Europa ( moon ) - wikipedia Europa ( moon ) For other uses, see Europa. `` Jupiter II '' redirects here. For the spaceship in the 1960s television series Lost in Space, see Jupiter 2. For the airplane, see Bristol Jupiter. For other uses, see Jupiter ( disambiguation ). Europa Europa 's trailing hemisphere in approximate natural color. The prominent crater in the lower right is Pwyll and the darker regions are areas where Europa 's primarily water ice surface has a higher mineral content. Imaged on 7 September 1996 by Galileo spacecraft. Discovery Discovered by Galileo Galilei Simon Marius Discovery date 8 January 1610 Designations Alternative names Jupiter II Adjectives Europan Orbital characteristics Epoch 8 January 2004 Periapsis 7008664862000000000 ♠ 664 862 km Apoapsis 7008676938000000000 ♠ 676 938 km Mean orbit radius 7008670900000000000 ♠ 670 900 km Eccentricity 0.009 Orbital period 7005306822038400000 ♠ 3.551 181 d Average orbital speed 7004137400000000000 ♠ 13.740 km / s Inclination 0.470 ° ( to Jupiter 's equator ) 1.791 ° ( to the ecliptic ) Satellite of Jupiter Physical characteristics Mean radius 7006156080000000000 ♠ 1560. 8 ± 0.5 km ( 0.245 Earths ) Surface area 7013309000000000000 ♠ 3.09 × 10 km ( 0.061 Earths ) Volume 7019159300000000000 ♠ 1.593 × 10 km ( 0.015 Earths ) Mass 7022479984400000000 ♠ ( 4.799 844 ± 0.000 013 ) × 10 kg ( 0.008 Earths ) Mean density 7003301300000000000 ♠ 3.013 ± 0.005 g / cm Surface gravity 7000131400000000000 ♠ 1.314 m / s ( 0.134 g ) Moment of inertia factor 6999346000000000000 ♠ 0.346 ± 0.005 ( estimate ) Escape velocity 7003202500000000000 ♠ 2.025 km / s Rotation period Synchronous Axial tilt 0.1 ° Albedo 0.67 ± 0.03 Surface temp. min mean max Surface ≈ 50 K 102 K ( − 171.15 ° C ) 125 K Apparent magnitude 5.29 ( opposition ) Atmosphere Surface pressure 0.1 μPa ( 10 bar ) Europa / jʊəˈroʊpə / ( listen ) yoor - OH - pə ( Jupiter II ) is the smallest of the four Galilean moons orbiting Jupiter, and the sixth - closest to the planet. It is also the sixth - largest moon in the Solar System. Europa was discovered in 1610 by Galileo Galilei and was named after Europa, the legendary mother of King Minos of Crete and lover of Zeus ( the Greek equivalent of the Roman god Jupiter ). Slightly smaller than Earth 's Moon, Europa is primarily made of silicate rock and has a water - ice crust and probably an iron -- nickel core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is striated by cracks and streaks, whereas craters are relatively rare. In addition to Earth - bound telescope observations, Europa has been examined by a succession of space probe flybys, the first occurring in the early 1970s. Europa has the smoothest surface of any known solid object in the Solar System. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably harbor extraterrestrial life. The predominant model suggests that heat from tidal flexing causes the ocean to remain liquid and drives ice movement similar to plate tectonics, absorbing chemicals from the surface into the ocean below. Sea salt from a subsurface ocean may be coating some geological features on Europa, suggesting that the ocean is interacting with the seafloor. This may be important in determining if Europa could be habitable. In addition, the Hubble Space Telescope detected water vapor plumes similar to those observed on Saturn 's moon Enceladus, which are thought to be caused by erupting cryogeysers. In May 2018, astronomers provided supporting evidence of water plume activity on Europa, based on an updated critical analysis of data obtained from the Galileo space probe, which orbited Jupiter between 1995 to 2003. Such plume activity could help researchers in a search for life from the subsurface European ocean without having to land on the moon. The Galileo mission, launched in 1989, provides the bulk of current data on Europa. No spacecraft has yet landed on Europa, although there have been several proposed exploration missions. The European Space Agency 's Jupiter Icy Moon Explorer ( JUICE ) is a mission to Ganymede that is due to launch in 2022, and will include two flybys of Europa. NASA 's planned Europa Clipper will be launched in the mid-2020s. Contents 1 Discovery and naming 2 Orbit and rotation 3 Physical characteristics 3.1 Internal structure 3.2 Surface features 3.2. 1 Lineae 3.2. 2 Other geological features 3.3 Subsurface ocean 3.3. 1 Composition 3.3. 2 Sources of heat 3.3. 3 Plumes 3.4 Atmosphere 4 Exploration 4.1 Future missions 4.2 Old proposals 5 Habitability potential 6 See also 7 Notes 8 References 8.1 Further reading 9 External links Discovery and naming Europa, along with Jupiter 's three other large moons, Io, Ganymede, and Callisto, was discovered by Galileo Galilei on 8 January 1610, and possibly independently by Simon Marius. The first reported observation of Io and Europa was made by Galileo Galilei on 7 January 1610 using a 20 × - magnification refracting telescope at the University of Padua. However, in that observation, Galileo could not separate Io and Europa due to the low magnification of his telescope, so that the two were recorded as a single point of light. The following day, 8 January 1610 ( used as the discovery date for Europa by the IAU ), Io and Europa were seen for the first time as separate bodies during Galileo 's observations of the Jupiter system. Europa is named after Europa, daughter of the king of Tyre, a Phoenician noblewoman in Greek mythology. Like all the Galilean satellites, Europa is named after a lover of Zeus, the Greek counterpart of Jupiter. Europa was courted by Zeus and became the queen of Crete. The naming scheme was suggested by Simon Marius, who discovered the four satellites independently. Marius attributed the proposal to Johannes Kepler. The names fell out of favor for a considerable time and were not revived in general use until the mid-20th century. In much of the earlier astronomical literature, Europa is simply referred to by its Roman numeral designation as Jupiter II ( a system also 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. Orbit and rotation Animation showing Io 's Laplace resonance with Europa and Ganymede Europa orbits Jupiter in just over three and a half days, with an orbital radius of about 670,900 km. With an eccentricity of only 0.009, the orbit itself is nearly circular, and the orbital inclination relative to Jupiter 's equatorial plane is small, at 0.470 °. Like its fellow Galilean satellites, Europa is tidally