地球化

维基百科，自由的百科全书

外星环境地球化(Terraforming),简称地球化,是设想中人为改变天体表面环境，使其气候、温度、生态类似地球环境的行星工程。有时候该词用来总指行星工程。地球化的观念根植在科幻小说和真实的科学中。创造这个词的可能是杰克·威廉森（Jack Williamson），在1942年发表在《Astounding Science Fiction》杂志上的一篇小说中^[1]。但地球化的具体设想则早于此。奥拉夫·斯蒂伯顿（Olaf Stapledon）1930年的《最后和最先的人》讲述了与反对地球化的金星原始居民展开长期战争的故事^[2]。

现在太空探索还处在萌芽阶段,很多地球化的计划还处在设想阶段。从我们对自己世界的了解来看，人为影响改变自然环境是可行的，虽然在另一个行星上建造不受自然控制的类地球生物圈的可行性还有待证明。很多人认为火星是最可行的地球化候选者。现在已有很多关于加热火星表面、改变其大气成分的研究，NASA甚至还主持了一个有关的辩论。然而，从现在到主动地球化火星等其他天体之间，还存在着很大差距。地球化所需要的长时间、以及其可能性还有待探讨。其他等待解决的问题包括伦理学, 物流管理, 经济, 政治方面的考虑，以及改变地球外世界环境的具体方法。

目录 1 学术研究历史 2 维持地球生命的要求 3 地球化的理论方法 3.1 建立大气层 3.2 转换大气成分 3.3 去除大气 3.4 小局域地球化 3.5 云顶殖民 3.6 增加热量 3.7 去除热量 3.8 建设辐射罩 3.9 行星自转速度 4 地球化的更远步骤 5 比较可行的地方 5.1 火星 5.2 金星 5.3 木卫二 5.4 其他可能的地方 6 伦理问题 7 经济问题 8 政治问题 9 通俗文化 10 参考资料 11 外在链接

[编辑] 学术研究历史

天文学家和科普作家卡尔·萨根1961年在科学杂志上发表了一篇名为《行星金星》的文章,建议对金星实行行星工程^[3]。 萨根设想在金星的大气中散布藻類来吸收二氧化碳，从而降低温室效应，直到表面温度降至“适宜”。30亿年前，地球的大气层也是以二氧化碳为主，后来由于藍綠藻和水分蒸发，才出现氢气和氧气的成分。后来的观测发现由于金星大气的质量太大，用藻类改变是不可能的。即使找到能在金星严酷干燥的外大气层生存的藻类，其从二氧化碳固定的有机物降落到高温的内大气层，又会被氧化成二氧化碳。

1973年，萨根又在《Icarus》杂志上发表文章名为《火星上的行星工程》，讨论把火星改造成宜于人类居住的可能性^[4] 三年后，NASA 的一个研究项目正式探讨了行星工程的问题，但用的称呼是“行星生态合成”（planet ecosynthesis)^[5]。结论是在改造火星，使其成为一个能维持生命的可居住行星方面，目前不存在已知的障碍。 同年，研究项目中的一位科学家Joel Levine组织了第一个关于地球化（当时称作“行星模拟”）的科学会议。

1979年三月, NASA 工程师、作家James Oberg在休斯敦的月球与行星科学会议上组织了第一次“地球化座谈会”。他在1981年把会议上提出的想法写成了一本通俗书籍《新地球》^[6]。1982年，行星学家Christopher McKay在《英国行星学会杂志》上发表了一篇题为《地球化火星》的文章，这是“地球化”这一名词首次被用于正式科学出版物中^[7]。该文章讨论了带有自行调节的火星生物圈。1984年，James Lovelock和Michael Allaby出版了一本题为《绿化火星》的书^[8]，首次提出了在火星大气中加入氟氯碳氢化合物以加热火星的方法。

从1985年以来，Martyn J. Fogg 发表了几篇关于地球化的文章，编辑了《英国行星学会杂志》1991年的的一期地球化专版，并于1995年写了一本书《地球化：行星的环境工程 》^[9]。他还有一个专门讨论地球化的网站地球化信息（英文）.

