sustained space habitat in orbit. Subsequently, the International Space Station (ISS) became the largest human settlement in space, serving as a model for future stations, such as those planned around or on the Moon.[34][35].

Contemporary speeches and international treaties.

In the century, authors such as Marianne J. Dyson, with Home on the Moon; Living on a Space Frontier (2003),[36] Peter Eckart, with Lunar Base Handbook (2006),[37] and Harrison Schmitt, with Return to the Moon (2007),[38] enriched the discourse on life in space. The Moon Treaty and the Artemis Accords have promoted an international regime for lunar activities.[39] However, challenges such as space debris due to the lack of regulation on the disposal of assets at the end of their mission, threaten the existing treaties. Until now, the only habitats on another celestial body have been temporary manned lunar modules. Similar to the Artemis program, China is leading a project to develop the International Lunar Research Station starting in the 2030s.

Justification and opposition to space colonization

Contenido

La colonización del espacio ha generado un amplio debate que abarca desde argumentos a favor basados en la supervivencia de la humanidad hasta críticas que cuestionan su viabilidad y ética. A continuación, se exploran las principales justificaciones y oposiciones a esta empresa.

Justification

One of the main arguments in favor of space colonization is to ensure the long-term survival of human civilization and terrestrial life.[40] Establishing colonies outside of Earth would allow the planet's species, including humans, to survive natural or man-made disasters.[41].

Theoretical physicist and cosmologist Stephen Hawking twice defended space colonization as a means to save humanity. In 2001, he predicted that humanity could become extinct within the next thousand years if colonies were not established in space.[42] In 2010, he stated that humanity faces two options: colonize space in the next two hundred years or face the prospect of long-term extinction.[43]

In 2005, then-NASA administrator Michael Griffin noted space colonization as the ultimate goal of space programs, stating:

Louis J. Halle Jr., a former United States State Department official, wrote in the American magazine Foreign Affairs (Summer 1980) that space colonization would protect humanity in the event of a global nuclear war.[45] Physicist Paul Davies also supports the idea that, if a planetary catastrophe threatens the survival of the human species on Earth, a self-sustaining colony could recolonize our planet and restore human civilization. Journalist William E. Burrows and biochemist Robert Shapiro proposed a private project, the Alliance to Rescue Civilization), to establish a backup of human civilization outside of Earth.[46]

Based on Copernicus's principle, John Richard Gott estimated that humanity could survive another 7.8 million years, but is unlikely to colonize other planets. However, he expressed his hope that he was wrong, since "colonizing other worlds is our best opportunity to diversify risks and improve the survival prospects of our species."[47].

A 2019 theoretical study analyzed the long-term trajectory of human civilization.[48] It is argued that, due to the finitude of the Earth and the limited lifespan of the solar system, humanity's survival in the distant future will likely require extensive space colonization.[48] This astronomic trajectory of humanity could unfold in four stages:.

- Establishment of space colonies in habitable locations, either in outer space or on celestial bodies, initially dependent on Earth.

- Gradual autonomy of the colonies, allowing them to survive if terrestrial civilization collapses.

- Development and expansion of colonies through terraforming or other means.

- Self-replication of colonies to establish new settlements in space, a process that could expand exponentially throughout the cosmos.

However, this trajectory may not be sustainable, since competition for resources or conflicts between human factions could interrupt it, generating a star wars scenario.[48].

The resources in space, both material and energy, are immense. The solar system has enough material and energy to support thousands to more than a billion times the current human population, mainly thanks to the Sun.[31] [49][50].

Asteroid mining will likely be a key pillar in space colonization. Asteroids provide water and materials to build structures and shielding, facilitating the creation of fueling and mining stations that optimize space travel.[51] NASA uses the term optical mining to describe the extraction of materials from asteroids, estimating that the use of propellants derived from asteroids for explorations to the Moon, Mars and beyond would save $100 billion. If funding and technology advance faster than anticipated, asteroid mining could be viable within a decade.[52].

Although some infrastructure elements, such as oxygen, water, and basic minerals, are already easily produced on Earth and would not be valuable as commercial items, other high-value products are more abundant, easier to produce, of higher quality, or unique to space. These could offer, in the long term, a high return on the initial investment in space infrastructure.[53] These high-value assets include precious metals,[54][55] gemstones,[56] energy,[57] solar cells, ball bearings, semiconductors and pharmaceuticals.[58].

Mining metals from a small asteroid, such as (3554) Amun_Am%C3%B3n "(3554) Amun") or (6178) 1986 DA_1986_DA "(6178) 1986 DA"), could produce 30 times more metal than anything mined in human history, worth approximately $20 trillion at 2001.[59].

The main obstacles to the commercial exploitation of these resources are the high cost of the initial investment,[60] the long period necessary to obtain returns (the Eros Project, The Eros Project, estimates 50 years of development)[61] and the fact that it has never been carried out, which implies a high investment risk.

