Martian heat and dust help its water escape into space

Researchers have used one of the instruments aboard the NASA MAVEN spacecraft to discover water vapor near the surface of Mars is pushed higher into the atmosphere than previously believed possible. Once the water vapor is high into what remains of the Martian atmosphere, it's easily destroyed by electrically charged gas particles and lost to space. Researchers believe the phenomenon they have discovered is one of several that led to Mars losing its oceans that are believed to have been up to hundreds of feet deep over billions of years.

Scientists on the project also point out that Mars continues to lose water today as vapor is transported to high altitudes after sublimating from frozen polar caps during warmer Martian seasons. One researcher on the project, Shane W. Stone, said that the team was surprised to find water so high in the atmosphere. Stone notes that measurements could have only come from MAVEN since it moves through the atmosphere of Mars high above the surface.

The instrument aboard MAVEN used by the team is called the Neutral Gas and Ion Mass Spectrometer, which was developed by the NASA Goddard Space Flight Center. Stone and other members of the research team tracked water ions high over Mars for more than two Martian years. They determined the amount of water vapor near the top of the Martian atmosphere, about 93 miles above the surface, is highest during the summer in the southern hemisphere.

Summer is when the planet is closest to the sun, making it warmer and dust storms more likely to happen. Both warm summer temperatures and strong winds associated with dust storms push water vapor in the uppermost parts of the atmosphere, where it's easily broken into hydrogen and oxygen, which escape to space. Before the study, scientists believe water vapor was trapped close to the surface of Mars as it is on Earth. This research has shown conclusively that the storm to interrupt the water cycle on Mars, lifting water vapor far above the surface.