Hua Feng noted that scientists at the time of history found that Europa's polar axis of rotation was offset by nearly 90 degrees, and such extreme changes indicate that there is a liquid ocean beneath the surface of Jupiter's ice crust, which will further indicate that Europa may be pregnant with extraterrestrial life.

The study, which was co-authored by scientists from the Carnegie Institution, the Association for the Study of the Lunar and Planetary Planets and the University of California, Santa Cruz, was published in the journal Nature.

Issam Cyanide Suyama of the Carnegie Institution's Division of Geomagnetism is part of the joint research team, and he used images taken by the Voyager, Galileo and New Horizon spacecraft to map large arc-shaped basins on Europa's surface that are more than 500 kilometers in diameter. It is reported that Europa has a radius of 1,500 kilometers, which is slightly smaller than the Moon.

By comparing the topography of the basin fracture formed by the offset pressure of the polar axis of rotation on Europa, the researchers measured that the polar axis of rotation was offset by more than 80 degrees, which was previously about 10 degrees away from the current equator.

The violent shift of the axis of rotation of the Europa Pole is most likely due to the presence of a thick layer of ice below the polar surface. "The rotating body needs to find a stable balance based on the maximum change in the axis of rotation. In the case of Europa, the inconsistent thickness of its shell would result in a large degree of imbalance, so Europa would have to change its axis of rotation in search of a new stable state during operation. ”

Changes like this are called "true polar shifts" and are not due to visual drift in slab architecture. There are also true polar shifts on Enceladus on Earth, Mars, and Saturn. The inclusion of Europa in our study suggests that more repositioning of the planet is needed, Matsuyama said.

The study also hints at the presence of liquid water inside Europa, and scientists have speculated that the planet has a vast subsurface ocean based on photographs taken by spacecraft that reveal fractured ice surfaces beneath Europa's surface. The tidal force created by Europa's gravity heats the ocean of ice crust into hot water, and even if the ocean is cut off from solar energy, the heat and liquid water can be life-threatening.

In November 2009, Richard Greenberg, a scientist at the University of Arizona in the United States, and others found that Europa may have life similar to that of fish. Many scientists now believe that Europa has no land on its surface, and that beneath the thick ice lies a global ocean that is about 160 kilometers deep.

Greenberg's latest research shows that Europa's ocean is absorbing a lot of oxygen, much more than previous simulations had predicted. Scientists believe that this oxygen is enough to support the existence of multiple life forms, and theoretically there should be at least 3 million tons of fish-like organisms in Europa's ocean. Greenberg explained, "Although it is not yet possible to say that life is definitely there, we at least know that the physical environment there supports the existence of life." ”

Timothy Shank, a deep-sea ecologist at Woods Hale, USA, believes that Europa's seafloor environment bears a great resemblance to the "hydrothermal outlet" at the bottom of the Earth's oceans. It is well known that many life forms exist at the hydrothermal outlet of the Earth's seafloor. So Shank insists, "It would be strange if there was no life on Europa." ”

Most of what is known about Europa comes from flyby observations during the two missions of Voyager and Galileo.

The ambitious Jupiter orbiter project was scrapped in 2005, but a variety of proposals for future exploration missions to Europa continue to be proposed.

The 2006 NASA (National Aeronautics and Space Administration) budget included a fund for the future Aeromede program at the oral request of the U.S. Congress. It is envisaged that the tasks of the project include the determination of the presence of an ocean beneath Europa's surface ice crust through gravity and altitude measurements, high-resolution photography of the surface over a large area, spectroscopic analysis to confirm the chemical composition of the surface material, and penetration detection of ice using ice-piercing radar. The plan even contemplates having the spacecraft carry a small landing device that could be used to directly analyze the chemical composition of Europa's surface, while collecting seismic wave data to determine the thickness and activity of the ice. However, it is not clear whether the plan is likely to be actually launched, and there is no such fund in the budget for NASA2007 years.

Another feasible plan is to use an impactor similar to the Deep Impact (DI) scheme. Slam the surface of Europa with an impactor to stir up debris smoke, allowing a small ship to pass through the smoke to collect debris. Since there would be no need to launch a lander from the orbital orbit of Jupiter or Europa – and of course the step of re-taking off from the satellite – fuel consumption would be greatly reduced, making it considered one of the most economical options.

There are also bolder ideas, such as launching a lander to look for possible signs of life frozen in the shallow layers of the ice crust, or going directly inside to explore the subglacial ocean. The proposal is to send a so-called "Melt P."

OBE) (Ice-Piercing Robot - C

Yobot), which melts ice and punches holes, drills all the way into the subglacial ocean, and then releases an autonomous underwater walker (Hanyong Robot - C

yobot）。 This device can transmit the collected information back to Earth. Both the ice-piercing and swimming robots are subjected to strict disinfection to avoid mistaking the organic matter that may be carried from the earth for local organisms and to prevent contamination of the ocean under the ice. This bill has not yet entered the stage of serious planning.

C

Yobot was tested in Antarctica. As the heat generated by the drill bit melts the ice, the detector "sinks deeper and deeper". Melting ice is a good concept in theory, but if the probe touches something deep in the ice, such as a large rock, it will get stuck in it. If the ice can't melt, the mission will come to an end. The Hong Kong Polytechnic University and the Raume Foster Institute in Grazwiltraum, Hungary, have devised an innovative approach that combines drilling technology and melting methods. They proposed the "hot drill" (the

mal d

The prototype of the ILL) system performed well in the experiments, and the results were published in the July 2008 issue of the journal Planetary and Space Science.

On September 27, 2016, NASA announced a major discovery, scientists observed that Jupiter's fourth largest moon, Europa, had a water vapor eruption, and the presence of water could lead to life.

The Hubble telescope observed a column of water vapor ejecting outward from Europa's surface at 7 o'clock. This is strong evidence of a liquid ocean beneath Europa's ice, which could create favorable conditions for life.

The researchers calculated the amount of hydrogen that can be produced in Europa's oceans when seawater interacts with rocks, a process known as serpentinization. In this process, water penetrates into the voids between the mineral particles and reacts with the rock, forming new minerals and releasing hydrogen.

Researchers believe that over time, there will be some cracks in the bottom of Europa's sea, because the interior of the planet's rocks has remained cold for billions of years since its formation. New cracks expose fresh rock to seawater, and more hydrogen-producing chemical reactions occur.

At the end of 2009, Richard Greenberg, a scientist at the University of Arizona in the United States, published a paper stating that Europa's oceans should be home to at least 3 million tons of fish-like complex organisms. This is another step forward in the Europa life hypothesis proposed by scientists 13 years ago. Europa was discovered by Galileo Galilei in 1610, and spacecraft exploration of Europa suggests that there may be oceans under the ice of its outer shell, and the presence of oceans means that there may be life in them. Scientists have been trying to unravel the mystery of their lives,

Can humans live on Europa? Experts from NASA believe that this Jupiter has great "habitable" potential and may be suitable for human habitation in the future.

Next, scientists will send probes to survey Europa's subglacial ocean to determine its thickness and distribution, and some studies suggest that Europa's ocean may be similar to Earth and also has a certain salinity. Dr. Robert Paparado of NASA's Jet Propulsion Laboratory believes that sending a probe to the surface of Europa is a very visionary planetary science goal, but also a difficult technical challenge.

An article from the journal Astrobiology details the three main goals of future Europa missions: first, to monitor Europa's sea salinity, organic matter, and other pollutants at at least two different depths;

Europa, known as Europa, has a wonderland of strange terrain on its surface, and according to Galileo Galileo observations, scientists still don't understand the intricate and intertwined "mysterious lines" on the surface of the object, and sending a probe to Europa could solve many key problems.

In March 2013, scientists concluded that there was ample evidence that Europa had a huge saltwater ocean beneath its frozen surface, and that there was an exchange of chemicals between the subglacial ocean and the surface, making the ocean even more abundant. Professor Mike Brown, an astronomer at the California Institute of Technology, believes that energy can enter Europa's subglacial ocean from these chemical cycle channels, which is very important for life.

Spacecraft probes of Europa suggest that there may be an ocean on it. For this reason, in the exploration of Jupiter's moons, scientists pay the most attention to Europa.

As early as 1979, when Voyager 1 and 2 explored Jupiter, they found Europa resembling a large sphere of ice mixed with creamy chocolate, with curved stripes on its surface. Scientists analyzed Europa's photographs and exploration data and suggested that the moon's surface was covered with 5,000 meters of ice, and that there could be an ocean up to 50 kilometers deep beneath the ice.

Photographed by Galileo Galilei at a distance of 160,000 kilometers from Europa in 1996 shows that the planet is in the shape of an ice crust with cracks on its surface, like an ice floe at the Earth's poles, indicating that the ice was once subjected to a huge force. Scientists believe that this force is a tidal force formed by the gravitational pull between Europa and Jupiter and the other three Galilean moons, which not only forms Europa's surface features, but also causes the water inside to exist in a liquid state.

Photographs taken by Galileo in late 1996 as it passed 688 kilometers from Europa showed the presence of water on Europa's surface. Scientists say this phenomenon indicates that Europa's inner core is hot, with large amounts of heat energy erupting from craters or hydrothermal vents, causing some of the surface ice to melt.

In January 1997, Galileo Galilei's magnetometer sounded Europa's magnetic field and showed that Europa had only one internal magnetic field to explain the results obtained. The conductivity of this inner conductive layer must be as strong as that of saline seawater. From this, scientists have once again concluded that there may be an ocean on Europa. At the same time, new photographs sent back show that Europa's surface cracks have changed location, suggesting that it is likely to be caused by ocean currents below the surface.