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Spacecraft Discharge Time Constants Determined From Electron‐Flux Suppression During Sounding‐Radar Operation at Mars

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posted on 2025-05-06, 15:18 authored by Sebastián Rojas Mata, Stas Barabash, Andrii Voshchepynets, Mats Holmström, Beatriz Sánchez‐Cano, Mark LesterMark Lester, Andrea Cicchetti, Roberto Orosei

Spacecraft discharge time constants are calculated from measurements of electron differential flux before and during operation of an ionospheric sounding radar. Determining these time constants provides insight into how the operation of a sounding radar affects the surrounding plasma's interaction with the spacecraft. The analysis is enabled by the fixed‐frequency operation mode of a sounding radar which enhances resonant interaction with the ambient plasma. This mode's effect on measured energy spectra of ion and electron fluxes is described. Measurements of electron fluxes disturbed by radar operation serve as input to a model of spacecraft discharge for calculating capacitive discharge time constants. A case study using electron fluxes measured at Mars yields discharge time constants in the range 0.6–0.8 ms and reveals that a residual potential around V remains on the spacecraft long after radar operation ceases. The minimum spacecraft potential cannot be determined with these data and model due to the narrow energy range of electrons in the ambient plasma.

Funding

Solar wind influence on terrestrial planets' upper atmospheres: unveiling their close interaction

Science and Technology Facilities Council

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STFC Grant. Grant Number: ST/W0089X/1

Swedish National Space Agency. Grant Number: Dnr 20/137

European Space Agency. Grant Number: RFP/3-17233/21/ES/JD

Italian Space Agency. Grant Number: 2024-40-HH.0

History

Author affiliation

College of Science & Engineering Physics & Astronomy

Version

  • VoR (Version of Record)

Published in

Journal of Geophysical Research: Space Physics

Volume

130

Issue

4

Publisher

American Geophysical Union (AGU)

issn

2169-9380

eissn

2169-9402

Copyright date

2025

Available date

2025-05-06

Language

en

Deposited by

Ms Beatriz Sanchez-Cano

Deposit date

2025-04-24

Data Access Statement

All MEX data are publicly accessible at the ESA Planetary Science Archive at https://www.cosmos.esa.int/web/psa/mars-express.

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