There were rivers and lakes on Mars, it is science had agreed. But now come to doubt on previous theories – after analysis of small meteorite crater.

Mars was in his past may not be so wet as previously thought . The researchers conclude by Edwin Kite from the California Institute of Technology from the analysis of meteorite craters on the Red Planet . Their small size shows that also amazingly small meteorites were stamped on the surface. The interpret in a surprisingly thin air back in the early days of Mars – they make it less likely that liquid water once flowed on the Red Planet is , the researchers write in the journal ” Nature Geoscience .”

Kite and colleagues had examined data from more than 300 craters in the 3.6 billion years old Aeolis – Dorsa region on Mars that had been taken by the space probe “Mars Reconnaissance Orbiter .” The size of the impact crater to document the extent of the smallest meteorites that have then reached the Martian soil . From this, the density of the atmosphere at that time determine : The closer it is, the larger the chunks that burn up in it and not reach the ground with it.

According to the analysis of the Martian atmosphere at that time was about as dense as Earth’s atmosphere today. While that is about 150 times denser than today’s gas envelope of Mars. Previous estimates were , however, assume that the atmosphere on the Red Planet must have been about five times as dense as today in order to ensure permanent pressure and temperature for liquid water. Because Mars is not only more distant from the Sun than the Earth , the sun shone then even weaker than it is today – water freezes in the cold more likely .

Mars Crater Analysis:However liquid water ?

The observation seems to be on Mars in contradiction to the numerous traces of liquid water: hundreds of kilometers long river beds and barren lakes are evidence of a wet-distant past of the red planet.

Is possible that over geological time temporarily liquid water has existed on the red planet again and again, writes Sanjoy Som from the Ames Research Center of the U.S. space agency Nasa in a comment in “Nature Geoscience.”

So stagger the rotation axis of Mars at a rate of 120,000 years. In this way gelange different amounts of sunlight on the polar ice caps of Mars, which are thereby possibly thawed repeatedly. The polar thaw could have so greatly enriched the atmosphere that liquid water could exist for a long time.

Even large asteroid impacts may have led temporarily to a denser atmosphere, writes Som. Or was so very salty that it could remain liquid despite the unexpectedly thin and so cold atmosphere to the water in the primeval Martian rivers.

If it be true that Mars has not has a permanently water, it will be even harder to find there evidence of this former life.

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