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Ions Accelerated by Sounder‐Plasma Interaction as Observed by Mars Express
Author(s) -
Voshchepynets A.,
Barabash S.,
Ramstad R.,
Holmstrom M.,
Andrews D.,
Nicolaou G.,
Frahm R. A.,
Kopf A.,
Gurnett D.
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja025889
Subject(s) - mars exploration program , ion , sounding rocket , plasma , solar wind , physics , spacecraft , antenna (radio) , ionosphere , ionospheric sounding , atomic physics , geophysics , astrobiology , astronomy , nuclear physics , electrical engineering , engineering , quantum mechanics
The ion sensor of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA‐3) experiment detects accelerated ions during pulses of radio emissions from the powerful topside sounder: the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) onboard Mars Express. Accelerated ions (O2 + , O + , and lighter ions) are observed in an energy range up to 800 eV when MARSIS transmits at a frequency close to the plasma frequency. Individual observations consist of almost monoenergetic ion beams aligned with the MARSIS antenna or lying in the plane perpendicular to the antenna. The observed ion beams are often accompanied by a small decrease in the electron flux observed by the electron sensor of Analyzer of Space Plasmas and Energetic Atoms 3. Observations indicate that the voltage applied to the antenna causes charging of the spacecraft to several hundreds of volts by the electrons of the ambient plasma. Positively charged ions are accelerated when the spacecraft discharges.