This thesis concerns spacecraft observations of magnetic field and plasma in Saturn’s near
space environment and compares these observations with those made in and near the Jovian
magnetosphere. Such comparisons are equivalent to ‘turning the experimental dial’ in planetary
magnetospheres and provide a valuable insight into the way different parameters govern the
structure and dynamics of magnetospheres throughout the solar system.
Saturn and its magnetosphere is currently being studied by the Cassini spacecraft which,
arriving at Saturn in the summer of 2004, became the first spacecraft ever to enter orbit around
the planet. As a result there has never been a better time to study the Saturn system and the
vast majority of the data utilized in this thesis were obtained by the Cassini spacecraft and
its onboard instrumentation. Additional data were also obtained from the Pioneer, Voyager,
Ulysses and Galileo spacecraft.
Chapter 1 provides a general overview of space plasma and magnetospheric physics while
Chapter 2 discusses the Saturn system in more detail. Chapter 3 describes the spacecraft and
instrumentation used in this thesis with particular emphasis placed on magnetometer instruments
and the Cassini-Huygens spacecraft. Chapter 4 compares the structure of Jupiter’s and
Saturn’s outer magnetospheres and discusses the similarities and differences between the two.
Chapter 5 presents a new empirical model of Saturn’s dayside bow shock and discusses the three
dimensional shape of this surface while, finally, Chapter 6 presents observations of a magnetic
cavity in the Saturnian magnetosphere which, as of writing, has yet to be explained. Chapter
7 summarises and concludes the thesis.
The three independent investigations described above each shed light on a different aspect of
Saturn’s magnetospheric structure and dynamics and contributes to an improved understanding
of magnetospheric physics in general.