The New Private Space Race

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Prospective planets



Mars

In many respects, MarsMarsMars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
is the most earthlike of all the other planets in our Solar system. 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.

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 carbonateCarbonateIn chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group O=C2....
s, thus drawing atmosphere off and binding it to the planetary surface. On Earth, this process is counteracted when plate tectonicsPlate tectonicsPlate tectonics is a scientific theory which describes the large scale motions of Earth's lithosphere...
works to cause volcanic eruptions that vent carbon dioxide back to the atmosphere. On Mars, the lack of such tectonic activity worked to prevent the recycling of gases locked up in sediments.

Second, the lack of a magnetosphereMagnetosphereA magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...
surrounding the entire surface of Mars may have allowed the solar windSolar windThe solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 10 and 100 eV. The stream of particles varies in temperature and speed over time...
to gradually erode the atmosphere. ConvectionConvectionConvection is the movement of molecules within fluids . It cannot take place in solids, since neither bulk current flows or significant diffusion can take place in solids....
within the core of Mars, which is made mostly of ironIronIron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. Like other group 8 elements, it exists in a wide range of oxidation states. Iron and iron alloys are by far the most common metals and the most common ferromagnetic materials in...
, originally generated a magnetic fieldMagnetic fieldA magnetic field is a field of force produced by a magnetic object or particle, or by a changing electrical field and is detected by the force it exerts on other magnetic materials and moving electric charges...
. However the dynamo ceased to function long ago, 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." Mars does still retain a limited magnetosphereMagnetosphereA magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...
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. It is within these regions that chunks of atmosphere are violently "blown away", as astronomer David Brain explains:

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.


Finally, between approximately 4.1 and 3.8 billion years ago, asteroidAsteroidthumb|260px|right|[[253 Mathilde]], a [[C-type asteroid]] measuring about across. Photograph taken in 1997 by the [[NEAR Shoemaker]] probe.Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are...
impacts during the Late Heavy BombardmentLate Heavy BombardmentThe Late Heavy Bombardment is a period of time approximately 4.1 to 3.8 billion years ago during which a large number of impact craters are believed to have formed on the Moon, and by inference on Earth, Mercury, Venus, and Mars as well...
caused significant changes to the surface environment of objects in our Solar system. The low gravity of Mars suggests that these impacts could have ejected much of the Martian atmosphere into deep space.

Terraforming Mars would entail two major interlaced changes: building the atmosphere and heating it. A thicker atmosphere of greenhouse gases such as carbon dioxideCarbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
would trap incoming solar radiation. Because the raised temperature would add greenhouse gases to the atmosphere, the two processes would augment each other.



Venus

Terraforming VenusVenusVenus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of -4.6, bright enough to cast shadows...
requires two major changes; removing most of the planet's dense 9 MPaPascal (unit)The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength. It is a measure of force per unit area, defined as one newton per square metre...
carbon dioxide atmosphere and reducing the planet's 450 °C (723.15 KKelvinThe kelvin is a unit increment of temperature and is one of the seven SI base units. The Kelvin scale is a thermodynamic temperature scale referenced to absolute zero, the theoretical absence of all thermal energy. So by definition, the temperature of a substance at absolute zero is zero kelvin...
) surface temperature. These goals are closely interrelated, since Venus' extreme temperature is thought to be due to the greenhouse effectGreenhouse effectThe greenhouse effect is a process by which radiative energy leaving a planetary surface is absorbed by some atmospheric gases, called greenhouse gases. They transfer this energy to other components of the atmosphere, and it is re-radiated in all directions, including back down towards the surface...
caused by its dense atmosphere. Sequestering the atmospheric carbon would likely solve the temperature problem as well.



