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80-561: The Jovian Europa Orbiter was part of ESA's "Technology Reference Studies", which was superseded in 2007 by ESA's "Cosmic Vision", which includes the Europa Jupiter System Mission . EJSM was halted in 2011 due to funding issues at that time, which included several spacecraft, and ESA component of that stage was rebooted as Jupiter Icy Moons Explorer planned for the 2020s Spacecraft of Jovian Minisat Explorer The relay would allow keeping spaceflight hardware out of

160-716: A 20×-magnification refracting telescope at the University of Padua , but the low resolution could not separate the two objects. The following night, he saw Io and Europa for the first time as separate bodies. The moon is the namesake of Europa , in Greek mythology the daughter of the Phoenician king of Tyre . Like all the Galilean satellites, Europa is named after a lover of Zeus , the Greek counterpart of Jupiter . Europa

240-425: 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 gravitational disturbances from the other Galileans, causes Europa's sub-Jovian point to oscillate around

320-492: A Europa lander 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 in funding to continue

400-420: A central band of lighter material. The most likely hypothesis is that the lineae on Europa were produced by a series of eruptions of warm ice as Europa's crust slowly spreads open to expose warmer layers beneath. The effect would have been similar to that seen on 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

480-442: 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

560-699: A frozen sea. An alternative hypothesis suggests that lenticulae are actually small areas of chaos and that the claimed pits, spots and domes are artefacts resulting from the 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, including researchers at University of Texas at Austin , presented evidence 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

640-443: 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. The mission was launched on 14 October 2024 aboard a Falcon Heavy . Conjectures regarding extraterrestrial life have ensured

720-447: A height of 190 km (120 mi) above the surface of Europa. 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. Europa

800-527: 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, e.g. using radar. Chaos features may also be a result of increased melting of the ice shell and deposition of marine ice at low latitudes as a result of heterogeneous heating. Work published by researchers from Williams College suggests that chaos terrain may represent sites where impacting comets penetrated through

880-440: 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,

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960-544: 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 to be 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

1040-544: A probe to study the icy satellites of the outer Solar System under the title Outer Planet Flagship Mission . Two primary candidate missions were considered under the study: EJSM and Titan Saturn System Mission (TSSM), also known under the ESA designation TandEM. In February 2009, it was announced that NASA/ESA had given EJSM priority ahead of the TSSM. The ESA contribution still faced funding competition from two other missions,

1120-510: 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

1200-503: A result of the moon's particle venting, the atmosphere requires continuous replenishment. Europa also contains a small magnetosphere (approximately 25% of Ganymede's). However, this magnetosphere varies in size as Europa orbits through Jupiter's magnetic field. This confirms that a conductive element, such as a large ocean, likely lies below its icy surface. As multiple studies have been conducted over Europa's atmosphere, several findings conclude that not all oxygen molecules are released into

1280-475: A single Earth day (24 hours). A Europan day is about 3.5 times as long as an Earth day. 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

1360-537: A study was published in the peer-reviewed scientific journal Geophysical Research Letters suggesting that the plumes may originate from water within the crust of Europa as opposed to its subsurface ocean. The study's model, using images from the Galileo space probe, proposed that a combination of freezing and pressurization may result in at least some of the cryovolcanic activity. The pressure generated by migrating briny water pockets would thus, eventually, burst through

1440-411: 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

1520-723: A succession of space-probe flybys, the first occurring in the early 1970s. In September 2022, the Juno spacecraft flew within about 320 km (200 miles) of Europa for a more recent close-up view. Europa has the smoothest surface of any known solid object in the Solar System. The apparent youth and smoothness of the surface is due to a water ocean beneath the surface, which could conceivably harbor extraterrestrial life , although such life would most likely be that of single celled organisms and bacteria -like creatures. The predominant model suggests that heat from tidal flexing causes

1600-503: A tilt in the spin axis would cause more heat to be generated by tidal forces. Such additional heat would have allowed the ocean to remain liquid for a longer time. However, it has not yet been determined when this hypothesized shift in the spin axis might have occurred. Europa is slightly smaller than the Earth's moon . At just over 3,100 kilometres (1,900 mi) in diameter , it is the sixth-largest moon and fifteenth-largest object in

1680-489: 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

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1760-492: 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

1840-560: 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 darker, 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

1920-470: Is a mission to Ganymede launched on 14 April 2023, that will include two flybys of Europa. NASA's Europa Clipper was launched on 14 October 2024, with a complementary lander possible based on its findings. 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 . On 7 January, Galileo had observed Io and Europa together using

