Nano dust impacts on spacecraft and boom antenna charging

TL;DR

This paper investigates how nano dust impacts generate voltage pulses on spacecraft, revealing that these signals result from interruption of photoelectron currents rather than direct plasma cloud potentials.

Contribution

It introduces a new interpretation of dust impact signals, emphasizing photoelectron current interruption over plasma cloud potential in spacecraft charging.

Findings

Voltage pulses are caused by photoelectron current interruption.

The plasma cloud's electrostatic field is too weak to produce observed pulses.

Impacts influence antenna charging through photoelectron dynamics.

Abstract

High rate sampling detectors measuring the potential difference between the main body and boom antennas of interplanetary spacecraft have been shown to be efficient means to measure the voltage pulses induced by nano dust impacts on the spacecraft body itself (see Meyer-Vernet et al, Solar Phys. 256, 463 (2009)). However, rough estimates of the free charge liberated in post impact expanding plasma cloud indicate that the cloud's own internal electrostatic field is too weak to account for measured pulses as the ones from the TDS instrument on the STEREO spacecraft frequently exceeding 0.1 V/m. In this paper we argue that the detected pulses are not a direct measure of the potential structure of the plasma cloud, but are rather the consequence of a transitional interruption of the photoelectron return current towards the portion of the antenna located within the expanding cloud.