Fogg用下列术语来区分地球化的不同方面:

• 行星工程: 用科技来影响一个行星的整体特性。
• 地球工程: 特用于地球的行星工程，不过仅包括影响全球的过程，例如改变全球变暖、大气组成等。
• 地球化: 行星工程应用于改变地外行星的环境使其能够支持生命。其最终目的是制造一个自主运行，能模拟地球生物圈全部功能，完全适于人类居住的环境。
• 天体物理工程: 比行星工程范围更广阔的可居住性工程。

他还提出了下列区分人类居住性的分类：

• 可居住行星: 环境类似地球，能够支持人类舒适自由生存的行星环境。
• 生物可生存行星 : 行星表面的物理环境允许生物繁殖。如果这类行星本身没有生命，则可以通过引入生物改变环境而不需要地球化。
• 易地球化行星: 不需要大量星际飞船或机器人资源，通过小规模行星工程就可以变成生物可生存的行星。

Fogg认为火星早年是一个易地球化行星，但其现在的环境要地球化困难很大。然而，火星是地球附近最适宜于地球化的一个。火星协会创始人Robert Zubrin 曾制定了一个人类永久定居火星和最终地球化的计划。

地球化的主要目的是建立一个适合人类居住的生态环境。但有些研究人员声称，从经济角度考虑太空站是合适的太空殖民手段。当然，如果纳米技术和其他的化学技术继续快速发展，地球化的过程可能从需要几十个世纪加快到几个世纪。但反过来，也可以利用这些技术改变人体生理，使人们不需要依赖现在地球上的氧气/氮气大气成份和地球重力就能舒适生存。这些改变会减少地球化的需要或者使其变得容易。

[编辑] 维持地球生命的要求

其实维持生命只有一个最低的要求--能量来源。然而要使一个行星适合居住却有很多地理、地化学和天体物理方面的要求，特别是要允许复杂的多细胞而不只是单细胞生物生存的话。

[编辑] 地球化的理论方法

[编辑] 建立大气层

Since 氨 is a powerful greenhouse gas, and it is possible that nature has stockpiled large amounts of it in frozen form on asteroidal sized objects orbiting in the outer solar system, it may be possible to move these and send them into a planet's 大气. Since ammonia is NH₃ it would also take care of the problem involved in needing a buffer gas in the 大气. 将一个彗星撞击到行星表面 might cause destruction to the point of being counter-productive. Aerobraking, if an option, would allow a comet's frozen mass to outgas and become part of the 大气 through which it would travel. It may be better to impact several smaller asteroids into the planet, both to build up the planet mass and to add to the 大气. Keeping these smaller impacts on their own will eventually build up the temperature as well as mass to both the planet and its 大气. The need for a buffer gas is a challenge that will face any potential 大气 builders. On 地球, 氮气 is the primary atmospheric component making up 77% of the 大气. Some planets would require a similar buffer gas component although not necessarily as much. Still, obtaining significant quantities of 氮气, 氩 or some other non-volatile gas could prove difficult.

氢气 importation could also be done for atmospheric and 水圈 工程. 依赖着大气层里的二氧化碳, importation and reaction of 氢气将产生热能,水和石墨 via the Bosch reaction. Adding water and heat to the environment will be key to making the dry, cold world suitable for 地球 life. Alternatively, reacting 氢气 with the 二氧化碳 大气 via the Sabatier reaction would yield 甲烷 and water. The methane could be vented into the 大气 where it would act to compound the greenhouse effect. Presumably, 氢气 could be obtained in bulk from the gas giants or refined from 氢气-rich compounds in other outer solar system objects, though the energy required to transport large quantities would be great. Simply thickening the planets 大气 will not make it 可居住e for 地球 life unless it contains the proper mix of gases. Achieving a suitable mixture of buffer gas, 氧气, 二氧化碳, water vapor and trace gases will entail either direct processing of the 大气 or altering it by means of plant life and other organisms. Genetic 工程 would allow such organisms to process the 大气 more efficiently and survive in the otherwise hostile environment.

