A monitoring campaign (2013-2020) of ESA's Mars Express to study interplanetary plasma scintillation

Kummamuru, P.; Molera Calvés, G.; Cimò, G.; Pogrebenko, S. V.; Bocanegra-Bahamón, T. M.; Duev, D. A.; Md Said, M. D.; Edwards, J. O.; Ma, M.; Quick, J.; Neidhardt, A.; de Vicente, P.; Haas, R.; Kallunki, J.; Maccaferri, G.; Colucci, G.; Yang, W. J.; Hao, L. F.; Weston, S.; Kharinov, M. A.; Mikhailov, A. G.; Jung, T.

doi:10.1017/pasa.2023.12

Published April 12, 2023 | Version Published

Journal Article Open

A monitoring campaign (2013-2020) of ESA's Mars Express to study interplanetary plasma scintillation

1. University of Tasmania
2. Jet Propulsion Lab
3. California Institute of Technology
4. Shanghai Astronomical Observatory
5. Hartebeesthoek Radio Astronomy Observatory
6. Technical University of Munich
7. Yebes Observatory
8. Chalmers University of Technology
9. Aalto University
10. National Institute for Astrophysics
11. e GEOS (Italy)
12. Xinjiang Astronomical Observatory
13. Yunnan Observatories
14. Auckland University of Technology
15. Institute of Applied Astronomy
16. Korea Astronomy and Space Science Institute

The radio signal transmitted by the Mars Express (MEX) spacecraft was observed regularly between the years 2013–2020 at X-band (8.42 GHz) using the European Very Long Baseline Interferometry (EVN) network and University of Tasmania's telescopes. We present a method to describe the solar wind parameters by quantifying the effects of plasma on our radio signal. In doing so, we identify all the uncompensated effects on the radio signal and see which coronal processes drive them. From a technical standpoint, quantifying the effect of the plasma on the radio signal helps phase referencing for precision spacecraft tracking. The phase fluctuation of the signal was determined for Mars' orbit for solar elongation angles from 0 to 180 deg. The calculated phase residuals allow determination of the phase power spectrum. The total electron content of the solar plasma along the line of sight is calculated by removing effects from mechanical and ionospheric noises. The spectral index was determined as -2.43±0.11 which is in agreement with Kolmogorov's turbulence. The theoretical models are consistent with observations at lower solar elongations however at higher solar elongation (> 160 deg) we see the observed values to be higher. This can be caused when the uplink and downlink signals are positively correlated as a result of passing through identical plasma sheets.

Additional Information

© The Author(s), 2023. Published by Cambridge University Press on behalf of the Astronomical Society of Australia. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited. This study was possible thanks to the observations carried out by the different operators across the array of EVN telescopes in China, Europe, Russia, Africa, and the AUT University (for Ww and Wa). The long-term study of plasma was also consolidated by the array of the Auscope VLBI telescopes operated by the University of Tasmania. The author acknowledges the valuable input from collaborators in JIVE and Shanghai Astronomical Observatory which helped improve the quality of the work. The collection of the data for research was possible thanks to the ESA's MEX communication team.

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