Geodesy constraints on the interior structure and composition of Mars

Aims. We study the period of the Slichter mode (vibrational mode of the inner core of a planet) of Mercury in relation to its interior structure and assess the possibility to observe this mode with the probes MESSENGER and BepiColombo. Methods. The methodology of Grinfeld & Wisdom (2005, Phys. Earth Planet. Int., 151, 77) for the determination of the period of the polar Slichter modes of a planetary interior consisting of three homogeneous layers is generalized to models with an arbitrary but finite number of layers. Slichter modes periods are calculated for a large set of interior structure models of Mercury. We study the possible excitation of Slichter modes by a colllision with a meteoroid and estimate the minimal size of the meteoroid that could lead to a detection of these modes by BepiColombo. Results. The Slichter mode period obtained is on the order of several hours. Observation of the Slichter mode of Mercury allows constraining the inner core. An impact by a meteoroid with a radius of at least 100 m could excite the Slichter mode to a level observable by BepiColombo (assuming that the Slichter mode is the only excited mode), but since the estimated damping time of the Slichter mode is well below the average time between impacts of at least that size such an impact must have occured recently (less than 0.5 My ago).

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“…The bulk modulus of a solution of Fe and FeS, and its derivative with respect to pressure are given by (Rivoldini et al 2011)…”

Section: Models Of Mercurymentioning

confidence: 99%

Period of the Slichter mode of Mercury and its possible observation

Coyette

Hoolst

Déhant

2012

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“…Mars (Mocquet and Menvielle, 2000;Rivoldini et al, 2011;Nimmo and Faul, 2013). This Martian 37 LVZ would be different than Earth's, being most pronounced within the thermal boundary layer 38 rather than near its deepest levels.…”

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confidence: 94%

“…304 Below we outline a prescription for calculating the sound-speed inside the core (assumed liquid). This 325 approach is significantly simplified compared with some other work (e.g., Gudkova and Zharkov,326 2004; Khan and Connolly, 2008;Rivoldini et al, 2011). Our rationale for a simplified approach is 327 twofold.…”

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confidence: 96%

“…This model matches 87 the observed bulk density and moment of inertia of Mars; it also satisfies the measured k 2 Love 88 number and the tidal dissipation factor Q inferred from observation of Phobos' orbit. This model is 89 simplified compared with other models in which detailed mineralogical and equation of state data are 90 employed (e.g., Gudkova and Zharkov, 2004;Khan and Connolly, 2008;Rivoldini et al, 2011). 91…”

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Seismological implications of a lithospheric low seismic velocity zone in Mars

Zheng

Nimmo

Lay

2015

Physics of the Earth and Planetary Interiors

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“…First-order constraints on the planetary Fe/Si ratio (Rivoldini et al 2011;Sohl and Spohn 1997) will be provided by the radius of Mars' core, which will be evident from core-reflected P and S (PcP and ScS) and core penetrating (SKS, SKKS) travel times. The next most important seismic observation relevant for dynamo activity will be the presence or absence of an inner core.…”

Section: Resultsmentioning

confidence: 99%

Feasibility of a magma ocean dynamo on Mars

Helffrich

2017

Prog Earth Planet Sci

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Crustal magnetization of rocks in regions of Mars surface testifies to an era of dynamo activity. I examine the possibility that the dynamo that operated then, in the first 400-600 Ma after Mars formed, was powered by a crystallizing subsurface magma ocean. Of the ways that a magma ocean dynamo could operate, on Mars only turbulent and magnetostrophic dynamos seem feasible; geostrophic dynamos do not seem so unless very high heat flows, 100-1000 times present, are invoked. Given the anticipated information from the future InSight lander mission, it will be difficult to assess where the dynamo originated unless an inner core is discovered, rendering the dynamo likely to have operated in the core.

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Geodesy constraints on the interior structure and composition of Mars

Abstract: International audienc

Cited by 203 publications

References 72 publications

Period of the Slichter mode of Mercury and its possible observation

Period of the Slichter mode of Mercury and its possible observation

Seismological implications of a lithospheric low seismic velocity zone in Mars

Feasibility of a magma ocean dynamo on Mars

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