In May , 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 to The tidal forces are about 1, times stronger than the Moon's effect on Earth. The only other moon in the Solar System exhibiting water vapor plumes is Enceladus.
Observations with the Goddard High Resolution Spectrograph of the Hubble Space Telescope, first described in , revealed that Europa has a thin atmosphere composed mostly of molecular oxygen O 2. 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. 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 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.
European Union website - EUROPA is the official EU website that provides access to information published by all EU institutions, agencies and bodies. Europa is the smallest of the four Galilean moons orbiting Jupiter, and the sixth- closest to the planet of all the 79 known moons of Jupiter. It is also the.
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 of Europa began with the Jupiter flybys of Pioneer 10 and 11 in and respectively. The first closeup photos were of low resolution compared to later missions. The two Voyager probes traveled through the Jovian system in , 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 , the Galileo space probe orbited Jupiter for eight years, until , and provided the most detailed examination of the Galilean moons to date. Conjectures regarding extraterrestrial life have ensured a high profile for Europa and have led to steady lobbying for future missions. In , a Europa mission was recommended by the U. Planetary Science Decadal Survey.
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. 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. 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 calls for a large nuclear-powered "melt probe" cryobot that would melt through the ice until it reached an ocean below. 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.
This may be important in determining if Europa could be habitable. The energy provided by tidal forces 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. 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 it is too salty, only extreme halophiles could survive in that environment. 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.
Evidence suggests that hydrogen peroxide is abundant across much of the surface of Europa. Clay-like minerals specifically, phyllosilicates , often associated with organic matter on Earth, have been detected on the icy crust of Europa. From Wikipedia, the free encyclopedia. The smallest of the four Galilean moons of Jupiter.
For other uses, see Europa. For the spaceship in the s television series Lost in Space, see Jupiter 2. For the airplane engine, see Bristol Jupiter. For other uses, see Jupiter disambiguation. 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 by Galileo spacecraft.
Mean orbit radius. Orbital period. Average orbital speed. Surface area. Mean density. Surface gravity. Moment of inertia factor.
Escape velocity. Rotation period. Axial tilt. Apparent magnitude. Surface pressure. See also: List of lineae on Europa. See also: List of geological features on Europa. In 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 by Voyager 2. Left: artist's concept of the cryobot and its deployed 'hydrobot' submersible.
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The mission will also carry a magnetometer to measure the strength and direction of the moon's magnetic field, which will allow scientists to determine the depth and salinity of its ocean. Gravity measurements will also help confirm the existence of Europa's subsurface ocean. A thermal instrument will survey Europa's frozen surface in search of recent eruptions of warmer water at or near the surface, while additional instruments will search for evidence of water and tiny particles in the moon's thin atmosphere.
NASA's Hubble Space Telescope observed water vapor above the south polar region of Europa in , providing potential evidence of water plumes.