An article published in the “Journal of Geophysical Research: Planets” reports an analysis of the composition of the atmosphere of the planet Mars based on data collected by NASA’s Mars Rover Curiosity. A team of researchers led by Melissa Trainer of NASA’s Goddard Space Center confirmed the presence of various gases already known with seasonal variations due to carbon dioxide’s freezing and evaporation. A surprise came from the detection of a remarkable growth of oxygen in spring and its drop back to the previous levels in fall. This is a new mystery added to that of the presence of methane on the red planet.