[编辑] 转换大气成分

A planet's 大气 could potentially be converted into some other form in situ by reacting it with externally supplied elements. For example, bombardment of 金星 with refined 镁 and 钙 metal from 水星 or some other source, could sequester 二氧化碳 in the form of calcium and magnesium carbonates. About 8×10²⁰ kg of calcium or 5×10²⁰ kg of magnesium would be required, which would entail a great deal of mining and mineral refining to obtain.^[10]

Bombardment with 氢气, possibly from some outer solar system source and reacting with 二氧化碳 could produce elemental carbon (石墨) and water by the Bosch reaction. It would take about considerable amounts of 氢气 to convert a planet's whole 大气. The amount of water produced would amount to around 10% of the water found on 地球.

A solar shade or equivalent would also be necessary, as water vapor is itself a greenhouse gas. Oceans would increase the planet's albedo and allow more incoming solar radiation to be reflected back into space. It would also be important to take into account water's capacity for absorbing CO₂ and O₂, and how much gas an ocean would hold. In addition to this planets need a significant percentage of a '缓冲气体' (meaning some inert gas, probably argon or 氮气) in its new 大气. 氮气 is present in the outer solar system in the form of NH₃ on comets and could be an important source of this gas.

A method proposed in 1961 by Carl Sagan involves the use of genetically engineered bacteria to fix carbon into organic forms.^[3] Although this method is still commonly proposed in discussions of 金星 地球化, later discoveries showed it would not be successful; organic carbon would be liberated into 二氧化碳 again by the hot surface environment. Though using the Bosch reaction to create more water would pave the way for microbes to survive in the 大气 which would lower the amount of 氢气 we would need to import.

[编辑] 去除大气

Removal of 大气 could be attempted by a variety of methods, possibly in combination. Directly lifting atmospheric gas into space would likely prove very difficult. For example, 金星 has sufficiently high escape velocity to make blasting it away with asteroid impacts impractical. Pollack and Sagan calculated in 1993 that an impactor of 700 km diameter striking 金星 at greater than 20 km/s, would eject all the 大气 above the horizon as seen from the point of impact, but since this is less than a thousandth of the total 大气 and there would be diminishing returns as the 大气's density decreased a very great number of such giant impactors would be required. Smaller objects would not work as well, requiring even more. The violence of the bombardment could well result in significant outgassing that replaces removed 大气. Furthermore, most of the ejected 大气 would go into solar orbit near 金星, eventually to fall right back onto 金星 again.

Removal of atmospheric gas in a more controlled manner could also prove difficult. A planet like 金星's extremely slow rotation means that space elevators would be impossible to construct, and the very 大气 to be removed makes mass drivers useless for removing payloads from the planet's surface. Possible workarounds include placing mass drivers on high-altitude balloons or balloon-supported towers extending above the bulk of the 大气, using space fountains, or rotovators. Such processes would take a great deal of technical sophistication and time, however, and may not be economically feasible without the use of extensive automation.

[编辑] 小局域地球化

Also known as the "worldhouse" concept, or domes in smaller versions, para地球化 involves the construction of a 可居住e enclosure on a planet which eventually grows to encompass most of the planet's usable area. The enclosure would consist of a transparent roof held one or more kilometers above the surface, pressurized with a breathable 大气, and anchored with tension towers and cables at regular intervals. Proponents claim worldhouses can be constructed with technology known since the 1960s.

Para地球化 has several advantages over the traditional approach to 地球化. For example, it provides an immediate payback to investors; the worldhouse starts out small in area (a domed city for example), but those areas provide 可居住e space from the start. The para地球化 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, para地球化 greatly reduces the amount of 大气 that one would need to add to planets like 火星 in order to provide 地球like atmospheric pressures. By using a solid envelope in this manner, even bodies which would otherwise be unable to retain an 大气 at all (such as asteroids) could be given a 可居住e environment. The environment under an artificial worldhouse roof would also likely be more amenable to artificial manipulation.