Human expansion and technological progress have frequently led to environmental devastation and destruction of ecosystems and their associated fauna. In the past, expansion has often involved the displacement of indigenous peoples, with treatments ranging from invasion of their territories to genocide. Since space, as far as is known, is devoid of life, some proponents of space colonization argue that these consequences would not be a problem.[62][63] However, on some bodies in the solar system, the possibility of native life forms exists, so the negative consequences of space colonization cannot be ruled out.[64].

On the other hand, some counterarguments maintain that changing only the location, but not the logic of exploitation, will not guarantee a more sustainable future.[65].

One argument in favor of space colonization is to mitigate the proposed impacts of Earth's overpopulation, such as resource depletion.[66] If space resources were accessible and viable, life-supporting habitats were built, Earth would no longer define the limits of growth. Although many Earth resources are non-renewable, extraterrestrial colonies could meet the majority of the planet's resource needs, reducing demand on Earth resources.[31][67] Proponents of this idea include Stephen Hawking[68] and Gerard K. O'Neill.[31].

However, others, including cosmologist Carl Sagan and science fiction writers Arthur C. Clarke,[69] and Isaac Asimov,[70] have argued that sending surplus population into space is not a viable solution to human overpopulation. According to Clarke, "the battle against overpopulation must be fought or won here on Earth."[69] The problem for these authors is not the lack of resources in space (as shown in books such as Mining the Sky[71]), but the physical impracticality of sending large numbers of people into space to solve overpopulation on Earth.

Proponents of space colonization highlight the innate human drive to explore and discover, considering it an essential quality for the progress and prosperity of civilizations.[72][73].

Nick Bostrom has argued that, from a utilitarian perspective, space colonization should be a primary goal, as it would allow a very large population to live for a very long time (possibly billions of years), generating an enormous amount of utility (or happiness).[74] He argues that it is more important to reduce existential risks to increase the probability of eventual colonization than to accelerate technological development so that it occurs sooner. In his article, he assumes that the lives created will have a positive ethical value despite the problem of suffering.

In a 2001 interview with Freeman Dyson, John Richard Gott and Sid Goldstein, they were asked for reasons why some humans should live in space.[75] Their answers included:

• - Spread life and beauty throughout the universe.

• - Ensure the survival of our species.

• - Generate revenue through new forms of space commercialization, such as solar energy satellites, asteroid mining, and space manufacturing.

• - Protect Earth's environment by moving people and industries into space.

Biotic ethics") is a branch of ethics that values life in itself. For biotic ethics and its extension to space as pambiotic ethics, it is a human purpose to secure and propagate life and to use space to maximize life.

Opposition

Space colonization has been seen as a solution to the problem of human overpopulation since at least 1758,[76] and was cited as one of Stephen Hawking's reasons for promoting space exploration.[77] However, critics point out that the slowdown in population growth rates since the 1980s has reduced the risk of overpopulation.[76].

Critics also argue that the costs of commercial activities in space are too high to be profitable compared to terrestrial industries, so significant exploitation of space resources is unlikely to be seen in the foreseeable future.[78].

Other objections include concerns that the future colonization and commodification of the cosmos is likely to benefit the already powerful, including large economic and military institutions such as major financial institutions, large aerospace companies, and the military-industrial complex, which could lead to new wars and exacerbate pre-existing exploitation of workers and resources, economic inequality, poverty, social division and marginalization, environmental degradation, and other harmful processes or institutions.[10][79][80].

Other concerns include the risk of creating a culture in which individuals are no longer seen as human beings, but rather as material assets. Issues such as human dignity, morality, philosophy, culture, bioethics, and the threat of megalomaniac leaders in these new societies should be addressed so that space colonization meets the psychological and social needs of people living in isolated colonies.[81].

As an alternative or complement to the future of humanity, many science fiction writers have explored the realm of inner space, that is, computer-assisted exploration of the human mind and human consciousness, possibly en route to a Matrioshka brain.[82].

Robotic spacecraft are proposed as an alternative to obtain many of the same scientific advantages without the limited mission duration and high cost of life support and return transportation that human missions entail.[83].

A corollary of the Fermi paradox—no one else is doing it[84]—is the argument that since there is no evidence of alien colonization technology, it is statistically unlikely that it would be possible to use that same level of technology ourselves.[85].

Space colonization has been discussed as a postcolonial continuation[89] of imperialism and colonialism,[90][91][92][8] advocating decolonization instead of colonization.[93][92] Critics argue that the current political-legal regimes and their philosophical foundation favor the imperialist development of space,[8] that the main decision-makers in space colonization are usually elites wealthy affiliated with private corporations and that space colonization would primarily attract their peers rather than ordinary citizens.[94][95] Furthermore, it is argued that an inclusive[96] and democratic process is necessary for the participation and implementation of any space exploration, infrastructure or habitation.[97][98] According to space law expert Michael Dodge, existing space law, such as the Outer Space Treaty, guarantees access to space, but does not ensure social inclusion or regulate non-state actors.[93].

