Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

You are viewing this page in draft mode.

Crustal and time-varying magnetic fields at the InSight landing site on Mars

Abstract

Magnetic fields provide a window into a planet’s interior structure and evolution, including its atmospheric and space environments. Satellites at Mars have measured crustal magnetic fields indicating an ancient dynamo. These crustal fields interact with the solar wind to generate transient fields and electric currents in Mars’s upper atmosphere. Surface magnetic field data play a key role in understanding these effects and the dynamo. Here we report measurements of magnetic field strength and direction at the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) landing site on Mars. We find that the field is ten times stronger than predicted by satellite-based models. We infer magnetized rocks beneath the surface, within ~150 km of the landing site, consistent with a past dynamo with Earth-like strength. Geological mapping and InSight seismic data suggest that much or all of the magnetization sources are carried in basement rocks, which are at least 3.9 billion years old and are overlain by between 200 m and ~10 km of lava flows and modified ancient terrain. Daily variations in the magnetic field indicate contributions from ionospheric currents at 120 km to 180 km altitude. Higher-frequency variations are also observed; their origin is unknown, but they probably propagate from even higher altitudes to the surface. We propose that the time-varying fields can be used to investigate the electrical conductivity structure of the martian interior.

This is a preview of subscription content

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: IFG data for sols 35–106.
Fig. 2: Regional geology and inferred magnetization.
Fig. 3: Time variations–daily signals.
Fig. 4: Pulsations.
Fig. 5: Toward interior electrical conductivity.

Data availability

All IFG data reported in this manuscript are available on the Planetary Data System (PDS) Planetary Plasma Interactions (PPI) node: https://pds-ppi.igpp.ucla.edu.

References

  1. 1.

    Banerdt, W. B. et al. Initial results from the InSight mission on Mars. Nat. Geosci. https://doi.org/10.1038/s41561-020-0544-y (2020).

  2. 2.

    Golombek, M. et al. Geology of the InSight landing site on Mars. Nat. Commun. https://doi.org/10.1038/s41467-020-14679-1 (2020).

  3. 3.

    Banfield, D. et al. InSight Auxiliary Payload Sensor Suite (APSS). Space Sci. Rev. 215, 4 (2018).

    Article  Google Scholar 

  4. 4.

    Acuna, M. H. et al. Global distribution of crustal magnetization discovered by the Mars global surveyor MAG/ER experiment. Science 284, 790–793 (1999).

    Article  Google Scholar 

  5. 5.

    Connerney, J. E. P. et al. First results of the MAVEN magnetic field investigation. Geophys. Res. Lett. 42, 8819–8827 (2015).

    Article  Google Scholar 

  6. 6.

    Luhmann, J. G., Russell, C. T., Brace, L. H. & Vaisberg, O. L. in Mars (ed. George, M.) 1090–1134 (Univ. Arizona Press, 1992).

  7. 7.

    Brain, D., Bagenal, F., Acuña, M. H. & Connerney, J. Martian magnetic morphology: contributions from the solar wind and crust. J. Geophys. Res. 108, 1424 (2003).

    Article  Google Scholar 

  8. 8.

    Mittelholz, A., Johnson, C. L. & Lillis, R. J. Global-scale external magnetic fields at Mars measured at satellite altitude. J. Geophys. Res. Planets 112, 1243–1257 (2017).

    Article  Google Scholar 

  9. 9.

    Langlais, B., Civet, F. & Thébault, E. In situ and remote characterization of the external field temporal variations at Mars. J. Geophys. Res. Planets 122, 110–123 (2017).

    Article  Google Scholar 

  10. 10.

    Lillis, R. J. et al. Modeling wind-driven ionospheric dynamo currents at Mars: expectations for InSight magnetic field measurements. Geophys. Res. Lett. 46, 5083–5091 (2019).

    Article  Google Scholar 

  11. 11.

    Jakosky, B. M. et al. The Mars atmosphere and volatile evolution (MAVEN) mission. Space Sci. Rev. 195, 3–48 (2015).

    Article  Google Scholar 

  12. 12.

    Mittelholz, A., Johnson, C. L. & Morschhauser, A. A new magnetic field activity proxy for Mars from MAVEN data. Geophys. Res. Lett. 45, 5899–5907 (2018).

    Google Scholar 

  13. 13.

    Langlais, B., Thébault, E., Houliez, A. & Purucker, M. E. A new model of the crustal magnetic field of Mars using MGS and MAVEN. J. Geophys. Res. Planet 124, 1542–1569 (2019).

