World Library  
Flag as Inappropriate
Email this Article

Terraforming

 

Terraforming

An artist's conception shows a terraformed Mars in four stages of development.

Terraforming (literally, "Earth-shaping") of a planet, moon, or other body is the theoretical process of deliberately modifying its atmosphere, temperature, surface topography or ecology to be similar to the biosphere of Earth to make it habitable by Earth-like life.

The term "terraforming" is sometimes used more generally as a synonym for planetary engineering, although some consider this more general usage an error. The concept of terraforming developed from both science fiction and actual science. The term was coined by Jack Williamson in a science-fiction story (Collision Orbit) published during 1942 in Astounding Science Fiction,[1] but the concept may pre-date this work.

Based on experiences with Earth, the environment of a planet can be altered deliberately; however, the feasibility of creating an unconstrained planetary biosphere that mimics Earth on another planet has yet to be verified. Mars is usually considered to be the most likely candidate for terraforming. Much study has been done concerning the possibility of heating the planet and altering its atmosphere, and NASA has even hosted debates on the subject. Several potential methods of altering the climate of Mars may fall within humanity's technological capabilities, but at present the economic resources required to do so are far beyond that which any government or society is willing to allocate to it. The long timescales and practicality of terraforming are the subject of debate. Other unanswered questions relate to the ethics, logistics, economics, politics, and methodology of altering the environment of an extraterrestrial world.

Contents

  • History of scholarly study 1
    • Aspects and definitions 1.1
  • Requirements for sustaining terrestrial life 2
  • Preliminary stages 3
  • Prospective planets 4
    • Mars 4.1
    • Venus 4.2
    • Europa (moon) 4.3
    • Other bodies in the Solar System 4.4
  • Paraterraforming 5
  • Ethical issues 6
  • Economic issues 7
  • Political issues 8
  • In popular culture 9
  • See also 10
  • References 11
  • Notes 12
  • External links 13

History of scholarly study

[3]

Sagan also visualized making Mars habitable for human life in "Planetary Engineering on Mars" (1973), an article published in the journal Icarus.[4] Three years later, NASA addressed the issue of planetary engineering officially in a study, but used the term "planetary ecosynthesis" instead.[5] The study concluded that it was possible for Mars to support life and be made into a habitable planet. The first conference session on terraforming, then referred to as "Planetary Modeling", was organized that same year.

In March 1979, NASA engineer and author

  • Red Colony
  • New Mars forum
  • Terraformers Society of Canada
  • Visualizing the steps of solar system terraforming
  • Research Paper: Technological Requirements for Terraforming Mars
  • Terraformers Australia
  • Terraformers UK
  • The Terraformation of Worlds
  • Terraformation de Mars
  • Fogg, Martyn J. The Terraforming Information Pages
  • BBC article on Charles Darwin's and Joseph Hooker's artificial ecosystem on Ascension Island that may be of interest to terraforming projects
  • "Bugs in Space- Microscopic miners could help humans thrive on other planets". Scientific American magazine. By Charles Q. Choi (October 1, 2010)
  • Robotic Lunar Ecopoiesis Test Bed Principal Investigator: Paul Todd (2004)

