Migration of Water Molecules in the Permanently Shaded Areas of Polar Areas of Mercury

• Published in: Earth, moon, and planets Vol. 125; no. 2; p. 5
• Main Authors: Feoktistova, E. A., Zharkova, A. Y., Kokhanov, A. A., Rodionova, Zh F.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.10.2021; Springer Nature B.V
• Subjects: Astronomy; Astrophysics and Astroparticles; Cold traps; Escape velocity; Exosphere; Mercury; Mercury (planet); Mercury exosphere; Mercury surface; Monte Carlo simulation; North Pole; Observations and Techniques; Photolysis; Physics; Physics and Astronomy; Planetology; Planets; Polar environments; Polar regions; Radar; South Pole; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Volatile compounds; Water chemistry; Polar region; Craters; Mercury; Volatiles
• ISSN: 0167-9295; 1573-0794
• DOI: 10.1007/s11038-021-09542-2

Radar observations of the surface of Mercury had revealed areas with bright reflective properties in both polar regions of the planet. It was suggested that such areas contain depositions of volatile compounds, including water. In this paper, we investigated migration of water molecules to the permanently shaded areas, located in the impact crater in the polar regions of Mercury. To simulate the migration of water molecules in the exosphere of Mercury, we used the Monte Carlo method. To estimate the proportion of water molecules falling into cold traps in the polar regions of Mercury, we estimated the area of such regions. We found that the area of permanently shaded areas near the north pole of the planet reaches 23,300 km 2 , and in the area of the south pole—45,500 km 2 . Most of the water molecules (~ 92%) will be destroyed as a result of photolysis, and ~ 7.5% of them will be destroyed while they are on the planet's surface between hops. The fraction of water molecules that left the planet's exosphere as a result of reaching the escape velocity is only 0.3%. The fraction of water molecules trapped in permanently shaded areas in the polar regions of Mercury reaches 7.8% of the total number of particles participating in the simulation. Only 2.2% of them can be trapped in cold traps in the North Pole region and 5.6% in the South Pole region.