locked to Jupiter, with one hemisphere of Europa constantly facing Jupiter. Because of this, there is a sub-Jovian point on Europa 's surface, from which Jupiter would appear to hang directly overhead. Europa 's prime meridian is the line intersecting this point. Research suggests that the tidal locking may not be full, as a non-synchronous rotation has been proposed : Europa spins faster than it orbits, or at least did so in the past. This suggests an asymmetry in internal mass distribution and that a layer of subsurface liquid separates the icy crust from the rocky interior. The slight eccentricity of Europa 's orbit, maintained by the gravitational disturbances from the other Galileans, causes Europa 's sub-Jovian point to oscillate around a mean position. As Europa comes slightly nearer to Jupiter, Jupiter 's gravitational attraction increases, causing Europa to elongate towards and away from it. As Europa moves slightly away from Jupiter, Jupiter 's gravitational force decreases, causing Europa to relax back into a more spherical shape, and creating tides in its ocean. The orbital eccentricity of Europa is continuously pumped by its mean - motion resonance with Io. Thus, the tidal flexing kneads Europa 's interior and gives it a source of heat, possibly allowing its ocean to stay liquid while driving subsurface geological processes. The ultimate source of this energy is Jupiter 's rotation, which is tapped by Io through the tides it raises on Jupiter and is transferred to Europa and Ganymede by the orbital resonance. Scientists analyzing the unique cracks lining Europa found evidence showing that it likely spun around a tilted axis at some point in time. If correct, this would explain many of Europa 's features. Europa 's immense network of crisscrossing cracks serves as a record of the stresses caused by massive tides in its global ocean. Europa 's tilt could influence calculations of how much of its history is recorded in its frozen shell, how much heat is generated by tides in its ocean, and even how long the ocean has been liquid. Its ice layer must stretch to accommodate these changes. When there is too much stress, it cracks. A tilt in Europa 's axis could suggest that its cracks may be much more recent than previously thought. The reason is that the direction of the spin pole may change by as much as a few degrees per day, completing one precession period over several months. A tilt also could affect the estimates of the age of Europa 's ocean. Tidal forces are thought to generate the heat that keeps Europa 's ocean liquid, and a tilt in the spin axis means that more heat is generated by tidal forces. This heat helps the ocean to remain liquid longer. Scientists did not specify when the tilt would have occurred and measurements have not been made of the tilt of Europa 's axis. Physical characteristics Size comparison of Europa ( lower left ) with the Moon ( top left ) and Earth ( right ) Europa is slightly smaller than the Moon. At just over 3,100 kilometres ( 1,900 mi ) in diameter, it is the sixth - largest moon and fifteenth - largest object in the Solar System. Though by a wide margin the least massive of the Galilean satellites, it is nonetheless more massive than all known moons in the Solar System smaller than itself combined. Its bulk density suggests that it is similar in composition to the terrestrial planets, being primarily composed of silicate rock. Internal structure It is estimated that Europa has an outer layer of water around 100 km ( 62 mi ) thick ; a part frozen as its crust, and a part as a 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. This layer is likely a salty liquid - water ocean. Portions of the crust are estimated to have undergone a rotation of nearly 80 °, nearly flipping over ( see true polar wander ), which would be unlikely if the ice were solidly attached to the mantle. Europa probably contains a metallic iron core. Surface features Approximate natural color ( left ) and enhanced color ( right ) Galileo view of leading hemisphere Europa is the smoothest known object in the Solar System, lacking large - scale features such as mountains and craters. However ; according to one theory, Europa 's equator may be covered in icy spikes called penitentes, which may be up to ten meters high, due to direct overhead sunlight on the equator, causing the ice to sublime forming vertical cracks. The prominent markings crisscrossing Europa appear to mainly be albedo features that emphasize low topography. There are few craters on Europa, because its surface is tectonically too active and therefore young. Europa 's icy crust has an albedo ( light reflectivity ) of 0.64, one of the highest of all moons. This indicates a young and active surface, based on estimates of the frequency of cometary bombardment that Europa likely experiences, the surface is about 20 to 180 million years old. There is currently no full scientific consensus among the sometimes contradictory explanations for the surface features of Europa. The radiation level at the surface of Europa is equivalent to a dose of about 5400 mSv ( 540 rem ) per day, an amount of radiation that would cause severe illness or death in human beings exposed for a single day. Lineae See also : List of lineae on Europa Realistic - color Galileo mosaic of Europa 's anti-Jovian hemisphere showing numerous lineae. Enhanced - color view showing the intricate pattern of linear fractures on Europa 's surface. 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. The most likely hypothesis states that the lineae on Europa may have been produced by a series of eruptions of warm ice as the Europan crust spread open to expose warmer layers beneath. The effect would have been similar to that seen in Earth 's oceanic ridges. These various fractures are thought to have been caused in large part by the tidal flexing exerted by Jupiter. Because Europa is tidally locked to Jupiter, and therefore always maintains the same approximate orientation towards Jupiter, 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 are. This could be explained if Europa 's surface rotates slightly faster than its interior, an effect that is possible due to the subsurface ocean mechanically decoupling Europa 's surface from its rocky mantle and the effects of Jupiter 's gravity tugging on Europa 's outer ice crust. 