Mechanochemical-UV generation of perchlorates and reactive nitrogen on Mars

When you strike a flint against another flint, you can make sparks.

These sparks form due to the breaking of strong chemical bonds on the flint surfaces, and some of these broken bonds are so reactive that they can combine nitrogen and oxygen in air to form nitrous oxides.

This project will investigate how similar 'mechanochemical' reactions on Mars, driven by the erosion of sand and dust particles by wind, can combine trace oxygen and sodium chloride (table salt) to form perchlorates, and oxygen with nitrogen to form nitrates. Both perchlorates and nitrates have been measured on the surface of Mars.

Figuring out how perchlorates form is important, as perchlorates lower the freezing point of water and expand the areas where life could survive today, or in the past, at or near the surface of Mars.

When heated, they can also react with organic molecules, potentially providing an explanation for some of the results of life detecting experiments carried out by the Viking lander missions in the 1970s.

Figuring out when on Mars nitrogen in the atmosphere was 'fixed' into other forms such as nitrate or nitrous oxides is also important, as nitrogen is (after carbon) the second most important nutrient for life. On Earth today, most of the fixed nitrogen from the atmosphere has been fixed by life.

This project will use experiments to mimic wind-driven chemical reactions on Mars in the laboratory, and also look at how ultraviolet rays from the sun can influence the chemicals that are formed.

Results will be used to help interpret previously analysed/ongoing analyses of perchlorate and nitrogen compounds on the Martian surface by the NASA Curiosity and Perseverance missions, and ongoing measurements of the Martian atmosphere by the ExoMars Trace Gas Orbiter.

The results can also be used to help interpret the origin of perchlorates and nitrogen-containing compounds in future samples returned from Mars for more detailed analyses in laboratories on Earth.