Terraforming of Europa

{{Original research|date=July 2011}}
[[File:Europa-moon.jpg|thumb|220px|[[Europa (moon)|Europa]]'s trailing hemisphere in approximate NATURAL color.]]
The '''[[terraforming]] of [[Europa (moon)|Europa]]''' is the hypothetical process of boosting the global environment of Europa, where its [[climate]], surface and known properties are deliberately changed with the goal of making it [[Habitability|habitable]] for human colonization without the use of a [[spacesuit]]. Although recent astronomical studies indicate it has the greatest potential for being the only other body in the [[Solar System]] to sustain [[life]] (along with planet [[Mars]]),<ref name="The Terraformed Europa">{{cite news|url=http://earthsky.org/space/study-shows-mars-and-jupiters-moon-europa-best-suited-for-habitability|title=Study shows Mars and Jupiter's moon Europa best suited for microbial life|author=Deborah Byrd|work=EarthSky.org|date=2009-10-05|accessdate=2011-07-04}}</ref> terraformation of this [[moon]] proves a challenge, as Europa is near a huge radiation belt around Jupiter,<ref name="Radiation Belts Harsher">{{cite news|url=http://www.sciencedaily.com/releases/2001/03/010329075139.htm|title=Jupiter Radiation Belts Harsher Than Expected|work=ScienceDaily|date=2001-03-29}}</ref> but through the usage of human-made [[space technology]], this radiation could be overcome. There are two major changes required in this:
*The establishment of a [[magnetic field]] at least half the strength of [[Earth]]'s, through [[convection]] that usually results in the setting up of a dynamo in the [[Planetary core|core]].
*An [[OZONE layer]] that absorbs [[ultraviolet radiation]] and decreases the total amount of harmful radiation reaching the surface, allowing life on land.
There are also other requirements for the ability for essential [[water]] to exist on the moon's crust, as well as breathable [[oxygen]], usually associated with atmospheric conditions:
*There would need to be a considerable percentage of oxygen<ref name="Humans on Europa">{{cite web|url=http://www.space.com/spaceflightmissions/europa_colonies_010606-1.html|title=Humans on Europa: A Plan for Colonies on the Icy Moon|accessdate=2006-04-28}}</ref> in the atmosphere (at least Earth's amount, AbOUT 20.95%) to create air (see [[atmosphere of Earth]]).
*It would be necessary for the moon to be heated to sustain a warm and suitable temperature.
*The [[atmospheric pressure]] would need to be increased.

==Reasons for terraforming==
{{See also|Ethics of terraforming}}
In the future, population growth and demand for resources may create pressure for humans to colonize new habitats such as [[Mars]], the [[Moon]], and nearby planets, as well as harvest the Solar System's energy and material resources.<ref>{{cite web|url=http://www.amazon.com/dp/0316771635 |title=Savage, Marshall T., '&#39;The Millennial Project: Colonizing the Galaxy in Eight Easy Steps'&#39; (Little Brown and Company, 1994) |publisher=Amazon.com |date= |accessdate=2011-08-20}}</ref>

In about 7.6 billion years, the Sun will move out of its [[main sequence]] and into its [[red giant]] phase,<ref>{{cite web|url=http://outreach.atnf.csiro.au/education/senior/astrophysics/stellarevolution_postmain.html|title=Post-Main Sequence Stars|work=Australia Telescope Outreach and Education|date=2006-10-12|accessdate=2011-07-07}}</ref> as the [[hydrogen]] fuel in the core is completely [[Nuclear fusion|consumed]], causing the Sun's core to contract and the outer layers to expand. At this point, the Sun's upper atmosphere will extend as far as 1.2 [[astronomical unit|AU]], out past the present ORBit of the Earth.<ref name="mnras361">{{Cite journal
| author=Schröder, K.-P.; Connon Smith, Robert
| title=Distant future of the Sun and Earth revisited
| journal=Monthly Notices of the Royal Astronomical Society | volume=386 | issue=1 | pages=155–163
| doi=10.1111/j.1365-2966.2008.13022.x
| year=2008 | bibcode=2008MNRAS.386..155S|arxiv = 0801.4031 }}</ref> This expansion will likely destabilize the orbits of the inner planets, causing them to spiral in towards the sun and be destroyed. The Sun will lose a significant fraction of its mass in the process of becoming a red giant, and this may cause a widening of the orbits of the other planets. Earth could technically achieve a widening of its orbit and could potentially maintain a sufficiently high angular velocity to keep it from being engulfed. In order to do so, its orbit would need to increase to between 1.3 AU and 1.7 AU.