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. Studies of Voyager and Galileo images have revealed evidence of subduction on Europa 's surface, suggesting that, just as the cracks are analogous to ocean ridges, so plates of icy crust analogous to tectonic plates on Earth are recycled into the molten interior. Together, the evidence for crustal spreading at bands and convergence at other sites marks the first evidence for plate tectonics on any world other than Earth. Other geological features See also : List of geological features on Europa Left : surface features indicative of tidal flexing : lineae, lenticulae and the Conamara Chaos region ( close - up, right ) where craggy, 250 m high peaks and smooth plates are jumbled together. 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. 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 Earth 's crust. The smooth, dark spots could be formed by meltwater released when the warm ice breaks through the surface. The rough, jumbled lenticulae ( called regions of `` chaos '' ; for example, Conamara Chaos ) would then be formed from many small fragments of crust, embedded in hummocky, dark material, appearing like icebergs in a frozen sea. 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. In November 2011, a team of researchers from the University of Texas at Austin and elsewhere presented evidence in the journal Nature suggesting that many `` chaos terrain '' features on Europa sit atop vast lakes of liquid water. These lakes would be entirely encased in Europa 's icy outer shell and distinct from a liquid ocean thought to exist farther down beneath the ice shell. Full confirmation of the lakes ' existence will require a space mission designed to probe the ice shell either physically or indirectly, for example, using radar. Subsurface ocean Two possible models of Europa Scientists ' consensus is that a layer of liquid water exists beneath Europa 's surface, and that heat from tidal flexing allows the subsurface ocean to remain liquid. 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. 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. 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 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. The best evidence for the 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 ; based on this and on the calculated amount of heat generated by Europan tides, it is estimated 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. This leads to a volume of Europa 's oceans of 3 × 10 m, between two or three times the volume of Earth 's oceans. The 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 that behave elastically when affected by Jupiter 's tides. One example is flexure analysis, in which Europa '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. Composition 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. The existence of the induced moment requires a layer of a highly electrically conductive material in Europa 's interior. The most plausible candidate for this role is a large subsurface ocean of liquid saltwater. Since the Voyager spacecraft flew past Europa in 1979, scientists have worked to understand the composition of the reddish - brown material that coats fractures and other geologically youthful features on Europa 's surface. 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. Sulfuric acid hydrate is another possible explanation for the contaminant observed spectroscopically. In either case, because 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. Another hypothesis for the colored regions is that they are composed of abiotic organic compounds collectively called tholins. The morphology of Europa 's impact craters and ridges is suggestive of fluidized material welling up from the fractures where pyrolysis and radiolysis take place. In order to generate colored tholins on Europa there must be a source of materials ( carbon, nitrogen, and water ) and a source of energy to make the reactions occur. Impurities in the water ice crust of Europa are presumed both to emerge from the interior as cryovolcanic events that resurface the body, and to accumulate from space as interplanetary dust. Tholins bring important astrobiological implications, as they may play a role in prebiotic chemistry and abiogenesis. Sources of heat Tidal heating occurs through the tidal friction and tidal flexing processes caused by tidal acceleration : orbital and rotational energy are dissipated as heat in the core of the moon, the internal ocean, and the ice crust. Tidal friction Ocean tides are converted to heat by frictional losses in the oceans and their interaction with the solid bottom and with the top ice crust. In late 2008, it was suggested Jupiter may keep Europa 's oceans warm by generating large planetary tidal waves on Europa because of its small but non-zero obliquity. This generates so - called Rossby waves that travel quite slowly, at just a few kilometers per day, but can generate significant kinetic energy. For the current axial tilt estimate of 0.1 degree, the resonance from Rossby waves would contain 7.3 × 10 J of kinetic energy, which is two thousand times larger than that of the flow excited by the dominant tidal forces. Dissipation of this energy could be the principal heat source of Europa 's ocean. Tidal flexing Tidal flexing kneads Europa 's interior and ice shell, which becomes a source of heat. Depending on the amount of tilt, the heat generated by the ocean flow could be 100 to thousands of times greater than the heat generated by the flexing of Europa 's rocky core in response to gravitational pull from Jupiter and the other moons circling that planet. Europa 's seafloor could be heated by the moon 's constant flexing, driving hydrothermal activity similar to undersea volcanoes in Earth 's oceans. Experiments and ice modeling published in 2016, indicate that tidal flexing dissipation can generate one order of magnitude more heat in Europa 's ice than scientists had previously assumed. Their results indicates that most of the heat generated by the ice actually comes from the ice 's crystalline structure ( lattice ) as a result of deformation, and not friction between the ice grains. The greater the deformation of the ice sheet, the more heat is generated. Radioactive decay In addition to tidal heating, the interior of Europa could also be heated by the decay of radioactive material ( radiogenic heating ) within the rocky mantle. But the models and values observed are one hundred times higher than those that could be produced by radiogenic heating alone, thus implying