Europa (moon)

EuropaEuropa (moon)Europa is the sixth moon of the planet Jupiter, and the smallest of its four Galilean satellites. Europa was discovered in 1610 by Galileo Galilei , and named after a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the queen of Crete.Roughly the size of Earth's Moon,...
, a moon of JupiterJupiterJupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with a mass slightly less than one-thousandth of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along...
, is a potential candidate for terraforming. One advantage to Europa is the presence of liquid waterWaterWater is a chemical substance with the chemical formula H2O. Its molecule contains one oxygen and to hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state, water vapor or...
which could be extremely helpful for the introduction of any form of life. The difficulties are numerous; Europa is in the middle of a huge radiation belt around Jupiter, and a human would die from the radiation within ten minutes on the surface. This would require the building of massive 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, though this could, at sufficient energy cost, be manufactured locally by electrolysisElectrolysisIn chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...
of the copious water available.

Other planets and solar system entities

Other possible candidates for terraforming (possibly only partial or paraterraforming) include TitanTitan (moon)Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere,...
, CallistoCallisto (moon)Callisto is a moon of the planet Jupiter, . It was discovered in 1610 by Galileo Galilei. It is the third-largest moon in the Solar System and the second largest in the Jovian system, after Ganymede. Callisto has about 99% the diameter of the planet Mercury but only about a third of its mass...
, GanymedeGanymede (moon)Ganymede is a satellite of Jupiter and the largest satellite in the Solar System. It is the seventh moon and third Galilean satellite outward from Jupiter. Completing an orbit in roughly seven days, Ganymede participates in a 1:2:4 orbital resonance with the moons Europa and Io, respectively...
, Luna (the Moon), and even MercuryMercury (planet)Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about the axis for every two orbits...
, Saturn's moon EnceladusEnceladus (moon)Enceladus is the sixth-largest moon of Saturn. It was discovered in 1789 by William Herschel. Until the two Voyager spacecraft passed near it in the early 1980s, very little was known about this small moon besides the identification of water ice on its surface...
and the dwarf planet Ceres. Most, however, have too little mass and gravity to hold an atmosphere indefinitely (although it is possible, but not 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 SunSunThe Sun is the star at the center of the Solar System. It has a diameter of about , about 109 times that of Earth, and its mass accounts for about 99.86% of the total mass of the Solar System....
that adding sufficient heat would be much more difficult than even MarsMarsMars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
would be. Terraforming Mercury would present a different series of 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 as a potential possibility. Saturn's Titan offers several unique advantages, such as an atmospheric pressure similar to Earth and an abundance of nitrogen and frozen water. Jupiter's Europa, Ganymede and Callisto also have an abundance of water ice.

Paraterraforming

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. 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 2Biosphere 2Biosphere 2 is a structure originally built to be an artificial, materially-closed ecological system in Oracle, Arizona by Space Biosphere Ventures, a joint venture whose principal officers were John P. Allen, inventor and Executive Director, and Margret Augustine, CEO. Constructed between 1987...
project built a dome on Earth that contained a habitable environment. The project encountered difficulties in construction and operation.

Paraterraforming has several advantages over the traditional approach to terraforming. For example, it provides an immediate payback to investors (assuming a capitalistic financing model); the worldhouse starts out small in area (a domed cityDomed cityA domed city is a kind of theoretical or fictional structure that encloses a large urban area under a single roof. In most descriptions, the dome is airtight and pressurized, creating a habitat that can be controlled for air temperature and quality...
for example), but those areas provide habitable space from the start. 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 asteroidAsteroidthumb|260px|right|[[253 Mathilde]], a [[C-type asteroid]] measuring about across. Photograph taken in 1997 by the [[NEAR Shoemaker]] probe.Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, especially in the inner Solar System; they are...
s) could be given a habitable environment. The environment under an artificial worldhouse roof would also likely be more amenable to artificial manipulation.

It has the disadvantage of requiring massive amounts of construction and maintenance activity. It also would not likely have a completely independent water cycle, as rainfall may be able to develop with a high enough roof, but still 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. MeteorMETEORMETEOR is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision...
strikes are a particular concern because without any external atmosphere they would reach the surface before burning up.

