Scientists have identified a previously unknown mechanism that may explain how Mars lost most of its water, finding that intense dust events known as “rocket storms” can rapidly push water vapor high into the planet’s atmosphere, where it is permanently destroyed.
The discovery comes from a new study that analysed data from six instruments aboard three international spacecraft, including the ExoMars mission, the Emirates Mars Mission, and NASA’s Mars Reconnaissance Orbiter.
For decades, researchers have known that Mars was once a wet planet, with rovers such as Perseverance and Curiosity confirming evidence of ancient rivers and lakes, yet the process behind the planet’s extreme water loss remained unclear.
Scientists found that rocket storms act like atmospheric elevators. During these dust storms, water vapor is lifted far above the Martian surface into the upper atmosphere. There, intense ultraviolet radiation breaks apart water molecules, allowing lighter hydrogen atoms to escape into space.
The study showed that these storms can heat Mars’s middle atmosphere by around 15 degrees Celsius. This warming prevents the formation of water ice clouds that would normally trap moisture at lower altitudes. Without that barrier, water vapor rises unchecked into regions where it is vulnerable to destruction by solar radiation.
Previously, researchers believed most water loss occurred only during Mars’s southern summer, when the planet is closest to the Sun. However, the spacecraft data captured a major rocket storm during the cooler northern summer of 2022, indicating the process is not limited to a single season.
The findings suggest Mars has been losing water throughout the year for billions of years. Scientists say this helps explain how a planet that once hosted deep oceans gradually transformed into the cold, arid world seen today.