that tidal heating has a leading role in Europa. Plumes Water plumes on Europa detected by the Galileo space probe. Photo composite of suspected water plumes on Europa. The Hubble Space Telescope acquired an image of Europa in 2012 that was interpreted to be a plume of water vapour erupting from near its south pole. The image suggests the plume may be 200 km ( 120 mi ) high, or more than 20 times the height of Mt. Everest. It has been suggested that if they exist, they are episodic and likely to appear when Europa is at its farthest point from Jupiter, in agreement with tidal force modeling predictions. Additional imaging evidence from the Hubble Space Telescope was presented in September 2016. In May 2018, astronomers provided supporting evidence of water plume activity on Europa, based on an updated critical analysis of data obtained from the Galileo space probe, which orbited Jupiter between 1995 to 2003. Galileo flew by Europa in 1997 within 206 km ( 128 mi ) of the moon 's surface and the researchers suggest it may have flown through a water plume. Such plume activity could help researchers in a search for life from the subsurface European ocean without having to land on the moon. The tidal forces are about 1,000 times stronger than the Moon 's effect on Earth. The only other moon in the Solar System exhibiting water vapor plumes is Enceladus. The estimated eruption rate at Europa is about 7000 kg / s compared to about 200 kg / s for the plumes of Enceladus. If confirmed, it would open the possibility of a flyby through the plume and obtain a sample to analyze in situ without having to use a lander and drill through miles of ice. Atmosphere Observations with the Goddard High Resolution Spectrograph of the Hubble Space Telescope, first described in 1995, revealed that Europa has a thin atmosphere composed mostly of molecular oxygen ( O ). The surface pressure of Europa 's atmosphere is 0.1 μPa, or 10 times that of the Earth. In 1997, the Galileo spacecraft confirmed the presence of a tenuous ionosphere ( an upper - atmospheric layer of charged particles ) around Europa created by solar radiation and energetic particles from Jupiter 's magnetosphere, providing evidence of an atmosphere. Magnetic field around Europa. The red line shows a trajectory of the Galileo spacecraft during a typical flyby ( E4 or E14 ). 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. 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. 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. 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. 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. The molecular hydrogen that escapes Europa 's gravity, along with atomic and molecular oxygen, forms a gas torus 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 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. Exploration In 1973 Pioneer 10 made the first closeup images of Europa -- however the probe was too far away to obtain more detailed images Europa seen in detail in 1979 by Voyager 2 Exploration of Europa began with the Jupiter flybys of Pioneer 10 and 11 in 1973 and 1974 respectively. The first closeup photos were of low resolution compared to later missions. The two Voyager probes traveled through the Jovian system in 1979, providing more - detailed images of Europa 's icy surface. The images caused many scientists to speculate about the possibility of a liquid ocean underneath. Starting in 1995, the Galileo spaceprobe orbited Jupiter for eight years, until 2003, and provided the most detailed examination of the Galilean moons to date. It included the `` Galileo Europa Mission '' and `` Galileo Millennium Mission '', with numerous close flybys of Europa. In 2007, New Horizons imaged Europa, as it flew by the Jovian system while on its way to Pluto. Future missions Conjectures regarding extraterrestrial life have ensured a high - profile for Europa and have led to steady lobbying for future missions. The aims of these missions have ranged from examining Europa 's chemical composition to searching for extraterrestrial life in its hypothesized subsurface oceans. Robotic missions to Europa need to endure the high - radiation environment around itself and Jupiter. Europa receives about 5.40 Sv of radiation per day. In 2011, a Europa mission was recommended by the U.S. Planetary Science Decadal Survey. In response, NASA commissioned Europa lander concept studies in 2011, along with concepts for a Europa flyby ( Europa Clipper ), and a Europa orbiter. The orbiter element option concentrates on the `` ocean '' science, while the multiple - flyby element ( Clipper ) concentrates on the chemistry and energy science. On 13 January 2014, the House Appropriations Committee announced a new bipartisan bill that includes $80 million funding to continue the Europa mission concept studies. In 2012, Jupiter Icy Moon Explorer ( JUICE ) was selected by the European Space Agency ( ESA ) as a planned mission. That mission includes 2 flybys of Europa, but is more focused on Ganymede. Europa Clipper -- In July 2013 an updated concept for a flyby Europa mission called Europa Clipper was presented by the Jet Propulsion Laboratory ( JPL ) and the Applied Physics Laboratory ( APL ). In May 2015, NASA announced that it had accepted development of the Europa Clipper mission, and revealed the instruments it will use. The aim of Europa Clipper is to explore Europa in order to investigate its habitability, and to aid selecting sites for a future lander. The Europa Clipper would not orbit Europa, but instead orbit Jupiter and conduct 45 low - altitude flybys of Europa during its envisioned mission. The probe would carry an ice - penetrating radar, short - wave infrared spectrometer, topographical imager, and an ion - and neutral - mass spectrometer. Europa Lander ( NASA ) is a recent concept mission under study. Old proposals Left : artist 's concept of the cryobot and its deployed ' hydrobot ' submersible. Right : Europa Lander Mission concept, NASA 2005 In the early 2000s, Jupiter Europa Orbiter led by NASA and the Jupiter Ganymede Orbiter led by the ESA were proposed together as an Outer Planet Flagship Mission to Jupiter 's icy moons called Europa Jupiter System Mission, with a planned launch in 2020. In 2009 it was given priority over Titan Saturn System Mission. At that time, there was competition from other proposals. Japan proposed Jupiter Magnetospheric Orbiter. Jovian Europa Orbiter was an ESA Cosmic Vision concept