Ethical issues

There is a philosophical debate within biologyBiologyBiology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy....
and ecologyEcologyEcology is the scientific study of the distributions, abundance, and relations of organisms and their interactions with each other in a common environment. The word ecology is also used in the medical field which has a somewhat different meaning. The definition here applies to the study of Nature...
as to whether terraforming other worlds is an ethicalEthicsEthics is a branch of philosophy that addresses questions about morality—that is, concepts such as good and bad, noble and ignoble, right and wrong, justice, and virtue.Major branches of ethics include:...
endeavor. From the point of view of a cosmocentric ethicCosmocentric ethicA Cosmocentric ethic maintains that the natural state of our universe should be preserved, without human attempts to terraform planets for human habitation...
, this involves balancing the need for the preservation of human life against the intrinsic value of existing planetary ecologies. On the pro-terraforming side of the argument, there are those like Robert ZubrinRobert ZubrinRobert Zubrin is an American aerospace engineer and author, best known for his advocacy of manned Mars exploration. He was the driving force behind Mars Direct—a proposal intended to produce significant reductions in the cost and complexity of such a mission...
, Martyn J. FoggMartyn J. Fogg-Biography:After becoming a dental surgeon, Fogg earned a degree in physics and geology and a master's degree in astrophysics, and is working on a Ph.D. in planetary science. Fogg lives in London.-Contributions to Planetary Engineering:...
, Richard L. S. TaylorRichard L. S. TaylorRichard Lionel Sidney Taylor is the author of "Moon Maps", and a leading supporter of terraforming other planets....
and the late Carl SaganCarl SaganCarl Edward Sagan was an American astronomer, astrophysicist, author, cosmologist, and highly successful popularizer of astronomy, astrophysics and other natural sciences. During his lifetime, he published more than 600 scientific papers and popular articles and was author, co-author, or editor of...
who believe that it is humanity's moral obligation to make other worlds suitable for lifeLifeLife is a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not,...
, as a continuation of the history of life transforming the environments around it on Earth. 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 extinctExtinctionIn biology and ecology, extinction is the end of an organism or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species...
. Terraforming totally barren planets, it is asserted, is not morally wrong as it does not affect any other life.

Others believe terraforming would be an unethical interference in natureNatureNature most commonly refers to the "natural environment", the Earth's environment or wilderness—including geology, forests, oceans, rivers, beaches, the atmosphere, life, and in general geographic areas that have not been substantially altered by humans, or which persist despite human intervention...
, 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 McKayChristopher McKayChristopher P. McKay is a planetary scientist at NASA Ames Research Center, studying planetary atmospheres, astrobiology, and terraforming. McKay received his PhD in astrogeophysics from the University of Colorado in 1982 and his bachelor's degree from Florida Atlantic University.-Overview: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 lifeExtraterrestrial lifeExtraterrestrial life is defined as life that does not originate from Earth. It is unknown whether any such life exists or ever existed in the past, although many scientists think it likely that on Mars, for instance, life either exists or has existed...
and help it thrive and co-evolve, or even co-exist with humans. Even this would be seen as a type of terraforming to the strictest of ecocentrists, whom would say that all life has the right, in its home biosphere, to evolve at its own pace as well as its own direction, free of any outside interference, apparently even when it lacks volition of its own, for evolution is not a personally directed process in non-sapient species.

Economic 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 technologyTechnologyTechnology is a term referring to whatever can be said at any particular historical period, concerning the state of the art in the whole general field of practical know-how and tool use. It therefore encompasses all that can be said about arts, crafts, professions, applied sciences, and skills...
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. 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 miningAsteroid miningAsteroid mining refers to the possibility of exploiting raw materials from asteroids and planetoids in space, especially near-Earth objects. Minerals and volatiles could be mined from an asteroid or spent comet to provide space construction material , to extract water and oxygen to sustain the...
, solar power satellites, In-Situ Resource UtilizationIn-Situ Resource UtilizationIn space exploration, in-situ resource utilization describes the proposed use of resources found or manufactured on other astronomical objects to further the goals of a space mission....
, bootstrappingBootstrappingBootstrapping or booting refers to a group of metaphors that share a common meaning: a self-sustaining process that proceeds without external help...
, space elevatorSpace elevatorA space elevator is a proposed structure designed to transport material from a celestial body's surface into space. Many variants have been suggested, all of which involve travelling along a fixed structure instead of using rocket powered space launch...
).

