Frequency range of dust detection in space with radio and plasma wave receivers: Theory and application to interplanetary nanodust impacts on Cassini

Abstract

Wave instruments can detect dust in space via the charges released by impact ionization of fast dust grains. Each hypervelocity dust impact produces an electrostatic pulse whose short risetime is a major property determining the frequency range of detection. We propose a simplified analytical model to calculate this risetime and its variation with grains' mass and photoelectron or ambient plasma density, for pulses in spacecraft potential due to fast interplanetary nanodust impacts. We test these calculations by analyzing the high‐frequency receiver data of the radio and plasma wave instrument during the cruise phase of the Cassini mission between Earth and Jupiter. These data confirm the dependence of the risetime on grains' mass and speed and heliocentric distance predicted by our calculations. Furthermore, the data show that the nanodust properties follow closely the fluctuations of the solar wind velocity component perpendicular to the magnetic field, as predicted by dynamics. The calculations can be generalized to microdust detection on other spacecraft and might explain previous observations left uninterpreted. These calculations are also relevant for the design of wave receivers, by determining the optimal frequency range for dust detection on future missions.

Magnetic Field Effect on Antenna Signals Induced by Dust Particle Impacts

“…These measured escaping electron charges can be considered to be close to the total impact charge, Q imp ≅ |Q e, esc |. This result can be interpreted as the electrons in the impact plasma are isotropic and about half of them will leave the SC after the expansion of the plasma is complete (e.g., Meyer-Vernet et al, 2017). The fraction of electrons escaping from the SC, however, varies strongly with more positive potentials.…”

One‐Year Analysis of Dust Impact‐Like Events Onto the MMS Spacecraft

“…There are several supportive indications for this hypothesis: The simultaneous monopole and dipole electric field measurements show that these events are related to changes of the spacecraft potential (Figure ). The fact that the duration of these pulses depends on the spacecraft potential (ambient plasma density) also suggests that these pulses are related to changes of the spacecraft potential. For example, pulses generated in the instrument electronics should be independent on ambient plasma conditions. The rising part of the pulse depends on the spacecraft potential (thus on the plasma density in a particular region) and the time needed to reach the maximum of the pulse is similar as predicted by Meyer‐Vernet et al () for ion cloud expansion. The pulses are distributed over the year evenly. Both spacecraft detected similar amount of the events (MMS1 0.7 events per hour and MMS3 0.8 events per hour). This means that the events are not related to some technical issue on one of the spacecraft. There are significantly more pulses with a smaller amplitude than bigger ones.…”

“…This fact is important to keep in mind during data analysis. The mechanism of the signal generation by dust impacts and its detection by the electric field instruments is described in more details, for example, in Zaslavsky (2015), Meyer-Vernet et al (2017), and Vaverka et al (2017aVaverka et al ( , 2018.…”

Are STEREO Single Hits Dust Impacts?

“…Its existence has been predicted in a number of papers by Mann and colleagues, and there is evidence from very small holes in foils that such small, fast dust exists however (Carpenter et al, , ). We note that, at Saturn (Meyer‐Vernet et al, ; Moncuquet et al, ), dust has 10 times the time and distance to become entrained, but calculations do not seem to be available to compare with the observation.…”

“…2008). We note that, at Saturn (Meyer-Vernet et al, 2017;Moncuquet et al, 2009), dust has 10 times the time and distance to become entrained, but calculations do not seem to be available to compare with the observation.…”