Comparison of Solitary waves and Dust Impact Signals Detected by Electric Field Instruments onboard MAVEN
Abstrakt
Dust impact on the spacecraft body can result in short pulses in the measured electric field. Our study is focused on these pulses detected by the Langmuir Probe and Waves (LPW) instrument onboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft.
LPW detects electric field signals in dipole and monopole configurations using two long identical stacer booms. Out of all the modes, we use the medium frequency burst mode, the data covers 62.5 milliseconds using 4096 measured points which gives us a sampling frequency of 66.67 kHz.
We present a preliminary statistical analysis over the year 2015 (360000 waveforms) and the analysis is focused on distinguishing dust impact signatures from solitary structures. To reliably distinguish solitary waves from dust impact signals by an automatic code is a challenging task as the solitary wave signatures in the electric field data can be similar to the transient pulses generated by dust impacts.
Therefore, we choose two different parameters to classify two groups of events: the ratio of rising and decay times and the ratio of positive and negative peaks of the pulse. In total, we find approximately 10000 events which compose both solitary waves and the most probable dust impacts.
We discuss signals generated by dust impacts and solitary waves for different operation modes of electric field probes, spacecraft potentials, and distance of probes to the spacecraft surface.