study from 2007. Another concept was Ice Clipper, which 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 that would then be collected by a small spacecraft flying through the plume. Jupiter Icy Moons Orbiter ( JIMO ) was a partially developed fission - powered spacecraft with ion thrusters that was cancelled in 2006. It was part of Project Prometheus. The Europa Lander Mission proposed a small nuclear - powered Europa lander for JIMO. It would travel with the orbiter, which would also function as a communication relay to Earth. Europa Orbiter -- Its objective would be to characterize the extent of the ocean and its relation to the deeper interior. Instrument payload could include a radio subsystem, laser altimeter, magnetometer, Langmuir probe, and a mapping camera. The Europa Orbiter received a go - ahead in 1999 but was canceled in 2002. This orbiter featured a special ice - penetrating radar that would allow it to scan below the surface. More ambitious ideas have been put forward including an impactor in combination with a thermal drill to search for biosignatures that might be frozen in the shallow subsurface. Another proposal put forward in 2001 calls for a large nuclear - powered `` melt probe '' ( cryobot ) that would melt through the ice until it reached an ocean below. Once it reached the water, it would deploy an autonomous underwater vehicle ( hydrobot ) that would gather information and send it back to Earth. 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. This suggested approach has not yet reached a formal conceptual planning stage. Habitability Potential A black smoker in the Atlantic Ocean. Driven by geothermal energy, this and other types of hydrothermal vents create chemical disequilibria that can provide energy sources for life. So far, there is no evidence that life exists on Europa, but Europa has emerged as one of the most likely locations in the Solar System for potential habitability. Life could exist in its under - ice ocean, perhaps in an environment similar to Earth 's deep - ocean hydrothermal vents. Even if Europa lacks volcanic hydrothermal activity, a 2016 NASA study found that Earth - like levels of hydrogen and oxygen could be produced through processes related to serpentinization and ice - derived oxidants, which do not directly involve volcanism. In 2015, scientists announced that salt from a subsurface ocean may likely be coating some geological features on Europa, suggesting that the ocean is interacting with the seafloor. This may be important in determining if Europa could be habitable. The likely presence of liquid water in contact with Europa 's rocky mantle has spurred calls to send a probe there. Europa -- possible effect of radiation on biosignature chemicals 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. Although 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. Life on Europa could exist clustered around hydrothermal vents on the ocean floor, or below the ocean floor, where endoliths are known to inhabit on Earth. Alternatively, it could exist clinging to the lower surface of Europa 's ice layer, much like algae and bacteria in Earth 's polar regions, or float freely in Europa 's ocean. If Europa 's ocean is too cold, biological processes similar to those known on Earth could not take place. If it is too salty, only extreme halophiles could survive in that environment. In 2010, a model proposed by Richard Greenberg of the University of Arizona proposed that irradiation of ice on Europa 's surface could saturate its crust with oxygen and peroxide, which could then be transported via tectonic processes into the interior ocean. Such a process could render Europa 's ocean as oxygenated as our own within just 12 million years, allowing for the existence of complex, multicellular lifeforms. Evidence suggests the existence of lakes of liquid water entirely encased in Europa 's icy outer shell and distinct from a liquid ocean thought to exist farther down beneath the ice shell. If confirmed, the lakes could be yet another potential habitat for life. Evidence suggests that hydrogen peroxide is abundant across much of the surface of Europa. Because hydrogen peroxide decays into oxygen and water when combined with liquid water, the authors argue that it could be an important energy supply for simple life forms. Clay - like minerals ( specifically, phyllosilicates ), often associated with organic matter on Earth, have been detected on the icy crust of Europa. The presence of the minerals may have been the result of a collision with an asteroid or comet. Some scientists have speculated that life on Earth could have been blasted into space by asteroid collisions and arrived on the moons of Jupiter in a process called lithopanspermia. See also Solar System portal Astrobiology portal Astronomy portal Colonization of Europa Jupiter 's moons in fiction List of craters on Europa List of geological features on Europa List of lineae on Europa Snowball Earth hypothesis Notes Jump up ^ Periapsis is derived from the semimajor axis ( a ) and eccentricity ( e ) : a ( 1 − e ). Jump up ^ Apoapsis is derived from the semimajor axis ( a ) and eccentricity ( e ) : a ( 1 + e ). Jump up ^ Surface area derived from the radius ( r ) : 4πr Jump up ^ Volume derived from the radius ( r ) : / πr Jump up ^ Surface gravity derived from the mass ( m ), the gravitational constant ( G ) and the radius ( r ) : Gm / r Jump up ^ Escape velocity derived from the mass ( m ), the gravitational constant ( G ) and the radius ( r ) : 2 G m r ( displaystyle \textstyle ( sqrt ( \frac ( 2Gm ) ( r ) ) ) ) References ^ Jump up to : Blue, Jennifer ( 9 November 2009 ). `` Planet and Satellite Names and Discoverers ''. USGS. ^ Jump up to : `` Overview of Europa Facts ''. NASA. Archived from the original on 26 March 2014. Retrieved 27 December 2007. Jump up ^ `` JPL HORIZONS solar system data and ephemeris computation service ''. Solar System Dynamics. NASA, Jet Propulsion Laboratory. Retrieved 10 August 2007. ^ Jump up to : Yeomans, Donald K. 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( 15 April 2010 ). `` Dual Drill Designed for Europa 's Ice ''. Astrobiology Magazine. Archived from the original on 18 April 2010. Jump up ^ Knight, Will ( 14 January 2002 ). `` Ice - melting robot passes Arctic test ''. New Scientist. Jump up ^ Bridges, Andrew ( 10 January 2000 ). `` Latest Galileo Data Further Suggest Europa Has Liquid Ocean ''. Space.com. Archived from the original on 8 February 2009. Jump up ^ Preventing the Forward Contamination of Europa. National Academy of Sciences Space Studies Board. Washington ( DC ) : National Academy Press. 