External links

  • Averner, M. M. & MacElroy, R. D. (1976). On the Habitability of Mars: An Approach to Planetary Ecosynthesis. NASA SP-414.
  • Carr, Michael H. (2007). "Mars: Surface and interior". In Adams-McFadden, Lucy-Ann; Weissman, Paul Robert; Johnson, Torrence V. Encyclopedia of the solar system. Academic Press. pp. 315–330.  
  • Dalrymple, G. Brent (2004). Ancient Earth, ancient skies: the age of Earth and its cosmic surroundings. Stanford University Press. ISBN 0-8047-4933-7
  • Faure, Gunter & Mensing, Teresa M. (2007). Introduction to planetary science: the geological perspective. Springer. ISBN 1-4020-5233-2.
  • Fogg, Martyn J. (1995). Terraforming: Engineering Planetary Environments. SAE International, Warrendale, PA.  
  • Fogg, Martyn J. (1996). "A Planet Dweller's Dream". In Schmidt, Stanley; Zubrin, Robert. Islands in the Sky. New York: Wiley. pp. 143–67. 
  • Fogg Martyn J. (2000). The Ethical Dimensions of Space Settlement (pdf format). Space Policy, 16, 205-211. Also presented (1999) at the 50th International Astronautical Congress, Amsterdam (IAA-99-IAA.7.1.07).
  •  
  • Forget, François; Costard, François & Lognonné, Philippe (2007). Planet Mars: Story of Another World. Springer. ISBN 0-387-48925-8.
  • Kargel, Jeffrey Stuart (2004). Mars: a warmer, wetter planet. Springer. ISBN 1-85233-568-8.
  • MacNiven, D. (1995). "Environmental Ethics and Planetary Engineering".  
  • Knoll, Andrew H. (2008). "Cyanobacteria and earth history". In Herrero, Antonia; Flores, Enrique. The cyanobacteria: molecular biology, genomics, and evolution. Horizon Scientific Press. pp. 1–20.  
  • McKay Christopher P. & Haynes, Robert H. (1997). Implanting Life on Mars as a Long Term Goal for Mars Exploration, in The Case for Mars IV: Considerations for Sending Humans, ed. Thomas R. Meyer (San Diego, California: American Astronautical Society/Univelt), Pp. 209–15.
  • Read, Peter L.; Lewis, Stephen R. (2004). The Martian climate revisited: atmosphere and environment of a desert planet. Springer. ISBN 3-540-40743-X.
  • Sagan, Carl & Druyan, Ann (1997). Pale Blue Dot: A Vision of the Human Future in Space. Ballantine Books. ISBN 0-345-37659-5.
  • Schubert, Gerald ; Turcotte, Donald L.; Olson, Peter (2001). Mantle convection in the earth and planets. Cambridge University Press. ISBN 0-521-79836-1
  • Solar wind ripping chunks off Mars. (November 25, 2008) Cosmos Accessed 6/18/2009.
  • Taylor, Richard L. S. (1992) Paraterraforming – The worldhouse concept. Journal of the British Interplanetary Society, vol. 45, no. 8, pp. 341–352. ISSN 0007-094X
  • Thompson, J. M. T. (2001). Visions of the future: astronomy and Earth science. Cambridge University Press. ISBN 0-521-80537-6.

Notes

  1. ^ "Science Fiction Citations: terraforming". Retrieved 2006-06-16. 
  2. ^ Sagan, Carl (1961). "The Planet Venus". Science 133 (3456): 849–58.  
  3. ^ a b c Sagan 1997, pp. 276-7.
  4. ^ Sagan, Carl (1973). "Planetary Engineering on Mars". Icarus 20 (4): 513.  
  5. ^ Averner& MacElroy, 1976
  6. ^ Oberg, James Edward (1981). New Earths: Restructuring Earth and Other Planets. Stackpole Books, Harrisburg, Pennsylvania. 
  7. ^ McKay, Christopher (1982). "Terraforming Mars". Journal of the British Interplanetary Society. 
  8. ^ Lovelock, James and Allaby, Michael (1984). The Greening of Mars. 
  9. ^ οἶκος. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project.
  10. ^ ποίησις in Liddell and Scott.
  11. ^ Fogg, Martyn J. (1995). Terraforming: Engineering Planetary Environments. SAE International, Warrendale, PA. 
  12. ^ a b Fogg 1995.
  13. ^ Fogg, 1996
  14. ^ Zubrin, Robert (1 November 1996). "Building a Solid Case". SpaceViews. Archived from the original on 2007-09-11. Retrieved 2006-09-26. 
  15. ^ "Goal 1: Understand the nature and distribution of habitable environments in the Universe". Astrobiology: Roadmap.  
  16. ^ Read and Lewis 2004, p.16; Kargel 2004, pp. 185–6.
  17. ^ Kargel 2004, 99ff
  18. ^ Forget, Costard & Lognonné 2007, pp. 80–1.
  19. ^ Forget, Costard & Lognonné 2007, p. 82.
  20. ^ Dave Jacqué (2003-09-26). "APS X-rays reveal secrets of Mars' core". Argonne National Laboratory. Retrieved 2009-06-10. 
  21. ^ Schubert, Turcotte & Olson 2001, p. 692
  22. ^ Carr 2007, p. 318
  23. ^ a b Solar Wind, 2008
  24. ^ Forget, Costard & Lognonné 2007, pp. 80.
  25. ^ Faure & Mensing 2007, p. 252.
  26. ^ Zubrin, Robert M. & McKay, Christopher P. (1997). Technological Requirements for Terraforming Mars. Journal of the British Interplanetary Society, 50, 83. Accessed 2009-06-09.
  27. ^ Brody, Dave (2005). Terraforming: Human Destiny or Hubris?. Ad Astra (National Space Society). Spring 2005. Accessed 2012–09–19.
  28. ^ ScienceDaily (2001, Mar. 29). Jupiter Radiation Belts Harsher Than Expected.
  29. ^ "Humans on Europa: A Plan for Colonies on the Icy Moon". Retrieved 2006-04-28. 
  30. ^ Taylor, 1992
  31. ^ Trouble in the bio bubble
  32. ^ Biosphere 2
  33. ^ Biosphere 2 Members 'aired out'
  34. ^ MacNiven 1995
  35. ^ Robert Zubrin, The Case for Mars: The Plan to Settle the Red Planet and Why We Must, pp. 248-249, Simon & Schuster/Touchstone, 1996, ISBN 0-684-83550-9
  36. ^ Fogg 2000
  37. ^ Christopher McKay and Robert Zubrin, "Do Indigenous Martian Bacteria have Precedence over Human Exploration?", pp. 177-182, in On to Mars: Colonizing a New World, Apogee Books Space Series, 2002, ISBN 1-896522-90-4
  38. ^ "The Political Economy of Very Large Space Projects". Retrieved 2006-04-28. 
  39. ^ "China's Moon Quest Has U.S. Lawmakers Seeking New Space Race". Bloomberg. 2006-04-19. Retrieved 2006-04-28. 
  40. ^ Thompson 2001 p. 108
  41. ^ For example, Greg Bear's novel Halo:_Cryptum (2011).

