NASA's Cassini Mission Reveals Life-Potential on Enceladus

New research from NASA's Cassini mission reveals that Enceladus, one of Saturn's moons, is releasing heat from both poles, suggesting that this icy world may have the long-term thermal balance necessary for life.

The study, published on November 7 in Science Advances, was conducted by a team of scientists from Oxford University, the Southwest Research Institute, and the Planetary Science Institute in Tucson, Arizona.

For years, it was believed that heat loss was only notable at Enceladus' south pole, where geysers eject water vapor and ice particles into space. However, the new findings indicate that the north pole is also thermally active, revealing significant heat flow.

This discovery points to the moon being far more geologically active than previously thought. Enceladus houses a global, salty ocean beneath its icy surface, considered one of the most promising environments in the solar system for life beyond Earth due to its liquid water, warmth, and essential chemical ingredients like phosphorus and complex hydrocarbons.

The stability of this ocean is critical for potential life, relying on a balance between energy gained and lost, maintained by tidal heating from Saturn's gravitational pull. If too little heat is produced, the ocean could freeze; too much energy could disrupt the environment that supports it.

The lead author of the study, Dr. Georgina Miles, emphasized the importance of understanding Enceladus' energy availability in the search for extraterrestrial life. The research team utilized data from Cassini to examine the north polar region during the deep winter of 2005 and summer of 2015.

They estimated the amount of heat that moves from the subsurface ocean to the surface, which remains extremely cold. Their findings showed that the north pole's surface was about seven Kelvin warmer than expected, attributed to heat leaking from the hidden ocean.

The team measured a heat flow of approximately 46 milliwatts per square meter, which is significant in terms of energy output. Combined with the heat detected at the south pole, Enceladus' total heat loss reaches about 54 gigawatts, closely aligning with predictions of tidal heating.

This perfect balance indicates that Enceladus' ocean could remain liquid for extended periods, fostering a stable environment for life to develop. The next step for scientists is to determine how long this ocean has existed.

If it has been stable for billions of years, the conditions for life could have emerged. The research also highlighted that thermal readings could help estimate the thickness of Enceladus' ice shell, which is crucial for future missions that may seek to explore its ocean.

The analysis suggests an ice thickness of 20 to 23 kilometers at the north pole and an average of 25 to 28 kilometers across the moon, slightly deeper than previous estimates. Dr. Miles noted that long-term missions to ocean worlds are essential for uncovering the secrets of these celestial bodies.