The uncertainty of science: Two new studies using data Europe’s Trace Gas Orbiter and Mars Express orbiters have found that Mars is losing water seasonally through its atmosphere.
The studies also found that global dust storms accelerate the process.
Anna and colleagues found that water vapour remained confined to below 60 km when Mars was far from the Sun but extended up to 90 km in altitude when Mars was closest to the Sun. Across a full orbit, the distance between the Sun and the Red Planet ranges from 207 million to 249 million km.
Near the Sun, the warmer temperatures and more intensive circulation in the atmosphere prevented water from freezing out at a certain altitude. “Then, the upper atmosphere becomes moistened and saturated with water, explaining why water escape rates speed up during this season – water is carried higher, aiding its escape to space,” adds Anna.
In years when Mars experienced a global dust storm the upper atmosphere became even wetter, accumulating water in excess at altitudes of over 80 km.
But wait, didn’t planetary scientists just announce that Mars hasn’t lost its water through the atmosphere, but instead lost it when it became chemical trapped in the planet’s soil? Yup, they did, but that was a model based on new ground data. This new result is based on atmospheric data.
Or to put it another way, the model was incomplete. While it could be true that a large bulk of Mars’ water is trapped chemically in the ground, that is not proven, only hypothesized. What has been proven, and is now confirmed by these two studies, is that, depending on weather and season, the water of Mars does leak into its upper atmosphere where it can escape into space, never to return.
What remains unknown is how much water escaped into space, and when. Moreover, the ground-based model could still be right, even if it is true that Mars is losing water through its atmosphere. At the moment the data is too incomplete to answer these questions with any certainty.
Meanwhile, this press release once again gives the false impression that the only water left on Mars is at its poles (and in this case, only the south pole). This is not accurate, based on numerous studies finding evidence of buried ice and glaciers everywhere on the planet down to the 30th latitude, in both the north and south hemispheres. Mars might have far less water now than it did billions of years ago, but it still has plenty, and that water is not found only at the poles.
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