That (with the exception that they&#x27;re taking the water to water-impoverished Mars, rather than Earth orbit or California) is basically the plot of The Martian Way by Asimov.<p>Unfortunately, it doesn&#x27;t work  that way in real life, because Saturn&#x27;s rings are more like diffuse snow flurries than mountain-sized ice chunks, as cool as that would be.  And coupling your little interplanetary probe to an ice mountain really cuts into your delta-V numbers.