    Google Scholar 

  14. 14.

    Golombek, M. et al. Geology and physical properties investigations by the InSight lander. Space Sci. Rev. 214, 84 (2018).

  15. 15.

    Pan, L. et al. Crust stratigraphy and heterogeneities of the first kilometers at the dichotomy boundary in western Elysium Planitia and implications for InSight lander. Icarus 338, 113511 (2020).

    Article  Google Scholar 

  16. 16.

    Tanaka, K. L. et al. Geologic Map of Mars Scientific Investigations Map 3292 (USGS, 2014).

  17. 17.

    Lognonné, P. et al. Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data. Nat. Geosci. https://doi.org/10.1038/s41561-020-0536-y (2020).

  18. 18.

    Parker, R. L. Ideal bodies for Mars magnetics. J. Geophys. Res. 108, 5006 (2003).

    Article  Google Scholar 

  19. 19.

    Lillis, R. J., Robbins, S., Manga, M., Halekas, J. S. & Frey, H. V. Time history of the martian dynamo from crater magnetic field analysis. J. Geophys. Res. Planets 118, 1488–1511 (2013).

    Article  Google Scholar 

  20. 20.

    Schubert, G., Russell, C. T. & Moore, W. B. Geophysics: timing of the martian dynamo. Nature 408, 666–667 (2000).

    Article  Google Scholar 

  21. 21.

    Gattacceca, J. et al. Martian meteorites and martian magnetic anomalies: a new perspective from NWA 7034. Geophys. Res. Lett. 41, 4859–4864 (2014).

    Article  Google Scholar 

  22. 22.

    Head, J. W., Kreslavsky, M. A. & Pratt, S. Northern lowlands of Mars: evidence for widespread volcanic flooding and tectonic deformation in the Hesperian Period. J. Geophys. Res. 107, 5003 (2002).

    Article  Google Scholar 

  23. 23.

    Voorhies, C. V., Sabaka, T. J. & Purucker, M. On magnetic spectra of Earth and Mars. J. Geophys. Res. 107, 5034 (2002).

    Article  Google Scholar 

  24. 24.

    Lewis, K. W. & Simons, F. J. Local spectral variability and the origin of the martian crustal magnetic field. Geophys. Res. Lett. 39, L18201 (2012).

    Article  Google Scholar 

  25. 25.

    Wieczorek, M. A. Strength, depth, and geometry of magnetic sources in the crust of the Moon from localized power spectrum analysis. J. Geophys. Res. Planets 123, 291–316 (2018).

    Article  Google Scholar 

  26. 26.

    Smrekar, S. E. et al. Pre-mission InSights on the Interior of Mars. Space Sci. Rev. 215, 3 (2018).

    Article  Google Scholar 

  27. 27.

    Mimoun, D. et al. The noise model of the SEIS seismometer of the InSight mission to Mars. Space Sci. Rev. 211, 383–428 (2017).

    Article  Google Scholar 

  28. 28.

    Chi, P. J. et al. Magnetic pulsations on martian surface: initial results from InSight fluxgate magnetometer. In Proc. 50th Lunar Planet. Sci. Conf. Abstract 1752 (Lunar and Planetary Institute, Houston, 2019).

  29. 29.

    Saito, T. Geomagnetic pulsations. Space Sci. Rev. 10, 319–412 (1969).

    Article  Google Scholar 

  30. 30.

    Chi, P. J., Russell, C. T., Wei, H. Y. & Farrell, W. M. Observations of narrowband ion cyclotron waves on the surface of the Moon in the terrestrial magnetotail. Planet. Space Sci. 89, 21–28 (2013).

    Article  Google Scholar 

  31. 31.

    Zhang, T. L., Baumjohann, W., Russell, C. T., Luhmann, J. G. & Xiao, S. D. Weak, quiet magnetic fields seen in the Venus atmosphere. Sci. Rep. 6, 23537 (2016).

    Article  Google Scholar 

  32. 32.

    Banfield, D. et al. The atmosphere of Mars as observed by InSight. Nat. Geosci. https://doi.org/10.1038/s41561-020-0534-0 (2020).

  33. 33.

    Jackson, T. L. & Farrell, W. M. Electrostatic fields in dust devils: an analog to Mars. IEEE Trans. Geosci. Remote Sens. 44, 2942–2949 (2006).

    Article  Google Scholar 

  34. 34.

    Farrell, W. M. Electric and magnetic signatures of dust devils from the 2000–2001 MATADOR desert tests. J. Geophys. Res. 109, E03004 (2004).

