Saturn’s Magnetic Field from the Cassini Grand Finale orbits

The fundamental aim of the Cassini magnetometer investigation during the Cassini Grand Finale orbits was determination of Saturn’s internal planetary magnetic field. The unique geometry of the orbits provided an unprecedented opportunity to measure the intrinsic magnetic field at close distances never before encountered. The surprising close alignment of Saturn’s magnetic axis with its spin axis known about since the days of Pioneer 11 has been a focus of the team’s analysis since Cassini Saturn Orbit Insertion. However, the varying northern and southern magnetospheric planetary period oscillations which fill the magnetosphere, has been a factor in masking the field signals from the interior. Prior to the Grand Finale orbits, the magnetic field data analysis had confirmed the extreme axisymmetry of the intrinsic magnetic field, with a dipole tilt of < 0.06°, shown no evidence for secular variation to date, established equatorial flux expulsion in the deep interior and revealed no polar field minimum up to spherical harmonic degree 5. Here we describe the magnetometer results from the Grand Finale orbits which include confirmation of the extreme axisymmetric nature of the planetary field.