On Earth, water is life ; it was an essential tool for the evolution of life on Earth. Other rocky planets like Mars and Venus also had this resource, lots of water, but today Mars is a dry, frozen desert and Venus a hellish world of pressurized acid.
In September 2020 we learned that there is much more water than previously thought under the ice of Mars ( salty liquid water ).
Mars loses its moisture
Now a team of scientists has determined that the water on Mars is slowly disappearing from the surface . According to data from NASA’s MAVEN spacecraft, the water in the atmosphere is not confined to the lower layer but they have discovered that it escapes into space , as MAVEN has found water in the upper atmosphere of Mars, where hydrogen and Oxygen breaks down when reacting with ions in the air and the released hydrogen is lost to space.
The scientists were able to track this behavior seasonally to show that the abundance of water peaked during the austral summer. Even more surprising, dust storms like the one that wiped out NASA’s Opportunity rover increase atmospheric loss.
“This completely changes the way we think that hydrogen, in particular, was being lost in space,” says planetary chemist Shane Stone of the University of Arizona in Tucson in his study published in the journal Science.
The surface of Mars was shaped by flowing water in the past, we already know that, but today the planet is an arid, reddish desert. Previously, scientists thought that water on Mars was lost in a “slow and steady trickle,” when sunlight split the water in the lower atmosphere and hydrogen gradually diffused upward, Stone says.
But MAVEN, which has been orbiting the red planet since 2014, collected water molecules in the ionosphere of Mars, at altitudes of about 150 kilometers. A really striking fact since, previously, the highest water that had been seen was barely 80 kilometers.
“Seasonal and dust storm-mediated water delivery to the upper atmosphere 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.” points out Stone.
MAVEN measurements suggest that the leaks are much higher than anticipated. Over the past billion years, seasonal warming, annual regional dust storms and decade-long superstorms caused Mars to lose enough water to cover the planet in a global ocean more than half a meter deep, the researchers estimated. That’s only a small percentage of the water that Mars has lost throughout its history (which would be enough to flood the planet in an ocean to even many tens of meters deep), says Stone, but it is the main way by the one that the planet continues to dry up to this day.
Does the Earth also lose atmospheric oxygen?
If you are wondering if the Earth can suffer the same fate, the answer is simple. The Earth does constantly lose water due to this ‘atmospheric escape’, but the rate is too slow for terrestrial organisms to be endangered. We still have about 2 billion years to enjoy this blue marble.
Referencia: S.W. Stone et al. “Hydrogen escape from Mars is driven by seasonal and dust storm transport of wáter”. 2020 Science.