Although [[Mars]] is the most popular candidate for [[Terraforming of Mars|terraforming]], even if human colonization of Mars lasts for billions of years, the [[habitable zone]] will eventually move out of Mars, towards Jupiter and its system.

It is speculated that Earth will be out of its [[habitable zone]] before the Sun enters its Red Giant phase.<ref name="mnras361"/> Astronomers estimate that the Sun will be 33% more luminous in three billion years. The warming Sun and increased solar radiation will cause the Earth's oceans to [[evaporation|evaporate]], and the Earth to eventually become molten again. The habitable zone would move farther out from the Sun, giving potential Mars colonists some thousands of additional years to develop further [[space technology]] to settle elsewhere in the [[Solar System]].

Even if Europa receives the same gravitational-kinetic and electromagnetic energy as Jupiter,<ref>{{cite web| url=http://www.nexialquest.com/The%20Terraformation%20of%20Worlds.pdf| title=The Terraformation of Worlds| author=Peter Ahrens| publisher=Nexial Quest| format=PDF| accessdate=2007-10-18}}</ref> the Sun will be large enough in the distant future that Europa may possess habitability.<ref name="The Terraformed Europa"/>

==Background==
[[File:EuropaInterior1.jpg|250px|thumb|right|Two possible models of Europa]]
{|class="toccolours" style="float: left; margin-left: 1em; margin-right: 2em; font-size: 95%; background:#FBEC5D; color:black; width:22em; max-width: 40%;" cellspacing="5"
|style="text-align: left;"|"It looks like the ocean could be [[Saturation (chemistry)|saturated]] with [[oxygen]]. Given that, it seems unlimited how complex life could be there."
|-
|style="text-align: left;"|&nbsp;—[[Richard Greenberg]] on the potential for life under Europa's surface.<ref name="Life on Jupiter Moon"/>
|}
It has been hypothesized that a [[Ice|water ice]] ocean may exist under Europa.<ref group=note>A heat source for this assumed subsurface ocean has not yet been substantiated, so the ocean is displayed with being mostly water ice, as Europa receives the same amount of sunlight as [[Jupiter]], but has no internal heat source, although underwater volcanoes may exist in Europa's subsurface ocean and act as a potent [[greenhouse gas]] that heats the ocean for microorganisms to survive.</ref><ref name="Under the Ice">{{cite web|url=http://www.sciencedaily.com/releases/2007/12/071213180823.htm|title=Jupiter's Moon Europa: What Could Be Under The Ice?|work=ScienceDaily|date=2007-12-14|accessdate=2011-07-04}}</ref> If water does indeed exist under the surface, even if frozen, [[life]] could also thrive in this profound water, although it may only be microbial and simple.<ref name="Life on Jupiter Moon">{{cite news|url=http://news.bbc.co.uk/2/hi/science/nature/8498281.stm|title=Could life exist on Jupiter moon?|work=BBC News|author=Emma Harding|date=2010-02-04|accessdate=2011-07-05}}</ref><ref>{{cite news|url=http://berkeley.edu/news/media/releases/2007/02/22_europa.shtml|title=Looking for life on Jupiter's moon Europa|publisher=University of California, Berkeley|author=Robert Sanders|date=2007-02-22|accessdate=2011-07-04}}</ref> Evidence of this life is that [[sea sponge|sponges]], [[crinoid]]s, [[scallop]]s, [[snail]]s, [[fish]] and many microorganisms thrive under the ice in the Antarctic area of New Harbor, despite the frigid conditions.

According to Dr. Robert Pappalardo, the study scientist for the ''Europa'' orbiter at [[NASA]]'s [[Jet Propulsion Laboratory]] (JPL) in [[California]], "there are charged particles that are hitting Europa and making chemical reactions – hitting the H₂O and creating oxygen on the surface."<ref name="Life on Jupiter Moon"/> Numerous of these charged particles could be utilized to hit the Europan surface and make chemical reactions, resulting in oxygen (O₂) and eventually the buildup of a major atmosphere if enough oxygen and other constituents are used.

Europa has no [[magnetic field]] to protect it from the [[Jupiter]] radiation belt that it is near to. It is suggested that an internal dynamo can be produced through [[convection]] (even if Europa is already internally active), though the magnetic field would not need to be stronger than [[Earth's magnetic field|Earth's]], for the measurable radiation on Europa is much less than previously predicted (although terraforming the moon would still prove a challenge).<ref name="Under the Ice"/><ref>{{cite web|url=http://www.astrobio.net/exclusive/3010/hiding-from-jupiters-radiation|title=Hiding from Jupiter's Radiation|work=Astrobiology Magazine|author=Michael Schirber|date=2009-01-09|accessdate=2011-07-05}}</ref><ref>{{cite news|url=http://www.nasa.gov/mission_pages/juno/news/juno20100712.html|title=Juno Armoured Up to Go to Jupiter|work=NASA|date=2010-07-12|accessdate=2011-07-05}}</ref> An [[ozone layer]] would also be necessary.

==Alterations required==
{| class="wikitable" | style="float:right;"
|+ '''Comparison of dry atmosphere'''
!
! [[Europa (moon)|Europa]]
! [[Earth]]
|-
! Pressure || 0.1 μPa (10⁻¹² bar) || {{convert|101.325|kPa|abbr=on}}
|-
! [[Carbon dioxide]] (CO₂) || 0% || 0.04%
|-
! [[Nitrogen]] (N₂) || 0% || 78.08%
|-
! [[Argon]] (Ar) || 0% || 0.93%
|-
! [[Oxygen]] (O₂) || 100% || 20.95%
|}
Terraforming Europa would entail three major alterations: building up the atmosphere, keeping it warm, and keeping the atmosphere from escaping away into space. The atmosphere of Europa is extremely thin and thus has a very low surface pressure of 0.1 μPa; compared to Earth with {{convert|101.325|kPa}} at sea level and {{convert|0.86|kPa}} at an altitude of {{convert|32|km}}. The atmosphere of Europa consists of mostly molecular oxygen (O₂), though from no biological origin, with no other constituents found. Although there was once molecular [[hydrogen]] (H₂) in the atmosphere, it escaped into [[outer space|space]] to leave behind oxygen. By comparison, the air on our planet is 78.08% [[nitrogen]], 20.95% [[oxygen]], 0.93% [[argon]], 0.04% [[carbon dioxide]], and other constituents.

===Building the atmosphere===
Although Europa has an [[atmosphere]] (revealed by the [[Hubble Space Telescope]] in 1995), it is relatively a surface bounded exosphere and totally unbreathable. A minimum 0.2 bar partial pressure of oxygen is required for human breathing, though in practice higher total pressure is needed. This could be supplied by breaking the surface ice into its component hydrogen and oxygen, though a suitable sink for the hydrogen will be required.

====Introduction of ammonia to the atmosphere====
Another intricate method of terraforming Europa is importing [[ammonia]] (NH₃) to the atmosphere. Ammonia not only acts as a powerful [[greenhouse gas]] that heats the planet for water-based temperatures, but also has high levels of [[nitrogen]], which takes care of the need for a [[buffer gas]] in the atmosphere.<ref>{{cite news|url=http://talesfromthelou.wordpress.com/2011/03/01/life-from-outer-space-meteorites-could-have-carried-nitrogen-to-earth/|title=Life from Outer Space: Meteorites 'could have carried nitrogen to Earth'|work=Word Press|date=2011-03-01|accessdate=2011-07-07}}</ref> Part of the ammonia might be imported from [[Jupiter]], Europa's host planet (containing at least 0.026% of ammonia), along with [[Saturn]] (0.01% ammonia), [[Uranus]] and [[Neptune]] (trace amounts of ammonia). It might also be technologically achievable to import ammonia from comets (as they did to Earth) in the asteroid belt, including blowing them up with very large [[nuclear bomb]]s.

The challenge facing atmosphere builders is the need for a buffer gas. On [[Earth]], [[nitrogen]] levels are around 78.08% in the atmosphere, the gas that is in most of the abundance on Earth. Europa would require a similar buffer gas component to pressurize the surface and regularize [[Cell (biology)|cell]] temperatures.<ref>{{cite journal|publisher=Peking University|location=Beijing|title=Applied Physics Letters; May 2008|volume=v. 92|issue=21|pages= 211104–211104-3|doi=10.1063/1.2937407|year=2008 Peking University of Beijing|contribution=Effect of buffer gas ratios on the relationship between cell temperature and frequency shifts of the coherent population trapping resonance|first=K.|journal=Peking University, Beijing, Applied Physics Letters |last=Deng|first2=T. |last2=Guo |first3=D. W. |last3=He |first4=X. Y. |last4=Liu |first5=L. |last5=Liu |first6=D. Z. |last6=Guo |first7=X. Z. |last7=Chen |first8=Z. |last8=Wang|url=http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4832961|ref=harv|postscript=<!--None-->|bibcode = 2008ApPhL..92u1104D }}</ref> Several inert gases, such as nitrogen, [[argon]] or [[neon]], could be utilized as buffer gases, although obtaining sufficient quantities would be difficult.