    Google Scholar 

  35. 35.

    Kurgansky, M. V., Baez, L. & Ovalle, E. M. A simple model of the magnetic emission from a dust devil. J. Geophys. Res. 112, E11008 (2007).

    Article  Google Scholar 

  36. 36.

    Vacher, P. & Verhoeven, O. Modelling the electrical conductivity of iron-rich minerals for planetary applications. Planet. Space Sci. 55, 455–466 (2007).

    Article  Google Scholar 

  37. 37.

    Civet, F. & Tarits, P. Electrical conductivity of the mantle of Mars from MGS magnetic observations. Earth Planet. Space 66, 85 (2014).

    Article  Google Scholar 

  38. 38.

    Verhoeven, O. & Vacher, P. Laboratory-based electrical conductivity at martian mantle conditions. Planet. Space Sci. 134, 29–35 (2016).

    Article  Google Scholar 

  39. 39.

    Christensen, P. R. et al. JMARS—A Planetary GIS. IN22A-06 (AGU Fall Meeting, 2009).

  40. 40.

    Joy, S. P., Mafi, J. N. & Slavney, S. Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport: mission Insight Fluxgate Magnetometer (IFG) PDS Archive Software Interface Specification (PDS Geosciences, 2019); https://pds-ppi.igpp.ucla.edu/search/view/?f=yes&id=pds://PPI/insight-ifg-mars/document

Download references

Acknowledgements

This research was funded through the InSight Project at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration, the InSight Participating Scientist Program, the Canadian Space Agency and the Centre National d’Etudes Spatiales. C.L.J. acknowledges support from the Green Foundation for Earth Sciences during leave at the Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography (2019–2020). This paper is InSight Contribution Number 106.

Author information

Affiliations

Authors

Contributions

W.B.B. and S.E.S. lead and co-lead the InSight mission, respectively. P.L. is the PI of the SEIS instrument on InSight; D.B. is the lead for the APSS instrument suite. C.T.R. led the development of the UCLA magnetometer contributed to the InSight mission. C.T.R. also directs the processing and delivery of IFG data by S.J. and X.L. to the team and the Planetary Data System. C.T.R. and C.L.J. are the co-leads of the InSight Magnetics Working Group. A.M. is the lead for weekly Event Request Proposals for IFG data. A.M., Y.Y., C.L.J. and S.N.T. have participated in IFG data processing and product review. C.L.J. led the synthesis of the magnetic field investigations reported here and wrote most of the main text. C.L.J. conducted the crustal magnetization inversion and coordinated the crustal field study together with A.M., B.L., C.T.R., M.A.W. and S.E.S. C.L.J. and A.M. produced all the figures and tables with the exception of Fig. 4 (P.J.C.) and Extended Data Figs. 5 and 6 (S.N.T.). P.J.C. identified the continuous pulsations and contributed the accompanying text. M.O.F. and Y.Y. contributed to the discussion of daily variations in the magnetic field. S.N.T. and A.M. contributed the assessment of lander activities on the magnetic field signals. V.A., M.G., C.M., C.Q.-N., L.P. and P.L. contributed the regional geology and crustal structure discussions to the paper. D.B., A.S. and F.F. contributed to discussions regarding external fields, in particular signals that might be driven by atmospheric phenomena and ionospheric fields. H.F.H. and S.S. reviewed the manuscript and Extended Data materials. All authors read and commented on the manuscript.

Corresponding author

Correspondence to Catherine L. Johnson.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Primary Handling Editor: Stefan Lachowycz.

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

Extended data

Extended Data Fig. 1 Contributions to the Magnetic Field Measured by the IFG.

Time-varying fields are either of external origin (orange), including the interplanetary magnetic field, ionospheric currents and weather events such as dust devils; they can also be of lander origin (blue), e.g., due to movement of the arm, RISE communications, Solar Array Currents, or martian temperature variations, measured by the temperature sensors on the lander. The martian static crustal field (red) results from crustal magnetization, represented schematically here as subsurface dipoles. A DC field is also associated with the lander itself (green). Inset shows the IFG sensor box and connecting cable.

Extended Data Fig. 2 All IFG data available as of Aug 1, 2019, covering sols 14-299.

