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Life hidden under the ice on Europa?

 

Many scientists think, that Europa is the first candidate to be inhabited world in the solar system (except the Earth obviously). It is one of the rare places, where the water appears in the liquid state, even though it is still unknown exactly, how deep under the ice surface. Nowadays it is expected that the ocean on Europa is about 50 km deep. Jupiter, the biggest planet in the solar system, makes a tidal impact on Europa, which produces such amount of heat, which is enough to keep water in liquid state on it. Ron Greeley, a professor of Geology at the State University of Arizona (ASU), doing the astronomic researches of this satellite says, that if life appears quickly in proper conditions, it should exist everywhere, where there is some liquid water, source of energy and basic chemical elements. It is necessary to remember, that an organism which would occur too close to the surface of the satellite, could be destroyed by the radiation of Jupiter.

Europa was examined on the basis of data gathered by Galileo probe. According to Professor Greeley, further researches should focus on areas, where the geologic processes could cause the ice melting. In that places organisms would be protected from destructive radiation and would have enough resources of nutrients.

In the opinion of Richard Greenberg, professor from the same University (ASU), it is not everything that life can exist on Europa, it can be stimulated to evolution, as well. Cooperation of many factors may lead to the creation of cracks suitable to be inhabited by organisms.

According to Greenberg, combination of tides caused by Jupiter, existence of warm water and periodic illumination of the surface could cause processes of biological evolution in the ocean. Since 1997 Professor Greenberg together with his group, analyzed photographs sent by Galileo probe.

Tides occurring on Europa are much stronger than on the Earth. Their height reaches 500 metres.  The water moves together with the surface. Tides also cause distribution of substances necessary for creation and existence of organisms.

For many years scientists thought, that the ice shell of Europa was many kilometers deep and it never exposed the oceans. Anyway, Professor Greenberg considers there are proves that sometimes fragments of an ocean are exposed.

 

 

Cracks at the surface of Europa. Photographed by the Galileo probe.

 

 

 

 

The tides are the reason of creating many kinds of objects on the surface of this satellite: cracks, ridges and chaotic areas.

The scientists are of opinion, that ridges are created by water leaking from deeper layers through cracks in the surface, which then freezes up closing the crack completely. That process may last for thousands of years.

Chaotic regions are created when the ice on the surface of Europa melts. In opinion of professor Greenberg, heat connected with tides is strong enough to melt the ice. Another explanation to this process can be underwater volcanoes or discovered in 70ties of the twentieth century geothermal outlets - springs of hot water extracting from the ocean’s bottom.

Professor Christopher Chyba from SETI Institute, specializing in astrobiology, is also of opinion that life can exist on the bottom of the ocean on Europa, close to geothermal outlets.

All this factors gathered, could create a stable, but changing all the time environment, what stimulates the process of evolution. Life, under the ice surface of Europa may remind simple organisms living in oceans on the Earth. Professor Richard Greenberg imagines, that such microbes submit the process of hibernation when the water freezes, and stay in that state, up to the moment when the ice melts again. Bacteria discovered on Antarctica behave in similar way.