====Introduction of methane to the atmosphere====
Sources of [[methane]] in the [[Solar System]] include [[Saturn]]'s moon [[Titan (moon)|Titan]]'s [[Lakes of Titan|lakes]] and [[atmosphere]], as well as trace amounts from the [[atmosphere of Mars]].<ref name="Mars Methane Discovery">{{cite news|url=http://articles.cnn.com/2009-01-15/tech/mars.methane_1_methane-martian-dust-storm?_s=PM:TECH|title=Methane discovery could mean life on Mars|work=[[CNN]]|author=Azadeh Ansari|date=2009-01-15|accessdate=2011-07-07}}</ref> Or [[hydrogen]] could be converted into methane (because methane is four atoms of hydrogen bound to a carbon atom).<ref name="Mars Methane Discovery"/> In this way, methane is used as a boost for a potent [[greenhouse effect]]. Methane, and other [[hydrocarbons]], also can be utilized in the increase for the insufficient Europan atmospheric pressure. These gases also can be used for production of water and CO₂ for Europan atmosphere, to initiate [[plant]]s' photosynthetic processes.

====Introduction of carbon dioxide to the atmosphere====
[[Carbon dioxide]] (CO₂) importation could also be done for atmospheric and hydrospheric engineering. [[Hydrogen]] (from some outer [[Solar System]] source) reacting with imported carbon dioxide could create heat, [[water]] and [[graphite]], per the [[Bosch reaction]].<ref>{{cite web| url=http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19710002858_19710002858.pdf| title=A CARBON DIOXIDE REDUCTION UNIT USING BOSCH REACTION AND EXPENDABLE CATALYST CARTRIDGES|first=R. F. |last=Holmes |first2=E. E. |last2=Keller |first3=C. D. |last3=King |work=NASA Langley Research Center |format=PDF |accessdate=2011-07-07}}</ref> Carbon dioxide is also a potent factor for [[plant]]s breathing in carbon dioxide and releasing [[oxygen]] as a waste product (the photosynthetic process), as the molecular oxygen (O₂) on Europa is extremely thin and not comfortably breathable by [[human]]s.

The CO₂ could be imported from the [[atmosphere of Venus]] and of [[atmosphere of Mars|Mars]], where the gas is found to be abundant (96.3% for Venus and 95.32% for [[Mars]]).<ref>{{cite web|url=http://www.windows2universe.org/physical_science/chemistry/carbon_dioxide.html&edu=high|title=Carbon Dioxide|work=Windows to the Universe|author=Jennifer Bergman|date=2011-02-08|accessdate=2011-07-09}}</ref> If there were enough frozen carbon (as much as the south pole of Mars) on Europa and in its [[regolith]] (or it could be imported from the surface of Mars), then sublimated to gas by a climate warming of only a few degrees it would increase the atmospheric pressure to 300 millibars (comparable to twice the altitude of [[Mount Everest]]'s peak), it would melt the water ice at Europa's north pole (flooding the northern area), and bring the year-round temperatures above freezing. This would enable the introduction of plant life, particularly plankton in the new northern sea, to start converting the CO₂ into oxygen of biological origin.

===Heating the satellite===
After building the atmosphere, heating the satellite would be an important requirement of terraforming Europa, as heat from the [[Sun]] is the primary driver of planetary climate. As the satellite becomes warmer, the CO₂ that is frozen into solid form in the Europan north and south poles, the CO₂ would [[sublimation (chemistry)|sublime]] into gas and further contribute to a potent greenhouse effect. Heating the satellite would also melt the [[ice]] on the surface into liquid form.

