Exobiology and Evolutionary Biology

Effects of radiation damage on the geology of Europa and Ganymede (2)

PI: Louise Prockter

The interaction of Jupiter’s radiation environment with the surfaces of Europa and Ganymede represents a source of energy for driving biological activity, and can lead to the production of organic material. This radiation is non-uniform across the surfaces of these moons due to shielding from their induced or permanent magnetic fields and the relationship between the plasma flow and the body. This asymmetric bombardment, coupled with the penetration depth of different charged species at various energies, creates radiolytically unique regions on each satellite. We propose to construct maps showing the variability of radiolytic processing as a function of energy, location and depth across the surfaces of Europa and Ganymede. These products will then be used to assess the potential habitability of these satellites on regional and local scales.

The proposed work will be carried out using data from the Voyager and Galileo spacecraft to estimate the approximate flux and its variations near Europa’s and Ganymede’s surfaces. Previously, we have developed a model to study how electrons differentially bombard Europa. We will use this model and a similar one for Ganymede to estimate the electron dose as a function of surface location, and hence to determine geological regions of highest astrobiological interest. The third and fourth objectives of the Solar System Exploration Roadmap are to determine the characteristics of the Solar System that led to the origin of life and understand how life begins and evolves, and the NRC Decadal Survey calls for missions to Europa that will map its surface in detail, determine the thickness of its icy shell, confirm the existence of a subsurface ocean, and determine if that ocean harbors life. In order to 'identify’ both the likelihood of organic material near the surfaces of the Galilean satellites and the locations of zones of
habitability, we propose that it is vitally important that the radiation environment surrounding these bodies and the effect of that environment on their surfaces be understood.