Study of Dust Impact Signals around Mars using MAVEN/LPW Observations

Electric field instruments can detect dust impacts on a spacecraft body as transient pulses in the measured electric field. Our study investigates these transient (millisecond) pulses detected by the Langmuir Probe and Waves (LPW) instrument onboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. We present a statistical analysis of 360,000 medium frequency burst electric field waveforms recorded in 2015; the study aims to identify and analyze the characteristics of these transient pulses. An automatic routine is used to detect waveforms with rapid fluctuations in the electric field data; this comprises over 12,000 events in the dipole and nearly 5,000 in the monopole configurations. Our findings reveal that most of the pulses in monopole configuration are likely the result of interference rather than dust impacts. Our analysis mainly focuses on dipole observations, which predominantly consist of bipolar events typically associated with dust impacts. These events are mainly detected in the Martian ionosphere, where the spacecraft is negatively charged. Fewer events are recorded when the spacecraft is positively charged, with a maximum at an altitude of 1200 km. The low detection rate of dust impact signals outside the ionosphere suggests that the planet is the most probable source of these dust particles. However, the physical processes by which dust grains are lifted from the surface of the planet to high altitudes are not clear, and thus a possibility that the signals observed might not be generated by dust impacts remains for further investigations.