The interior structure and thermal state of Venus: what we can learn from future missions
Abstract
Venus is similar to Earth in terms of size and bulk composition but its interior structure and present thermal state are not well constrained. Fundamental parameters such as the size of its core and whether the core is solid or liquid are unknown or uncertain [e.g., 1]. More constraints will be gained from precise measurements of the moment of inertia factor, MoIF, the tidal potential Love number, k 2 , and the tidal phase lag, ɛ . These parameters are related to the internal mass redistribution in response to tides exerted by the Sun (tidal forcing period of 58.4 days) and will be measured with the proposed VERITAS mission [2].
Here, we will present models of the interior structure and thermal state of Venus and discuss what we can learn from measurements of the MoIF, k 2 and ɛ . We first compute structural and thermal models [3], which are then used to calculate the tidal response of the planet [4]. The interior models consist of three chemically separated layers: an iron-rich core surrounded by a silicate mantle and a basaltic crust. The mantle mineralogy is obtained using Perple_X [5] and the thermal state using a mixing-length formulation [6]. The viscoelasticity of the mantle is parameterized with an Andrade rheology to calculate the tidal phase lag. Applying deformation theories to Venus requires corrections due to surface loads by the dense atmosphere. To explore a large parameter set, we vary the crust thickness and density, the mantle mineralogy and viscosity, the core density, the internal heat production rate, and the core-mantle heat flow. These parameters affect the MoIF, k 2 and ɛ differently. We will discuss these dependencies and what we can learn about the interior structure and thermal state of Venus from future measurements. References: [1] Dumoulin et al. 2017, J. Geophys. Res. Planets, 122, 1338-1352, doi:10.1002/2016JE005249. [2] Mazarico et al. 2019, this meeting. [3] Wagner et al 2011, Icarus, 214, 366-376, doi:10.1016/j.icarus.2011.05.027. [4] Steinbrügge et al. 2018, J. Geophys. Res. Planets., 123, 2760-2772, doi:10.1029/2018JE005569. [5] Connolly 2009, Geochem. Geophys. Geosyst., 10, Q10014, doi:10.1029/2009GC002540. [6] Wagner et al. 2019, Geophys. J. Int., 217, 75-89, doi:10.1093/gji/ggy543.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P14B..01B
- Keywords:
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- 5405 Atmospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5410 Composition;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5455 Origin and evolution;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5494 Instruments and techniques;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS