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Europa (moon)

Europa (moon)
Europa Surface area Volume Mass Mean density Equatorial surface gravity Escape velocity Rotation period Axial tilt Albedo
Europa, as seen by the Galileo spacecraft

3.09 × 107 km2 (0.061 Earths)[4] 1.593 × 1010 km3 (0.015 Earths)[4] 4.80 × 1022 kg (0.008 Earths)[3] 3.01 g/cm3[3] 1.314 m/s2 (0.134 g)[2] 2.025 km/s[2] Synchronous[5] 0.1°[6] 0.67 ± 0.03[7] min ~50 K[8] mean 102 K max 125 K

Surface temp. Surface

Discovery Discovered by Discovery date Designations Alternate name Adjective Jupiter II Europan G. Galilei S. Marius January 7, 1610 Apparent magnitude Atmosphere Surface pressure

5.29 (opposition)[7]

0.1 µPa (10-12 bar)[9]

Orbital characteristics[1]
Epoch January 8, 2004

Periapsis Apoapsis Mean orbit radius Eccentricity Orbital period Average orbital speed Inclination Satellite of

664 862 km[2] 676 938 km[2] 670 900 km[3] 0.009[3] 3.551 181 d[3] 13.740 km/s[3] 0.470° (to Jupiter’s equator)[3] Jupiter

Physical characteristics Mean radius 1569 km (0.245 Earths)[3]

Europa (pronounced /jʊˈroʊpə/[10] listen ; or as Greek Ευρώπη) is the sixth moon of the planet Jupiter. Europa was discovered in 1610 by Galileo Galilei (and possibly independently by Simon Marius), and named after a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the queen of Crete. It is the smallest of the four Galilean moons. At just over 3,100 kilometres (1,900 mi) in diameter, Europa is slightly smaller than Earth’s Moon and is the sixth-largest moon in the Solar System. Though by a wide margin the least massive of the Galilean satellites, its mass nonetheless significantly exceeds the combined mass of all moons in the Solar System smaller than itself.[11] It is primarily made of silicate rock and likely has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. This young surface is striated by

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cracks and streaks, while craters are relatively infrequent. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably serve as an abode for extraterrestrial life.[12] Heat energy from tidal flexing ensures that the ocean remains liquid and drives geological activity.[13] Although only fly-by missions have visited the moon, the intriguing characteristics of Europa have led to several ambitious exploration proposals. The Galileo mission provided the bulk of current data on Europa. A new mission to Jupiter’s icy moons, the Europa Jupiter System Mission (EJSM) is proposed for a launch in 2020. Conjecture on extraterrestrial life has ensured a high profile for the moon and has led to steady lobbying for future missions.[14][15]

Europa (moon)

Interior of Europa (click for description) of silicate rock. It has an outer layer of water thought to be around 100 km (62 mi) thick; some as frozen-ice upper crust, some as liquid ocean underneath the ice. Recent magnetic field data from the Galileo orbiter showed that Europa has an induced magnetic field through interaction with Jupiter’s, which suggests the presence of a subsurface conductive layer. The layer is likely a salty liquid water ocean. The crust is estimated to have undergone a shift of 80°, nearly flipping over (see true polar wander), which would be unlikely if the ice were solidly attached to the mantle.[19] Europa probably contains a metallic iron core.[20]

Discovery and naming
Europa, along with Jupiter’s three other largest satellites, Io, Ganymede, and Callisto, was discovered by Galileo Galilei in 1610. Like all the Galilean satellites, Europa is named after a lover of Zeus, the Greek counterpart of Jupiter, in this case Europa, daughter of the king of Tyre. The naming scheme was suggested by Simon Marius, who apparently discovered the four satellites independently, though Galileo alleged that Marius had plagiarized him. Marius attributed the proposal to Johannes Kepler.[16][17] The names fell out of favor for a considerable time, and were not revived in general use until the mid-20th century.[18] In much of the earlier astronomical literature, Europa is simply referred to by its Roman numeral designation as Jupiter II (a system introduced by Galileo) or as the "second satellite of Jupiter". In 1892, the discovery of Amalthea, whose orbit lay closer to Jupiter than those of the Galilean moons, pushed Europa to the third position. The Voyager probes discovered three more inner satellites in 1979, so Europa is now considered Jupiter’s sixth satellite, though it is still sometimes referred to as Jupiter II.[18]

Surface features

Physical characteristics
Internal structure
Europa is similar in bulk composition to the terrestrial planets, being primarily composed

Mosaic of Galileo images showing features indicative of internal geologic activity: lineae, domes, pits and Conamara Chaos. Europa is one of the smoothest objects in the Solar System.[21] The prominent markings

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crisscrossing the moon seem to be mainly albedo features, which emphasize low topography. There are few craters on Europa because its surface is tectonically active and young.[22][23] Europa’s icy crust gives it an albedo (light reflectivity) of 0.64, one of the highest of all moons.[24][23] This would seem to indicate a young and active surface; based on estimates of the frequency of cometary bombardment that Europa probably endures, the surface is about 20 to 180 million years old.[25] There is currently no full scientific consensus among the sometimes contradictory explanations for the surface features of Europa.[26]

Europa (moon)
are. This could be explained if Europa’s surface rotates slightly faster than its interior, an effect which is possible due to the subsurface ocean mechanically decoupling the moon’s surface from its rocky mantle and the effects of Jupiter’s gravity tugging on the moon’s outer ice crust.[29] Comparisons of Voyager and Galileo spacecraft photos serve to put an upper limit on this hypothetical slippage. The full revolution of the outer rigid shell relative to the interior of Europa occurs over a minimum of 12,000 years.[30]

Other geological features
See also: List of geological features on Europa

Lineae

Approximately natural color image of Europa by the Galileo spacecraft, showing lineae See also: List of lineae on Europa Europa’s most striking surface features are a series of dark streaks crisscrossing the entire globe, called lineae (English: lines). Close examination shows that the edges of Europa’s crust on either side of the cracks have moved relative to each other. The larger bands are more than 20 km (12 mi) across, often with dark, diffuse outer edges, regular striations, and a central band of lighter material.[27] The most likely hypothesis states that these lineae may have been produced by a series of eruptions of warm ice as the Europan crust spread open to expose warmer layers beneath.[28] The effect would have been similar to that seen in the Earth’s oceanic ridges. These various fractures are thought to have been caused in large part by the tidal stresses exerted by Jupiter. Since Europa is tidally locked to Jupiter, and therefore always maintains the same approximate orientation towards the planet, the stress patterns should form a distinctive and predictable pattern. However, only the youngest of Europa’s fractures conform to the predicted pattern; other fractures appear to occur at increasingly different orientations the older they

Enhanced-color view of part of Conamara Chaos, showing ice rafts up to 10 km (6 mi) across. White areas are ejecta rays from the crater Pwyll.

Craggy, 250 m high "mountains" and smooth plates are jumbled together in a close-up of Conamara Chaos. Other features present on Europa are circular and elliptical lenticulae (Latin for "freckles"). Many are domes, some are pits and some are smooth, dark spots. Others have a jumbled or rough texture. The dome tops look like pieces of the older plains around them, suggesting that the domes formed when the plains were pushed up from below.[31] One hypothesis states that these lenticulae were formed by diapirs of warm ice rising up through the colder ice of the outer crust, much like magma chambers in the Earth’s crust.[31] The smooth, dark spots

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could be formed by meltwater released when the warm ice breaks through the surface, and the rough, jumbled lenticulae (called regions of "chaos", for example the Conamara Chaos) would then be formed from many small fragments of crust embedded in hummocky, dark material, appearing like icebergs in a frozen sea.[32] An alternative hypothesis suggest that lenticulae are actually small areas of chaos, and that the claimed pits, spots and domes are artefacts resulting from over-interpretation of early, low-resolution Galileo images. The implication is that the ice is too thin to support the convective diapir model of feature formation. [33] [34]

Europa (moon)

Subsurface ocean
Most planetary scientists believe that a layer of liquid water exists beneath Europa’s surface, kept warm by tidally generated heat.[35] The heating by radioactive decay, which is almost the same as in Earth (per kg of rock), cannot provide necessary heating in Europa, because the volume-to-surface ratio is much lower due to the moon’s smaller size. Europa’s surface temperature averages about 110 K (−160 °C; −260 °F) at the equator and only 50 K (−220 °C; −370 °F) at the poles, keeping Europa’s icy crust as hard as granite.[8] The first hints of a subsurface ocean came from theoretical considerations of tidal heating (a consequence of Europa’s slightly eccentric orbit and orbital resonance with the other Galilean moons). Galileo imaging team members argue for the existence of a subsurface ocean from analysis of Voyager and Galileo images.[35] The most dramatic example is "chaos terrain", a common feature on Europa’s surface that some interpret as a region where the subsurface ocean has melted through the icy crust. This interpretation is extremely controversial. Most geologists who have studied Europa favor what is commonly called the "thick ice" model, in which the ocean has rarely, if ever, directly interacted with the present surface.[36] The different models for the estimation of the ice shell thickness give values between a few kilometers and tens of kilometers.[37] The best evidence for the so-called "thick ice" model is a study of Europa’s large craters. The largest impact structures are surrounded by concentric rings and appear to be filled with relatively flat, fresh ice;

Two possible models of Europa based on this and on the calculated amount of heat generated by Europan tides, it is predicted that the outer crust of solid ice is approximately 10–30 km (6–19 mi) thick, including a ductile "warm ice" layer, which could mean that the liquid ocean underneath may be about 100 km (60 mi) deep.[25] This leads to a volume of Europa’s oceans of 3 × 1018 m3, slightly more than two times the volume of Earth’s oceans. The so-called "thin ice" model suggests that Europa’s ice shell may be only a few kilometers thick. However, most planetary scientists conclude that this model considers only those topmost layers of Europa’s crust which behave elastically when affected by Jupiter’s tides. One example is flexure analysis, in which the moon’s crust is modeled as a plane or sphere weighted and flexed by a heavy load. Models such as this suggest the outer elastic portion of the ice crust could be as thin as 200 metres (660 ft). If the ice shell of Europa is really only a few kilometers thick, this "thin ice" model would mean that regular contact of the liquid interior with the surface could occur through open ridges, causing the formation of areas of chaotic terrain.[37]

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The Galileo orbiter found that Europa has a weak magnetic moment, which is induced by the varying part of the Jovian magnetic field. The field strength at the magnetic equator (about 120 nT) created by this magnetic moment is about one-sixth the strength of Ganymede’s field and six times the value of Callisto’s.[38] The existence of the induced moment requires a layer of a highly electrically conductive material in the moon’s interior. The most plausible candidate for this role is a large subsurface ocean of liquid saltwater.[20] Spectrographic evidence suggests that the dark, reddish streaks and features on Europa’s surface may be rich in salts such as magnesium sulfate, deposited by evaporating water that emerged from within.[39] Sulfuric acid hydrate is another possible explanation for the contaminant observed spectroscopically.[40] In either case, since these materials are colorless or white when pure, some other material must also be present to account for the reddish color, and sulfur compounds are suspected.[41]

Europa (moon)
surface pressure of Europa’s atmosphere is 0.1 μPa, or 10−12 that of the Earth.[9] In 1997, the Galileo spacecraft confirmed the presence of a tenuous ionosphere (an upperatmospheric layer of charged particles) around Europa created by solar radiation and energetic particles from Jupiter’s magnetosphere,[44][45] providing evidence of an atmosphere. Unlike the oxygen in Earth’s atmosphere, Europa’s is not of biological origin. The "surface-bounded atmosphere" forms through radiolysis, the dissociation of molecules through radiation[46]. Solar ultraviolet radiation and charged particles (ions and electrons) from the Jovian magnetospheric environment collide with Europa’s icy surface, splitting water into oxygen and hydrogen constituents. These chemical components are then adsorbed and "sputtered" into the atmosphere. The same radiation also creates collisional ejections of these products from the surface, and the balance of these two processes forms an atmosphere.[47] Molecular oxygen is the densest component of the atmosphere because it has a long lifetime; after returning to the surface, it does not stick (freeze) like a water or hydrogen peroxide molecule but rather desorbs from the surface and starts another ballistic arc. Molecular hydrogen never reaches the surface, as it is light enough to escape Europa’s surface gravity.[48][49] Observations of the surface have revealed that some of the molecular oxygen produced by radiolysis is not ejected from the surface. Because the surface may interact with the subsurface ocean (considering the geological discussion above), this molecular oxygen may make its way to the ocean, where it could aid in biological processes.[50] One estimate suggests that, given the turnover rate inferred from the apparent ~0.5 Gyr maximum age of Europa’s surface ice, subduction of radiolytically generated oxidizing species might well lead to oceanic free oxygen concentrations that are comparable to those in terrestrial deep oceans.[51] The molecular hydrogen that escapes Europa’s gravity, along with atomic and molecular oxygen, forms a torus (ring) of gas in the vicinity of Europa’s orbit around Jupiter. This "neutral cloud" has been detected by both the Cassini and Galileo spacecraft, and has a greater content (number of atoms and molecules) than the neutral cloud

Atmosphere

Magnetic field around Europa. The red line shows a trajectory of the Galileo spacecraft during a typical flyby (E4 or E14). Observations with the Goddard High Resolution Spectrograph of the Hubble Space Telescope, first described in 1995, revealed that Europa has a tenuous atmosphere composed mostly of molecular oxygen (O2).[42][43] The

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surrounding Jupiter’s inner moon Io. Models predict that almost every atom or molecule in Europa’s torus is eventually ionized, thus providing a source to Jupiter’s magnetospheric plasma. [52]

Europa (moon)

Possible extraterrestrial life
This giant tube worm colony dwells beside a Pacific Ocean vent. While the worms require oxygen, some microbes in the vent communities do not. sugars from carbon dioxide and water, releasing oxygen in the process, and are then eaten by oxygen-respiring animals, passing their energy up the food chain. Even life in the ocean depths, where sunlight cannot reach, was believed to obtain its nourishment either from consuming organic detritus rained down from the surface waters or from eating animals that did.[57] A world’s ability to support life was thought to depend on its access to sunlight. However, in 1977, during an exploratory dive to the Galapagos Rift in the deep-sea exploration submersible Alvin, scientists discovered colonies of giant tube worms, clams, crustaceans, mussels, and other assorted creatures clustered around undersea volcanic features known as black smokers.[57] These creatures thrive despite having no access to sunlight, and it was soon discovered that they comprise an entirely independent food chain. Instead of plants, the basis for this food chain was a form of bacterium that derived its energy from oxidization of reactive chemicals, such as hydrogen or hydrogen sulfide, that bubbled up from the Earth’s interior. This chemosynthesis revolutionized the study of biology by revealing that life need not be sun-dependent; it only requires water and an energy gradient in order to exist. It opened up a new avenue in astrobiology by massively expanding the number of possible extraterrestrial habitats. Europa’s unlit interior is now considered to be the most likely location for extant extraterrestrial life in the Solar System.[58] While the tube worms and other multicellular eukaryotic organisms around these hydrothermal vents respire oxygen and thus are

A black smoker in the Atlantic Ocean. Driven by geothermal energy, such hydrothermal vents create chemical disequilibria that can provide energy sources for life. It has been suggested that life may exist in Europa’s under-ice ocean, perhaps subsisting in an environment similar to Earth’s deepocean hydrothermal vents or the Antarctic Lake Vostok.[53] Life in such an ocean could possibly be similar to microbial life on Earth in the deep ocean.[54][55] So far, there is no evidence that life exists on Europa, but the likely presence of liquid water has spurred calls to send a probe there.[56] Until the 1970s, life, at least as the concept is generally understood, was believed to be entirely dependent on energy from the Sun. Plants on Earth’s surface capture energy from sunlight to photosynthesize

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indirectly dependent on photosynthesis, anaerobic chemosynthetic bacteria and archaea that inhabit these ecosystems provide a possible model for life in Europa’s ocean — and as previously noted, on Europa, radiolytically generated free radicals delivered by subduction of surface ice may provide a sufficient source of free oxygen, even in the absence of photosynthesis.[51] The energy provided by tidal flexing drives active geological processes within Europa’s interior, just as they do to a far more obvious degree on its sister moon Io. While Europa, like the Earth, may possess an internal energy source from radioactive decay, the energy generated by tidal flexing would be several orders of magnitude greater than any radiological source.[59] However, such an energy source could never support an ecosystem as large and diverse as the photosynthesis-based ecosystem on Earth’s surface.[60] Life on Europa could exist clustered around hydrothermal vents on the ocean floor, or below the ocean floor, where endoliths are known to habitate on Earth. Alternatively, it could exist clinging to the lower surface of the moon’s ice layer, much like algae and bacteria in Earth’s polar regions, or float freely in Europa’s ocean.[61] However, if Europa’s ocean were too cold, biological processes similar to those known on Earth could not take place. Similarly, if it were too salty, only extreme halophiles could survive in its environment.[61] In 2006, Robert Pappalardo, an assistant professor within the University of Colorado’s space department, said, "We’ve spent quite a bit of time and effort trying to understand if Mars was once a habitable environment. Europa today, probably, is a habitable environment. We need to confirm this … but Europa, potentially, has all the ingredients for life … and not just four billion years ago … but today."[62]

Europa (moon)
flybys followed in 1979, while the Galileo mission orbited Jupiter for eight years beginning in 1995 and provided the most detailed examination of the Galilean moons that is expected until the end of the 2020s. Various proposals have been made for future missions. Any mission to Europa would need to be protected from the high radiation levels sustained by Jupiter.[14] The aims of these missions have ranged from examining Europa’s chemical composition to searching for extraterrestrial life in its subsurface ocean.[54][63]

Spacecraft proposals and cancellations
Plans to send a probe to study Europa for signs of liquid water and possible life have been plagued by false starts and budget cuts.[64] But finally that is changing. Proposed for a launch in 2020, the Europa Jupiter System Mission (EJSM) is a joint NASA/ESA proposal for exploration of Jupiter’s moons. In February 2009 it was announced that ESA/NASA had given this mission priority ahead of the Titan Saturn System Mission.[65] ESA’s contribution will still face funding competition from other ESA projects.[66] EJSM consists of the NASA-led Jupiter Europa Orbiter, the ESA-led Jupiter Ganymede Orbiter, and possibly a JAXA-led Jupiter Magnetospheric Orbiter. Russia has expressed interest in sending a lander to Europa as part of an international flotilla. Prior to EJSM, the plan for the extremely ambitious Jupiter Icy Moons Orbiter was cancelled in 2005.[64][14]. Before that, the Europa Orbiter received a go-ahead in 1999 but was canceled in 2002. Another possible mission, known as the Ice Clipper mission, would have used an impactor similar to the Deep Impact mission—it would make a controlled crash into the surface of Europa, generating a plume of debris which would then be collected by a small spacecraft flying through the plume.[67][68] More ambitious ideas have been put forward for the far future, including a capable lander to test for evidence of life that might be frozen in the shallow subsurface, or even to directly explore the possible ocean beneath Europa’s ice. One proposal calls for a large nuclear-powered "melt probe" (cryobot) which would melt through the ice until it hit the ocean below.[69][14] Once it reached the

Exploration
Most human knowledge of Europa has been derived from a series of flybys since the 1970s. The sister crafts Pioneer 10 and Pioneer 11 were the first to visit Jupiter, in 1973 and 1974, respectively; the first photos of Jupiter’s largest moons produced by the Pioneers were fuzzy and dim.[21] The Voyager

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Europa (moon)
http://adsabs.harvard.edu/abs/ 2005Icar..175..233B. [7] ^ Yeomans, Donald K. (2006-07-13). "Planetary Satellite Physical Parameters". JPL Solar System Dynamics. http://ssd.jpl.nasa.gov/ ?sat_phys_par. Retrieved on 2007-11-05. [8] ^ Lucy-Ann McFadden, Paul Weissman, Torrence Johnson (2007). The Encyclopedia of the Solar System. Elsevier. pp. 432. [9] ^ McGrath (2009). "Atmosphere of Europa". in Pappalardo, R.T.; McKinnon, W. B.; Khurana, K.. Europa. University of Arizona Press. ISBN 0-816-52844-6. [10] In US dictionary transcription, us dict: ū·rō′·pə. [11] Mass of Europa: 48 Yg. Mass of Triton plus all smaller moons: 39.5 Yg (see note g here) [12] Tritt, Charles S. (2002). "Possibility of Life on Europa". Milwaukee School of Engineering. http://people.msoe.edu/ ~tritt/sf/europa.life.html. Retrieved on 2007-08-10. [13] "Tidal Heating". geology.asu.edu. http://web.archive.org/web/ 20060329000051/http://geology.asu.edu/ ~glg_intro/planetary/p8.htm. Retrieved on 2007-10-20. [14] ^ Friedman, Louis (2005-12-14). "Projects: Europa Mission Campaign; Campaign Update: 2007 Budget Proposal". The Planetary Society. http://www.planetary.org/programs/ projects/explore_europa/ update_12142005.html. Retrieved on 2007-08-10. [15] David, Leondard (2006-02-07). "Europa Mission: Lost In NASA Budget". Space.com. http://www.space.com/news/ 060207_europa_budget.html. Retrieved on 2007-08-10. [16] "Simon Marius". Students for the Exploration and Development of Space. University of Arizona. http://seds.lpl.arizona.edu/messier/xtra/ Bios/marius.html. Retrieved on 2007-08-09. [17] Marius, S.; (1614) Mundus Iovialis anno M.DC.IX Detectus Ope Perspicilli Belgici [1], where he attributes the suggestion to Johannes Kepler [18] ^ Marazzini, C. (2005). "The names of the satellites of Jupiter: from Galileo to

Artist’s concept of the cryobot and hydrobot water, it would deploy an autonomous underwater vehicle (hydrobot) which would gather information and send it back to Earth.[70] Both the cryobot and the hydrobot would have to undergo some form of extreme sterilization to prevent detection of Earth organisms instead of native life and to prevent contamination of the subsurface ocean.[71] This proposed mission has not yet reached a serious planning stage[72]

See also
• • • • • • Colonization of Europa Jupiter’s moons in fiction List of craters on Europa List of geological features on Europa List of lineae on Europa Moons of Jupiter

References
[1] "JPL HORIZONS solar system data and ephemeris computation service". Solar System Dynamics. NASA, Jet Propulsion Laboratory. http://ssd.jpl.nasa.gov/ horizons.cgi. Retrieved on 2007-08-10. [2] ^ Calculated on the basis of other parameters [3] ^ "Overview of Europa Facts". NASA. http://www2.jpl.nasa.gov/galileo/europa/. Retrieved on 2007-12-27. [4] ^ Using the mean radius [5] See Geissler et al. (1998) in orbit section for evidence of non-synchronous orbit. [6] Bills, Bruce G. (2005). "Free and forced obliquities of the Galilean satellites of Jupiter". Icarus 175: 233–247. doi:10.1016/j.icarus.2004.10.028.

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http://www.sciencedirect.com/ Simon Marius". Lettere Italiana 57 (3): science?_ob=ArticleURL&_udi=B6WGF-4M645DK-6& 391–407. Retrieved on 2007-12-20. [19] Cowen, Ron (2008-06-07). "A Shifty [30] Kattenhorn, Simon A. (2002). Moon". Science News. "Nonsynchronous Rotation Evidence and http://www.sciencenews.org/view/ Fracture History in the Bright Plains generic/id/32135/title/A_shifty_moon. [20] ^ Kivelson, M. G.; et al. (2000). "Galileo Region, Europa". Icarus 157: 490–506. Magnetometer Measurements: A doi:10.1006/icar.2002.6825. Stronger Case for a Subsurface Ocean at http://adsabs.harvard.edu/abs/ 2002Icar..157..490K. Europa". Science 289 (5483): [31] ^ Christophe Sotin, James W. Head III 1340–1343. doi:10.1126/ and Gabriel Tobie (2001). "Europa: Tidal science.289.5483.1340. PMID heating of upwelling thermal plumes and 10958778. the origin of lenticulae and chaos [21] ^ "Europa: Another Water World?". melting" (PDF). Project Galileo: Moons and Rings of http://planetary.brown.edu/planetary/ Jupiter. NASA, Jet Propulsion documents/2685.pdf. Retrieved on Laboratory. 2001. 2007-12-20. http://www2.jpl.nasa.gov/galileo/moons/ [32] Jason C. Goodman, Geoffrey C. Collins, europa.html. Retrieved on 2007-08-09. John Marshall, Raymond T. [22] Arnett, B.; Europa (November 7, 1996) Pierrehumbert. "Hydrothermal Plume [23] ^ Hamilton, C. J.. "Jupiter’s Moon Dynamics on Europa: Implications for Europa". http://www.solarviews.com/eng/ Chaos Formation" (PDF). http://wwweuropa.htm. paoc.mit.edu/paoc/papers/ [24] "Europa, a Continuing Story of europa_plume.pdf. Retrieved on Discovery". Project Galileo. NASA, Jet 2007-12-20. Propulsion Laboratory. [33] O’Brien, D. P.; Geissler, P.; Greenberg, http://www2.jpl.nasa.gov/galileo/europa/ R. (Oct 2000). "Tidal Heat in Europa: Ice #overview. Retrieved on 2007-08-09. Thickness and the Plausibility of Melt[25] ^ Schenk, P. M.; Chapman, C. R.; Zahnle, K.; Moore, J. M.; Chapter 18: Through". Bull. Amer. Astron. Soc. 30: Ages and Interiors: the Cratering Record 1066. http://adsabs.harvard.edu/abs/ of the Galilean Satellites, in Jupiter: The 2000DPS....32.3802O. Planet, Satellites and Magnetosphere, [34] Richard Greenberg (2008). "Unmasking Cambridge University Press, 2004 Europa". http://www.springer.com/ [26] "High Tide on Europa". Astrobiology astronomy/book/978-0-387-47936-1. Magazine. astrobio.net. 2007. [35] ^ Greenberg, R.; Europa: The Ocean http://www.astrobio.net/news/ Moon: Search for an Alien Biosphere, article603.html. Retrieved on Springer Praxis Books, 2005 2007-10-20. [36] Greeley, R. et al.; Chapter 15: Geology of [27] P. E. Geissler, R. Greenberg et al. (1998). Europa, in Jupiter: The Planet, Satellites "Evolution of Lineaments on Europa: and Magnetosphere, Cambridge Clues from Galileo Multispectral Imaging University Press, 2004 Observations". [37] ^ Billings, S. E.; Kattenhorn, S. A. http://www.sciencedirect.com/ (2005). "The great thickness debate: Ice science?_ob=ArticleURL&_udi=B6WGF-45K1008-2F&_user=10&_rdoc=1&_fmt=&_orig=search&_so shell thickness models for Europa and Retrieved on 2007-12-20. comparisons with estimates based on [28] Patricio H. Figueredo and Ronald flexure at ridges". Icarus 177 (2): Greeley (2003). "Resurfacing history of 397–412. doi:10.1016/ Europa from pole-to-pole geological j.icarus.2005.03.013. mapping". http://www.sciencedirect.com/ [38] Zimmer, C.; Khurana, K. K. (2000). science?_ob=ArticleURL&_udi=B6WGF-4B28TH7-7&_user=10&_rdoc=1&_fmt=&_orig=search&_sor "Subsurface Oceans on Europa and Retrieved on 2007-12-20. Callisto: Constraints from Galileo [29] T.A. Hurford, A.R. Sarid and R. Magnetometer Observations" (PDF). Greenberg (2006). "Cycloidal cracks on Icarus 147: 329–347. doi:10.1006/ Europa: Improved modeling and nonicar.2000.6456. synchronous rotation implications". http://www.igpp.ucla.edu/people/

