Semi-Empirical Modeling of Radiolytic Production in the Mars Northern Polar Region

A model to simulate the radiolytic production of various compounds in the Mars northern polar region was developed. Galactic cosmic rays are used as the source of particle radiation. Particle energy distributions are modeled semi-empirically with the energy deposition inside the ice layers computed using the Stopping and Ranging of Ions in Matter (SRIM) model simulation or a customized Bethe-Bloch formula. The rate of species production is derived from laboratory measurement. Seasonal variations of the ice layers are either obtained from Global Multiscale Mars Model (GM3) results or estimation based on observed quantities.

Preliminary results show that for species such as carbon monoxide, as much as 9,000 tons can be released into the atmosphere annually. Without the use of atmospheric transport models, a direct comparison to observations is not possible. As radiolysis can potentially explain the existence of compounds such as methane on Mars, the model warrants further investigation.