References

See also

In Zack Snyder's Man of Steel, General Zod attempts to use terraforming to revive the environment of planet Krypton on Earth.

John Christopher's "Tripods" trilogy has a twist on terraforming. Aliens have conquered the earth. They live in three domed cities located in Germany, China, and Panama where they breathe an atmosphere poisonous to earth life (probably containing chlorine). As the plot unfolds, the protagonist determines the aliens are awaiting the arrival of another ship from their home star containing the equipment for them to terraform (or alienscape) the earth. If this occurs, all earth life will be wiped out by the poisoned atmosphere. In M. Night Shyamalan's After Earth, the planet Nova Prime has been terraformed to be adaptable for human life as the Earth has lost all properties of being adjustable for humanity (e.g. violent thermal shifts)

In the video game Halo (2001), the main setting is an ancient ring-shaped structure whose radius is nearly that of Earth; the structure is terraformed to support an Earth-like ecosystem. The rings are created using Forerunner technology, and terraformed during their construction by an extra-galactic construct known as The Ark or Installation 00. Various works of fiction based on Halo also mention the terraforming of planets.[41]

Terraforming has also been explored on television and in feature films, including the "Genesis device", developed to quickly terraform barren planets, in the movie The Wrath of Khan. A similar device exists in the animated feature film Titan A.E. which depicts the eponymous ship Titan, capable of creating a planet. The word 'terraforming' was used in James Cameron's Aliens to describe the act of processing a planet's atmosphere through nuclear reactors over several decades in order to make it habitable. The 2000 movie Red Planet also uses the motif: after humanity faces heavy overpopulation and pollution on Earth, uncrewed space probes loaded with algae are sent to Mars with the aim of terraforming and creating a breathable atmosphere. The television series Firefly and its cinematic sequel Serenity (circa 2517) are set in a solar system with about seventy terraformed planets and moons. In the 2008 video game Spore, the player is able to terraform any planet by using either terraforming rays or a "Staff of Life" that completely terraforms the planet and fills it with creatures. Doctor Who episode "The Doctor's Daughter" also references terraforming, where a glass orb is broken to release gases which terraform the planet the characters are on at the time. One crew member in Ridley Scott's 2012 Prometheus bets another that the purpose of their visit is terraforming.

