Abstract
The Mars Atmosphere and Volatile EvolutionN (MAVEN) spacecraft can act
as an intermittent upstream solar wind monitor at ~ 1.5
AU. To inspect the evolution of solar wind turbulence in the Martian
exosphere, we have gathered proton (i.e., ionized hydrogen) temperature
measurements taken by the Solar Wind Ion Analyzer (SWIA) onboard the
MAVEN spacecraft. Here we investigate instabilities driven by the proton
temperature anisotropy at Mars. We look at the temperature anisotropy
T⊥p/T||p (i.e., the
ratio of the perpendicular proton temperature component to the parallel
proton temperature component) and the parallel plasma beta,
β||p, to determine the active plasma
instability mode. Furthermore, we report on the properties of turbulence
near Mars’ orbital location during upstream solar wind intervals from
January 2015 to December 2016 (~ 1 Martian year). We
find that the probability distributions of
(β||p, Rp)-values are
limited at Rp >1 and Rp
<1. We also find evidence of intermittency implying nonlinear,
non-homogeneous energy transfer. Additionally, spectral index values
near the Kolmogorov scaling value are observed for the inertial range
(10-4 Hz to 0.1 Hz).