Mars' External Magnetic Field as Seen From the Surface With InSight. Issue 1 (23rd January 2023)

• Record Type: Journal Article
• Authors: Mittelholz, A.; Johnson, C. L.; Fillingim, M.; Grimm, R. E.; Joy, S.; Thorne, S. N.; Banerdt, W. B.
• Is Part Of: Journal of geophysical research. Volume 128:Issue 1(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-23
• Subjects: Mars -- magnetic field -- external magnetic field -- InSight -- magnetic sounding; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2022JE007616
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: The magnetometer of the InSight mission operated on the Martian surface from November 2018 until May 2022. Previously, satellites have provided information on the Martian magnetic field environment from orbit; however, the degree to which external fields penetrate to and interact with the surface could not be studied prior to the InSight landing. Here, we present an overview of the complete surface magnetic field data from InSight sols 14 to 1241 that display different external magnetic field phenomena, transient and periodic. Periodic observations range from short period waves (100–1000s of seconds), diurnal variations, ∼26 sol Carrington rotations, to seasonal fluctuations. Transient events are observed in response to space weather and dust movement. We find that ionospheric variations are the dominant contribution as seen from the surface, while contributions from the undisturbed interplanetary magnetic field are more subtle. We discuss limitations associated with a single point measurement and opportunities that future missions could enable. Including magnetometers on future missions at a variety of locations for long‐duration continuous observations will be of great value in understanding a range of external field phenomena and will enable further investigations in different crustal magnetic field settings. Plain Language Summary: The magnetometer of the InSight mission has measured the magnetic field at the planetary surface for the first time. Although satellites previously sampled the magnetic field globally from orbit, InSight enables a local view from the surface. Here, we focus on time‐varying magnetic fields driven by the Sun and the uppermost region of the atmosphere (the ionosphere); this includes the interplanetary magnetic field and the ionosphere interacting with the planet. A range of physical phenomena can be observed. Some of those are periodic, such as the diurnal signature or seasonal variations, some are transient, such as the effect of space weather. We find that ionospheric variations are the dominant signal at the surface. We discuss limitations of such observations due to the single point measurement and possibilities future missions will provide. Key Points: InSight's magnetometer provides the first surface recordings of the Martian magnetic field environment over 1241 sols Transient and periodic external fields with timescales of minutes up to a year are observed and their origins discussed Time variations in the surface magnetic field are primarily driven by the ionosphere, affected by atmospheric seasonal variations