Possible effects of Mercury surface temperatures on the exosphere
- 1ASI Space Science Data Center (SSDC), Via del Politecnico, 00133 Rome, Italy
- 2INAF-OAR Osservatorio Astronomico di Roma, Via Frascati 33, 00078, Monte Porzio Catone (RM), Italy
- 3INAF-IAPS Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, 00133 Rome, Italy
- 4Agenzia Spaziale Italiana (ASI), Via del Politecnico snc, 00133, Rome, Italy
The BepiColombo mission is the first European mission to Mercury; the spacecraft will reach its destination in December 2025, and will study in detail the surface, the exosphere and the magnetosphere of the planet.
We have developed a thermophysical model with the aim to analyze the dependence of the temperature of the surface and of the layers close to it on the assumptions on the thermophysical properties of the soil. The code solves the one-dimensional heat equation, assumes purely conductive heat propagation and no internal heat sources; the surface is assumed to be composed of a regolith layer with high porosity and density increasing with depth. The illumination conditions are calculated by using a Mercury shape model and the SPICE routines [1].
The model will help us to interpret the data that will be provided by the instruments onboard the BepiColombo mission. Preliminary calculations have been carried out to analyze the thermal response of the soil as a function of thermal conductivity. The model is currently also used to study the sodium content in the planet's exosphere, whose origin is under investigation [2]; the MESSENGER mission has measured the exospheric sodium content as a function of time, detecting an increase at the "cold poles" (so called because of their lower than average temperature). We therefore want to study the effect of surface temperatures on the sodium content in the exosphere; for this purpose, the temperature distribution calculated with the code is used together with an atmospheric circulation model that calculates the exospheric sodium content [3].
A simplified version of the thermophysical code is almost ready to be available to the scientific community through MATISSE [4], the software developed at the SSDC in ASI and available at https://tools.ssdc.asi.it/Matisse.
[1] Acton, C. H. (1996), Planetary and Space Science, 44, 65-70
[2] Cassidy, T., et al. (2016), GRL, 43, 11 121-128
[3] Mura, A., et al. (2009), Icarus, 1, 1-11
[4] Zinzi, A., et al. (2016), Astronomy & Computing, 15, 16-28
How to cite: Rognini, E., Mura, A., Capria, M. T., Zinzi, A., Milillo, A., and Galluzzi, V.: Possible effects of Mercury surface temperatures on the exosphere, Europlanet Science Congress 2020, online, 21 September–9 Oct 2020, EPSC2020-838, https://doi.org/10.5194/epsc2020-838, 2020