Political issues


There are many potential political issues arising from terraforming a planet, such as who gets to own the extraterrestrial land on the new planet, with contenders being national governments, trans-national organizations like the United NationsUnited NationsThe United Nations Organization or simply United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and the achieving of world peace...
, corporations or individual settlers themselves. Such settlements may become national disputes as countries try to make portions of other planets part of their own national territory. National pride, rivalries between nations, and the politics of public relationsPublic relationsPublic Relations is a field concerned with maintaining public image for high-profile people, commercial businesses and organizations, non-profit associations or programs...
have been a primary motivation for shaping space projects.

In popular culture


Terraforming is a common concept in science fictionScience fictionScience fiction is a genre of fiction. It differs from fantasy in that, within the context of the story, its imaginary elements are largely possible within scientifically established or scientifically postulated laws of nature...
, ranging from televisionTelevisionTelevision is a widely used telecommunication medium for transmitting and receiving moving images, either monochromatic or color, usually accompanied by sound. "Television" may also refer specifically to a television set, television programming or television transmission...
, movies and novels to video games. The concept of changing a planet for habitation precedes the use of the word 'terraforming', with H. G. WellsH. G. WellsHerbert George Wells was an English author, now best known for his work in the science fiction genre. He was also a prolific writer in many other genres, including contemporary novels, history, politics and social commentary...
describing a reverse-terraforming, where aliens in his story The War of the Worlds change Earth for their own benefit. Also, Olaf StapledonOlaf StapledonWilliam Olaf Stapledon was a British philosopher and author of several influential works of science fiction.-Life:...
's Last and First MenLast and First MenLast and First Men: A Story of the Near and Far Future is a science fiction novel written in 1930 by the British author Olaf Stapledon. A work of unprecedented scale in the genre, it describes the history of humanity from the present onwards across two billion years and eighteen distinct human...
(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 WilliamsonJack WilliamsonJohn Stewart Williamson , who wrote as Jack Williamson was a U.S. writer often referred to as the "Dean of Science Fiction" following the death in 1988 of Robert A...
, but features in many other stories of the 1950s & 60s, such Poul AndersonPoul AndersonPoul William Anderson was an American science fiction author who wrote during a Golden Age of the genre. Anderson also authored several works of fantasy....
's The Big Rain, and James BlishJames BlishJames Benjamin Blish was an American author of fantasy and science fiction. Blish also wrote literary criticism of science fiction using the pen-name William Atheling Jr.-Biography:...
's "Pantropy" stories. Recent works involving terraforming of Mars includes the novels in the Mars trilogyMars trilogyThe Mars trilogy is a series of award-winning science fiction novels by Kim Stanley Robinson that chronicle the settlement and terraforming of the planet Mars through the intensely personal and detailed viewpoints of a wide variety of characters spanning almost two centuries...
, by Kim Stanley RobinsonKim Stanley RobinsonKim Stanley Robinson is an American science fiction writer known for his award-winning Mars trilogy. His work delves into ecological and sociological themes regularly, and many of his novels appear to be the direct result of his own scientific fascinations, such as the fifteen years of research...
.

Terraforming has also been explored on television and in feature films, including the "Genesis device", a device developed to quickly terraform barren planets in the Star TrekStar TrekStar Trek is an American science fiction entertainment franchise.The original Star Trek is an American television series, created by Gene Roddenberry, which debuted in 1966 and ran for three seasons, following the interstellar adventures of Captain James T...
movie The Wrath of Khan. A similar device exists in the animated feature film Titan A.E.Titan A.E.Titan A.E. is a 2000 American animated post-apocalyptic/dystopian science fiction adventure film directed by Don Bluth and Gary Goldman. The title refers to the spacecraft that is central to the plot, with A.E. meaning "After Earth."...
which depicts the eponymous ship Titan, capable of creating a planetPlanetA planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
. The solar system that is the setting for the Firefly television seriesFirefly (TV series)Firefly is an American space western television series created by writer and director Joss Whedon, creator of Buffy the Vampire Slayer and Angel, under his Mutant Enemy Productions. Its future setting, modeled after traditional Western movie motifs, has been praised as an "oddball genre mix"...
consists of hundreds of terraformed planets and moons.

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