ハーシェル宇宙望遠鏡
The estimated mean volume ratio of molecular oxygen (O2) in the Martian atmosphere is 0.174%. It is one of the products of the photolysis of CO2, water vapor and ozone (O). It can react with atomic oxygen (O) to re-form ozone (O). In 2010, the Herschel Space Observatory detected molecular oxygen in the Martian atmosphere.