They actually did have this option, see http://www.sciencedirect.com/science/article/pii/S009457651200149X http://www.sciencedirect.com/science/article/pii/S00

They actually did have this option, see http://www.sciencedirect.com/science/article/pii/S009457651200149X http://www.sciencedirect.com/science/article/pii/S0094576512... However, it was evaluated as inferior to the option chosen (there was apparently no concern at all about contaminating Saturn itself); see the slide titled "EOM Options with Science Evaluation": http://www.lpi.usra.edu/opag/march_08_meeting/presentations/spilker.pdf http://www.lpi.usra.edu/opag/march_08_meeting/presentations/...