The interior of Mars as seen by InSight (Invited)

InSight is the first planetary mission dedicated to exploring the whole interior of a planet using geophysical methods, specifically seismology and geodesy. To this end, we observed seismic waves of distant marsquakes and inverted for interior models using differential travel times of phases reflected at the surface (PP, SS...) or the core mantle-boundary (ScS), as well as those converted at crustal interfaces. Compared to previous orbital observations1-3, the seismic data added decisive new insights with consequences for the formation of Mars: The global average crustal thickness of 24-75 km is at the low end of pre-mission estimates5. Together with the the thick lithosphere of 450-600 km5, this requires an enrichment of heat-producing elements in the crust by a factor of 13-20, compared to the primitive mantle. The iron-rich liquid core is 1790-1870 km in radius6, which rules out the existence of an insulating bridgmanite-dominated lower mantle on Mars. The large, and therefore low-density core needs a high amount of light elements. Given the geochemical boundary conditions, Sulfur alone cannot explain the estimated density of ~6 g/cm3 and volatile elements, such as oxygen, carbon or hydrogen are needed in significant amounts. This observation is difficult to reconcile with classical models of late formation from the same material as Earth. We also give an overview of open questions after three years of InSight operation on the surface of Mars, such as the potential existence of an inner core or compositional layers above the CM

Initial results from the InSight mission on Mars

NASA’s InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed in Elysium Planitia on Mars on 26 November 2018. 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 Mw = 3–4. The detections thus far are consistent with tectonic origins, with no impact-induced seismicity yet observed, and indi- cate a seismically active planet. An assessment of these detections suggests that the frequency of global seismic events below approximately Mw = 3 is similar to that of terrestrial intraplate seismic activity, but there are fewer larger quakes; no quakes exceeding Mw = 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

Research data supporting "Formation of the lunar primary crust from a long-lived slushy magma ocean"

Model results from calculations on the formation of the lunar crust, as detailed in the manuscript "Formation of the lunar primary crust from a long-lived slushy magma ocean" submitted to the journal Geophysical Research Letters

NUCM2 Monte Carlo results - wet crust and dry mantle rheology

Monte Carlo results for NUCM2 simulations (Figure 9b)<div>Rheology = dry mantle and wet crust, diffusion creep</div><div><br></div><div><div><b>Files:</b></div><div>Each line of the files (scores, thickness, enrichment factor and crustal radioelement content) corresponds to a model with given crustal parameters (crustal thickness in meters and enrichment factor) and the results obtained for this model.<div><br></div><div>Gaussian scores for the three constraints on elastic thickness are given in the files "score". To compute scores between 0 and 1, these scores have to be divided by the maximum of the corresponding gaussian (given in "Gaussian_maximum.csv": in order for the Noachian, the Southern polar cap and the Northern polar cap)</div><div><br></div><div>The file "MeltFormation" gives the difference in meters between the depth of the stagnant lid and the depth of melt formation in the Southern hemisphere. Models with present-day formation in the South are those where this difference is lower than 100 km.</div></div></div><div><br></div><div>The percentage of radioelement contained in the Northern and Southern crusts are given in files "RadioelementContents".</div

UCM Monte carlo results - dry crust, dry mantle rheology

<div>Rheology = dry mantle and dry crust, diffusion creep<br></div>Monte Carlo results for UCM simulations (Figure 10a). <div><br></div><div><div><b>Files:</b></div><div>Each line of the files (scores, thickness, enrichment factor and crustal radioelement content) corresponds to a model with given crustal parameters (crustal thickness in meters and enrichment factor) and the results obtained for this model.<div><br></div><div>Gaussian scores for the three constraints on elastic thickness are given in the files "score". To compute scores between 0 and 1, these scores have to be divided by the maximum of the corresponding gaussian (given in "Gaussian_maximum.csv": in order for the Noachian, the Southern polar cap and the Northern polar cap)</div><div><br></div><div>The file "MeltFormation" gives the difference in meters between the depth of the stagnant lid and the depth of melt formation in the Southern hemisphere. Models with present-day formation in the South are those where this difference is lower than 100 km.</div></div></div

present-day temperature profiles

North and South present-day temperature profiles of suitable models (Figure 11) (in kelvins). Corresponding radius are given in the files "radius" (in kilometers).<div><br><div>Files with BestModel correspond to the best model described in section 4.1. Files with Min and Max correspond to the extremum temperatures observed among suitable models.</div></div