The concept of changing a planet for habitation precedes the use of the word 'terraforming', with H. G. Wells describing a reverse-terraforming, where aliens in his story The War of the Worlds change Earth for their own benefit. Olaf Stapledon's Last and First Men (1930) provides the first example in fiction in which Venus is modified, after a long and destructive war with the original inhabitants, who naturally object to the process. The word itself was coined in fiction by Jack Williamson, but features in many other stories of the 1950s & 60s, such Poul Anderson's The Big Rain, and James Blish's "Pantropy" stories. Recent works involving terraforming of Mars include the Mars trilogy by Kim Stanley Robinson and The Platform by James Garvey. In Isaac Asimov's Robot Series, fifty planets have been colonized and terraformed by the powerful race of humans called Spacers, and when Earth is allowed to attempt colonization once more, the Settlers begin the process of terraforming their new worlds immediately. After twenty thousand years in the future, all the habitable planets in the galaxy have been terraformed and form the basis of the Galactic Empire in Asimov's Foundation Series. In the Star Wars series, the planet Manaan uses a paraterraforming-like infrastructure, with all buildings being built above the water as the habitable land of the planet. There is no natural land on the planet. In the Star Wars Expanded Universe, the planet Taris is restored to its former state after a Sith bombardment through aggressive terraforming.

Terraforming is a common concept in science fiction, ranging from television, movies and novels to video games.

In popular culture

National pride, rivalries between nations, and the politics of public relations have in the past been the primary motivations for shaping space projects.[39][40] It is reasonable to assume that these factors would also be present in planetary terraforming efforts.

Political issues

The initial cost of such projects as planetary terraforming would be gargantuan, and the infrastructure of such an enterprise would have to be built from scratch. Such technology is not yet developed, let alone financially feasible at the moment. John Hickman has pointed out that almost none of the current schemes for terraforming incorporate economic strategies, and most of their models and expectations seem highly optimistic.[38] Access to the vast resources of space may make such projects more economically feasible, though the initial investment required to enable easy access to space will likely be tremendous (see Asteroid mining, solar power satellites, In-Situ Resource Utilization, bootstrapping, space elevator).

Economic issues

The opposing argument posits that terraforming would be an unethical interference in nature, and that given humanity's past treatment of the Earth, other planets may be better off without human interference. Still others strike a middle ground, such as Christopher McKay, who argues that terraforming is ethically sound only once we have completely assured that an alien planet does not harbor life of its own; but that if it does, while we should not try to reshape the planet to our own use, we should engineer the planet's environment to artificially nurture the alien life and help it thrive and co-evolve, or even co-exist with humans.[37] Even this would be seen as a type of terraforming to the strictest of ecocentrists, who would say that all life has the right, in its home biosphere, to evolve without outside interference.

On the pro-terraforming side of the argument, there are those like Robert Zubrin, Martyn J. Fogg, Richard L. S. Taylor and the late Carl Sagan who believe that it is humanity's moral obligation to make other worlds suitable for life, as a continuation of the history of life transforming the environments around it on Earth.[35][36] They also point out that Earth would eventually be destroyed if nature takes its course, so that humanity faces a very long-term choice between terraforming other worlds or allowing all terrestrial life to become extinct. Terraforming totally barren planets, it is asserted, is not morally wrong as it does not affect any other life.

There is a philosophical debate within biology and ecology as to whether terraforming other worlds is an ethical endeavor. From the point of view of a cosmocentric ethic, this involves balancing the need for the preservation of human life against the intrinsic value of existing planetary ecologies.[34]

Ethical issues

It has the disadvantage of requiring massive amounts of construction and maintenance activity. It also would not likely have a completely independent water cycle, because although rainfall may be able to develop with a high enough roof, but probably not efficiently enough for agriculture or a water cycle. The extra cost might be off-set somewhat by automated manufacturing and repair mechanisms. A worldhouse might also be more susceptible to catastrophic failure if a major breach occurred, though this risk might be reduced by compartmentalization and other active safety precautions. Meteor strikes are a particular concern because without any external atmosphere they would reach the surface before burning up.

Paraterraforming has several advantages over the traditional approach to terraforming. For example, it provides an immediate payback to investors (assuming a capitalistic financing model). Although it starts out in a small area (a domed city for example), it quickly provides habitable space. The paraterraforming approach also allows for a modular approach that can be tailored to the needs of the planet's population, growing only as fast and only in those areas where it is required. Finally, paraterraforming greatly reduces the amount of atmosphere that one would need to add to planets like Mars to provide Earth-like atmospheric pressures. By using a solid envelope in this manner, even bodies which would otherwise be unable to retain an atmosphere at all (such as asteroids) could be given a habitable environment. The environment under an artificial worldhouse roof would also likely be more amenable to artificial manipulation. Paraterraforming is also less likely to cause harm to any native lifeforms that may hypothetically inhabit the planet, as the parts of the planet outside the enclosure will not normally be affected unlike terraforming which affects the entire planet.