Challenges to overcome

La colonización más allá de la Tierra implica superar numerosos desafíos técnicos, ambientales y humanos.

Distance from Earth

The outer planets are much farther from Earth than the inner ones, making travel difficult and prolonged. Return travel could be prohibitive due to time and distance. Even communication with Earth is slow, with delays of 4 to 24 minutes for messages to Mars "Mars (planet)"),[114] and 35 to 52 minutes to Jupiter and its satellites.[115].

Extreme environments

Extreme cold, due to the distance from the Sun, brings temperatures close to absolute zero in many parts of the outer solar system.[116][117].

Sustainable energy sources

Solar energy is much less concentrated in the outer solar system, raising questions about its viability even with concentrating mirrors. Nuclear energy may be necessary.[118] Geothermal systems may be practical on some planets and natural satellites.[119].

Physical and mental risks for settlers

The health of humans who might participate in colonization would be subject to significant physical, mental and emotional risks:.

• - Effects of low gravity: The natural satellites of the gas giants and the outer dwarf planets have very low gravities, the highest being that of Io "Ío (satellite)") (), less than a fifth of Earth's. Since the Apollo program, manned flights have been limited to low Earth orbit, with no data on the effects of such low gravities. It is speculated that they could be similar to prolonged exposure in weightlessness, but this is not confirmed. Rotating ships that generate artificial gravity could mitigate these effects.

• - Dust: Inhalation of fine dust from rock surfaces poses respiratory risks, similar to the harmful effects of lunar dust.[120].

• - Bone loss: NASA has observed that, without gravity, bones lose minerals "Mineral (nutrient)", causing osteoporosis.[121] Bone density can decrease by 1% per month,[122] increasing the risk of osteoporosis-related fractures in the future. The movement of fluids towards the head can cause vision problems.[123].

• - Mental health: NASA found that isolation in closed environments, such as the International Space Station, causes depression, sleep disorders and reduced personal interactions, probably due to confined spaces and the monotony of long flights.[122][124].

• - Circadian rhythm: Space living can disrupt the circadian rhythm due to the interruption of the dawn and dusk cycle, causing exhaustion, insomnia and other sleep problems that reduce productivity and affect mental health.[125].

• - Radiation: High energy radiation in deep space is more dangerous than in low Earth orbit. The metal shielding of the ships only blocks between 25 and 30% of the radiation, leaving the colonists exposed to the rest, with short and long-term health complications.[126].

Places to consider

La colonización espacial ha sido concebida en diversos lugares dentro y fuera del sistema solar, siendo los más destacados Marte y la Luna.

Near-Earth space

The geostationary orbit was the subject of early space colonization debate. The equatorial countries, through the Bogotá Declaration, claimed special rights over this orbit due to its location on the equator.[89].

Space debris, especially in low Earth orbit, has been considered a byproduct of colonization by occupying space and making access difficult due to excessive contamination, exacerbated by military activities and lack of proper management.[89].

Most of the delta-v") requirement, and therefore propellant, in a launch is used to reach low Earth orbit.[127] As Jerry Pournelle stated, "if you can get your ship into orbit, you are halfway to anywhere."[128] Therefore, the main advantages of building a space settlement in Earth orbit are accessibility to Earth and existing economic incentives, such as space hotels and space manufacturing. However, a major disadvantage is the absence of materials exploitable in orbit. Space colonization could require the launch of large quantities of cargo, making thousands of daily launches unsustainable. Theoretical concepts such as orbital rings and sky hooks have been proposed to reduce the costs of access to space.[127]

The Moon is a priority target for colonization due to its proximity to Earth and low escape velocity. It is reachable in three days, allows almost instantaneous communication with Earth, has exploitable minerals, lacks an atmosphere and has low gravity, which makes it easy to send materials and products to orbit.[127] Ice is found in craters of eternal darkness near the poles, which could satisfy the water needs of a lunar colony.[129] However, the presence of mercury "Mercury (element)") in these areas could raise concerns. [130][131] Native precious metals, such as gold, silver, and probably platinum, are concentrated at the lunar poles due to electrostatic transport of dust.[131] Only some materials, such as helium-3 (for fusion energy) and rare earth minerals (for electronics), make economic sense to be sent directly to Earth. It is more feasible to use these materials in space or transform them into valuable products for export. The lack of atmosphere leaves the Moon unprotected from space radiation or meteoroids, so lunar lava tubes have been proposed as protected sites.[132] The low lunar gravity () raises questions about its ability to maintain long-term human health.[133].

