Suitable conditions for life may exist on many other planets

■ Tectonic plates not necessary

Washington, July 31: There may be more habitable planets in the universe than previously thought, according to a study.

Geoscientists at Pennsylvania State University in the US suggest that plate tectonics — long assumed to be a requirement for suitable conditions for life — are in fact not necessary.

When searching for habitable planets or life on other planets, scientists look for biosignatures of atmospheric carbon dioxide.

On Earth, atmospheric carbon dioxide increases surface heat through the greenhouse effect, according to the research published in the journal Astrobiology.

“Volcanism releases gases into the atmosphere, and then through weathering, carbon dioxide is pulled from the atmosphere and sequestered into surface rocks and sediment,” said Bradford Foley, an assistant professor of geosciences at Penn State.

“Balancing those two processes keeps carbon dioxide at a certain level in the atmosphere, which is really important for whether the climate stays temperate and suitable for life,” said Foley.

Most of Earth’s volcanoes are found at the border of tectonic plates, which is one reason scientists believed they were necessary for life.

Subduction, in which one plate is pushed deeper into the subsurface by a colliding plate, can also aid in carbon cycling by pushing carbon into the mantle.

Planets without tectonic plates are known as stagnant lid planets, researchers said.

On these planets, the crust is one spherical plate floating on mantle, rather than separate pieces, they said. These are thought to be more widespread than planets with plate tectonics. In fact, Earth is the only planet with confirmed tectonic plates.