NASA Scientists Say There Are More Planets With Oceans In Our Galaxy

There may be more ocean worlds outside our solar system that could potentially host life. That is according to a new NASA study that looked for exoplanets similar to the watery moons around Jupiter and Saturn. 

Saturn's moon Enceladus and Jupiter's moon Europa are covered in ice but scientists believe they have water flowing beneath. The presence of liquid water gives the two moons an environment that may support some form of life. 

"Plumes of water erupt from Europa and Enceladus, so we can tell that these bodies have subsurface oceans beneath their ice shells, and they have energy that drives the plumes, which are two requirements for life as we know it," Lynnae Quick, a planetary scientist at NASA’s Goddard Space Flight Center, said in a statement. "So if we're thinking about these places as being possibly habitable, maybe bigger versions of them in other planetary systems are habitable too."

To look for other ocean worlds, Quick and her colleagues analyzed 53 exoplanets with sizes most similar to Earth. Earlier research suggested planets of this size are more likely to be solid than gaseous, allowing liquid water on or below their surfaces.

After creating a list of Earth-size planets, the team then measured the energy they could be generating and releasing as heat. They found that some planets could produce either radiogenic heat, which comes from radioactive materials in their mantle and crust, or tidal force, which is generated from the gravitational tugging when one object orbits another.

Through a mathematical analysis, the scientists found that more than a quarter of the exoplanets studied could be ocean worlds. They said the majority of the planets may have oceans beneath the surface ice, similar to Europa and Enceladus.

The findings, published in the journal Publications of the Astronomical Society of the Pacific, also suggest many of the ocean worlds release more energy than the two moons in our solar system. Quick’s mathematical models are expected to help other scientists in studying promising exoplanets to find life. 

"Future missions to look for signs of life beyond the solar system are focused on planets like ours that have a global biosphere that's so abundant it's changing the chemistry of the whole atmosphere," Aki Roberge, a NASA Goddard astrophysicist, said.  "But in the solar system, icy moons with oceans, which are far from the heat of the Sun, still have shown that they have the features we think are required for life."

NASA has scheduled its Europa Clipper to explore the surface and subsurface of Europa in the next decade. The mission aims to understand the environment on the moon and provide more data on its capability to support life. 

Enceladus Processed using calibrated infrared, green and ultraviolet (IR3, GRN, UV3) filtered images of Enceladus taken by Cassini on March 12, 2008. NASA/JPL-Caltech/SSI/Kevin M. Gill

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