It has the disadvantage of requiring a great deal of construction and maintenance activity, the cost of which could be ameliorated to some degree through the use of automated manufacturing and repair mechanisms. A worldhouse could also be more susceptible to catastrophic failure in the event of a major breach, though this risk can likely be reduced by compartmentalization and other active safety precautions. Meteor strikes are a particular concern in the absence of any external 大气 in which they would burn up before reaching the surface.

[编辑] 云顶殖民

Geoffrey A. Landis proposes colonizing the cloud-tops of planets like 金星.^[11] Initially, the image of floating cities may seem fanciful, but Landis' proposal points out that a Terran breathable air mixture (21:79 氧气-氮气) is a lifting gas in the dense 金星ian 大气. In effect, a gasbag full of human-breathable air would sustain itself and extra weight (such as a colony) in midair. At an altitude of 50 kilometers above 金星ian surface, the environment is the most 地球like in the solar system - a pressure of approximately 1 bar and temperatures in the 0-50 Celsius range. Because there is not a significant pressure differential between the inside and the outside of the breathable-air balloon, any rips or tears would not result in an explosive decompression, but rather would only diffuse at normal atmospheric mixing rates, giving time to repair any such defects.

Such colonies could be constructed at any rate desired, allowing a dynamic approach instead of needing any 'fell swoop' solutions. They could be used to gradually transform the 大气, with their impact directly related to the number of colonies in the 大气. As the constructed colonies increased, more solar panels could be used to absorb insolation and thus cool 金星; they could also be used to grow plant matter that would reduce the amount of 二氧化碳 in the air. In the beginning, any impact would be insignificant, but as the number of colonies grew, they could transform 金星 more and more rapidly.

[编辑] 增加热量

將鋁化PET薄膜製成的反照鏡放置在環火星軌道上，增加火星的總體日照 ^[12] 與地表溫度，並蒸發水與乾冰以增強溫室效應。而直接把光反射到極冠上會使這個方法更有效。

生產、釋放鹵化碳亦可增厚大氣並加強吸收光照。鹵化碳（例如氟氯碳化合物（CFCs）和全氟化碳（PFCs））是很強的溫室氣體，且能在大氣中保持長時間的穩定。這些氣體可由基因改造的好氧菌^{[來源請求]}或是由遍佈火星表面的工廠製造。

改變地表反照率能使光照做更有效的利用。散佈於地表的黑塵、煤灰、暗色的微生物或地衣，能讓更多光照在被反射至太空前就被地表吸收轉為熱能。能運用生物是特別吸引人的，因為它能自我繁殖。

Nuclear bombardment of the crust and the polar caps has been suggested as a quick-and-dirty way of heating up the planet. If detonated on polar regions, the intense heat would melt vast quantities of water and frozen 二氧化碳. The gases produced would thicken the 大气 and contribute to the greenhouse effect. Additionally, the dust kicked up by a nuclear explosion would fall on the ice and decrease its albedo thus allowing it to melt faster under the sun’s rays. Detonation of 核武器s under the surface would heat the crust and help speed outgassing of trapped 二氧化碳. While using nuclear devices is attractive in the sense that it makes use of aging and dangerous 地球 weaponry and adds quick and cheap heat to the planet, it carries the ugly connotations of mass destruction to the native environment and potential harmful effects of nuclear fallout.

Another possibility to heat a planet's surface would be to place a microwave array, powered by solar cells, 核反应堆, or a combination of the two, into geosynchronous orbit.^{[來源請求]} Microwaves of approximately 2.45 GHz are used in 微波炉 to cause vibrations in water molecules and produce heat. If microwaves of this frequency with sufficient amplitude were focused onto the surface it would heat the ice crystals trapped in the soil. A long enough exposure to the microwaves would release the water into the 大气 and gradually heat the surface of the planet. Several such arrays could be placed in orbit and designed to gradually sweep the beam across vast areas. One drastic proposal for adding some heat to 火星, for example, is to brake the inner moon, Phobos, so that it crashes into the surface. Apart from the comparatively little heat generated by this, it removes an important danger for future settlements: A thickening 大气 would slow down Phobos so much that it would crash land within a few hundred years anyway. Thinking far into the future, some scientists point out that the 太阳 will eventually grow too hot for 地球 to sustain life, even before it becomes a 红巨星 star. All main sequence stars brighten slowly throughout their lifetimes. As a result, a planet like 火星 will warm up on its own, making 地球化 easier.

