Increased Hydrogen escape from Mars atmosphere during periods of high obliquity

I will talk about a recent study led by IAA-CSIC focused on the atmospheric H escape during high obliquity period in recent Mars (average ~35º in last millions of years). Observations show that current thermal H escape (major water loss process) varies seasonally, with considerable increases during dust storms of both  water abundance in the upper atmosphere and H escape rate. Present H-loss rates agree with 3D simulations by the Mars Planetary Climate Model used in this study, varying with season between 1-11 x10²⁶ atoms/s. However, if we apply current escape rates to Mars’ entire history, those values cannot fully explain the large volumes of ancient surface water suggested by several geological and mineralogical observatios.

Our simulations with an obliquity of 35º indicate that the H escape rate could have been up to 20 times larger than today. The accumulated H loss over Mars history would translate into ~80 m Global Equivalent Layer, aligning with the lower range of geological estimates and highlighting atmospheric H loss as a key factor in Mars’ desiccation.