Water-group pickup ions from Europa: A window into surface ice evolution

<p>Water-group gas continuously escapes from Jupiter&#8217;s icy moon Europa in both charged and neutral states. The neutral species form co-orbiting populations of particles, or neutral toroidal clouds, eventually becoming ionized to be incorporated into the Jovian plasma environment. In September 2022, Juno performed a close flyby at ~350 km, an altitude less than the satellite&#8217;s radius, allowing it to make direct observations of water-group pickup-ions originating from the moon&#8217;s surface. These observations, along with more remote measurements by Juno of Europa-genic water-group pickup ions, provide critical constraints on the evolution and loss processes of Europa&#8217;s icy surface. We will present direct observations of water-group pickup-ions from Europa in the context of understanding the breakdown and evolution of Europa&#8217;s surface ice.</p>