[编辑] 去除热量

Solar shades placed in the 太阳-金星 拉格朗日点 or in a more closely-orbiting ring could be used to reduce the total insolation received by 金星, 冷却 the planet somewhat. This does not directly deal with the immense atmospheric density of 金星, but could make it easier to do so by other methods. They could also serve double duty as solar power generators. Construction of a suitably large solar shade is a potentially daunting task. The sheer size of such a structure would necessitate construction in space. There would also be the difficulty of balancing a thin-film shade at the 太阳-金星 拉格朗日点 with the incoming radiation pressure which would tend to turn the shade into a huge 太阳帆. If the shade is left at the L1 point, the pressure would add too much force to the sunward side and necessitate moving the shade even closer to the sun then the L1 point. The size of the shade would be twice the diameter of 金星 itself if at the L1 point. But modifications do exist that can reduce this size and the location of the shade. If the shade's panels are not perpendicular to the sun's rays but instead at an angle of 30 degrees and then the light is reflected to the next panel outward which will be +/- 1 degree off the 30 degrees which then reflects the light back just 4 degrees from striking 金星. The photon pressure from this arrangement is very small. Another element necessary to bring the shade closer to 金星 and reduce its size is to use polar orbiting, sun-synchronous mirrors that reflects light from the non sunward side of 金星. Photon pressure would push the support mirrors to an angle of 30 degrees away from the sunward side. ^[13]

Other proposed 冷却 solutions involve 彗星s, or creating artificial rings. A comet at the 太阳-金星 拉格朗日点 could produce a coma which could provide at least temporary shade for the planet, possibly allowing enough time for atmospheric processing to be done. Keeping a continuously decaying comet in a stable position could prove to be a difficult feat. Rings created by putting debris in orbit would provide some shade but to a lesser extent. The inclination of the rings would also need to be such that they present a significant amount of surface area to the 太阳. Space-based solar shade techniques are largely speculative due to the fact that they are beyond our current technological grasp. The vast sizes require material strengths and construction methods that have not even reached their infancy.

冷却 could be sustained by placing reflectors in the 大气 or on the surface. Reflective balloons floating in the upper 大气 could create shade. The number and/or size of the balloons would necessarily be great. Increasing the planet's albedo by deploying light color or reflective material on the surface could help keep the 大气 cool. The amount would be large and would have to be put in place after the 大气 had been modified already since 金星's surface is currently completely shrouded by clouds. The advantage of atmospheric and surface 冷却 solutions is that they take advantage of existing technology.^{[來源請求]}

[编辑] 建设辐射罩

Another significant, and probably most over-looked aspect of 地球化火星, would be the lack of a magnetosphere. The magnetosphere deflects most of the hard particulate radiation from the 太阳风. Without some form of radiation protection anyone on 火星 would have prolonged exposure to an unhealthy amount of radiation every time a serious solar eruption occurred. 地球化 involves making life viable on another world, and so long as that life is going to be exposed to high levels of radiation it will not be desirable. The lack of a magnetosphere is also thought to have caused the 火星 大气 to become as thin as it is in the first place, the 太阳风 adding a significant amount of heating to the 大气's top layers which enables the atmospheric particles to reach escape velocity and leave 火星 (essentially "blowing" the 大气 away, though that particular word would be inaccurate in this case). Indeed, this effect has even been detected by 火星-orbiting probes. 金星, however, shows that the lack of a magnetosphere does not preclude an 大气. A thick 大气 will also provide radiation protection for the surface, as it does at 地球's polar regions where aurorae form, so in the short term the lack of a magnetosphere would not seriously impact the habitability of a terraformed 火星.

