2023-07-02 11:15:11
There are mysterious channels on Mars that resemble canyons in Antarctica caused by melting glaciers, but the high places of many of the features are not places where we would expect to find running water. How did these Martian valleys form? Sublimation of carbon dioxide ice has been put forward as an alternative hypothesis, but a new study by a team of scientists in the US suggests that, under the right conditions, liquid water could actually do the job. Moreover, it would have happened relatively recently on geological time scales, perhaps as little as 630,000 years ago. The key is the tilt of the planet’s axis. When the gradient reaches 35 degrees, new simulations of temperature and circulation show that the density of the atmosphere causes the surface temperature to rise briefly above freezing. It is enough to melt part of the remaining snow and ice on Mars. We know from much of our research and other research that early in the history of Mars, there was flowing water on the surface with networks of valleys and lakes. But about 3 billion years ago, all that liquid water disappeared. And Mars has become what we call an extremely dry desert or a polar desert,” says Brown University planetary scientist Jim Head. Calculations by the research team shed light on how these valleys form, how much they erode and how far they spread. The team was able to fit their model to data from the Terra Sirenum region of Mars, matching it to periods when valleys were thought to be rapidly expanding in the region. The two-groove scenario is where glacier-induced channels are eroded by evaporation of frozen carbon dioxide. It is possible that these places still have reserves of ice trapped below the surface, and there may be more of them than before. Flowing water erosion is more consistent with landscape characteristics on Mars than CO2-related erosion, which has no equivalent on Earth that we can study, and does not tend to have the same effects on the rocks it comes into contact with. This type of activity has been observed in modern times through high-resolution satellite images of Mars. “Our study shows that the global distribution of canyons can be best explained by liquid water in the past million years. Water explains the higher distribution of the grooves in a way that carbon dioxide cannot. This means that Mars could be “producing liquid water.” enough to erode the canals over the past million years, which is very recent on the scale of Mars’ geological history.” The tilt of Mars’ axis changes over time, although it takes hundreds of thousands of years. This motion has previously been linked to ice ages on the Red Planet. Just as the flow of magma on Mars in the relatively recent past made it easier for organisms to evolve, this research also provides an interesting new perspective on the possibility of life on Mars. Finally, the planet tilts backwards at an angle of 35 degrees, which allows spotting of liquid water to flow back in. To bring water back into the dry valleys of Antarctica, when no liquid water is available, life freezes. It is not inconceivable that something like this could happen on Mars as well.
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