Magnetic field components Bx, By, Bz in the local lander level (LL) frame from 11 December, 2019 until 29 September, 2019. Data gaps occur due to safing at times of APSS anomalies. The average field ± 1 std for the entire period is [BX, BY, BZ] = [-1353 ± 6, 1168 ± 5, -925 ± 6] nT. As nighttime data are less contaminated by external fields (ionospheric currents and the draped interplanetary magnetic field, IMF) we report the average field computed between local times of 8pm and 4am in the main paper. This is indistinguishable from that computed for all local times. The uncertainty in the crustal field is dominated by the uncertainty in the spacecraft field as described in the main text. Corrections for temperature and solar array currents are described in detail in the IFG Software Interface Specification (SIS) document available on the PDS (https://pds-ppi.igpp.ucla.edu/search/view/?f=yes&id=pds://PPI/insight-ifg-mars/document).

Extended Data Fig. 3 Predictions for the surface magnetic field strength from satellite-based models.

Surface magnetic field strength, B, in the vicinity of the InSight landing site (asterisk) predicted by two recent magnetic field models that use MAVEN and MGS data. a, The regional model of12 predicts B = 236 nT at the InSight landing site. b, The global model of13 predicts B = 314 nT at the InSight landing site. Within about 60 km to the northwest of the landing site there are locally stronger fields, reaching 324 nT in12 and 400 nT in13. Both models use the same equivalent source dipole modeling approach and use MAVEN and MGS data. Adapted from14.

Extended Data Fig. 4 Time variable signals.

Expected and/or observed periodicities in the magnetic field, together with their causes and any challenges associated with observing them in IFG data to date. IMF refers to Interplanetary Magnetic Field. A ‘Yes’ in the last column means that these signals have been unambiguously detected in IFG data a ‘No’ means they have not yet been identified. Time variations for which there are hints in current data but that require a longer time series or better statistics for confident detection are marked with a question mark.

Extended Data Fig. 5 Magnetic field signatures of various lander activities.

IFG data contain many transient signals that are of spacecraft origin, shown in this example of data from sols (a) 182 and (b) 189 (1 June 2019 and 8 June 2019, respectively). Time series are plotted in Local Mean Solar Time (LMST). From ~0700 LMST on sol 182 onwards the continuous IFG data have been available at 2 Hz, c.f. 0.2 Hz prior to this and during periods such as solar conjunction (August 2019). For each sol, the top 3 panels show BX, BY, BZ in the spacecraft frame, with the 2 Hz data shown in color (red = BX, green = BY, blue = BZ) and data down-sampled to 0.2 Hz data shown in gray. The bottom panel shows the actual (red dots) total solar array current (SACT; channel G_0036) and the model current (blue) used to estimate and subtract the effect of the solar array current in the IFG data. Also shown are four spacecraft activities that have associated transients in the IFG data. For each activity, the start and end times are shown by vertical dashed and dotted lines respectively. The activities include: (1) the lander transitions from ON to OFF or vice versa (yellow); (2) RISE communications (cyan); (3) lander communications (brown); and (4) arm operations (magenta). Lander-on times are typically followed by spikes in all 3 magnetic field components. Jumps or drops are associate with lander and RISE communications, and a sawtooth signal is often seen in association with arm movements. Furthermore, the 2 Hz data (and 20 Hz event data) show substantial noise typically between about 10:00 and 16:00 LMST. Examination of multiple sols of data indicate that the onset of this IFG noise above 0.2 Hz occurs in association with times of increased scatter in the solar array current data. Similarly, the termination of the noise correlates with a transition to solar array currents that are more smoothly-varying in time. Although important to diagnose, none of the transients or noise characteristics shown here impact the results discussed in the main text. They are, however, important for understanding whether small, short time-duration signals such as those discussed in Extended Data Fig. 6 can be reliably interpreted to be of martian rather than spacecraft origin.

Extended Data Fig. 6 Magnetic field signals during vortices.

A few vortices show a very small (<1 nT) magnetic signal, typically in the North and East components. One example is shown here for sol 15 (11 December, 2018). 20 Hz IFG data are routinely requested in a 6-minute interval around a pressure drop identified by the Mars Weather Service team. (a) BX, (b) BY in the LL frame for 20 Hz IFG data (gray dots), and for these data down-sampled via FIR-filtering to 1 Hz and 0.2 Hz (the cadence of the continuous data on sol 15), and (c) pressure. Time of the pressure drop (> 1Pa) indicated by vertical dashed line.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Johnson, C.L., Mittelholz, A., Langlais, B. et al. Crustal and time-varying magnetic fields at the InSight landing site on Mars. Nat. Geosci. 13, 199–204 (2020). https://doi.org/10.1038/s41561-020-0537-x

Download citation

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing