Construction of Martian Interior Model

Abstract

In most of these papers, the authors constructed models of the Martian interior using a chemical model suggested by W ä nke and Dreibus (the DW model; see W ä nke, 1981 ; Dreibus and W ä nke, 1989; W ä nke and Dreibus, 1994). Abstract -We present the results of extensive numerical modeling of the Martian interior. Yoder et al. in 2003 reported a mean moment of inertia of Mars that was somewhat smaller than the previously used value and the Love number k 2 obtained from observations of solar tides on Mars. These values of k 2 and the mean moment of inertia impose a strong new constraint on the model of the planet. The models of the Martian interior are elastic, while k 2 contains both elastic and inelastic components. We thoroughly examined the problem of partitioning the Love number k 2 into elastic and inelastic components. The information necessary to construct models of the planet (observation data, choice of a chemical model, and the cosmogonic aspect of the problem) are discussed in the introduction. The model of the planet comprises four submodels-a model of the outer porous layer, a model of the consolidated crust, a model of the silicate mantle, and a core model. We estimated the possible content of hydrogen in the core of Mars. The following parameters were varied while constructing the models: the ferric number of the mantle (Fe#) and the sulfur and hydrogen content in the core. We used experimental data concerning the pressure and temperature dependence of elastic properties of minerals and the information about the behavior of Fe ( γ -Fe ), FeS, FeH, and their mixtures at high P and T . The model density, pressure, temperature, and compressional and shear velocities are given as functions of the planetary radius. The trial model M13 has the following parameters: Fe# = 0.20; 14 wt % of sulfur in the core; 50 mol % of hydrogen in the core; the core mass is 20.9 wt %; the core radius is 1699 km; the pressure at the mantle-core boundary is 20.4 GPa; the crust thickness is 50 km; Fe is 25.6 wt %; the Fe/Si weight ratio is 1.58, and there is no perovskite layer. The model gives a radius of the Martian core within 1600-1820 km while ≥ 30 mol % of hydrogen is incorporated into the core. When the inelasticity of the Martian interior is taken into account, the Love number k 2 increases by several thousandths; therefore, the model radius of the planetary core increases as well. The prognostic value of the Chandler period of Mars is 199.5 days, including one day due to inelasticity. Finally, we calculated parameters of the equilibrium figure of Mars for the M13 model: = 1.82 × 10 -3 , = -7.79 × 10 -6 , = 1/242.3 (the dynamical flattening of the core-mantle boundary). J 2 0 J 4 0 e c-m D 344 SOLAR SYSTEM RESEARCH Vol. 39 No. 5 2005 ZHARKOV, GUDKOVA

Crustal S-Wave Velocity from Apparent Incidence Angles: A Case Study in Preparation for InSight

“…16). To better capture the uncertainty in seismic velocities of Mars, we did not only consider the models of the ETH Instaseis database here, but also the four models by Mocquet et al (1996) with molar fraction of iron in the Martian mantle between 10% and 40%, varied in 10% increments, the two models by Sohl and Spohn (1997), model M6 (Gudkova and Zharkov 2004) and M13 (Zharkov and Gudkova 2005). A maximum hypocentral depth of 100 km has also been assumed in generating seismicity catalogues for testing procedures for InSight , though recent thermal evolution modeling indicates that under certain conditions, the seismogenic depth of Mars might extent down to 450 km (Plesa et al 2018).…”

“…In addition to the ETH Instaseis models (Fig. 1), we considered the models by Mocquet et al (1996), Sohl and Spohn (1997), M6 by Gudkova and Zharkov (2004), and M13 by Zharkov and Gudkova (2005) slowness by randomly changing the slowness values for each event by a value drawn from a normal distribution scaled to a maximum absolute value of 1 s/deg. The perturbed values were than used to calculate the v S,app (T ) curves using Eq.…”

Preparing for InSight: An Invitation to Participate in a Blind Test for Martian Seismicity

“…The 1D structural model is selected from a suite of 14 a priori structural models extended from Panning et al (2016), based on structural models from Zharkov and Gudkova (2005), Rivoldini et al (2011), and Khan et al (2016) (see Table 1 and Fig. 2).…”

“…1). Radially symmetric models of seismic P-and S-wave velocities, shear and bulk attenuation, and density are taken from the studies of Zharkov and Gudkova (2005), Rivoldini et al (2011), and Khan et al (2016), respectively. The models are generally constructed so that the current set of available geodetic data (mean mass and moment of inertia, tidal Love number, and global tidal dissipation) is satisfied.…”

Mars: a small terrestrial planet

“…Geochemical models of the interior were subsequently examined against the geophysical parameters (Sanloup et al 1999;Longhi et al 1992;Zharkov and Gudkova 2005). The Monday, October 17, 2016 at 5:11 pm, the initial MOI value of 0.3662 ± 0.0017 of Folkner et al 1997 was revised by Yoder et al (2003) from the analysis of Mars Global Surveyor radio tracking.…”