Some argue that due to extreme temperature changes and toxic lunar regolith, the Moon will not be a habitable place, but will attract polluting extractive and manufacturing industries. It has been proposed that moving these industries to the Moon could protect Earth's environment and free poorer countries from the shackles of neocolonialism imposed by rich nations. Within the framework of space colonization, the Moon would become an industrial center of the solar system.[127].

Interest in establishing a lunar base has grown over the century as an intermediate step toward colonizing Mars. In October 2018, the director of the European Space Agency (ESA), Jan Woerner, proposed at the International Astronautical Congress in Bremen, Germany, international cooperation to develop lunar capabilities, a concept called lunar village.[134].

In December 2017, the first Trump administration issued Space Policy Directive 1"), ordering NASA to include a lunar mission on the path to destinations beyond Earth's orbit.[135][134].

In 2023, the United States Department of Defense began a study on the infrastructure and capabilities necessary to develop a lunar economy over the next ten years.[136].

In 2024, China, together with partner countries, announced its intention to establish the International Lunar Research Station. For its part, the United States, in collaboration with international partners, is advancing its Artemis program, which includes plans to build lunar bases near the poles, close to craters of eternal darkness, in the 2030s. The Chinese Lunar Exploration Program is seen as a means to strengthen China's political influence and support its aspirations to become a superpower, while the United States seeks to maintain its position as the leading space power.

Another near-Earth possibility is the stable Earth-Moon Lagrangian points, L and L, where a space colony could float indefinitely. The L5 Society") was founded to promote settlement by building space stations at these points. In 1974, Gerard K. O'Neill suggested that the stable region around L could support thousands of floating colonies and would facilitate travel to and from the colonies due to the low effective potential at this point.[137]

Mars

The hypothetical colonization of Mars has attracted the interest of public space agencies and private corporations, and has been widely depicted in science fiction, film and art.

Although many plans have been proposed for a human mission to Mars, including some affordable ones like Mars Direct, none have materialized until 2025. Both the United States and China plan to send humans to Mars in the 2040s, but these plans lack hardware and funding.[127] However, SpaceX is developing Starship, a reusable super-heavy-lift launch vehicle, with the vision of sending humans to Mars. In November 2024, the company plans to send five unmanned Starships to Mars in the 2026 or 2028-2029 launch windows.[138] SpaceX CEO Elon Musk has reiterated his financial and political support for these efforts.[139].

Mars is more suitable for habitability than the Moon, with stronger gravity, an abundance of materials necessary for life, a day/night cycle almost identical to Earth's, and a thin atmosphere that protects against micrometeoroids. The main disadvantage compared to the Moon is the transit time of six to nine months and the launch window, which occurs approximately every two years. If Martian materials can be used to produce propellant (such as methane via the Sabatier reaction) and supplies (such as oxygen for crews), the amount of supplies needed would be significantly reduced.[140][127] Even so, Martian colonies will not be economically viable in the short term, so the reasons for colonizing Mars will be primarily ideological and prestige, such as the desire for freedom.[127].

Other bodies of the inner solar system

Mercury is rich in metals, volatiles and solar energy. However, it is the body in the solar system that requires the most energy to land from Earth, based on the delta-v requirement, and astronauts must deal with extreme temperature and radiation differentials.[127].

Although once thought to be a volatile-free body like the Moon, Mercury is now known to be rich in volatiles, more so than any other terrestrial body in the inner solar system.[141] In addition, it receives six and a half times more solar flux than the Earth-Moon system,[142] making solar energy an efficient source, which could be harnessed by orbital solar panels and transmitted to the surface or exported to other planets.[143].

In 1996, geologist Stephen Gillett suggested that Mercury might be an ideal place to build and launch spacecraft with solar sails, which could be launched as folded chunks by an electromagnetic catapult from the surface. Once in space, the solar sails would be deployed. Solar power for the launcher would be easy to produce and solar sails near Mercury would have 6.5 times more thrust than near Earth. This could make Mercury an ideal place to obtain useful materials to build hardware intended to terraform Venus. Huge solar collectors could also be built on or near Mercury to power large-scale engineering activities, such as laser-driven light sails to nearby star systems.[144].

Since Mercury has practically zero axial tilt, the crater floors near its poles are in eternal darkness, functioning as cold traps&action=edit&redlink=1 "Cold trap (astronomy) (not yet written)") that trap volatiles during geological periods. It is estimated that the poles of Mercury contain between 10 and 10 kg of water, probably covered by about 5.65x10 m of hydrocarbons, which would make agriculture possible. It has been suggested to develop varieties of plants that take advantage of the high light intensity and long day of Mercury. The poles do not experience the significant day-night variations of the rest of the planet, making them the best place to start a colony.[142].

Another option would be to live underground, where day-night variations are buffered enough to maintain constant temperatures. There are indications that Mercury contains lava tubes, similar to those on the Moon and Mars, that would be suitable for this purpose.[143] Underground temperatures in a ring around the poles can reach Earth's ambient temperature, , at depths starting at . The presence of volatiles and the abundance of energy have led Alexander Bolonkin and James Shifflett to consider Mercury preferable to Mars for colonization.[142][145].

