Scientists from the University of Chicago and Pennsylvania State University have disproved the popular assumption that planets completely covered by oceans are not habitable. This was reported in a press release Phys.org.
It is known that liquid water is necessary for the existence of life, and there must be a lot of it for a long period of time (sufficient for evolution). The climate can change significantly, therefore, for the survival of organisms, geochemical cycles are also needed, which, for example, maintain a balance between volcanic emissions and the fixation of atmospheric gases by rocks. Many scientists believe that the planets covered by the ocean are lifeless, since they lack many of the cycles of substances that exist on Earth.
However, in the new work, the researchers showed that geochemical cycles are not always necessary for life to exist. Experts have modeled several scenarios of changes in temperature and chemical composition of the oceans over billions of years for rocky planets. It turned out that quite a few water worlds from the very beginning of their existence maintain stable and favorable conditions for life for a fairly long time. The reason for this is the pressure exerted by the ocean on the earth's crust, as a result of which the exchange of substances between the mantle and the hydrosphere is hampered.
Thus, the existence of living organisms on oceanic planets does not depend on geochemical cycles, but on the initial distribution of carbon and other substances between the water envelope, atmosphere and crust. Moreover, red dwarfs may be suitable candidates for the role of a parent star in a system with such a planet, since they heat up more slowly than the Sun, which gives life more time to develop.