2000-457: 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

2080-511: Is due to a lack of substantial energy for organisms to thrive off, unlike proposed hydrothermal vents on the subsurface ocean floor. The atmosphere of Europa can be categorized as thin and tenuous (often called an exosphere), primarily composed of oxygen and trace amounts of water vapor. However, this quantity of oxygen is produced in a non-biological manner. Given that Europa's surface is icy, and subsequently very cold; as solar ultraviolet radiation and charged particles (ions and electrons) from

2160-534: Is due to direct overhead sunlight near the equator causing the ice to sublime , forming vertical cracks. Although the imaging available from the Galileo orbiter does not have the resolution for confirmation, radar and thermal data are consistent with this speculation. The ionizing radiation level at Europa's surface is equivalent to a daily dose of about 5.4  Sv (540  rem ), an amount that would cause severe illness or death in human beings exposed for

2240-406: Is now counted as Jupiter's sixth satellite, though it is still referred to as Jupiter II . The adjectival form has stabilized as Europan . Europa orbits Jupiter in just over three and a half days, with an orbital radius of about 670,900 km. With an orbital eccentricity of only 0.009, the orbit itself is nearly circular, and the orbital inclination relative to Jupiter's equatorial plane

2320-401: Is one of the few moons in our solar system with a quantifiable atmosphere, along with Titan , Io , Triton , Ganymede and Callisto . Europa is also one of several moons in our solar system with very large quantities of ice (volatiles) , otherwise known as "icy moons". Europa is also considered to be geologically active due to the constant release of hydrogen-oxygen mixtures into space. As

2400-530: 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. A full revolution of the outer rigid shell relative to the interior of Europa takes at least 12,000 years. Studies of Voyager and Galileo images have revealed evidence of subduction on Europa's surface, suggesting that, just as

2480-405: 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 a line passing through this point. Research suggests that tidal locking may not be full, as

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2560-408: 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

2640-474: Is the smallest of the four Galilean moons orbiting Jupiter , and the sixth-closest to the planet of all the 95 known moons of Jupiter . It is also the sixth-largest moon in the Solar System . Europa was discovered independently by Simon Marius and Galileo Galilei and was named (by Marius) after Europa , the Phoenician mother of King Minos of Crete and lover of Zeus (the Greek equivalent of

2720-459: Is tidally locked to Jupiter, and therefore always maintains approximately the same 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

2800-426: Is too low to hold an atmosphere substantial enough for those features. Europa's gravity is approximately 13% of Earth's. The temperature on Europa varies from −160 °C at the equator, to −220 °C at either of its poles. Europa's subsurface ocean is thought to be significantly warmer however. It is hypothesized that because of radioactive and tidal heating (as mentioned in the sections above), there are points in

2880-443: 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 for this 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 could also affect estimates of the age of Europa's ocean. Tidal forces are thought to generate the heat that keeps Europa's ocean liquid, and

2960-584: The Galileo space probe, which orbited Jupiter from 1995 to 2003. Such plume activity could help researchers in a search for life from the subsurface Europan ocean without having to land on the moon. In March 2024, astronomers reported that the surface of Europa may have much less oxygen than previously inferred. 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)

3040-424: The Galileo space probe, which orbited Jupiter between 1995 and 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 Europan ocean without having to land on the moon. The tidal forces are about 1,000 times stronger than

3120-701: The Jupiter Icy Moons Explorer (JUICE) that will be based on the JGO design. Selection of JUICE for the L1 launch slot of ESA's Cosmic Vision science programme was announced on 2 May 2012. JUICE was launched on 14 April 2023. Later, in June 2015, NASA approved the Europa Clipper , which was launched on October 14th, 2024. In February 2008, NASA and ESA began joint investigations into sending

3200-684: The Laser Interferometer Space Antenna (LISA) and the International X-ray Observatory (IXO), which is why NASA kept a contingency plan of sending its part of the mission as a stand-alone project. The most distinctive feature of the EJSM/Laplace-study, was the proposed collaboration with multiple orbiters and landers: The baseline EJSM architecture consisted of JEO and JGO, which were proposed to be launched in 2020 and explore

3280-506: The Roscosmos (Russian Space Agency) had expressed their interest in contributing to EJSM-Laplace, although no deals had been finalized. JEO was estimated to cost US$ 4.7 billion, while ESA would spend US$ 1.0 billion (€710 million) on JGO. In April 2011, European Space Agency (ESA) stated that it seemed unlikely that a joint US–European mission will happen in the early 2020s given NASA's budget, so ESA continued with its initiative, called