A third option would be to move continuously to stay on the night side, since Mercury's day-night cycle causes the terminator to move very slowly.[143].

Due to Mercury's high density, its surface gravity is , similar to that of Mars, despite being a smaller planet.[142] This would be easier to accommodate than lunar gravity (), and offers advantages in terms of a lower escape velocity from Mercury compared to Earth.[143] Mercury's proximity gives it advantages over asteroids and outer planets, and its low synodic period means that launch windows from Earth to Mercury are longer. more frequent than to Venus or Mars.[143].

giant planets

Robotic aerostats have been proposed to be placed in the upper atmospheres of the solar system's giant planets for exploration and possibly mining for helium-3, which could have a very high value per unit mass as a thermonuclear fuel.[147][148].

Robert Zubrin identified Saturn, Uranus and Neptune as the Persian Gulf of the solar system, as being the largest sources of deuterium and helium-3 to fuel a fusion energy economy, with Saturn being the most important and valuable due to its relative proximity, low radiation and extensive satellite system. On the other hand, planetary scientist John Lewis, in his 1997 book Mining the Sky, argues that Uranus is the most likely location. to extract helium-3 due to its shallower gravitational well, making it easier for a loaded ship to take off. Additionally, as an ice giant, Uranus likely allows for easier separation of helium from its atmosphere.

Since Uranus "Uranus (planet)") has the lowest escape velocity of the four giant planets, it has been proposed as a mining site for helium-3.[148] Being a gas giant with no viable surface, one of Uranus's satellites could serve as a base.[149].

It has been proposed that one of Neptune's satellites "Neptune (planet)"), Triton "Triton (satellite)"), could be used for colonization. Triton's surface shows signs of extensive geological activity, suggesting a subsurface ocean, possibly composed of ammonia and water.[150] If technology were to advance to allow the harnessing of this geothermal energy, it could make colonization of a cryogenic world like Triton viable, complemented by nuclear fusion energy.[151].

Human missions to the outer planets would need to arrive quickly due to the effects of space radiation and microgravity during the journey.[152] In 2012, Thomas B. Kerwick noted that the distance to the outer planets makes their human exploration currently impractical, noting that round trips to Mars are estimated to take two years, while Jupiter's closest approach to Earth is more than ten times that of Mars.[153] However, he suggested this could change with "significant advances in spacecraft design." Nuclear thermal or nuclear electric engines have been proposed to make the trip to Jupiter in a reasonable time.[154] Another possibility would be magnetic plasma sails, a technology already suggested to quickly send probes to Jupiter.[155] Cold would also be a factor, requiring a robust source of thermal energy for spacesuits and bases.[153] Most of the largest satellites of the outer planets contain water ice, liquid water and compounds. organics that could be useful to sustain human life.[156][157].

Robert Zubrin has suggested that Saturn, Uranus, and Neptune are advantageous locations for colonization because their atmospheres are good sources of fusion fuels, such as deuterium and helium-3. Zubrin noted that Saturn would be the most important and valuable due to its relative closeness, low radiation and extensive satellite system.[158] However, fusion energy has not yet been achieved and fusion with helium-3 is more difficult than conventional fusion of deuterium and tritium").[159] Jeffrey Van Cleve, Carl Grillmair and Mark Hanna focus on Uranus, since the delta-v necessary to extract helium-3 from its atmosphere and take it to orbit is the half that of Jupiter, and its atmosphere is five times richer in helium than that of Saturn.[148].

Transneptunian region

Freeman Dyson proposed that trans-Neptunian objects, rather than planets, represent the main potential habitat for life in space.[174] It is estimated that several hundred billion to a trillion icy comet-like bodies exist beyond the orbit of Neptune ("Neptune (planet)"), in the Kuiper Belt and the inner and outer Oort cloud. These objects could contain all the ingredients necessary for life (ice, ammonia, and carbon-rich compounds), plus significant amounts of deuterium and helium-3. Since Dyson's proposal, the number of known trans-Neptunian objects has increased considerably.

Beyond the solar system

Colonization beyond the solar system could focus on nearby stars. The main obstacle is the enormous distances to other stars.

With today's technology, travel times would be millennia. At average speeds of even 0.1% of the speed of light (c), interstellar expansion through the Milky Way would take up to half the Sun's galactic orbital period, approximately 240 million years, comparable to the time scale of other galactic processes.[175] Due to fundamental reaction energy and mass considerations, such speeds would be limited to small spacecraft with current technology. If humanity had access to large amounts of energy, on the order of the mass-energy of entire planets, it might be possible to build ships with Alcubierre drives.[176].

The following are plausible approaches with current technology:.

