Solar Orbiter’s first Venus flyby: Observations from the Radio and Plasma Wave instrument

¹ LPP, CNRS, Observatoire de Paris, PSL Research University, Sorbonne Université, École Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
e-mail: lina.hadid@lpp.polytechnique.fr
² Swedish Institute of Space Physics, Box 537 75121 Uppsala, Sweden
³ Department of Space Physics, Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czech Republic
⁴ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Meudon, France
⁵ LPC2E, CNRS, University of Orléans, 3A avenue de la recherche scientifique, Orléans, France
⁶ Radboud Radio Lab, Department of Astrophysics, Radboud University, Nijmegen, The Netherlands
⁷ Johns Hopkins Applied Physics Lab, Laurel, MD 20723, USA
⁸ Space Research Institute, Austrian Academy of Sciences, Graz, Austria
⁹ Space Sciences Laboratory, University of California, Berkeley, CA, USA
¹⁰ Istituto per la Scienza e Tecnologia dei Plasmi (ISTP), Consiglio Nazionale delle Ricerche, Via Amendola 122/D, 70126 Bari, Italy
¹¹ Space and Plasma Physics, KTH Royal Institute of Technology, 10405 Stockholm, Sweden
¹² Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
¹³ Department of Astrophysics, Astronomy and Mechanics, Faculty of Physics, School of Science National and Kapodistrian University of Athens, 15783 Zographos, Greece
¹⁴ Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
¹⁵ National Observatory of Athens, IAASARS, Metaxa and Vas. Pavlou str., Pedeli, 15236 Athens, Greece
¹⁶ School of Physics and Astronomy, University of Glasgow, G12 8QQ Glasgow, UK
¹⁷ Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242-1479, USA
¹⁸ Physics Department, University of California, Berkeley, CA, USA
¹⁹ Department of Physics, Imperial College, SW7 2AZ London, UK
²⁰ Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
²¹ Department of Space and Plasma Physics, School of Electrical Engineering and Computer, Stockholm, Sweden
²² CNES, 18 Avenue Edouard Belin, 31400 Toulouse, France
²³ Technische Universität Dresden, Wärzburger Str. 35, 01187 Dresden, Germany
²⁴ Astronomical Institute of the Czech Academy of Sciences, Prague, Czech Republic
²⁵ Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czech Republic
²⁶ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
²⁷ European Space Agency (ESA), European Space Astronomy Centre (ESAC), Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain

Received: 30 March 2021
Accepted: 3 June 2021

Abstract

Context. On December 27, 2020, Solar Orbiter completed its first gravity assist manoeuvre of Venus (VGAM1). While this flyby was performed to provide the spacecraft with sufficient velocity to get closer to the Sun and observe its poles from progressively higher inclinations, the Radio and Plasma Wave (RPW) consortium, along with other operational in situ instruments, had the opportunity to perform high cadence measurements and study the plasma properties in the induced magnetosphere of Venus.

Aims. In this paper, we review the main observations of the RPW instrument during VGAM1. They include the identification of a number of magnetospheric plasma wave modes, measurements of the electron number densities computed using the quasi-thermal noise spectroscopy technique and inferred from the probe-to-spacecraft potential, the observation of dust impact signatures, kinetic solitary structures, and localized structures at the bow shock, in addition to the validation of the wave normal analysis on-board from the Low Frequency Receiver.

Methods. We used the data products provided by the different subsystems of RPW to study Venus’ induced magnetosphere.

Results. The results include the observations of various electromagnetic and electrostatic wave modes in the induced magnetosphere of Venus: strong emissions of ∼100 Hz whistler waves are observed in addition to electrostatic ion acoustic waves, solitary structures and Langmuir waves in the magnetosheath of Venus. Moreover, based on the different levels of the wave amplitudes and the large-scale variations of the electron number densities, we could identify different regions and boundary layers at Venus.

Conclusions. The RPW instrument provided unprecedented AC magnetic and electric field measurements in Venus’ induced magnetosphere for continuous frequency ranges and with high time resolution. These data allow for the conclusive identification of various plasma waves at higher frequencies than previously observed and a detailed investigation regarding the structure of the induced magnetosphere of Venus. Furthermore, noting that prior studies were mainly focused on the magnetosheath region and could only reach 10–12 Venus radii (R_V) down the tail, the particular orbit geometry of Solar Orbiter’s VGAM1, allowed the first investigation of the nature of the plasma waves continuously from the bow shock to the magnetosheath, extending to ∼70R_V in the far distant tail region.