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The concept of the artist portrays Kepler-69c, a super-terrestrial planet in the habitable zone of a star like our sun, located about 2700 light-years from the Earth in the constellation Cygnus Credit: NASA
There may be more habitable planets in the universe than we thought, according to Penn State geoscientists, who suggest that plate tectonics – long supposed to be a condition for life – is not necessary.
When searching for habitable planets or living on other planets, scientists look for biosignatures of atmospheric carbon dioxide. On Earth, atmospheric carbon dioxide increases surface heat by the greenhouse effect. "The volcano releases gases into the atmosphere, and then, through the weather, carbon dioxide is extracted from the atmosphere and sequestered in surface rocks and sediments," he said. Bradford Foley. , Assistant Professor of Geosciences. "Balancing these two processes keeps carbon dioxide at a certain level in the atmosphere, which is really important if the climate stays temperate and adapted to life."
Most of Earth's volcanoes lie on the border of tectonic plates. one of the reasons why scientists believed that they were necessary for life. Subduction, in which a plate is pushed deeper into the subsurface by a collision plate, can also help the carbon cycle by pushing carbon into the mantle
Planets without tectonic plates are known as stagnant planets . On these planets, the crust is a giant, spherical plate floating on the mantle, rather than separate pieces. They are thought to be more prevalent than planets with plate tectonics. In fact, Earth is the only planet with confirmed tectonic plates.
Foley and Andrew Smye, badistant professor of geoscience, created a computer model of the life cycle of a planet. They examined the amount of heat that its climate could hold depending on its initial heat budget or the amount of heat and thermal elements present during the formation of a planet. Some elements produce heat when they disintegrate. On Earth, decaying uranium produces thorium and heat, and decomposing thorium produces potbadium and heat.
After performing hundreds of simulations to change the size and chemical composition of a planet, years. At the highest level, they could sustain life up to four billion years, or about the lifetime of the Earth.
"You still have volcanism on stagnant planets, but it's a lot shorter than on planets with plate tectonics." Not so much cycling, "said Smye." Volcanoes result in a succession of lava flows buried over time: rocks and sediments heat up as they are buried. "
Researchers found that at high temperature and pressure, Carbon gas can escape rocks and smash their way to the surface, a process known as degbading.On land, says Smye, the same process occurs with water in areas of subduction faults
This degbading process increases depending on the types and amounts of thermal elements present on a planet up to a certain point, says Foley. "19659005]" There is a spot area sweet where a planet releases enough carbon dioxide to prevent to freeze the planet from freezing, but not so much that alteration can not extract carbon dioxide from the atmosphere and maintain the temperate climate "According to the model of the researchers, the presence and the amount of Heat producing elements were better indicators of the life potential of a planet.
"An interesting point to remember from this study is that the composition or initial size of a planet is important to define the path of habitability," said Smye. "The future fate of a planet is defined from the beginning of its birth. "
The researchers published their results in the current issue of Astrobiology .
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