Is salt the key to unlocking the interiors of Neptune and Uranus?

The interiors of several of our Solar System’s planets and moons are icy, and ice has been found on distant extrasolar planets, as well.  But these bodies aren’t filled with the regular kind of water ice that you avoid on the sidewalk in winter. The ice that’s found inside these objects must exist under extreme pressures and high-temperatures, and potentially contains salty impurities, too.