2000. ISBN 0 - 309 - 57554 - 0. Archived from the original on 13 February 2008. Jump up ^ Powell, Jesse ; Powell, James ; Maise, George ; Paniagua, John ( 2005 ). `` NEMO : A mission to search for and return to Earth possible life forms on Europa ''. Acta Astronautica. 57 ( 2 -- 8 ) : 579 -- 593. Bibcode : 2005AcAau... 57... 579P. doi : 10.1016 / j. actaastro. 2005.04. 003. Jump up ^ Schulze - Makuch, Dirk ; Irwin, Louis N. ( 2001 ). `` Alternative Energy Sources Could Support Life on Europa '' ( PDF ). Departments of Geological and Biological Sciences, University of Texas at El Paso. Archived from the original ( PDF ) on 3 July 2006. Retrieved 21 December 2007. Jump up ^ Jones, Nicola ( 11 December 2001 ). `` Bacterial explanation for Europa 's rosy glow ''. New Scientist. Retrieved 26 September 2016. Jump up ^ `` Europa 's Ocean May Have An Earthlike Chemical Balance '', Jpl.nasa.gov, retrieved 18 May 2016 Jump up ^ Wall, Mike ( 9 June 2015 ). `` NASA Aiming for Multiple Missions to Jupiter Moon Europa ''. Space.com. Retrieved 10 June 2015. Jump up ^ Phillips, Cynthia ( 28 September 2006 ) Time for Europa, Space.com. Jump up ^ Wilson, Colin P. ( 2007 ). `` Tidal Heating on Io and Europa and its Implications for Planetary Geophysics ''. Geology and Geography Dept., Vassar College. Retrieved 21 December 2007. ^ Jump up to : Marion, Giles M. ; Fritsen, Christian H. ; Eicken, Hajo ; Payne, Meredith C. ( 2003 ). `` The Search for Life on Europa : Limiting Environmental Factors, Potential Habitats, and Earth Analogues ''. Astrobiology. 3 ( 4 ) : 785 -- 811. Bibcode : 2003AsBio... 3... 785M. doi : 10.1089 / 153110703322736105. PMID 14987483. Jump up ^ Richard Greenberg ( May 2010 ). `` Transport Rates of Radiolytic Substances into Europa 's Ocean : Implications for the Potential Origin and Maintenance of Life ''. Astrobiology. 10 ( 3 ) : 275 -- 283. Bibcode : 2010AsBio... 10... 275G. doi : 10.1089 / ast. 2009.0386. Jump up ^ NASA -- Mapping the Chemistry Needed for Life at Europa Archived 8 April 2013 at the Wayback Machine... Nasa.gov ( 4 April 2013 ). Retrieved on 23 July 2013. ^ Jump up to : Cook, Jia - Rui c. ( 11 December 2013 ). `` Clay - Like Minerals Found on Icy Crust of Europa ''. NASA. Jump up ^ Choi, Charles Q. ( 8 December 2013 ). `` Life Could Have Hitched a Ride to Outer Planet Moons ''. Astrobiology Magazine. Astrobiology Web. Further reading Rothery, David A. ( 1999 ). Satellites of the Outer Planets : Worlds in Their Own Right. Oxford University Press US. ISBN 0 - 19 - 512555 - X. Harland, David M. ( 2000 ). Jupiter Odyssey : The Story of NASA 's Galileo Mission. Springer. ISBN 1 - 85233 - 301 - 4. Greenberg, Richard ( 2005 ). EUROPA The Ocean Moon. Springer. ISBN 3 - 540 - 22450 - 5. External links Wikimedia Commons has media related to Europa ( moon ). Europa Profile at NASA Europa Facts at The Nine Planets Europa Facts at Views of the Solar System Preventing Forward Contamination of Europa -- USA Space Studies Board ( 2000 ) Images of Europa at JPL 's Planetary Photojournal Movie of Europa 's rotation from the National Oceanic and Atmospheric Administration Europa map with feature names from Planetary Photojournal Europa nomenclature and Paul Schenk 's 3D images and flyover videos of Europa and other outer Solar System satellites ; see also Large, high - resolution Galileo image mosaics of Europan terrain from Jason Perry at JPL : 1, 2, 3, 4, 5, 6, 7 Europa image montage from Galileo spacecraft NASA View of Europa from Galileo flybys Google Europa 3D, interactive map of the moon Natural satellites of the Solar System Moons of Earth, Mars and the Asteroids Earth Mars Asteroid moons The Moon Phobos Deimos Binaries List Moons of Jupiter Listed in approximately increasing distance from Jupiter. Provisional designations in italics. Inner moons Metis Adrastea Amalthea Thebe Galilean moons Io Europa Ganymede Callisto Themisto group Themisto Himalia group Leda Himalia S / 2018 J 1 S / 2017 J 4 Lysithea Elara Dia Carpo group Carpo S / 2016 J 2 group S / 2016 J 2 Ananke group S / 2003 J 12 ( ? ) Euporie Jupiter LX Jupiter LV Jupiter LII Thelxinoe Euanthe Helike Orthosie S / 2017 J 7 Jupiter LIV S / 2017 J 3 Iocaste S / 2003 J 16 Praxidike Harpalyke Mneme Hermippe Thyone S / 2017 J 9 Ananke Carme group S / 2011 J 1 ( ? ) Herse Aitne Kale Taygete S / 2003 J 19 Chaldene S / 2003 J 10 ( ? ) Erinome Kallichore S / 2017 J 5 S / 2017 J 8 Kalyke Carme S / 2017 J 2 Pasithee Jupiter LI Eukelade Arche Isonoe S / 2003 J 9 Jupiter LVII Pasiphae group S / 2017 J 6 Jupiter LVIII S / 2003 J 23 Aoede Callirrhoe Eurydome Kore Cyllene Jupiter LVI Jupiter LIX S / 2003 J 4 ( ? ) Pasiphae Hegemone Sinope Sponde Autonoe Megaclite S / 2003 J 2 ( ? ) Rings of Jupiter In fiction Moons of Saturn Listed in approximately increasing distance from Saturn. Temporary names in italics. Ring shepherds S / 2009 S 1 Ring moonlets Pan Daphnis Atlas Prometheus Pandora Co-orbitals Epimetheus Janus G Ring Aegaeon Mimas and Alkyonides Mimas Methone Anthe Pallene Inner large ( with trojans ) Enceladus Tethys Telesto Calypso Dione Helene Polydeuces Outer large Rhea Titan Hyperion Iapetus Inuit group Kiviuq Ijiraq Paaliaq Siarnaq Tarqeq Norse group Phoebe Skathi S / 2007 S 2 ( ? ) Skoll S / 2004 S 13 ( ? ) Greip Hyrrokkin Jarnsaxa Mundilfari S / 2006 S 1 ( ? ) S / 2004 S 17 ( ? ) Bergelmir Narvi Suttungr Hati S / 2004 S 12 ( ? ) Farbauti Thrymr Aegir S / 2007 S 3 ( ? ) Bestla S / 2004 S 7 ( ? ) S / 2006 S 3 Fenrir Surtur Kari Ymir Loge Fornjot Gallic group Albiorix Bebhionn Erriapus Tarvos Rings of Saturn Cassini -- Huygens Themis Chiron S / 2004 S 6 S / 2004 S 4 S / 2004 S 3 In fiction Moons of Uranus Generally listed in increasing distance from Uranus Inner Rings of Uranus Cordelia Ophelia Bianca Cressida Desdemona Juliet Portia Rosalind Cupid Belinda Perdita Puck Mab Major ( spheroid ) Miranda Ariel Umbriel Titania Oberon Outer ( irregular ) Francisco Caliban Stephano Trinculo Sycorax Margaret Prospero Setebos Ferdinand Geological features Arielian Kachina Chasmata Yangoor Mirandian Verona Rupes Oberonian Hamlet Mommur Chasma Puckian Titanian Gertrude Messina Chasmata Ursula Rousillon Rupes Umbrielian Wunda Vuver Skynd Moons of Neptune Generally listed in increasing distance from Neptune Regular ( inner ) Naiad Thalassa Despina Galatea Larissa S / 2004 