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3360-426: 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 terrestrial planets , being primarily composed of silicate rock . It is estimated that Europa has an outer layer of water around 100 km (62 mi) thick –

3440-446: 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. Analysis of the unique cracks lining Europa yielded evidence that it likely spun around

3520-709: The Europa mission concept studies. 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 would use. The aim of Europa Clipper is to explore Europa in order to investigate its habitability , and to aid in selecting sites for

3600-452: The Jovian magnetospheric environment collide with Europa's surface, water vapor is created and instantaneously separated into oxygen and hydrogen constituents. As it continues to move, the hydrogen is light enough to pass through the surface gravity of the atmosphere leaving behind only oxygen. The surface-bounded atmosphere forms through radiolysis, the dissociation of molecules through radiation. This accumulated oxygen atmosphere can get to

3680-760: The Jupiter System before settling into orbit around Europa and Ganymede, respectively. The JEO and JGO were separate and independent spacecraft developed, launched and operated by their respective organizations to work together. Their launch dates and interplanetary trajectories were not to be dependent on each other, but would have been synergistic. The goal was to determine whether the Jupiter system harbors habitable environments , while focusing on Europa and Ganymede . The main science objectives supporting this goal were: Europa (moon) Europa / j ʊ ˈ r oʊ p ə / , or Jupiter II ,

3760-536: 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 space probe orbited Jupiter for eight years, until 2003, and provided

3840-498: 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 kilometres of ice. In November 2020,

3920-478: The Roman god Jupiter ). Slightly smaller than Earth's Moon , Europa is made of silicate rock and has a water-ice crust and probably an iron–nickel core. It has a very thin atmosphere, composed primarily of oxygen. Its geologically young white- beige surface is striated by light tan cracks and streaks, with very few impact craters. In addition to Earth-bound telescope observations, Europa has been examined by

4000-626: The atmosphere. This unknown percentage of oxygen may be absorbed into the surface and sink into the subsurface. 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. Through

4080-568: 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 . The presence of sodium chloride in the internal ocean has been suggested by a 450 nm absorption feature, characteristic of irradiated NaCl crystals, that has been spotted in HST observations of the chaos regions, presumed to be areas of recent subsurface upwelling. The subterranean ocean of Europa contains carbon and

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4160-479: The calculated amount of heat generated by Europan tides, it is estimated that the outer crust of solid ice is approximately 10 to 30 km (6 to 20 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

4240-426: The cracks are analogous to ocean ridges, so plates of icy crust analogous to tectonic plates on Earth are recycled into the molten interior. This evidence of both crustal spreading at bands and convergence at other sites suggests that Europa may have active plate tectonics , similar to Earth. However, the physics driving these plate tectonics are not likely to resemble those driving terrestrial plate tectonics, as

4320-632: The crust, thereby creating these plumes. The hypothesis that cryovolcanism on Europa could be triggered by freezing and pressurization of liquid pockets in the icy crust was first proposed by Sarah Fagents at the University of Hawai'i at Mānoa, who in 2003, was the first to model and publish work on this process. A press release from NASA's Jet Propulsion Laboratory referencing the November 2020 study suggested that plumes sourced from migrating liquid pockets could potentially be less hospitable to life. This

4400-402: The depths of Europa's ocean that may be only slightly cooler than Earth's oceans. Studies have also concluded that Europa's ocean would have been rather acidic at first, with large concentrations of sulfate, calcium, and carbon dioxide. But over the course of 4.5 billion years, it became full of chloride , thus resembling our 1.94% chloride oceans on Earth. Exploration of Europa began with

4480-615: 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

4560-428: The forces resisting potential Earth-like plate motions in Europa's crust are significantly stronger than the forces that could drive them. 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

4640-405: 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. 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

4720-698: The height of Mt. Everest., though recent observations and modeling suggest that typical Europan plumes may be much smaller. It has been suggested that if plumes 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

4800-447: The highest of any moon. This indicates a young and active surface: based on estimates of the frequency of cometary bombardment that Europa experiences, the surface is about 20 to 180 million years old. There is no scientific consensus about the explanation for Europa's surface features. It has been postulated Europa's equator may be covered in icy spikes called penitentes , which may be up to 15 meters high. Their formation

4880-454: The ice crust and into an underlying ocean. The scientific 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

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4960-401: 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. Large impacts going fully through the ice crust would also be a way that the subsurface ocean could be exposed. The Galileo orbiter found that Europa has

