Life under the ice outside the Earth: what we know about Europa, the satellite of Jupiter

Perhaps extraterrestrial life is much closer to us than it seems, since liquid water, which is needed for the emergence and maintenance of the existence of an analogue of terrestrial life, is not uncommon in the solar system. So, it has already been proven (or almost proven) the existence of oceans of liquid water in a number of satellites of giant planets.

As far as is known, there is ice even in the craters of the planet closest to the Sun – Mercury. It is likely that ice sometimes melts there, so that water can form there from time to time, although, probably, not for long. But on Europa, the moon of Jupiter, liquid water certainly exists under a multi-kilometer layer of ice. Maybe there is life there, although it needs to be proven. What do we know about this moon of Jupiter?

It all started with the discovery of geysers

Europa’s heterogeneous surface has been known for a long time, as well as the fact that its surface is ice. For a long time, it was believed that the moon of Jupiter is covered with a layer of many kilometers of ice, so that the satellite is something like a snowball with a stone core inside. But, as it turned out, the reality is much more interesting – the Galileo spacecraft found signs of the existence of geysers above the surface of Europa.

During his scientific mission, he flew 11 times around Europe with a minimum distance from the surface of several hundred kilometers. Having studied the data transmitted by the apparatus, the scientists found out that in several cases the readings of the magnetometer changed greatly. This happened, in particular, on December 16, 1997, when the distance to the surface of the satellite of Jupiter was only 206 kilometers. Scientists have suggested that the Galileo passed through the geyser.

Hubble Orbital Telescope helped prove the existence of geysers. Well, since they exist, it means that under the ice of Europe there is liquid water, and there is a lot of it. It can be (and most likely it is) salty, and the salt can be not table, but “English”, that is. it is potassium salt. But in any case, there is a far from zero chance of life under the surface of Europa – even microscopic, even multicellular.

The depth of the oceans (or rather, the ocean) of Europe can reach 80-179 km, which means that the water on Jupiter’s moon is about twice as much as all the oceans of the Earth contain.

What is your evidence?

Of course, scientists do not have direct evidence of the existence of life in Europe, but there is indirect evidence, and this is not one set of data. In particular, in 2013, researchers at the University of California noticed traces of hydrogen peroxide. It is required for a process called methanogenesis – the production of methane by anaerobic archaea.

In addition to resources like peroxide, heat energy is also needed for the existence of life. And she, most likely, is also in Europe. There are several speculations about the possibility of liquid water on Europa. One of them is the gravitational effect of a satellite with a gas giant. Europa revolves around Jupiter, causing the inner layers to shift and deform under the influence of gravity. All this leads to friction with heat generation. The mantle of Jupiter’s moon is warming up, which heats the bottom layers of the ocean. It is perhaps warmest at the poles of the satellite, where the maximum amount of heat should be generated.

This effect is called “tidal heating” and is not unique to the solar system. Scientists have every reason to believe that tidal heating is characteristic of other satellites of the gas giant planets. According to Joachim Saur, a planetary scientist at the University of Cologne, Europe is one of the best candidates for detecting extraterrestrial life, because here liquid water interacts with a silicate mantle. This means that mineral compounds are washed out, supplying resources for living organisms (if they are there, of course).

Besides friction, there is another possibility – volcanic activity. If there are volcanoes under the ice, then they create the conditions necessary for the existence of life. There are examples on Earth – these are hydrothermal vents at the bottom of our planet’s oceans.

There is still a far from zero probability of oxygen getting into the water. Some scientists suggest that this element is formed on the surface of Europa under the influence of the solar wind, and then enters the ocean in the course of purely geological processes. True, it is still impossible to determine the concentration of oxygen in water – a specialized mission is needed.

As for life itself, a possible configuration of ecosystems is described by a company created about 20 years ago. documentary BBC Natural History of an Alien. Its creators believe that chemotrophic bacteria will be at the heart of the trophic chain. They will form layers of organic sediments on the ocean floor, and other living organisms will feed on these sediments. These organisms are analogous to herbivores on Earth. Accordingly, there will be predators that may resemble sharks.

Missions? Please

Europa Clipper

NASA launches the assembly and testing phase of the new station. The device is planned to be sent in 2024. He will explore the icy surface and subglacial ocean of Europa’s satellite.

The main goal of the Europa Clipper project is to study the satellite of Jupiter. The unique ocean of Europe is of particular interest to researchers. Now almost no one doubts its existence.

The start of the mission is aimed at 2024. The device will launch an SLS launch vehicle into space. The flight duration to the satellite will be 7 years. The main scientific program will last 109 days.

What will the mission to Europe include?

  • Collecting accurate information about the inland ocean;
  • collection of cartographic data on the relief and nature of the surface;
  • search for traces of water vapor that may appear from under the ice crust.

Its main characteristics:

  • The presence of a disk antenna with a diameter of 3 meters for data exchange with the Earth.
  • Two massive solar panels that will unfold in space like wings. They provide power to the probe system. The area of ​​the batteries is 90 square meters.
  • The dimensions of the station in the unfolded state will be more than the length of the basketball field by 30.5 meters.

This year, work will begin with all devices, and next year, complex tests of the station. The ship’s engine module will be built at the Johns Hopkins Applied Physics Laboratory in Maryland. The core of the module consists of two cylinders stacked on top of each other. Their height is about 3 m. They contain engine tanks and 16 rocket engines.

Jupiter Icy Moon Explorer (JUICE)

This is a multipurpose project that involves studying not only Europe, but also Ganymede and Callisto. As for Europe, scientists are planning 2 flybys for JUICE at an altitude of 400-500 km from the satellite’s surface. Unfortunately, a full-fledged study of Europe will require about 50-100 flights, which is not yet possible. Nevertheless, within 36 days, the device will study Europe in the most detailed way, being in close proximity. And remote research will take about a year. Study Objectives satellite of Jupiter:

  • Determination of the composition of substances not related to ice cover.
  • Exploration of reservoirs under the most active places. These studies will help to find out how much the liquid of Europa’s ocean is similar in composition to Earth’s oceans.
  • Investigation of the processes that took place relatively recently (it is believed that the surface of Europa is very young – the age does not exceed 180 million years, and the age of wormwood, periodically appearing on the surface, does not exceed 50-100 thousand years). It is also necessary to find out the geological activity of the satellite.

Exotic missions

If the two missions above are approved, then others, only supposed ones, are still being discussed. One of the most interesting is penetration through a crack under the ice. This is difficult, but possible. Such a mission will include two vehicles. The first will carry the second, bringing it under the ice.

The second may look like a “floating all-terrain vehicle”, which was successfully tested in 2019 in a lake near Utkiagvik, Alaska.

This module is called Buoyant Rover for Under-Ice Exploration. It is designed not to sink, but to crawl on the bottom of the sea ice. He has a positive buoyancy, due to which the sea pushes him to the ice from below, where he crawls, collecting scientific data.

During the tests, the robot was continuously under the ice for 42 hours and 30 minutes.

In general, the hopes of scientists can be expressed in the words of a specialist from NASA, Mohit Melvani Daswani. He is engaged in modeling the conditions of Europe, including the composition and physical properties of the core, silicate layer and the ocean. Daswani stated the following: “Europe is one of our best chances to find life in our solar system. NASA’s Europa Clipper mission will be launched in the next few years, and therefore our work is aimed at preparing for a mission that will study the question of Europe’s habitability. “

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