Understanding ozone on Mars
Long-term studies of ozone and water vapour in the atmosphere of Mars could lead to better understanding of atmospheric chemistry for the Earth. A new analysis of data from ESA's Mars Express mission has revealed that our knowledge of the way these atmospheric gases interact with each other is incomplete.
Ozone is produced on Mars when carbon dioxide molecules are split apart by ultraviolet radiation from the Sun. Ozone can be split apart by hydrogen radicals, which are produced when water vapour is split apart by ultraviolet light.
The fact that Mars’ atmosphere is 95% carbon dioxide suggests that a global ozone signature is to be expected, except where there is water vapour. But, for a given amount of water vapour, Mars Express observes twice as much ozone as predicted by climate models. Perhaps the ozone destruction by hydrogen radicals is less efficient than expected, or ice clouds could absorb the hydrogen radicals before they have time to split apart the ozone.
