Science Seminars

The Subsurface Ocean of Enceladus: A Habitable Place in Our Solar System

Speaker: Frank Postberg (Freie Universität Berlin)
Date: Thursday, Apr 02, 2020
Time: 1:00 PM
Location: Zoom

Seminar Abstract:

Saturn’s icy moon Enceladus harbours a global ocean, which lies sandwiched between a rocky core at depth and an ice crust of just a few kilometers thickness. Through warm cracks in the crust a cryo-volcanic plume ejects ice grains and vapour into space, providing access to materials originating from the ocean. Cassini measurements suggest this ocean to be 30 – 55 km deep, mildly saline and with an alkaline pH. Hydrothermal activity is suspected to be occurring at the bottom of the ocean and also deep inside the probably water-percolated porous core of the moon, where the majority of the energy driving this activity is delivered via tidal dissipation. This presentation reviews the science produced by the two mass spectrometers onboard the Cassini spacecraft, which frequently carried out compositional in situ measurements of plume material emerging from the subsurface of Enceladus. Excitingly, the latest results indicate that a wide range of organic compounds are being emitted, trapped inside the ice grains, with some grains even containing concentrated macromolecular organic material. By probing these compounds from a spacecraft, humans have, for the first time, been able to get insights into the organic chemistry of an extraterrestrial water world.

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