Terraforming
[1] The term was coined by Jack Williamson in a science-fiction short story ("Collision Orbit") published in 1942 in Astounding Science Fiction.
As the subject has gained traction, research has expanded to other possibilities including biological terraforming, para-terraforming, and modifying humans to better suit the environments of planets and moons.
Despite this, questions still remain in areas relating to the ethics, logistics, economics, politics, and methodology of altering the environment of an extraterrestrial world, presenting issues to the implementation of the concept.
In March 1979, NASA engineer and author James Oberg organized the First Terraforming Colloquium, a special session at the Lunar and Planetary Science Conference in Houston.
[9] Lovelock's book was one of the first to describe a novel method of warming Mars, where chlorofluorocarbons (CFCs) are added to the atmosphere to produce a strong greenhouse effect.
Motivated by Lovelock's book, biophysicist Robert Haynes worked behind the scenes[citation needed] to promote terraforming, and contributed the neologism Ecopoiesis,[10] forming the word from the Greek οἶκος, oikos, "house",[11] and ποίησις, poiesis, "production".
In the context of space exploration, Haynes describes ecopoiesis as the "fabrication of a sustainable ecosystem on a currently lifeless, sterile planet".
[13] A 2019 opinion piece by Lopez, Peixoto and Rosado has reintroduced microbiology as a necessary component of any possible colonization strategy based on the principles of microbial symbiosis and their beneficial ecosystem services.
Of particular interest in the context of terraforming is the set of factors that have sustained complex, multicellular animals in addition to simpler organisms on Earth.
In its astrobiology roadmap, NASA has defined the principal habitability criteria as "extended regions of liquid water, conditions favorable for the assembly of complex organic molecules, and energy sources to sustain metabolism.
"[21] The general temperature range for all life on Earth is -20 °C to 122 °C,[18] set primarily by the ability of water (possibly saline, or under high pressure in the ocean bottom) to be available in liquid form.
The "Habitable Zone" of a solar system is generally defined as the region in which stable surface liquid water may be present on a planetary body.
On Earth, life generally requires six elements in high abundance: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.
[30][31] It is thought that Mars once had 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.
On Earth, this process is counteracted when plate tectonics works to cause volcanic eruptions that vent carbon dioxide back to the atmosphere.
[38] Finally, between approximately 4.1 and 3.8 billion years ago, asteroid impacts during the Late Heavy Bombardment caused significant changes to the surface environment of objects in the Solar System.
[41] Carbon dioxide alone would not suffice to sustain a temperature above the freezing point of water, so a mixture of specialized greenhouse molecules might be manufactured.
At an oxygen pressure of 0.2-0.3 bar, the atmosphere would be breathable and nitrogen may be added as required to allow for plant growth in the presence of nitrates.
In order to achieve this, multiple approaches have been proposed, such as the management of solar radiation, the sequestration of carbon dioxide, and the design and release of climate altering genetically engineered organisms.
In reality, Ceres' surface is "a layer of mixed ice, silicates and light strong phases best matched by hydrated salts and clathrates".
[60][61] As synthetic biology matures over the coming decades it may become possible to build designer organisms from scratch that directly manufacture desired products efficiently.
[62] Lisa Nip, Ph.D. candidate at the MIT Media Lab's Molecular Machines group, said that by synthetic biology, scientists could genetically engineer humans, plants and bacteria to create Earth-like conditions on another planet.
[63][64] Gary King, microbiologist at Louisiana State University studying the most extreme organisms on Earth, notes that "synthetic biology has given us a remarkable toolkit that can be used to manufacture new kinds of organisms specially suited for the systems we want to plan for" and outlines the prospects for terraforming, saying "we'll want to investigate our chosen microbes, find the genes that code for the survival and terraforming properties that we want (like radiation and drought resistance), and then use that knowledge to genetically engineer specifically Martian-designed microbes".
He sees the project's biggest bottleneck in the ability to genetically tweak and tailor the right microbes, estimating that this hurdle could take "a decade or more" to be solved.
[70] 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.
[71] It has also been suggested that instead of or in addition to terraforming a hostile environment humans might adapt to these places by the use of genetic engineering, biotechnology and cybernetic enhancements.
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.
[79][80] 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.
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.
[83] A related concept from science fiction is xenoforming – a process in which aliens change the Earth or other planets to suit their own needs, already suggested in the classic The War of the Worlds (1898) of H.G.
