The water on Mars is not confined to its inner atmosphere, but is transported to the upper atmosphere and there it becomes atomic hydrogen that escape into space, according to the evidence published this Thursday in a study by the magazine Science.

In the past, water flowed across the Martian surface, where it has left marks in the form of river beds and coasts, However, today there are far fewer and it is considered that most are enclosed in the polar caps, with only a few traces of water vapor in the atmosphere.

A team led by Shane Stone from the University of Arizona used data taken by the US space probe MAVEM in the upper part of the Martian atmosphere, where they found traces of water at higher altitudes than expected.

The arrival of water to the upper atmosphere, through dust and seasonal storms, “could have played a substantial role in the evolution of the Martian climate from its hot and humid state billions of years ago to the cold, dry planet we observe today, “according to Stone.

This same process dominates the current loss of water from the red planet, indicate the authors of the research.

Most of the water on Mars has slowly been converted into hydrogen in the atmosphere, which is lost to space, gradually wiping it out over several billion years, in a process that continues today.

The study indicates that water is transported directly to the upper atmosphere and converted there into atomic hydrogen through reactions with atmospheric ions.

The abundance of water in the upper atmosphere of Mars varies with the seasons. It reaches its maximum in the austral summer, increasing during the storms of regional and global dust.