American planetary scientist Alan Stern, chief investigator of the New Horizons mission, has named a simple reason for the invisibility of aliens, Science News reports.
The scientist believes that most extraterrestrial living things do not live on the surface of their mother planet, but in its bowels. Such life exists, Stern believes, in the subsurface oceans of planets and their satellites, invisible to an observer in outer space.
“Worlds with inner oceans are cut off from outer space by a thick layer of ice or rock and ice, so it is not easy for them to show themselves,” says Stern.
The main source of energy in such celestial bodies will not be the light of the mother star, but hydrothermal sources at the bottom of the subsurface oceans, and the protection from stellar radiation will not be their own magnetosphere and atmosphere, but a thick ice or rock shell.
In the solar system, there are or are allowed to have many celestial bodies with liquid or frozen subsurface oceans. Among them, in particular, are the satellites of Jupiter (Ganymede and Europa), Saturn (Enceladus and Dione), and Pluto.
In April 2017, the interplanetary station Cassini discovered that water jets erupting from the bowels of Enceladus contain up to 1.4 percent molecular hydrogen and up to 0.8 percent carbon dioxide. These compounds are critical for the biosynthesis of methane by microorganisms and indicate that hydrothermal vents are present in the subsurface ocean of Saturn's moon.
“And if living organisms in the icy ocean worlds evolve into intelligent beings, they probably will not know about the existence of the night sky, like humans,” writes Science News.
Station New Horizons on July 14, 2015 flew past Pluto at a minimum distance. The main objective of the mission is to study the dwarf planet and its satellite Charon.
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