Laboratory modeling of dust impact detection by the Cassini spacecraft

Nouzak, Libor; Hsu, Sean; Malaspina, D.; Thayer, F.; Ye, S.-Y.; Pavlu, Jiri; Němeček, Z.; Šafránková, Jana; Sternovsky, Z.

doi:10.1016/j.pss.2017.11.014

Cited by 29 publications

(77 citation statements)

References 25 publications

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“…The results confirmed the finding by Nouzák et al (2018) that in case of dust impacts on the SC body (including the HGA), the dominant signal is measured between the monopole antenna E W and the SC, that is, The results confirmed the finding by Nouzák et al (2018) that in case of dust impacts on the SC body (including the HGA), the dominant signal is measured between the monopole antenna E W and the SC, that is,…”

Section: Methodssupporting

confidence: 86%

“…The impact experiments are performed using the 1:20 scaled-down model of the Cassini spacecraft used in previous studies and described in detail by Nouzák et al (2018). The model consists of the HGA (17.5 cm in diameter), a cylindrical SC body (20 cm in length), and the magnetometer boom.…”

Section: Methodsmentioning

confidence: 99%

“…The model consists of the HGA (17.5 cm in diameter), a cylindrical SC body (20 cm in length), and the magnetometer boom. The amplifiers are housed inside the cylindrical SC body, have bandwidths of 50 Hz-100 kHz, and gains of 100 (Nouzák et al, 2018). In the model setup the E U and E V antennas are configured as a dipole, and E W is operated as a monopole.…”

Section: Methodsmentioning

confidence: 99%

“…The charge responsible for generating the recorded voltage is calculated as Q = UC SC /g, where g = 100 is the gain of the amplifier and C SC = 120 pF is the capacitance of the model SC body (Nouzák et al, 2018). The charge responsible for generating the recorded voltage is calculated as Q = UC SC /g, where g = 100 is the gain of the amplifier and C SC = 120 pF is the capacitance of the model SC body (Nouzák et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

“…Here we provide the summary of recent findings based on laboratory measurements that are precursors to the work presented in this article. Nouzák et al (2018) expanded on the initial study by using a scaled-down model of the Cassini spacecraft with a combination of monopole and dipole antennas. This work has identified three signal-generating mechanisms: charge collection by the SC body, charge collection by the antenna from nearby dust impacts, and induced charging from the space charge of the expanding impact plasma cloud.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic Field Effect on Antenna Signals Induced by Dust Particle Impacts

et al. 2020

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The Radio and Plasma Wave Science instrument on Cassini has observed fewer than expected dust particle impacts during the mission's Grand Finale orbits. The relatively strong magnetic field in the close vicinity of the planet has been suggested to affect the intensity of the dust impact generated signals. A laboratory investigation is performed using dust particles accelerated to ≥20 km/s speed impacting onto a previously developed model of the spacecraft and the Radio and Plasma Wave Science antennas. The external magnetic field is generated by two sets of magnetic coils. The recorded antenna waveforms are decomposed into contributions from the electrons and ions of the dust impact generated plasma cloud. A good qualitative understanding of the waveforms is achieved by dividing the electron and ion population into two portions: one that is escaping from the spacecraft and another that is collected by the spacecraft. The experimental results show that the part of the signal corresponding to escaping electrons is affected by the magnetic field and that dust impact signals can be significantly reduced for spacecraft floating potentials close to zero.

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Section: Methodssupporting

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic Field Effect on Antenna Signals Induced by Dust Particle Impacts

et al. 2020

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Interpreting Dust Impact Signals Detected by the STEREO Spacecraft

2017

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There is no comprehensive understanding yet of how dust impacts on spacecraft (SC) generate signals detected by antenna instruments. The high sensitivity of the S/WAVES instrument and the large number and high diversity of dust impacts detected make the STEREO mission particularly well suited for a closer investigation. A floating perturbation model (FPP) was recently proposed to explain the characteristic shape of dust impact signals with an overshoot. The FPP model posits that the overshoot is due to the different discharge time constant of the SC and the individual antennas. Kinetic simulations are performed to demonstrate that, contrary to common belief, antennas are inefficient collectors of charged particles from impact plasmas. The collection efficiency is small, only 0.1–1%, varying weakly with the bias potential between the antenna and the SC, and more strongly with impact location. The low recollection efficiencies and an analysis of the shapes and scaling of typical and atypical signals recorded by S/WAVES suggest that, besides the mechanism described by the FPP model, there is another, possibly stronger mechanism that is responsible for generating the characteristic overshoot for most dust impact signals observed by STEREO.

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Variability of Antenna Signals from Dust Impacts

Shen

Sternovsky

Malaspina

2022

Preprint

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Antenna instrument carried by spacecraft is complementary to dedicated dust detectors by registering transient voltage perturbations caused by impact-generated plasma. The signal waveform contains information about the interaction between the impact-generated plasma cloud and the elements of spacecraft -antenna system. Variability of antenna signals from dust impacts has not yet been systematically characterized. A set of laboratory measurements are performed to characterize signal variations in response to spacecraft parameters (bias voltage and antenna configuration) and impactor parameters (impact speed and composition). These measurements demonstrate that dipole antenna configurations are sensitive to impact location because of how the asymmetric expansion of impact plasma cloud produces different signals among antennas. This result revises previous conclusions that dipole antenna configurations should be insensitive to impacts. When dust impacts occur at low speeds, antenna instruments typically register smaller amplitudes and less characteristic impact signal shapes. In this case, impact event identification becomes challenged by low signal-to-noise ratios and complex waveforms, indicating the compound nature of non-fully developed impact-generated plasmas. Laboratory studies of aluminum dust particle hypervelocity impacts were used to explore the dependence of impact waveform variability on dust composition. No significant variations were determined compared to common iron dust measurements, consistent with prior studies. Additionally, electrostatic model fitting is used to obtain impact plasma parameters from antenna-detected waveform signals. The recovered parameters are comparable to those from Fe dust. This suggests a similarity of fully developed impact plasma cloud behaviors upon hypervelocity impact.

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Laboratory modeling of dust impact detection by the Cassini spacecraft

Cited by 29 publications

References 25 publications

Magnetic Field Effect on Antenna Signals Induced by Dust Particle Impacts

Magnetic Field Effect on Antenna Signals Induced by Dust Particle Impacts

Interpreting Dust Impact Signals Detected by the STEREO Spacecraft

Variability of Antenna Signals from Dust Impacts

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