NASA expands the search for extraterrestrial life by identifying 17 exoplanets

NASA has broadened its quest for extraterrestrial life by identifying 17 exoplanets that may host habitable oceans beneath icy shells. These planets were chosen based on their potential for subsurface oceans, which might occasionally erupt through the icy crust as geysers. This research, led by Dr. Lynnae Quick of NASA’s Goddard Space Flight Center, challenges the traditional focus on a star’s habitable zone and explores the possibility of habitable conditions on cold exoplanets.

The study, published in the Astrophysical Journal on October 4, investigated the internal heating mechanisms of these exoplanets by leveraging the knowledge of icy moons in our solar system, such as Europa and Enceladus. These moons have subsurface oceans due to gravitational forces from their host planets and nearby moons.

The 17 exoplanets in question are Earth-sized, with lower density, indicating significant ice and water content. While the exact compositions remain unknown, estimates of surface temperatures suggest much colder conditions than Earth, hinting at potential ice coverings. The study considered internal heating from the decay of radioactive elements and tidal forces from host stars, predicting that these planets could maintain internal oceans and possibly exhibit cryovolcanic eruptions in the form of geyser-like plumes.

Surface temperatures on these exoplanets 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. The estimates of geyser activity ranged from 17.6 pounds per second for Kepler 441b to 13.2 million pounds per second for Proxima Centauri b.

Geyser activity could be observable when these exoplanets pass in front of their stars, blocking certain colors of starlight due to water vapor from geysers. The sporadic detection of varying water vapor over time could indicate geological activity and the presence of cryovolcanic eruptions. This study opens up new possibilities for exploring the potential habitability of exoplanets beyond traditional habitable zones.