On a longer timescale, and with the technology of the future (in perhaps 25-50 years), an artificial magnetosphere seems possible: If the energy of several large fusion-power-stations is used to power large superconducting magnets - the field should be strong enough to protect at least local settlements. However, recent scientific evidence suggest that just a thick enough 大气 like 地球's is enough to create a magnetic shielding in an absence of a magnetosphere. In the past, 地球 regularly had periods where the magnetosphere changed direction and collapsed for some time. Scientists believe that in the ionosphere, a magnetic shielding was created almost instantly after the magnetosphere collapsed.^[14] A principle that applies to 金星 as well and would also be the case in every other planet or moon with a large enough 大气. 金星 also lacks a magnetic field. It is thought that this may have contributed greatly to its current unin可居住e state, as the upper 大气 is exposed to direct erosion by solar wind and has lost most of its original 氢气 to space. However, this process is extremely slow, and so is unlikely to be significant on the timescale of any civilization capable of 地球化 the planet in the first place.

[编辑] 行星自转速度

金星's extremely slow rotation rate would result in extremely long days and nights, which could prove difficult for most 地球 life to adapt to. Speeding up 金星's rotation would require many orders of magnitude greater amounts of energy than removing its 大气 would, and so is likely to be infeasible (at least by any current technology). Instead, a system of orbiting solar mirrors might be used to provide sunlight to the night side of 金星. Alternately, instead of requiring that 金星 support life identical to 地球's, 地球 life could instead be modified to adapt to the long 金星ian day and night. However, 金星ian cloud-top colonies can have the ability of having a faster period, even down to 24 days, by using anti-corrosive wind sails to propel it around the planet instead of depending on the planet's rotation or appendages.^{[來源請求]}

[编辑] 地球化的更远步骤

Once conditions become more suitable to life from 地球, the importation of microbial life could begin.^[15] As conditions approach that of 地球, plant life could also be brought in. This would accelerate the production of 氧气, which theoretically would make the planet eventually able to support animal and human life.

[编辑] 比较可行的地方

[编辑] 火星

There is some scientific debate over whether it would even be possible to terraform 火星, or how stable its climate would be once terraformed. It is possible that over geological timescales - tens or hundreds of millions of years—火星 could lose its water and 大气 again, possibly to the same processes that reduced it to its current state. Indeed, it is thought that 火星 once did have a relatively 地球like environment early in its history, with a thicker 大气 and abundant water that was lost over the course of hundreds of millions of years. The exact mechanism of this loss is still unclear, though several mechanisms have been proposed. The lack of a magnetosphere surrounding 火星 may have allowed the solar wind to erode the 大气, the relatively low gravity of 火星 helping to accelerate the loss of lighter gases to space. The lack of plate tectonics on 火星 is another possibility, preventing the recycling of gases locked up in sediments back into the 大气. The lack of magnetic field and geologic activity may both be a result of 火星's smaller size allowing its interior to cool more quickly than 地球's, though the details of such processes are still unrealised. However, none of these processes are likely to be significant over the typical lifespan of most animal species, or even on the timescale of human civilization, and the slow loss of 大气 could possibly be counteracted with ongoing low-level artificial 地球化 activities. 地球化 火星 would entail two major interlaced changes: building the 大气 and heating it. Since a thicker 大气 of 二氧化碳 and/or some other greenhouse gases would trap incoming solar radiation the two processes would augment one another.

