The search for life beyond Earth received a slight boost from new research published in Nature this month. Scientists working with data collected by NASA's Cassini mission to Saturn discovered evidence of phosphates in ice particles ejected via cryovolcanism into the E-ring structure by the tiny moon Enceladus. Although a mere 500 kilometers in diameter, Enceladus is a huge target in the quest for astrobiology in our solar system as beneath the outer ice shell lies a subsurface ocean about 10 km deep. That ocean is warmed via tidal heating, and plumes of water vapor escape through cracks in the surface.

Enter the Cassini mission, which spent over 13 years orbiting Saturn, collecting data on the gas giant, the rings, and various moons, including Enceladus. The spacecraft even flew through the plumes, using instruments such as the ion and neutral mass spectrometer (INMS) and the cosmic dust analyzer (CDA) to directly sample the material. Over the years, five of the six elements considered to be the building blocks for life as we know it - carbon, hydrogen, nitrogen, oxygen, and sulfur - have been found within those ice grains. The recent discovery of the sixth element, in the form of phosphates, not only completes the set but provides an ingredient necessary for the creation of DNA and RNA.

While the discovery is not evidence of life on Enceladus, the potential for life in that subsurface ocean continues to grow. Please join lead author Frank Postberg, a planetary scientist at Freie Universität Berlin, and SETI Institute senior scientist Franck Marchis as they discuss the impact of this discovery, the deeper meaning for the search for life beyond Earth, and what's next for the research.

Press releases: https://www.fu-berlin.de/en/presse/informationen/fup/2023/fup_23_137-saturnmond-enceladus-ozean-phosphate/index.html

https://www.nasa.gov/feature/jpl/nasa-cassini-data-reveals-building-block-for-life-in-enceladus-ocean

https://www.swri.org/press-release/key-building-block-life-found-saturn-moon-enceladus

Paper: https://www.nature.com/articles/s41586-023-05987-9

Recorded 22 June 2023