====Volcanic steam====
In Europa's subsurface ocean, there is probably volcanic activity that warms alleged microorganisms without the requirement of sunlight.<ref>{{cite web|url=http://www.phenomenica.com/2008/12/europa.html|title=Jupiter's moon Europa to harbor life|work=Phenomenica|date=2008-12-15|accessdate=2011-07-10}}</ref><ref group=note>As aforementioned, this might be a way that microorganisms could survive under the surface, where subsurface volcanoes spew [[steam]], a potent [[greenhouse gas]], into the water, providing a possible heat source. See reference #18 for more information.</ref> If a hole large enough for volcanic steam to go through was dug, the steam (and, in particular, [[water vapor]]),<ref>{{cite web|url=http://www.greenpeace.org/international/en/campaigns/climate-change/science/other_gases/|title=Other gases|publisher=Greenpeace International|date=March 16, 2006|accessdate=July 23, 2011 }}</ref> since it is a [[greenhouse gas]], would not only heat the satellite (along with [[methane]], [[ammonia]], [[water vapor]] and [[carbon dioxide]]), it would also cause clouds to be formed and condense into water droplets that could rain upon Europa to create some of the current suggested quantities of [[water]], although forming water even the size of [[Earth]]'s smallest country would last many years.

====Bombardment====
[[Asteroid]]s could be directed onto the Europan surface for their composition, including [[ammonia]]<ref>{{cite news|url=http://www.cosmosmagazine.com/news/4096/meteorites-may-have-seeded-earth-life|title=Ammonia-rich meteorite may explain life on Earth|work=[[Cosmos (magazine)|Cosmos Magazine]]|author=Ian Randall|date=2011-03-01|accessdate=2011-07-10}}</ref> (which is a [[greenhouse gas]], as aforementioned, and may have seeded [[Earth]]), and because the impacting energy could release [[heat]] into the atmosphere. Impacting asteroids on these nitrate beds would release additional nitrogen and thicker oxygen into the satellite's tenuous atmosphere.

==Magnetic field and Jupiter radiation belts==
Earth is covered with [[water]] (about 70% of Earth's surface) because the [[ionosphere]] is permeated with a strong [[Magnetosphere|magnetic field]].<ref>{{cite web|url=http://science.nasa.gov/science-news/science-at-nasa/2003/29dec_magneticfield/|title=Earth's Inconstant Magnetic Field|work=Science@Nasa|author=Tony Phillips|date=2003-12-29|accessdate=2009-12-27}} {{Dead link|date=October 2010|bot=H3llBot}}</ref> The [[hydrogen]] ions present in its ionosphere move very fast due to their small mass, but they cannot escape to [[outer space]] because their trajectories are deflected by the magnetic field. [[Venus]] has a dense atmosphere, but only traces of [[water vapor]] (20 ppm) because it lacks a magnetosphere. The Europan atmosphere also does occasionally lose molecular oxygen (O₂) to space.

Earth is provided extra protection from [[ultraviolet radiation]] by its [[ozone layer]], which is somewhere in the [[stratosphere]]. Ultraviolet light is blocked before it can dissociate water into hydrogen and oxygen. Since little water vapor rises above the [[troposphere]] and the ozone layer is in the upper stratosphere, little water is dissociated into hydrogen and oxygen.

Europa receives about 540 [[Röntgen equivalent man|rem]] a day<ref>{{cite web |date=2000-02-29 |title=SPS 1020 (Introduction to Space Sciences) |publisher=California State University, Fresno |author=Frederick A. Ringwald |url=http://zimmer.csufresno.edu/~fringwal/w08a.jup.txt |accessdate=2009-07-04}}</ref> (500 is already potentially fatal) from [[Jupiter]]'s large radiation belts (10 times stronger than [[Earth]]'s [[Van Allen radiation belt]]s), and may prove a health threat to colonists. The satellite lacks a magnetosphere, which not only leaves it exposed to [[radiation]] by Jupiter, but to the [[solar wind]].

Despite this, an atmosphere engineered to be much denser than [[Earth]]'s can provide protection from cosmic radiation and Jupiter's radiation, and carefully selected upper-atmospheric components may block UV radiation before it can ionize water.

==Notes and citations==
===Footnotes===
{{reflist|group=note}}

===Cited sources===
{{reflist}}

==References==
*{{cite book
|author=Arthur C. Clarke
|editor=Zharchenko, Vasili
|year=1982|title=2010: Odyssey Two
|edition=1st
|publisher=Granada Publishing Ltd.
|location=United Kingdom|isbn=0-345-31282-1
}}
{{Jupiter}}

[[Category:Planetary engineering]]
[[Category:Europa (moon)]]