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

Johnson, C. L.; Mittelholz, A.; Langlais, B.; Russell, C. T.; Ansan, V.; Banfield, D.; J., P.; Fillingim, M. O.; Forget, F.; Haviland, H. Fuqua; Golombek, M.; Joy, S. P.; Lognonné, Philippe; Liu, Xinping; Michaut, Chloé; Pan, Lu; Quantin‐Nataf, Cathy; Spiga, Aymeric; Stanley, S.; Thorne, Shea N.; Wieczorek, M. A.; Yu, Yang; Smrekar, S. E.; Banerdt, W. B.

doi:10.1038/s41561-020-0537-x

Cited by 92 publications

(112 citation statements)

References 34 publications

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“…The crustal field in this region is quite heterogeneous with field strengths at 130‐km altitude varying by a factor of 2 (see extended data figure in Johnson et al. 2020, for surface field). This would affect currents produced in the dynamo region, and predictions in this study are limited to the crustal field right above the InSight landing site.…”

Section: Wind‐driven Ionospheric Currentsmentioning

confidence: 88%

The Origin of Observed Magnetic Variability for a Sol on Mars From InSight

et al. 2020

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Day‐night variations in the magnetic field at Mars have been previously observed at satellite altitudes. The InSight Fluxgate Magnetometer (IFG) has provided the first evidence for diurnal magnetic field variations at the martian surface. IFG data show diurnal variations with typical peak amplitudes of 20–40nT in the early morning to midmorning; the amplitude of the magnetic field varies over the first 389 sols of the mission and peaks between sols 50 and 100. Temperature variations, solar array currents, and lander activities all generate magnetic fields. Particularly, the first two of these also produce signals with clear diurnal variations. We first assess the IFG data calibration and conclude that temperature and solar array currents have only minimal effects on the variability we observe in the final calibrated magnetic field data. We use satellite magnetic field data and a Mars global circulation model to make predictions for the temporal evolution of wind‐driven fields in the ionosphere. Such fields vary due to seasonal changes in the ionization profile and the winds, and in the altitude range of the dynamo region, that is, the region in which electric currents can be produced. We find that the amplitude and seasonal variability of the surface magnetic fields are generally consistent with those predicted from wind‐driven currents. Moreover, a regional dust storm in the vicinity of the InSight landing site, which started around sol 45, might be responsible for the higher magnetic field amplitudes observed in the IFG data in the early part of the mission.

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Section: Wind‐driven Ionospheric Currentsmentioning

confidence: 88%

The Origin of Observed Magnetic Variability for a Sol on Mars From InSight

et al. 2020

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“…Furthermore, the inferred magnetization is consistent with an Earth-like ancient dynamo field and is probably carried within a layer that is at least 3.9 Ga (ref. 7 ).…”

Section: Atmospheric and Magnetic Measurementsmentioning

confidence: 99%

“…With a longer time series, we expect to find signals with seasonal and/ or annual variations and 26-sol cyclicity that results from solar rotations and the resulting periodic changes in the interplanetary field at Mars. More details are provided by Johnson and colleagues 7 .…”

Section: Atmospheric and Magnetic Measurementsmentioning

confidence: 99%

“…We present the first measurement of seismic activity rate, which fundamentally constrains the geological vigour of the planet (note that this study is part of the first set of InSight science reports; two additional papers 1,2 also include interpretation of InSight seismic data 3,4 ). The data acquired thus far also enable the characterization of Mars's seismic background and upper crust structure, a preliminary analysis of the basic character of seismicity, local geology and atmospheric processes at the surface, and the characteristics of the surface magnetic field 1,2,[5][6][7] . InSight's payload (Extended Data Fig.…”