• - A generational ship that would travel much slower than light, with interstellar travel times of decades or centuries. The crew would go through generations before completing the journey, so none of the initial crew would survive to reach the destination, assuming current human lifespans.[177].

• - A sleeper ship, where most or all of the crew spends the trip in some form of hibernation or suspended animation, allowing some or all of them to reach the destination.[178].

• - An interstellar ship that transports embryos, much smaller than a generation or dormitory ship, which would carry human embryos or DNA in a frozen or inactive state to the destination. (The obvious biological and psychological problems in the birth, upbringing and education of these travelers, omitted here, may not be fundamental).[179].

• - A ship powered by nuclear fusion or nuclear fission (for example, an ion thruster), reaching speeds of up to 10% of c, allowing one-way trips to nearby stars with durations comparable to a human life.[180].

• - A Project Orion ship, a nuclear propulsion concept proposed by Freeman Dyson that would use nuclear explosions to propel a starship. A special case of previous nuclear rocket concepts, with similar potential speed capability, but possibly simpler technology.[181].

• - Laser propulsion concepts, using some form of energy transmission from the solar system, could allow a light-sail craft to reach high speeds, comparable to those theoretically achievable by the electric fusion rocket mentioned above.[182] These methods would need some means, such as supplemental nuclear propulsion, to stop at the destination, but a hybrid system (light-sail for acceleration, fusion-electric for deceleration) could be possible.

• - Transferred human minds or artificial intelligences could be transmitted via radio or laser at the speed of light to interstellar destinations where self-replicating spacecraft have traveled at sublight speeds and established infrastructure, possibly carrying some minds. Extraterrestrial intelligence could be another viable destination.[183].

Implementation

La construcción de colonias espaciales demanda acceso a recursos esenciales como agua, alimentos, espacio habitable, materiales de construcción, energía, transporte, comunicaciones, sistemas de soporte vital, gravedad artificial, protección contra radiación, migración, gobernanza e inversión de capital. Es probable que las colonias se ubiquen cerca de recursos físicos necesarios, como agua o minerales. La arquitectura espacial busca transformar los viajes espaciales, pasando de pruebas extremas de resistencia humana a experiencias cómodas y sostenibles. Según expertos como John Hickman[187] y Neil deGrasse Tyson,[188] la inversión inicial probablemente provendría de gobiernos,[189] como ha ocurrido en otros proyectos de exploración de fronteras.

Life support

In space settlements, life support systems must recycle or import all nutrients without collapsing. The closest terrestrial analogue is that of a nuclear submarine, which uses mechanical systems to sustain humans for months without surfacing. This technology could be adapted for space use. However, submarines operate in open loop, extracting oxygen from seawater and releasing carbon dioxide, although they recycle existing oxygen.[190] Another proposal is a closed ecological system, such as Biosphere 2.[191].

Although future settlers will face physical, mental and emotional risks, solutions have been proposed. Projects such as MARTE-500, HI-SEAS and SMART-OP seek to mitigate the effects of loneliness and prolonged confinement. Maintaining contact with family members, celebrating holidays, and preserving cultural identities help minimize the deterioration of mental health.[192] Tools to reduce anxiety and strategies to control the spread of germs in closed environments are also being developed.[193] To reduce the risk of radiation, frequent monitoring and minimizing time outside protected areas are proposed.[126] Space agencies could require mandatory daily exercise to prevent muscle degradation.[126].

Cosmic rays and solar flares create a deadly radiation environment in space. In orbits around planets with magnetospheres, like Earth, the Van Allen belts make life outside the atmosphere difficult. Settlements must be surrounded by enough mass to absorb radiation, unless magnetic or plasma shields are developed.[194] The Van Allen belts could be drained using orbital cables[195] or radio waves.[196].

A passive mass shielding of four metric tons per square meter would reduce the radiation dose to several mSv or less per year, well below the levels of some terrestrial areas with high natural background radiation.[197] This shielding could be leftover material (slag) from processing lunar soil or asteroids into oxygen, metals, and other useful resources. However, it represents a significant obstacle to the maneuverability of large-volume ships (mobile spacecraft often use less massive active shields).[194] However, the inertia of these masses requires powerful thrusters or electric motors to start or stop the rotation of spacecraft.

The monotony and loneliness of prolonged space missions can lead astronauts to suffer cabin fever or psychotic breaks. Lack of sleep, fatigue, and work overload also affect performance in environments where every action is critical.[198].

Law, governance and sovereignty

Various models of transplanetary or extraterrestrial governance have been proposed, often highlighting the need for independent governance due to the current lack of regulation and inclusivity in space. It is argued that spatial colonization could generate colonial national identities, similar to land settlement colonialism.[199] Federalism has been studied as a solution for distant and autonomous communities.[200].

Space activity is primarily governed by the Outer Space Treaty, but space law encompasses other international agreements, such as the less ratified Moon Treaty and various national laws. The Outer Space Treaty establishes in its first article that:

And he continues in the second article saying:

The development of international space law has largely revolved around the definition of outer space as the common heritage of humanity. The Magna Carta of Space of 1966 presented by William A. Hyman, which defined it as res communis (common thing) instead of terra nullius (no man's land) which later influenced the work of the United Nations Commission on the Peaceful Uses of Outer Space.[89][202].

Economic aspects

Space colonization will be viable when the necessary methods are sufficiently economical, thanks to cheaper launch systems and accumulated funds, in addition to projected benefits from the commercial use of space.[203].

Although traditional high launch costs limit immediate prospects,[204] advances in the 2010s, such as the SpaceX Falcon 9 rockets, costing $56.5 million per launch up to low orbit,[205] are the most economical in the industry. Advances being made under SpaceX's reusable launch system development program to enable reusable Falcon 9s "could reduce the price by an order of magnitude, leading to more space ventures and, in turn, further reducing the cost of access to space through economies of scale." "Competition (economics)") of space launch services.[207].

The Presidential Commission on the Implementation of the United States Space Exploration Policy proposed an incentive award, perhaps by the government, to encourage colonization by rewarding the first organization to place humans on the Moon and maintain them for a fixed period before returning.[208]

The use of coins in space societies has been debated. The Quasi Universal Intergalactic Denomination (QUID), a PTFE polymer physical currency designed for interplanetary travelers by scientists at the British National Space Center and the University of Leicester for currency exchange company Travelex.[209] QUID and cryptocurrencies (proposed by Elon Musk as possible currencies on Mars)[210] are options under consideration.

Human spaceflight has allowed only the temporary relocation of a few privileged people, with no permanent migrants. The social motivation for space migration has been questioned due to its possible roots in colonialism, highlighting the need to reflect on the inclusivity and foundations of space colonization in addition to the technical challenges for its application.[211][212].

Resources

Colonies on the Moon, Mars, asteroids or Mercury "Mercury (planet)") could mine local materials. The Moon lacks volatiles such as argon, helium and compounds of carbon, hydrogen and nitrogen. The impact of the LCROSS spacecraft on the Cabeus crater ("Cabeus (crater)"), which was chosen for its high concentration of water, revealed that the crater contains material with 1% water or possibly more.[213] Ice could also be in permanently shadowed craters near the lunar poles. Although helium is present in low concentrations, it is estimated that there are one million tons of helium-3 on the Moon, deposited by the solar wind in the regolith.[214] The Moon also has oxygen, silicon, and industrially important metals such as iron, aluminum, and titanium.

Launching materials from Earth is expensive, so colonies could use resources from the Moon, Near Earth Objects (NEOs), Phobos (satellite) or Deimos (Satellite). These offer lower gravity, lack of atmospheric resistance "Resistance (fluids)") and have no biospheres to protect. Many NEOs contain metals and some, such as dormant comets, have billions of tons of ice and kerogen, as well as nitrogenous compounds.[215] Jupiter Trojan asteroids are also ice-rich and volatile.[216] Recycling of raw materials will be essential.

Solar energy in orbit is abundant and reliable, currently used to power satellites. With no nights, clouds or atmosphere to block the light, solar intensity follows the inverse square law: E = 1367/d W/m, where d is the distance in astronomical units (AU) and 1367 W/m is the energy available at the distance of the Earth's orbit from the Sun, 1 AU.[217][218].

In a vacuum, solar cookers with parabolic sheet metal reflectors and very light support structures can reach high temperatures for industrial processes. Even lighter and easier to build are flat mirrors to reflect sunlight around radiation shields in inhabited areas (to prevent cosmic rays from entering your line of sight, or to make the image of the Sun appear to move across your "sky") or over crops.

Large photovoltaic panels or solar thermal plants would be needed to meet electrical demands, which on Earth average per person (about 10 megawatt hours per person per year) in developed areas.[219] These plants could be close to major structures if a wired system is used or further away with wireless power transmission.

A key product of the initial colonies would be solar power satellites (SPS), which would transmit power via microwave beams or lasers to the Earth, Moon, or other colonies. For terrestrial locations this requires less area per watt than conventional solar panels. Once these satellites are built primarily with materials derived from the Moon or asteroids, the price of SPS electricity could be lower than that of energy from fossil fuels or nuclear power; Replacing these would have important advantages, such as the elimination of greenhouse gases and nuclear waste from electricity generation.[220].

Self-sufficiency

Space manufacturing could enable self-replication, a key goal that would enable exponential growth of colonies and eliminate dependence on Earth.[227] This would be Earth's first act of self-replication.[228] Intermediate goals include colonies that only require information (science, engineering, entertainment) or light supplies, such as integrated circuits, medicines, genetic material, and tools.

