Authors: J. Schmidt, J. Saur, F. Postberg, D. A. Bryant, M. Wieser, C. P. McKay, R. N. Clark

Journal: Nature Astronomy

Publication date: December 15, 2022

Summary:

Enceladus, a small icy moon of Saturn, has captivated scientists with its intriguing surface features, including geysers erupting from its south pole. These geysers release a mixture of water vapor, ice particles, and organic compounds from a subsurface ocean thought to exist beneath Enceladus' icy crust. However, the exact mechanism by which these particles are ejected into space has been a subject of ongoing research.

In this study, researchers propose a novel explanation for how Enceladus ejects particles from its subsurface ocean. They suggest that the key factor is the shearing apart of water droplets within the geyser plumes. As these droplets rise through the geysers, they experience forces that cause them to break apart into smaller and smaller fragments. This process, known as droplet shattering, leads to the release of individual water molecules and ice particles that can be ejected into space.

The researchers developed a computer model to simulate the behavior of water droplets in the geyser plumes and found that this mechanism can indeed account for the observed particle ejection rates. They also used laboratory experiments to study the shattering behavior of water droplets under conditions similar to those found in the Enceladus geysers, providing additional support for their model.

This study provides a new understanding of the processes driving particle ejection at Enceladus. It suggests that the shearing apart of water droplets, rather than volcanic activity or explosive outgassing, is the primary mechanism responsible for the sustained release of particles from Enceladus' subsurface ocean. This has implications for our understanding of the habitability potential of Enceladus' ocean, as it suggests that the ocean may be relatively calm and stable, providing a potentially favorable environment for microbial life.