Also known as the "worldhouse" concept, or domes in smaller versions, paraterraforming involves the construction of a habitable enclosure on a planet which eventually grows to encompass most of the planet's usable area.[30] The enclosure would consist of a transparent roof held one or more kilometers above the surface, pressurized with a breathable atmosphere, and anchored with tension towers and cables at regular intervals. Proponents claim worldhouses can be constructed with technology known since the 1960s. The Biosphere 2 project built a dome on Earth that contained a habitable environment. The project encountered difficulties in operation, including unexpected population explosions of some plants and animals,[31][32] and a lower than anticipated production of oxygen by plants, requiring extra oxygen to be pumped in.[33]

Paraterraforming

Other possible candidates for terraforming (possibly only partial or paraterraforming) include Titan, Callisto, Ganymede, the Moon, and even Mercury, Saturn's moon Enceladus and the dwarf planet Ceres. Most, however, have too little mass and gravity to hold an atmosphere indefinitely (although it may be possible, but it is not quite certain, that an atmosphere could remain for tens of thousands of years or be replenished as needed). In addition, aside from the Moon and Mercury, most of these worlds are so far from the Sun that adding sufficient heat would be much more difficult than it would be for Mars. Terraforming Mercury would present different challenges, but in certain aspects would be easier than terraforming Venus. Though not widely discussed, the possibility of terraforming Mercury's poles has been presented. Saturn's moon Titan offers several unique advantages, such as an atmospheric pressure similar to Earth and an abundance of nitrogen and frozen water. Jupiter's moons Europa, Ganymede, and Callisto also have an abundance of water ice.

Other bodies in the Solar System

Artist's conception of what the Moon might look like terraformed

Europa, a moon of Jupiter, is a potential candidate for terraforming. One advantage to Europa is the presence of liquid water which could be extremely helpful for the introduction of any form of life.[27] The difficulties are numerous; Europa is near a huge radiation belt around Jupiter.[28] This would require the building of radiation deflectors, which is currently impractical. Additionally, this satellite is covered in ice and would have to be heated, and there would need to be a supply of oxygen,[29] though this could, at sufficient energy cost, be manufactured locally by electrolysis of the copious water available.

Europa (moon)

Terraforming Venus requires two major changes; removing most of the planet's dense 9 MPa carbon dioxide atmosphere and reducing the planet's 450 °C (723.15 K) surface temperature. These goals are closely interrelated, since Venus' extreme temperature is thought to be due to the greenhouse effect caused by its dense atmosphere. Sequestering the atmospheric carbon would likely solve the temperature problem as well.

Venus

Artist's conception of a terraformed Venus

Terraforming Mars would entail two major interlaced changes: building the atmosphere and heating it.[25] A thicker atmosphere of greenhouse gases such as carbon dioxide would trap incoming solar radiation. Because the raised temperature would add greenhouse gases to the atmosphere, the two processes would augment each other.[26]

Finally, between approximately 4.1 and 3.8 billion years ago, [24]

The joined fields wrapped themselves around a packet of gas at the top of the Martian atmosphere, forming a magnetic capsule a thousand kilometres wide with ionised air trapped inside... Solar wind pressure caused the capsule to 'pinch off' and it blew away, taking its cargo of air with it.[23]

Second, the lack of a [19] Convection within the core of Mars, which is made mostly of iron,[20] originally generated a magnetic field. However the dynamo ceased to function long ago,[21] and the magnetic field of Mars has largely disappeared, probably due to "... loss of core heat, solidification of most of the core, and/or changes in the mantle convection regime."[22] Mars does still retain a limited magnetosphere that covers approximately 40% of its surface. Rather than uniformly covering and protecting the atmosphere from solar wind, however, the magnetic field takes the form of a collection of smaller, umbrella-shaped fields, mainly clustered together around the planet's southern hemisphere.[23] It is within these regions that chunks of atmosphere are violently "blown away", as astronomer David Brain explains:

The exact mechanism of this loss is still unclear, though three mechanisms in particular seem likely: First, whenever surface water is present, carbon dioxide reacts with rocks to form [18]

In many respects, Mars is the most earthlike of all the other planets in our Solar system.[16] Indeed, it is thought that Mars once did have a more Earth-like environment early in its history, with a thicker atmosphere and abundant water that was lost over the course of hundreds of millions of years.[17]

Mars

Artist's conception of a terraformed Mars

Prospective planets

Once conditions become more suitable for life of the introduced species, the importation of microbial life could begin.[12] As conditions approach that of Earth, plant life could also be brought in. This would accelerate the production of oxygen, which theoretically would make the planet eventually able to support animal life.