In 2002, anthropologist John H. Moore estimated that a population of 150 to 180 people would allow a stable society for 60 to 80 generations, about 2,000 years. hundreds.[230][231] In 2020, Jean-Marc Salotti proposed a method to determine the minimum number of colonists to survive on an extraterrestrial world. It is based on the comparison between the time necessary to carry out all activities and the working time of all human resources. For Mars, 110 individuals would be needed.[232].

Political advocacy

Diversas empresas privadas han anunciado planes para la colonización de Marte. Entre los emprendedores que lideran esta causa se encuentran Elon Musk, Dennis Tito y Bas Lansdorp.[233][234].

Organizations involved

The following organizations actively promote space colonization:.

• - Blue Origin: Led by Jeff Bezos, this company works on space colonization, starting with a lunar base. Develops the reusable New Glenn launcher to reduce costs and the Blue Moon lunar module.[235].

• - Mars Society: Promotes Robert Zubrin's Mars Direct plan for the settlement of Mars.

• - National Space Society: Its vision is for people to live and work in thriving communities beyond Earth. It maintains an extensive library of articles and books on space settlements.[236].

• - Space Frontier Foundation: Advocates for space development with a focus on free markets and capitalism.

• - Space Settlement Institute: Find ways to make space colonization a reality in one generation.[237].

• - SpaceX: Develops space transportation infrastructure to enable permanent human settlements on Mars.[238][239].

• - Institute of Spatial Studies: Funds studies on spatial settlements, especially O'Neill cylinders.

• - Alliance to Rescue Civilization: Plans to establish security backups for human civilization on the Moon and other places outside Earth.

• - British Interplanetary Society (BIS; British Interplanetary Society): Promotes ideas for space exploration, including a Mars colony, advanced propulsion systems (Daedalus project), terraforming and the search for habitable worlds.[240] In 2013, it initiated the SPACE project to re-examine Gerard O'Neill's space colony studies from the 1970s, with advances detailed in a special edition of its magazine in September 2019.[241].

• - Asgardia (nation): is an organization that aims to overcome the limitations of the Outer Space Treaty.

• - Cyprus Space Exploration Organization: Promotes space exploration and colonization, encouraging international collaboration.

Experiments with terrestrial analogues

Many space agencies build testbeds on Earth to test advanced life support systems, designed for long-duration spaceflight, although not for permanent colonization:.

• - Biosphere 2: The best-known attempt to create an analogue of a self-sufficient settlement, seeking to replicate the terrestrial biosphere.

• - BIOS-3: A closed ecosystem completed in 1972 in Krasnoyarsk, Siberia.[242].

• - Mars Desert Research Station: A habitat for similar tests, located in a less hostile environment.[243].

• - Mars Arctic Research Station on Devon Island: Provides practice for building and operating outposts outside of Earth.[244].

Influence of science fiction

Space colonization is a recurring theme in science fiction.[246] NASA began evaluating space colonization issues in 1975 with its Space Settlements Design Study, which recognizes the influence of science fiction, citing Robert Salkeld and highlighting the connection between writers such as Jules Verne and astronautics pioneers such as Konstantin Tsiolkovski.[247]

Science fiction and colonization research are interconnected: research inspires fiction, and fiction motivates research. Many of the most interesting ideas in science did not arise in the laboratory, but in the minds of science fiction writers such as Arthur C. Clarke and Ray Bradbury. Clarke's 1945 article on communications satellites was the basis for modern satellites.[248] Bradbury's novel The Martian Chronicles addresses the exploration and colonization of Mars and is considered the primary inspiration for NASA's numerous missions to Mars.[249] Star Trek's communicators and tricorders influenced mobile phones and wireless medical devices.[250][251] Fiction has driven innovations in communications, governance principles and advanced technological devices, all essential for the survival of extraterrestrial colonies.[252] The Innovative Technologies in Science Fiction for Space Applications (ITSF) project of the European Space Agency offers a similar reflection on this cross-fertilization between fiction and science.[253].

Science fiction writer Norman Spinrad highlights the role of science fiction as a visionary force that promoted the conquest of space, although he criticizes its imperialist background.[254] He also points out that political scientist and science fiction writer Jerry Pournelle, in the 1980s, promoted the strategic defense initiative of the Reagan administration, which he considers a failure, because instead of the military program reactivating the space program, the opposite occurs: the 40 billion dollars that the program costs They are actually deducted from the construction of a base on the Moon.[254].

Arthur C. Clarke, writer of 2001: A Space Odyssey (novel) and defender of the ideas of Marshall Savage, predicted in a 2001 article that by 2057 there would be humans on the Moon, Mars, Europa, Ganymede, Titan and in orbit around Venus, Neptune and Pluto.[255] Contemporary science fiction, such as the series The Expanse, based In the novels of James S. A. Corey, he explores the politics and conflicts of a humanity that has colonized the solar system, with Mars as an independent military power. An essay by Theresa Hitchens in 2021 compares this fiction to the current development of corporate-led space exploration.[256].