N 1 Proteus Triton Triton ( Atmosphere Geological features Sky ) Irregular Nereid Halimede Sao Laomedeia Psamathe Neso See also Neptune trojans Rings of Neptune Book Category Portal Moons of dwarf planets Official dwarf planets Pluto Haumea Makemake Eris Charon Styx Nix Kerberos Hydra Namaka Hiʻiaka S / 2015 ( 136472 ) 1 Dysnomia Likely dwarf planets Orcus Quaoar ( 55637 ) 2002 UX 25 ( 229762 ) 2007 UK 126 ( 208996 ) 2003 AZ 84 Salacia Varda Huya Vanth Weywot S / 2007 ( 55637 ) 1 S / 2008 ( 229762 ) 1 S / 2005 ( 208996 ) 1 ( unrecovered ) Actaea Ilmarë S / 2012 ( 38628 ) 1 Natural satellites of the Solar System Planetary satellites Terrestrial Martian Jovian Saturnian Uranian Neptunian Other satellites Minor - planet moons Plutonian Haumean Makemakean Eridian Largest satellites ( mean radius ≥ 100 km ) size Ganymede largest / 2634 km / 0.413 Earths Titan Callisto Io Moon Europa Triton Titania Rhea Oberon Iapetus Charon Umbriel Ariel Dione Tethys ( Dysnomia ) Enceladus Miranda Proteus Mimas ( Hi'iaka ) Nereid Hyperion Phoebe abc 's Ariel Callisto Charon Dione ( Dysnomia ) Enceladus Europa Ganymede ( Hi'iaka ) Hyperion Iapetus Io Mimas Miranda Moon Nereid Oberon Phoebe Proteus Rhea Tethys Titan Titania Triton Umbriel Discovery timeline Inner moons Irregular moons List Naming Regular moons Trojan moons NOTE : Italicized moons are not close to being in hydrostatic equilibrium ; ( bracketed ) moons may or may not be close to being in hydrostatic equilibrium. Regular moons Inner moons Irregular moons Trojan moons Discovery timeline List Naming Natural satellites of the Solar System Planetary satellites Terrestrial Martian Jovian Saturnian Uranian Neptunian Other satellites Minor - planet moons Plutonian Haumean Makemakean Eridian Largest satellites ( mean radius ≥ 100 km ) size Ganymede largest / 2634 km / 0.413 Earths Titan Callisto Io Moon Europa Triton Titania Rhea Oberon Iapetus Charon Umbriel Ariel Dione Tethys ( Dysnomia ) Enceladus Miranda Proteus Mimas ( Hi'iaka ) Nereid Hyperion Phoebe abc 's Ariel Callisto Charon Dione ( Dysnomia ) Enceladus Europa Ganymede ( Hi'iaka ) Hyperion Iapetus Io Mimas Miranda Moon Nereid Oberon Phoebe Proteus Rhea Tethys Titan Titania Triton Umbriel Discovery timeline Inner moons Irregular moons List Naming Regular moons Trojan moons NOTE : Italicized moons are not close to being in hydrostatic equilibrium ; ( bracketed ) moons may or may not be close to being in hydrostatic equilibrium. Jupiter Outline of Jupiter Geography Atmosphere Great Red Spot Magnetosphere Rings Moons Inner moons Adrastea Amalthea Metis Thebe Galilean moons Callisto Europa Ganymede Io Irregular moons Ananke group Carme group Himalia group Pasiphae group Ungrouped moons Carpo Themisto S / 2003 J 2 S / 2003 J 12 S / 2011 J 1 S / 2016 J 2 Astronomy General Jupiter - crossing minor planets Solar eclipses Trojans Greek camp Trojan camp Impact events Comet Shoemaker -- Levy 9 2009 Jupiter impact event 2010 Jupiter impact event Exploration and orbiting missions Current Juno Past Cassini Galileo New Horizons Pioneer program Pioneer 10 Pioneer 11 Ulysses Voyager program Voyager 1 Voyager 2 Future Jupiter Icy Moons Explorer ( 2022 ) Europa Clipper ( 2025 ) Proposed Io Volcano Observer ( 2021 ) Laplace - P ( 2023 ) Smara ( 2030 ) Related Fiction Jovian Jupiter Moons Mythology Book Category Portal Europa Geology Chaotic terrain Conamara Chaos Craters Pwyll Cilix Lists List of lineae on Europa List of geological features on Europa List of craters on Europa Exploration Past Pioneer 10 Pioneer 11 Voyager 1 Voyager 2 Galileo Cassini -- Huygens New Horizons Planned Jupiter Icy Moons Explorer ( 2022 ) Europa Clipper ( 2025 ) Cancelled / Concepts Jupiter Europa Orbiter Europa Lander Europa Orbiter Jupiter Icy Moons Orbiter Jovian Europa Orbiter Europa Lander ( rerouted to Ganymede as Laplace - P ) Other Colonization of Europa Life Europa in fiction Atmospheres Star Sun Exoplanet HD 209458 b Kepler - 7b Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Dwarf planet Ceres Pluto Makemake Satellite Callisto Dione Enceladus Europa Ganymede Io Moon Rhea Titan Triton See also Coma ( cometary ) Extraterrestrial atmosphere Stellar atmosphere Extraterrestrial life Events and objects ALH84001 Cells in the stratosphere CI1 fossils Murchison meteorite Nakhla meteorite Polonnaruwa meteorite Red rain in Kerala Shergotty meteorite Viking lander biological experiments Yamato 000593 Signals of interest CP 1919 ( misidentified pulsar ) CTA - 102 ( misidentified quasar ) Fast radio burst ( unknown origin ) Wow ! signal ( inconclusive ) KIC 8462852 ( unusual light fluctuations ) SHGb02 + 14a ( radio source ) HD 164595 signal ( unknown origin ) Life in the Universe Earliest known life forms Life on Enceladus Life on Europa Life on Mars Life on Titan Life on Venus Planetary habitability Catalog of Nearby Habitable Systems Circumstellar habitable zone Earth analog Extraterrestrial liquid water Galactic habitable zone Habitability of binary star systems Habitability of orange dwarf systems Habitability of red dwarf systems Natural satellite habitability Planetary habitability Space missions Beagle 2 Biological Oxidant and Life Detection BioSentinel Curiosity Darwin Enceladus Explorer Enceladus Life Finder Europa Clipper ExoMars ExoLance EXPOSE Foton - M3 Icebreaker Life Journey to Enceladus and Titan Laplace - P Life Investigation For Enceladus Living Interplanetary Flight Experiment Mars Geyser Hopper Mars sample return mission Mars 2020 Northern Light Opportunity SpaceX Red Dragon Spirit Tanpopo Titan Mare Explorer Venus In Situ Explorer Viking 1 Viking 2 Interstellar communication Active SETI Allen Telescope Array Arecibo message Arecibo Observatory Berkeley SETI Research Center Bracewell probe Breakthrough Initiatives Breakthrough Listen Breakthrough Message Communication with extraterrestrial intelligence Gauss 's Pythagorean right triangle proposal Lincos language NIROSETI Pioneer plaque Project Cyclops Project Ozma Project Phoenix SERENDIP Search for extraterrestrial intelligence SETI@home setiQuest Voyager Golden Record Water hole Xenolinguistics Exhibitions The Science of Aliens Hypotheses Ancient astronauts Aestivation hypothesis Aurelia and Blue Moon Cosmic pluralism Directed panspermia Drake equation Extraterrestrial hypothesis Fermi paradox Great Filter Hypothetical types of biochemistry Interplanetary contamination Kardashev scale Mediocrity principle Neocatastrophism Panspermia Planetarium hypothesis Rare