An artist's rendering of possible hydrothermal activity on and under the seafloor of Enceladus' subsurface ocean, based on recently published results from NASA's Cassini mission. Image via NASA/JPL
Enceladus – Saturn’s sixth-largest moon – has caught the attention of astronomers and astrobiologists considerably after it has been found to have a warm ocean beneath its icy surface.
For years, Jupiter’s icy moon Europa has intrigued many as to whether life could exist beneath its surface, but now with this discovery of hydrothermal activity on Enceladus, US space agency NASA said the implications of this find offer ‘unprecedented scientific possibilities’.
Hydrothermal activity is a common occurrence in our own oceans, where seawater infiltrates and reacts with the planet’s rocky crust and emerges as a heated, mineral-laden solution.
NASA’s probe Cassini made the actual discovery on Enceladus back in 2004, when its cosmic dust analyser (CDA) instrument repeatedly detected miniscule rock particles rich in silicon.
An illustration depicts potential origins of methane found in the plume of gas and ice particles that sprays from Enceladus. Image via NASA/JPL
Since then, teams from Heidelberg University in Germany and University of Tokyo in Japan have worked on the findings and have now published them in two separate papers. The teams said that by the process of elimination, the particles the CDA found must be comprised of silica, between six and nine nanometres, which are typically created on Earth through hydrothermal activity.
Due to the small size of the silica particles, the Japanese team led by Yasuhito Sekine believes they must be travelling up rather quickly from the moon’s ocean floor 50km below the surface, in a process that still takes up to a few months or even a few years.
One of the key potential causes of hydrothermal activity could be created by Enceladus’ porous core, which would react with the vast volumes of water that surrounds it.
“These findings add to the possibility that Enceladus, which contains a subsurface ocean and displays remarkable geologic activity, could contain environments suitable for living organisms,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington.
“The locations in our solar system where extreme environments occur in which life might exist may bring us closer to answering the question: are we alone in the universe?”
