Abstract
In theory the width of the quasi-perpendicular bow shock ramp is on the
scale of a few electron inertial lengths, but as this work will show the
quasi-perpendicular bow shock at Mars is often wider. This is important
because it implies that the conditions at Mars create a behaviour at the
shock which cannot be described by current theory. Furthermore, the
width could affect processes at the shock such as energy transfer of the
ions and their subsequent thermalization. To investigate the cause of
the width, two sets of quasi-perpendicular bow shock crossings measured
by MAVEN are compared, one of unusual width (average 370 km or
5r$_{gi}$), and one of typical width (average 30 km or
0.7r$_{gi}$). These sets are labeled wide and thin shocks
respectively. It is seen that the wide shocks have no distinct overshoot
and have a higher level of magnetic field fluctuations than the thin
shocks. Factors that are known to affect the standoff distance, such as
the magnetosonic Mach number and mass loading of the solar wind by
planetary species, were found not to affect the width of the bow shock.
It is found that the temperature of the solar wind plasma increases more
as it passes through a wide than a thin shock, indicating that ions are
thermalized to a larger extent than at thin shocks. The
larger-than-predicted by theory width of the Martian quasi-perpendicular
bow shock indicate that there are conditions at Mars which we do not yet
understand.