NASA identifies 17 exoplanets hosting 'hidden' oceans beneath icy shells, erupting geysers

NASA has expanded the search for extraterrestrial life by identifying 17 exoplanets with the potential for habitable oceans hidden beneath their icy shells. "Water from these oceans could occasionally erupt through the ice crust as geysers. The science team calculated the amount of geyser activity on these exoplanets, the first time these estimates have been made," NASA said in a statement.

The study, led by Dr. Lynnae Quick of NASA’s Goddard Space Flight Center, challenged the conventional focus on a star’s "habitable zone" and explored the possibility of subsurface oceans on distant and cold exoplanets.

The research, published in the Astrophysical Journal on October 4, delved into the internal heating mechanisms of these exoplanets, by taking known properties of icy moons in our solar system like Europa and Enceladus, which harbour subsurface oceans due to gravitational forces from their host planets and other moons nearby them.

"Our analyses predict that these 17 worlds may have ice-covered surfaces but receive enough internal heating from the decay of radioactive elements and tidal forces from their host stars to maintain internal oceans," explained Dr. Quick.

"Thanks to the amount of internal heating they experience, all planets in our study could also exhibit cryovolcanic eruptions in the form of geyser-like plumes."

The team focused on Earth-sized exoplanets with lower density, suggesting significant ice and water content. While their exact compositions remain unknown, estimates of surface temperatures indicated much colder conditions than Earth, implying potential ice coverings.

The study also estimated total internal heating by considering tidal forces and radioactive activity. Comparing these figures to Europa's allowed the team to predict ice layer thickness and geyser activity on the exoplanets.

Surface temperature up to 60 degrees Fahrenheit colder

Surface temperatures were estimated to be up to 60 degrees Fahrenheit colder than previous assessments. Ice shell thickness varied among the exoplanets, ranging from 190 feet to 24 miles. Geyser activity estimates ranged from 17.6 pounds per second for Kepler 441b to 13.2 million pounds per second for Proxima Centauri b.

The geyser activity could be seen when exoplanets pass in front of their stars. Water vapour from geysers could block certain colours of starlight, providing evidence of cryovolcanic eruptions. Sporadic detections of water vapour varying over time would suggest geological activity.

(With inputs from agencies)