Preliminary stages

In its astrobiology roadmap, [15]

An absolute requirement for life is an energy source, but the notion of planetary habitability implies that many other geophysical, geochemical, and astrophysical criteria must be met before the surface of an astronomical body is able to support life. Of particular interest is the set of factors that has sustained complex, multicellular animals in addition to simpler organisms on this planet. Research and theory in this regard is a component of planetary science and the emerging discipline of astrobiology.

Requirements for sustaining terrestrial life

Fogg suggests that Mars was a biologically compatible planet in its youth, but is not now in any of these three categories, since it could only be terraformed with greater difficulty. Mars Society founder Robert Zubrin produced a plan for a Mars return mission called Mars Direct that would set up a permanent human presence on Mars and steer efforts towards eventual terraformation.[14]

  • Habitable Planet (HP): A world with an environment sufficiently similar to the Earth as to allow comfortable and free human habitation.
  • Biocompatible Planet (BP): A planet possessing the necessary physical parameters for life to flourish on its surface. If initially lifeless, then such a world could host a biosphere of considerable complexity without the need for terraforming.
  • Easily Terraformable Planet (ETP): A planet that might be rendered biocompatible, or possibly habitable, and maintained so by modest planetary engineering techniques and with the limited resources of a starship or robot precursor mission.

Fogg also devised definitions for candidate planets of varying degrees of human compatibility:[13]

  • Planetary engineering: the application of technology for the purpose of influencing the global properties of a planet.
  • Geoengineering: planetary engineering applied specifically to the Earth. It includes only those macroengineering concepts that deal with the alteration of some global parameter, such as the greenhouse effect, atmospheric composition, insolation or impact flux.
  • Terraforming: a process of planetary engineering, specifically directed at enhancing the capacity of an extraterrestrial planetary environment to support life as we know it. The ultimate achievement in terraforming would be to create an open planetary biosphere emulating all the functions of the biosphere of the Earth, one that would be fully habitable for human beings.
  • Astrophysical engineering: taken to represent proposed activities, relating to future habitation, that are envisaged to occur on a scale greater than that of "conventional" planetary engineering.

Beginning in 1985, Martyn J. Fogg began publishing several articles on terraforming. He also served as editor for a full issue on terraforming for the Journal of the British Interplanetary Society in 1992. In his book Terraforming: Engineering Planetary Environments (1995), Fogg proposed the following definitions for different aspects related to terraforming:[12]

Aspects and definitions

Motivated by Lovelock's book, biophysicist Robert Haynes worked behind the scenes to promote terraforming, and contributed the neologism Ecopoiesis, forming the word from the Greek οἶκος, oikos, "house",[9] and ποίησις, poiesis, "production".[10] Ecopoiesis refers to the origin of an ecosystem. In the context of space exploration, Haynes describes ecopoiesis as the "fabrication of a sustainable ecosystem on a currently lifeless, sterile planet". Ecopoiesis is a type of planetary engineering and is one of the first stages of terraformation. This primary stage of ecosystem creation is usually restricted to the initial seeding of microbial life.[11] As conditions approach that of Earth, plant life could be brought in, and this will accelerate the production of oxygen, theoretically making the planet eventually able to support animal life.

(CFCs) are added to the atmosphere. chlorofluorocarbons Lovelock's book was one of the first to describe a novel method of warming Mars, where [8].The Greening of Mars and Michael Allaby published James Lovelock The paper discussed the prospects of a self-regulating Martian biosphere, and McKay's use of the word has since become the preferred term. In 1984, [7].Journal of the British Interplanetary Society used in the title of a published journal article. Planetologist Christopher McKay wrote "Terraforming Mars", a paper for the terraforming Not until 1982 was the word [6]

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.