5040-502: The ice were solidly attached to the mantle. Europa probably contains a metallic iron core. Europa is the smoothest known object in the Solar System, lacking large-scale features such as mountains and craters. The prominent markings crisscrossing Europa appear to be mainly albedo features that emphasize low topography. There are few craters on Europa, because its surface is tectonically too active and therefore young. Its icy crust has an albedo (light reflectivity) of 0.64, one of

5120-536: The intense radiation zones near Europa, but they would be launched and transit to Jupiter together. This article related to the European Space Agency is a stub . You can help Misplaced Pages by expanding it . This article about one or more spacecraft of a European multinational organisation is a stub . You can help Misplaced Pages by expanding it . Europa Jupiter System Mission The Europa Jupiter System Mission – Laplace ( EJSM-Laplace )

5200-459: 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

5280-432: 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. 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

5360-418: 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 . In 2022, the Juno orbiter flew by Europa at a distance of 352 km (219 mi). In 2012, Jupiter Icy Moons Explorer (JUICE)

5440-589: 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 the 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 indicate that most of

5520-762: 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 sea floor. This may be important in determining whether 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 analysis of data obtained from

5600-444: 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,

5680-492: The process of neutral particles exchanging electrons with its charged particles. Since Europa's magnetic field rotates faster than its orbital velocity, these ions are left in the path of its magnetic field trajectory, forming a plasma. It has been hypothesized that these ions are responsible for the plasma within Jupiter's magnetosphere. On 4 March 2024, astronomers reported that the surface of Europa may have much less oxygen than previously inferred. The atmosphere of Europa

5760-400: 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 kneads Europa's interior and ice shell, which becomes a source of heat. Depending on the amount of tilt, the heat generated by

5840-469: The slow release of oxygen and hydrogen, a neutral torus around Europa's orbital plane is formed. 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. This torus was officially confirmed using Energetic Neutral Atom (ENA) imaging. Europa's torus ionizes through

5920-670: Was Ganymede, the handsome son of King Tros, whom Jupiter, having taken the form of an eagle, transported to heaven on his back, as poets fabulously tell... I think, therefore, that I shall not have done amiss if the First is called by me Io, the Second Europa, the Third, on account of its majesty of light, Ganymede, the Fourth Callisto... The names fell out of favor for a considerable time and were not revived in general use until

6000-462: Was a proposed joint NASA / ESA uncrewed space mission slated to launch around 2020 for the in-depth exploration of Jupiter's moons with a focus on Europa , Ganymede and Jupiter's magnetosphere . The mission would have comprised at least two independent elements, NASA's Jupiter Europa Orbiter (JEO) and ESA's Jupiter Ganymede Orbiter (JGO), to perform coordinated studies of the Jovian system. The Japan Aerospace Exploration Agency ( JAXA ) and

6080-476: Was courted by Zeus and became the queen of Crete . The naming scheme was suggested by Simon Marius, who attributed the proposal to Johannes Kepler : Jupiter is much blamed by the poets on account of his irregular loves. Three maidens are especially mentioned as having been clandestinely courted by Jupiter with success. Io, daughter of the River Inachus, Callisto of Lycaon, Europa of Agenor. Then there

6160-492: Was first discovered in 1995 by astronomers D. T. Hall and collaborators using the Goddard High Resolution Spectrograph instrument of the Hubble Space Telescope . This observation was further supported in 1997 by the Galileo orbiter during its mission within the Jovian system. The Galileo orbiter performed three radio occultation events of Europa, where the probe's radio contact with Earth

6240-528: Was observed on the surface ice as a concentration of carbon dioxide within Tara Regio, a geologically recently resurfaced terrain. Europa receives thermal energy from tidal heating , which 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. Ocean tides are converted to heat by frictional losses in

6320-546: Was selected by the European Space Agency ( ESA ) as a planned mission. That mission includes two flybys of Europa, but is more focused on Ganymede . It was launched in 2023, and is expected to reach Jupiter in July 2031 after four gravity assists and eight years of travel. In 2011, a Europa mission was recommended by the U.S. Planetary Science Decadal Survey . In response, NASA commissioned concept studies of

6400-473: Was temporarily blocked by passing behind Europa. By analyzing the effects Europa's sparse atmosphere had on the radio signal just before and after the occultation, for a total of six events, a team of astronomers led by A. J. Kliore established the presence of an ionized layer in Europa's atmosphere. Despite the presence of a gas torus , Europa has no weather producing clouds. As a whole, Europa has no wind, precipitation, or presence of sky color as its gravity

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