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Europa (moon)

mkivelson/Publications/ [47] Shematovich, V. I.; Cooper, J. F.; ICRUS147329.pdf. Johnson, R. E. (April 2003). "Surface[39] T. B. McCord, G. B. Hansen et al. (1998). bounded oxygen atmosphere of Europa". "Salts on Europa’s Surface Detected by EGS - AGU - EUG Joint Assembly Galileo’s Near Infrared Mapping (Abstracts from the meeting held in Nice, Spectrometer". France). http://adsabs.harvard.edu/abs/ http://www.sciencemag.org/cgi/content/ 2003EAEJA....13094S. Retrieved on abstract/280/5367/1242. Retrieved on 2007-08-10. 2007-12-20. [48] Liang, M. C.; Lane, B. F.; Pappalardo, R. [40] R.W. Carlson, M.S. Anderson (2005). T. et al. (2005). "Atmosphere of Callisto" "Distribution of hydrate on Europa: (PDF). Journal of Geophysics Research Further evidence for sulfuric acid 110: E02003. doi:10.1029/ hydrate". http://www.sciencedirect.com/ 2004JE002322. http://ylyscience?_ob=ArticleURL&_udi=B6WGF-4G9Y58G-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sor mac.gps.caltech.edu/ReprintsYLY/ Retrieved on 2007-12-20. N164Liang_Callisto%2005/ [41] Calvin, Wendy M.; Clark, Roger Liang_callisto_05.pdf. N.;Brown, Robert H.; and Spencer John [49] Smyth, W.H.; Marconi, M.L. (August 15, R. (1995). "Spectra of the ice Galilean 2007). "Processes Shaping Galilean satellites from 0.2 to 5 µm: A Satellite Atmospheres from the Surface compilation, new observations, and a to the Magnetosphere" (pdf) in recent summary". J.of Geophys. Res. Workshop on Ices, Oceans, and Fire: 100: 19,041–19,048. doi:10.1029/ Satellites of the Outer Solar System, 94JE03349. http://adsabs.harvard.edu/ Boulder, Colorado. Abstracts: 131-132. abs/1995JGR...10019041C. [50] Chyba and Hand, "Life without [42] Hall, D. T. et al.; Detection of an oxygen photosynthesis" [2] atmosphere on Jupiter’s moon Europa, [51] ^ Hand, Kevin P.; Carlson, Robert W.; Nature, Vol. 373 (23 February 1995), Chyba, Christopher F. (December 2007). 677–679 (accessed 15 April 2006) "Energy, Chemical Disequilibrium, and [43] Savage, Donald; Jones, Tammy; Villard, Geological Constraints on Europa". Ray (1995-02-23). "Hubble Finds Oxygen Astrobiology 7 (6): 1006-1022. Atmosphere on Europa". Project Galileo. doi:10.1089/ast.2007.0156. NASA, Jet Propulsion Laboratory. http://www.liebertonline.com/doi/abs/ http://www2.jpl.nasa.gov/galileo/europa/ 10.1089/ast.2007.0156. hst.html. Retrieved on 2007-08-17. [52] Smyth, W. H.; Marconi, M. L. (2006). [44] Kliore, A. J.; Hinson, D. P.; Flasar, F. M.; "Europa’s atmosphere, gas tori, and Nagy, A. F.; Cravens, T. E. (July 1997). magnetospheric implications". Icarus "The Ionosphere of Europa from Galileo 181: 510. doi:10.1016/ Radio Occultations". Science 277 (5324): j.icarus.2005.10.019. 355–358. doi:10.1126/ http://adsabs.harvard.edu/abs/ science.277.5324.355. PMID 9219689. 2006Icar..181..510S. http://www.sciencemag.org/cgi/content/ [53] Exotic Microbes Discovered near Lake abstract/277/5324/355. Retrieved on Vostok, Science@NASA (December 10, 2007-08-10. 1999) [45] "Galileo Spacecraft Finds Europa has [54] ^ Chandler, D. L. (2002-10-20). "Thin ice Atmosphere". Project Galileo. NASA, Jet opens lead for life on Europa". Propulsion Laboratory. July 1997. NewScientist.com. http://www2.jpl.nasa.gov/galileo/ http://www.newscientist.com/ status970718.html. Retrieved on article.ns?id=dn2929. 2007-08-10. [55] Jones, N.; Bacterial explanation for [46] Johnson, R. E.; Lanzerotti, L. J.; Brown, Europa’s rosy glow, NewScientist.com W. L. (1982). "Planetary applications of (11 December 2001) ion induced erosion of condensed-gas [56] Phillips, C.; Time for Europa, Space.com frosts". http://adsabs.harvard.edu/abs/ (28 September 2006) 1982NucIM.198..147J. Retrieved on [57] ^ Sean Chamberlin (1999). "Creatures 2007-12-20. Of The Abyss: Black Smokers and Giant Worms". Fullerton College.

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From Wikipedia, the free encyclopedia

Europa (moon)

http://earthscape.org/t2/chs01/chs01i/ [67] Goodman, J.; Re: Galileo at Europa, chs01ib.html. Retrieved on 2007-12-21. MadSci Network forums, September 9, [58] Dirk Schulze-Makuch and Louis N. Irwin 1998 (2001). "Alternative Energy Sources [68] McKay C. P. (2002). "Planetary Could Support Life on Europa" (PDF). protection for a Europa surface sample Departments of Geological and Biological return: The ice clipper mission". Sciences, University of Texas at El Paso. Advances in Space Research 30 (6): http://www.geo.utep.edu/pub/dirksm/ 1601–1605. doi:10.1016/ geobiowater/pdf/EOS27March2001.pdf. S0273-1177(02)00480-5. Retrieved on 2007-12-21. [69] Knight, W.; Ice-melting robot passes [59] Wilson, Colin P. (2007). "Tidal Heating Arctic test, NewScientist.com (14 on Io and Europa and its Implications for January 2002) Planetary Geophysics". Geology and [70] Bridges, A.; Latest Galileo Data Further Geography Dept, Vassar College. Suggest Europa Has Liquid Ocean, http://gsa.confex.com/gsa/2007NE/ Space.com (10 January 2000) finalprogram/abstract_117688.htm. [71] National Academy of Sciences Space Retrieved on 2007-12-21. Studies Board, Preventing the Forward [60] McCollom, T. M. (1999). Contamination of Europa, National "Methanogenesis as a potential source of Academy Press, Washington (DC), June chemical energy for primary biomass 29, 2000 production by autotrophic organisms in [72] . Powell, J.; Powell, J.; Maise, G.; and hydrothermal systems on Europa". Paniagua, J. (July 2005). "NEMO: A Woods Hole Oceanographic Institute. mission to search for and return to Earth http://adsabs.harvard.edu/abs/ possible life forms on Europa". Acta 1999JGR...10430729M. Retrieved on Astronautica 57 (2–8): 579–593. 2007-12-21. doi:10.1016/j.actaastro.2005.04.003. [61] ^ Giles M. Marion, Christian H. Fritsen, Hajo Eicken, Meredith C. Payne (2003). Further reading "The Search for Life on Europa: Limiting • Bagenal, Fran; Dowling, Timothy Edward; Environmental Factors, Potential McKinnon, William B (2004). Jupiter: The Habitats, and Earth Analogues". Planet, Satellites and Magnetosphere. Astrobiology. Cambridge University Press. ISBN http://www.liebertonline.com/doi/abs/ 0521818087. 10.1089/ • Rothery, David A. (1999). Satellites of the 153110703322736105?cookieSet=1&journalCode=ast. Outer Planets: Worlds in Their Own Right. Retrieved on 2007-12-21. Oxford University Press US. ISBN [62] David, L.; Europa Mission: Lost In NASA 019512555X. Budget, Space.com (7 February 2006) • Harland, David M. (2000). Jupiter [63] Muir, H.; Europa has raw materials for Odyssey: The Story of NASA’s Galileo life, NewScientist.com (22 May 2002) Mission. Springer. ISBN 1852333014. [64] ^ Berger, B.; NASA 2006 Budget Presented: Hubble, Nuclear Initiative Suffer Space.com (7 February 2005) [65] Rincon, Paul (2009-02-20). "Jupiter in • Europa, a Continuing Story of Discovery at space agencies’ sights". BBC News. NASA/JPL http://news.bbc.co.uk/1/hi/sci/tech/ • Europa Profile by NASA’s Solar System 7897585.stm. Retrieved on 2009-02-20. Exploration [66] "Cosmic Vision 2015–2025 Proposals". • The Calendars of Jupiter ESA. 2007-07-21. http://sci.esa.int/ • Are our nearest living neighbours on one science-e/www/object/ of Jupiter’s Moons? index.cfm?fobjectid=41177. Retrieved on 2009-02-20.

External links

Retrieved from "http://en.wikipedia.org/wiki/Europa_(moon)" Categories: Jupiter's moons, Europa

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From Wikipedia, the free encyclopedia

Europa (moon)

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