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confidence: 99%

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Initial results from the InSight mission on Mars

et al. 2020

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It aims to determine the interior structure, composition and thermal state of Mars, as well as constrain present-day seismicity and impact cratering rates. Such information is key to understanding the differentiation and subsequent thermal evolution of Mars, and thus the forces that shape the planet's surface geology and volatile processes. Here we report an overview of the first ten months of geophysical observations by InSight. As of 30 September 2019, 174 seismic events have been recorded by the lander's seismometer, including over 20 events of moment magnitude M w = 3-4. The detections thus far are consistent with tectonic origins, with no impact-induced seismicity yet observed, and indicate a seismically active planet. An assessment of these detections suggests that the frequency of global seismic events below approximately M w = 3 is similar to that of terrestrial intraplate seismic activity, but there are fewer larger quakes; no quakes exceeding M w = 4 have been observed. The lander's other instruments-two cameras, atmospheric pressure, temperature and wind sensors, a magnetometer and a radiometer-have yielded much more than the intended supporting data for seismometer noise characterization: magnetic field measurements indicate a local magnetic field that is ten-times stronger than orbital estimates and meteorological measurements reveal a more dynamic atmosphere than expected, hosting baroclinic and gravity waves and convective vortices. With the mission due to last for an entire Martian year or longer, these results will be built on by further measurements by the InSight lander. Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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“…SEIS is further equipped with a geophysical sensor suite, including wind speed and direction sensors, barometer, thermometer, and magnetometer, which help to identify and remove environmental effects on SEIS. These sensors also produce remarkable science of their own, e.g., by providing continuous meteorological data sampled at a much higher rate than on all previous missions 9 , or by measuring the crustal magnetization at the Martian surface, instead of that from the orbit, for the first time 10 .…”

Section: Insight's Heritage and Challengesmentioning

confidence: 99%

NASA’s InSight mission on Mars—first glimpses of the planet’s interior from seismology

Knapmeyer‐Endrun

Kawamura

2020

Nat Commun

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NASA's InSight mission is the first lander to deploy a seismometer on a planetary body since more than 40 years. With a year of seismic data from Mars, new discoveries on Mars' tectonics and interior structure are just emerging. Aiming at the heart of the planet Unlike all previous Mars missions, which explored the geology, chemistry, and atmosphere of the red planet in great detail, the Interior exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission is focused on the interior structure and processes of Mars. It is high time to address these topics as our knowledge of the Martian interior-or, in fact, that of any other terrestrial planet-is poorer than our knowledge for the Earth was 100 years ago. While it is generally assumed that differentiation processes early in the formation of terrestrial planets lead to a subdivision into a brittle rocky crust, a silicate mantle, and an iron-rich core 1 , the finer details are widely uncertain for Mars. This lack of knowledge hampers our understanding of its geodynamic history, and the formation and evolution of terrestrial planets in general. The three experiments carried out by InSight, and specifically the Seismic Experiment for Interior Structure (SEIS), are about to change this. The study of seismic waves generated by earthquakes has been key to our understanding of the internal structure of the Earth and the Moon. For example, detection of signals reflected at the core-mantle boundary resulted in the determination of the Moon's core radius. The thickness of the lunar crust was determined using waves converted at the crust-mantle boundary. On Earth, the absence of direct waves from distances beyond 10,000 km, a so-called shadow zone, led to the discovery of Earth's liquid outer core. Terrestrial seismology nowadays studies 3D fine structure, using 1000 s of seismometers, but on Mars, which was predicted to be seismically active 2 , we still need to answer more basic questions. Current estimates for the average crustal thickness of Mars range from 30 to >100 km 3,4. Accurate estimates of crustal thickness are needed to provide an important constraint on the mantle evolution through time along with the formation of the crust. Crustal thickness directly relates to the mantle's cooling rate, with implications for the style of convection during Mars' early history (i.e., global mantle overturn, stagnant lid convection, or plate tectonics). Gravity and topography constrain relative crustal thickness variations well, but need at least one tie point to obtain absolute values 3. Seismology is the only means for this direct measurement. Mars' mantle may retain compositional layering from its early evolution, which has been destroyed on Earth by vigorous convection. As Mars lacks plate tectonics, but is of sufficient size to have undergone most of the same differentiation processes as early Earth, its mantle structure

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

Cited by 92 publications

References 34 publications

The Origin of Observed Magnetic Variability for a Sol on Mars From InSight

The Origin of Observed Magnetic Variability for a Sol on Mars From InSight

Initial results from the InSight mission on Mars

NASA’s InSight mission on Mars—first glimpses of the planet’s interior from seismology

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