The fact that ancient Mars was flowing with streams of water, has long been recognized. Traces of H2O are visible everywhere: it left the ducts, in massive sedimentary deposits, and even in the channels cut by the stones, thrown inland mega-tsunami. Scientists have even calculated how much water was previously on the red planet. But all this raises a natural question: how Mars was able to support a hydrosphere?
Now the average temperature on the planet’s surface is 40 degrees. But in those days, the Sun shone on a third weaker than it is now.
As-stick wand scientists have always used the atmosphere of Mars. It is believed that in ancient times it was much denser, and by the greenhouse effect provided a much higher surface temperature than it is now, provided the possibility of the existence of water in liquid form.
But this theory has problems. A few years ago scientists noticed that Mars is much smaller deposits of carbonates (a mineral formed by the interaction of water and carbon dioxide) than it should be come from the intended composition of the ancient atmosphere. And now, new data from the Mars Rover Curiosity also suggests that the atmosphere of ancient Mars wasn’t as dense as it is considered to be.
All the matter in the carbonates. Or rather their absence. The Gale crater, which Curiosity is now crisscrossing, 3.5 billion years ago filled the lake, leaving behind layers of sediment. Curiosity have researched them, but never found in them traces of carbonates. This means that during their deposition the CO2 level in the atmosphere of the planet was 10 to 100 times less than the level that ensures the surface temperature above the freezing point of water.
Thus, on the face of the obvious contradiction. One of his possible explanations is that the crater lake was obscured by a layer of ice. But in this case, the deposits were to remain certain traces, and their Curiosity was not found. But if the lake was open, so astronomers are missing something. Perhaps ancient Martian atmosphere had a completely different composition than is generally assumed. Maybe the whole thing in some more global factor, providing the necessary heating of Mars.