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# The global current systems of the Martian induced magnetosphere

## Abstract

Induced magnetospheres form around conductive non-magnetized planetary objects (such as the ionospheres of Mars, Venus, Titan, Pluto and comets) in the electrodynamic interaction with a magnetized flowing plasma, such as the solar wind. The resulting induced currents couple the ionosphere and the deflected plasma, thus they provide insight into the solar wind’s role in powering the heating, escape and evolution of planetary atmospheres. In contrast to the analogous current systems in intrinsic magnetospheres, which were mapped decades ago at Earth, the current systems of induced magnetospheres are largely unexplored. Here, we use five years of magnetic field measurements from the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter to empirically map the current systems of the Martian induced magnetosphere. We find unexpected features, in particular: coupling of the ionosphere and the bow shock, asymmetries between the north–south electric hemispheres and a twist in the near-Mars current system. The current flow pattern in the induced magnetosphere of Mars indicates a system driven by a magnetospheric convective electric field, powered by the solar wind interaction.

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## Data availability

All datasets analysed in this study are publicly available through the NASA Planetary Data System (https://pds.nasa.gov/). MAVEN data are hosted at the Planetary Plasma Interactions node, provided by the University of California, Los Angeles (https://pds-ppi.igpp.ucla.edu/mission/MAVEN/). The data that support the plots within this paper and other findings of this study are also available from the corresponding author upon reasonable request.

## Code availability

Code related to the implementation of methods presented in this study will be provided upon reasonable request to the corresponding author.

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## Acknowledgements

This study was made possible thanks to NASA’s Mars Exploration Program through their continued support of the MAVEN mission.

## Author information

Authors

### Contributions

R.R. conceptualized the study and produced the published results based on MAVEN physical data products. The production of the relevant MAVEN data products is led by J.E. and J.H. based on direct measurements acquired from the spacecraft instruments, measurements which they also plan and continuously calibrate. R.R., D.A.B., Y.D., J.E. and J.H. contributed substantially to scientific interpretation of the results and drafting of the manuscript. B.J. directs the operation of the spacecraft, acquisition of data, and related scientific investigations as principal investigator for the MAVEN mission. All authors discussed the results and conclusions of the manuscript.

## Ethics declarations

### Competing interests

The authors declare no competing interests.

Peer review information Nature Astronomy thanks Matthew Fillingim, Catherine Johnson and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

## Supplementary information

### Supplementary Information

Summary of supplementary information, Supplementary Figs. 1–3

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Reprints and Permissions

Ramstad, R., Brain, D.A., Dong, Y. et al. The global current systems of the Martian induced magnetosphere. Nat Astron 4, 979–985 (2020). https://doi.org/10.1038/s41550-020-1099-y

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