Nutational constraints on the interior structure of Mars
Abstract
Knowledge about the rotation of Mars provides insight about its global scale atmosphere dynamics and interior structure. In particular, inferences about the core of Mars can be made by observing its nutation as foreseen by the forthcoming RISE and LaRa experiments on InSight and ExoMars. Nutation can be resonantly amplified if the planet's core is liquid and the amplification depends on the core's polar moment of inertia, figure, and capacity to deform. By combining measured nutation amplitudes with the already well known polar moment of inertia and tidal Love number the size of the core and its material properties can be determined more precisely than from the latter quantities alone. Additionally, the polar moment of the mantle can then be determined from which its composition and thermal state be constrained. Here, we first reconsider the study of the nutations of a rigidly rotating Mars. Then, we use models of Mars' interior structure that agree with its moment of inertia, tidal Love number, and global dissipation to predict the nutations of the real Mars. Our models have been constructed from depth-dependent material properties and use recent thermoelastic and melting properties of plausible core constituents. For each model we determine nutation amplitudes and assess what constraints on the interior structure of the core can be expected from RISE and LaRa.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.P13A2547R
- Keywords:
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- 1221 Lunar and planetary geodesy and gravity;
- GEODESY AND GRAVITY;
- 1294 Instruments and techniques;
- GEODESY AND GRAVITY;
- 6024 Interiors;
- PLANETARY SCIENCES: COMETS AND SMALL BODIES;
- 5430 Interiors;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS