Warm Ocean Beneath Enceladus May Harbor Life

New research from NASA's Cassini mission reveals that Enceladus, one of Saturn's moons, is releasing heat from both its north and south poles. This discovery, published in Science Advances, suggests that Enceladus has the long-term thermal balance necessary for life.

A team of scientists from Oxford University, the Southwest Research Institute, and the Planetary Science Institute found significant heat flow at Enceladus' north pole, challenging the previous assumption that heat loss was limited to the south pole, where geysers expel water vapor and ice particles.

The findings indicate that Enceladus is more thermally active than previously thought, suggesting it generates and releases more heat than a dormant moon would. Enceladus is known to have a global, salty ocean beneath its icy surface, which scientists believe is the primary source of the moon's internal heat.

This ocean, combined with warmth and essential chemical ingredients, makes Enceladus a prime candidate for hosting extraterrestrial life. For life to thrive, the ocean needs to remain stable over time, maintaining a balance between the energy gained and lost.

This balance is created through tidal heating from Saturn's gravitational pull, which stretches and compresses the moon as it orbits. If too little heat is generated, the ocean may freeze; if too much is produced, it could disrupt the ecosystem.

Dr. Georgina Miles, the study's lead author, emphasized the importance of understanding Enceladus' energy availability in the search for life beyond Earth. The research team utilized Cassini data to analyze the north polar region during two key periods: the deep winter of 2005 and summer of 2015.

They found that the north pole's surface was approximately seven degrees Kelvin warmer than expected, attributed to heat escaping from the hidden ocean. The measured heat flow was about 46 milliwatts per square meter, which is equivalent to about two-thirds of the average heat escaping through Earth's continental crust.

In total, Enceladus' heat loss reaches around 54 gigawatts, supporting predictions of tidal heating, indicating that its ocean could remain liquid for extended periods. This stability is crucial for potential life development.

The next challenge lies in determining how long the ocean has existed, with billions of years providing a stable environment for life to emerge. The study also suggests that thermal readings can help estimate the thickness of Enceladus’ ice shell, which is about 20 to 23 kilometers thick at the north pole and 25 to 28 kilometers on average across the moon.

This information is essential for planning future exploratory missions to Enceladus. Dr. Miles highlighted the need for long-term missions to ocean worlds, as data may not reveal all its secrets immediately.