Addition of a Low Altitude Tethys Flyby to the Nominal Cassini Tour

Of the eight Saturnian icy satellites, all but Mimas and Tethys have low altitude targeted flybys during the 4-year nominal Cassini spacecraft tour. In November 2004, the existence of a potential low-altitude Tethys flyby was discovered; this low-altitude Tethys flyby, added to the nominal tour in March 2005, corresponds to a 1500 km nontargeted periapsis altitude on September 24, 2005 and requires a Av cost of 8 mls. This paper details the methods used to determine the Tethys non-targeted flyby altitude, driven by navigational requirements and operational constraints, in addition to several trajectory modifications implemented to reduce total Av costs, and in some cases, simultaneous increases in scientific return.