[编辑] 金星

将金星地球化需要两个重要的变化：去除大部分大气中的二氧化碳和降低金星的500摄氏度高温。这些变化都是非常相关的，因为金星的超高温是因為温室效应所造成的，而温室效应是被大量的二氧化碳造成的。^{[來源請求]}

[编辑] 木卫二

木卫二, 也叫欧罗巴木星的一个卫星，是一个地球化的潜在候选人。木卫二的一个优点是液态水，因为液态水对引进复杂的生命是非常有帮助的。^[16]. 但是将木卫二地球化困难重重。木卫二在木星的辐射带的正中。在其表面上的人类会在10分钟之内死亡。这就需要建大的反辐射装置（现在来说是不切实际的）。再说，这个卫星被厚厚的冰层覆盖，要加热的话就需要充足的氧气。 ^[17]

[编辑] 其他可能的地方

其他可能的候选人包括泰坦（土星的卫星），水星，木卫三，木卫一，木卫四， 和月亮, 甚至一些大的小行星，像谷神星。但是大多数都没有足够的质量来保持大气层。 这样的大气层不一定会保持几万年。再说，除去月亮，大多数都离太阳非常远，加上足够的热量甚至比火星还要难。^{[來源請求]}

[编辑] 伦理问题

There is a philosophical debate within biology and ecology as to whether 地球化 other worlds is an ethical endeavor. On the pro-地球化 side of the argument, there are those like Robert Zubrin, Martyn J. Fogg, and Richard L. S. Taylor 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. ^[18][19] 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 地球化 other worlds or allowing all Earth life to become extinct. Some more cautious thinkers believe 地球化 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 地球化 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 工程师the planet's environment to artificially nurture the alien life and help it thrive. ^[20]

[编辑] 经济问题

把行星地球化的工程需要庞大的花销， and the infrastructure of such an enterprise would have to be built from scratch. Such technology is not even possible at the moment, let alone financially possible, and people like John Hickman point out almost none of the current schemes for 地球化 incorporate economic strategies, and most of their models and expectations are highly optimistic. ^[21]

[编辑] 政治问题

There are many potential issues arising from 地球化 a planet, such as who gets to own the extra terrestrial land on the new planet, with contenders being national governments, trans-national organizations like the United Nations and private owners such as companies and citizens. Such settlements may become part of national disputes as countries try to make parts of other planets national territory. Another issue would be the stationing of weapons on other worlds, giving a distinct military advantage to those who put their weapons there. Even a more substantial scientific presence than another country has been threatening in the early 21st century, perhaps giving a preview of the controversy more critical disparities will produce.^[22] Further terraformation beyond early phases could also provoke controversy. For example, if a paraterraformed colony is set up, it may become hard for the rest of the planet to be terraformed with human settlements already present, or may even provoke their opposition. ^{[來源請求]}

[编辑] 通俗文化

地球化是一個共同的概念在科幻, 範圍從電視、電影、電子遊戲及動漫畫。改變一個行星的概念為居住實際上在概念之前地球化, with 赫伯特·乔治·威尔斯 alluding to xeno-地球化, where aliens in his story '《星际战争]]》change Earth for their own benefit. It is revealed in an interview that the aliens in the new game Crysis will also xeno-terraform the Earth into an icy environment. Also, Olaf Stapledon's Last and First Men (1930) provides the first example in fiction in which 金星 is modified, after a long and destructive war with the original inhabitants, who naturally object to the process.

地球化 has also been explored on television and in feature films, most prominently and famously in the 星艦奇航記 universe, in which, during the 22nd century, humanity has started 地球化 火星. In the series, part of this process involved diverting comets so that they would strike 火星 in predetermined places, helping release water and 氧气 into the 大气, and by 2154 the process had gotten far enough along that pressure suits were no longer required - just 氧气 masks to help compensate for the still thin 大气 and cold weather garments were all that was needed by then. A century later the process had been completed. In the Star Trek movie The Wrath of Khan, Khan, the former dictator of most of Asia during the Eugenic Wars of the late 1990's, comes forward in time and obtains the "Genesis Process", a nanotechnology-like process to quickly terraform barren planets like 火星, and wields it as a weapon, threatening to use it against already populated planets in order to conquer the Galaxy.

[编辑] 参考资料

[编辑] 外在链接

• Red Colony
• Visualizing the steps of solar system terraforming
• Research Paper: Technological Requirements for Terraforming Mars
• An approach to terraforming Venus
• The Terraforming Information Pages
• The Terraforming of Worlds