AOKI Shohei / Dept. of Solar System Sciences, ISAS
It is almost certain that Mars once supported a large quantity of water. However, it is still unknown how so much water was lost. Previous studies have suggested that dust storms that occur near the surface increase water vapor in the middle atmosphere, and drive the escape of water into space. However, there have been no direct observations to confirm the whole process. In this study, we simultaneously observed a regional dust storm that occurred in January-February 2019 using three different Mars orbiters: NASA's MRO and MAVEN, and ESA's ExoMars TGO. Four instruments onboard the three orbiters successfully captured the impact of the regional dust storm from surface to space, which allows us to quantify the amount of water loss and response time. Since such a regional dust storm occurs almost every Mars year, it is suggested that small dust storms play an important role in water loss on Mars.