Earth hypothesis Zoo hypothesis Related topics Astrobiology Astroecology Biosignature Rejection of Earth - based abiogenesis ( Fred Hoyle ) Brookings Report Planetary protection Potential cultural impact of extraterrestrial contact Exotheology Extraterrestrials in fiction Extremophile Nexus for Exoplanet System Science Noogenesis San Marino Scale Technosignature UFO religion Xenoarchaeology Astrobiology Disciplines Astrochemistry Astrophysics Atmospheric sciences Biochemistry Evolutionary biology Exoplanetology Geomicrobiology Microbiology Paleontology Planetary science Main topics Allan Hills 84001 Biomolecule Biosignature Drake equation Earliest known life forms Earth analog Extraterrestrial life Extremophiles Hypothetical types of biochemistry List of microorganisms tested in outer space Molecules detected in outer space Ocean planet Origin of life Panspermia Search for extraterrestrial intelligence ( SETI ) Yamato meteorite Planetary habitability Habitability of binary star systems Habitability of K - type main - sequence star systems Habitability of natural satellites Habitability of red dwarf systems Circumstellar habitable zone Earth analog List of potentially habitable exoplanets Tholin Extraterrestrial liquid water Galactic habitable zone Space missions Earth orbit BIO BIOCORE Biolab Bion BIOPAN Biosatellite program E-MIST ERA EXOSTACK EXPOSE O / OREOS OREOcube Tanpopo VEGGIE Mars missions Beagle 2 ExoMars ExoMars Trace Gas Orbiter Schiaparelli EDM lander Fobos - Grunt Mars Science Laboratory Curiosity Phoenix Viking Planned BioSentinel Dragonfly Europa Clipper ExoMars ExoMars rover ExoMars 2020 surface platform Mars 2020 Mars Global Remote Sensing Orbiter and Small Rover Proposed CAESAR Enceladus Explorer Enceladus Life Finder ‎ Enceladus Life Signatures and Habitability Europa Lander ExoLance Explorer of Enceladus and Titan Journey to Enceladus and Titan Laplace - P Life Investigation For Enceladus Mars sample return mission Oceanus THEO Cancelled and undeveloped Astrobiology Field Laboratory Beagle 3 Biological Oxidant and Life Detection Icebreaker Life Living Interplanetary Flight Experiment Mars Astrobiology Explorer - Cacher MELOS Northern Light Red Dragon Terrestrial Planet Finder Institutions and programs Astrobiology Society of Britain Astrobiology Science and Technology for Exploring Planets Breakthrough Initiatives Breakthrough Listen Breakthrough Message Breakthrough Starshot Carl Sagan Institute European Astrobiology Network Association NASA Astrobiology Institute Nexus for Exoplanet System Science Ocean Worlds Exploration Program Category Portal The Solar System The Sun Mercury Venus Earth Mars Ceres Jupiter Saturn Uranus Neptune Pluto Haumea Makemake Eris Planets and Dwarf planets Terrestrial planets Mercury Venus Earth Mars Giant planets Jupiter Saturn Uranus Neptune Dwarf planets Ceres Pluto Haumea Makemake Eris Rings Jovian Saturnian ( Rhean ) Charikloan Chironean Uranian Neptunian Haumean Moons Terrestrial Moon other near - Earth objects Martian Phobos Deimos Jovian Ganymede Callisto Io Europa all 79 Saturnian Titan Rhea Iapetus Dione Tethys Enceladus Mimas Hyperion Phoebe all 62 Uranian Titania Oberon Umbriel Ariel Miranda all 27 Neptunian Triton Proteus Nereid all 14 Plutonian Charon Nix Hydra Kerberos Styx Haumean Hiʻiaka Namaka Makemakean S / 2015 ( 136472 ) 1 Eridian Dysnomia Lists Solar System objects By size By discovery date Minor planets Gravitationally rounded objects Possible dwarf planets Natural satellites Comets Small Solar System bodies Meteoroids Minor planets moons Comets Damocloids Mercury - crossers Venus - crossers Venus trojans Near - Earth objects Earth - crossers Earth trojans Mars - crossers Mars trojans Asteroid belt Asteroids first discovered : Ceres Pallas Juno Vesta Families Notable asteroids Kirkwood gap Main - belt comets Jupiter trojans Jupiter - crossers Centaurs Saturn - crossers Uranus trojans Uranus - crossers Neptune trojans Cis - Neptunian objects Trans - Neptunian objects Neptune - crossers Plutoids Kuiper belt Plutinos Cubewanos Scattered disc Detached objects Sednoids Hills cloud Oort cloud Hypothetical objects Vulcan Vulcanoids Phaeton Planet V Theia Fifth giant Planets beyond Neptune Tyche Nemesis Planet Nine Exploration ( outline ) Discovery Astronomy Timeline Spaceflight Robotic spacecraft Human spaceflight List of crewed spacecraft Colonization List of probes Timeline Mercury Venus Moon Mars Ceres Asteroids Mining Comets Jupiter Saturn Uranus Neptune Pluto Deep space Outline of the Solar System Portals Solar System Astronomy Earth sciences Mars Jupiter Uranus Cosmology Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Virgo Supercluster → Laniakea Supercluster → Observable universe → Universe Each arrow ( → ) may be read as `` within '' or `` part of ''. GND : 4456671 - 2 LCCN : sh97004538 VIAF : 241200489 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Europa_(moon)&oldid=853809988 '' Categories : Europa ( moon ) Hidden categories : Articles containing Greek - language text Webarchive template webcite links Webarchive template wayback links Use dmy dates from January 2018 Articles with hAudio microformats Articles including recorded pronunciations ( English ) Articles containing Latin - language text Articles containing explicitly cited English - language text Articles contradicting other articles Wikipedia articles with GND identifiers Wikipedia articles with LCCN identifiers Wikipedia articles with VIAF identifiers Featured articles Talk Contents About Wikipedia Wikiversity Afrikaans Alemannisch Arpetan Asturianu Azərbaycanca تۆرکجه Bân - lâm - gú Беларуская Български Bosanski Brezhoneg Català Чӑвашла Čeština Corsu Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 Հայերեն हिन्दी Hrvatski Ido Bahasa Indonesia Íslenska Italiano עברית ქართული Коми Кыргызча Latina Latviešu Lëtzebuergesch Lietuvių Lumbaart Magyar മലയാളം मराठी مصرى Bahasa Melayu Mìng - dĕ̤ng - ngṳ̄ Mirandés မြန်မာဘာသာ Nederlands 日本 語 Norsk Norsk nynorsk Occitan ਪੰਜਾਬੀ پنجابی Plattdüütsch Polski Português Română Русский Scots Sicilianu සිංහල Simple English سنڌي Slovenčina Slovenščina Ślůnski Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் Татарча / tatarça ไทย Тоҷикӣ Türkçe Українська اردو Tiếng Việt 文言 Winaray 吴语 粵語 Zazaki 中文 82 more Edit links This page was last edited on 7 August 2018, at 03 : 09 ( UTC ). 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Question: what is the atmosphere of europa made of
Answer: primarily of oxygen