At the end of November, Hua Feng and the others began to learn about Europa. Europa Eu

Opa (pronounced "yoo Roh puh" in English), discovered by Galileo in 1610, is Jupiter's sixth known moon, the fourth largest of Jupiter, and the second closest to Jupiter among the moons discovered by Galileo. Slightly smaller than Earth's moon, the Moon, with a diameter of 3,100 kilometers, Europa is the sixth largest moon and fifteenth largest object in the solar system's celestial system. Observations from the Hubble telescope revealed that Europa has an oxygen-containing rarefied atmosphere (1e-11 bar).

Only seven of the approximately 165 moons in the solar system (Europa, Europa, Europa, Europa, Europa, Titan, and Triton) are known to have atmospheres. Unlike oxygen in Earth's atmosphere, Europa's oxygen is not biologically formed. It is most likely due to the impact of charged particles in sunlight on Europa's icy surface, producing water vapor, which then splits into hydrogen and oxygen. The hydrogen detached, leaving behind oxygen.

Europa and Europa are similar in composition to terrestrial planets: mostly composed of silicate rocks. However, unlike Europa, Europa has an outer layer of ice up to 100 kilometers thick, and due to its internal energy source, deep under the ice or a liquid water world, the surface of the object is very "smooth" and the number of impact craters is small, indicating that the geological structure of the planet Europa is relatively active, and the data sent back from Galileo indicate that Europa has an internal layered structure and may have a small metal core.

On December 11, 2013, NASA announced that the discovery of clayey minerals on Europa's surface may breed new life. Europa's surface is covered with ice, and the ice temperature is around minus 26 degrees Celsius, and there is an ocean under the ice, which is 96 kilometers deeper than the deepest ocean on Earth.

On September 26, 2016, NASA expert Jeff Youde said that Europa's underground ocean is considered the most promising place for life in the solar system.

Europa and Europa are similar in composition to terrestrial planets: mostly composed of silicate rocks. But unlike Europa, Europa has a thin crust of ice. Data sent back from Galileo suggests that Europa has internal layering and may have a small metal core. But Europa's surface doesn't resemble something from the inner solar system, it's extremely smooth: only a handful of terrain hundreds of meters high can be seen. The protruding marks appear to be only albedo characteristics or minor fluctuations.

Photos of Europa's surface are similar to those of ice in Earth's oceans. This may be due to a layer of liquid water beneath the ice on Europa's surface, perhaps 50 kilometers deep, and the heat from the gravitational forces remains liquid. If the assumption is true, this would be the only place in the solar system outside of Earth where there is a large amount of liquid water.

Europa's most striking appearance is the strings of cross stripes that can be found all over the world. The larger one spreads outwards into a zone of pale material, nearly 20 kilometers long. The most recent theory of their origin is that they are produced by a series of volcanic ejections or fountains.

Images from Galileo's two approaches to Europa seem to confirm earlier theories: there are very few craters on Europa, with only three craters larger than 5 kilometers in diameter found. This indicates that it has a youthful and active surface. However, Voyager made a small section of the surface high-definition map, and the exact age of Europa's surface is an open question. [2] But some activity is clearly taking place, and some areas look a lot like the melting of ice in the polar oceans at the arrival of spring. The exact nature of Europa's surface and interior is not yet clear, but there is definite evidence of a surface "ocean".

Europa is another moon in the solar system like no other. Europa is the brightest moon in the solar system, and what makes it so bright is because it has a thick ice crust on its surface that is covered with meteorite impact craters and streaks. Europa's interior is likely to be very active, and beneath the ice crust is likely to hide the largest ocean of liquid water in the solar system, and it is highly likely that life is present in this ocean.

1994, Hubble Space Telescope Godda

dHigh Interpretance Spectrometer observed that Europa's surface was covered with an extremely thin atmosphere composed mainly of oxygen (1 surface pressure of about 1 micropascal). Of all the moons of the solar system known, only seven have atmospheres (the other six are Europa, Callisto, Titan, Ganymede, Titan, and Triton), and unlike Earth, Europa's atmospheric oxygen is of abiotic origin. It is likely that the impact of charged particles and the exposure of ultraviolet rays from sunlight cause some of the water molecules in the ice on Europa's surface to break down into oxygen and hydrogen, which escapes due to its low atomic weight, while oxygen with relatively high atomic weight is retained.

The average distance between Europa and Jupiter is 670,900 kilometers, and it takes only three and a half days to complete one revolution. Its orbit is very close to a perfect circle, with an eccentricity of only 0.009. Like other Galilean moons, Europa is tidally locked, so there is a hemisphere that is forever facing Jupiter. The heat and energy converted by the gravitational pull of Jupiter and other moons in different directions provides the necessary conditions for the possibility of liquefaction of the interior of the ice into oceans and the driving of geological movements beneath the surface.

Europa's main body is similar to that of terrestrial planets, i.e., it is mostly composed of silicate rocks. Its surface is covered in water, presumably hundreds of kilometers thick (frozen ice crust above, liquid ocean below), and magnetic data collected by the Galileo spacecraft that orbited Jupiter between 1995 and 2003 suggests that Europa is capable of generating an induced magnetic field of its own under the influence of Jupiter's magnetic field, a discovery that suggests that there is likely a conductive layer similar to that of a saltwater ocean within its surface, and that Europa may also have a metallic iron core.

Europa's surface is generally smooth, with few undulations of more than a few hundred meters, although drops of close to a kilometer can be observed in some areas. Europa is the smoothest object in the solar system. Its conspicuous criss-crossing lines, the so-called retrospective features, are caused by the low and shallow terrain. With very few impact craters, Europa is one of the highest illumination moons. This also suggests that its surface is quite "young" and "active", with an estimated "surface" age of between 20 million and 180 million years, based on estimates of the frequency of comet impacts Europa may have experienced.

The most striking feature of Europa's surface is the dark streaks that spread across the planet. Close observation shows that the plates on both sides of the stripe move in opposite directions. The larger stripes span up to 20 km laterally, and a blurred transition can be observed between the dark parts of these wide stripes and the outer edge of the plate. Regular lines, as well as wide stripes interspersed with light-colored fine lines, are most likely caused by glacial volcanic eruptions or geysers caused by the cracking of the surface ice crust and the exposure of warmer underlying material. This has a similar effect to ocean ridges on Earth. It is speculated that most of the rifts were inflicted by Jupiter

Caused by strong tidal pressures, since Europa is tidally locked, it always maintains one direction towards Jupiter, and a fixed pressure pattern should allow for a specific predictable exception.

However, only the most recent rifts on Europa's surface are as predicted, and other rifts can extend in all directions, the older they are. A more logical explanation is that Europa's surface rotates slightly faster than its interior, with the ocean beneath the ice separating its crust from the lower mantle, which is torn apart by Jupiter's gravity. Comparing photographs taken by Voyager and Galileo suggests that Europa's outer shell rotates one more week than its interior approximately every 10,000 years.

Another distinctive feature of Europa is the dark spots that are large or small, round or oval, or le in Latin

ticulae, meaning "freckles". Some of these dark spots are protruding like a dome, some are sunken like pits, some are flat like mirrors, and some are rough in texture. The protruding hillocks are mostly flat at the top, showing that they were originally integrated with the surrounding plains, and were formed by pushing up. It is hypothesized that the formation of dark spots is caused by the "warm ice" with higher temperature in the lower layer (diapi).

It is caused by the upward upwelling of "ice" that penetrates the surface layer under the action of the (Earth), and its movement mechanism is similar to that of the lava cave (magma chambe) in the crust of the earth

Similar.

The smooth dark spots are caused by meltwater oozing out of the case as the "warm ice" breaks through the case, and the rough and mismatched spots (also known as the "chaos" area, such as the Connamara chaos) are made up of a large number of tiny case fragments embedded in the dark doll, like icebergs floating in the polar oceans.

Europa's surface temperature averages 110 K (-163 °C) at the equatorial region and even lower at 50 K (-223 °C) at the poles, so the water on the surface is permanently frozen. But the heat energy provided by tidal forces may keep the water below the surface ice in a liquid state. This conjecture was initially triggered by a series of speculations about tidal heat (a consequence of the slightly eccentric orbit and the orbital resonance between Europa and other Galilean moons).

It is speculated that Europa's topographic features imply the presence of an underglacial ocean. Some scholars have explained Europa's characteristic chaotic zone on the surface as the result of the seeping of seawater from below. But this explanation is highly controversial, and most geologists who study Europa prefer to support a theory known as the "thick ice" model, arguing that even if such an ocean exists, it is unlikely that it will have a direct impact on the surface. Estimates of the thickness of the ice crust also differ considerably, with some believing it to be in the range of several kilometres and others in the tens of kilometres.

If you're in Jupiter's moon Europa, you'll see a spectacular fountain up to 200 kilometers high. This is probably the best evidence that Europa hides a huge ocean beneath its frozen surface. U.S. and German researchers reported in the journal Science on December 12, 2013, that they used images taken by the Hubble Space Telescope in November and December 2012 and 1999 to determine that there was too much hydrogen and oxygen in two different regions of Europa's southern hemisphere, with only one explanation: that the hydrogen and oxygen were electrolyzed from the water ejected from Europa.

The fountains on Europa erupt intermittently, each erupting lasts about 7 hours. Since this phenomenon occurs at Europa's farthest point from Jupiter and disappears at its closest approach, the researchers speculate that Jupiter plays an important role in Europa's tidal gravity, which may cause cracks in Europa's surface ice at its farthest point, from which fountains erupt and gradually close when Jupiter's periphysis is reached.

The appearance of the fountain suggests that parts of Europa's frozen surface may be easily "breached" by the ocean inside, which has important implications for future exploration of Europa's habitability. Because this intermittent fountain spews material from Europa's surface and deep layers into the air, future research on Europa's composition eliminates the need to drill holes in the ice.