New water cycle on Mars discovered



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** New water cycle on Mars discovered

Millions of years ago, Mars may have looked like this with an ocean covering part of its surface. Credit: NASA / GSFC

About two to two years in the summer, in the southern hemisphere, a window opens: at this time, water vapor can efficiently rise from the lower to the upper Martian atmosphere. There, the winds carry the rare gas to the north pole. While part of the water vapor decides and escapes into space, the rest sinks back down at the poles. The researchers at the Moscow Institute of Physics and Technology and the Max Plankk Institute for Solar System System Research (MPs) in Germany describe the unusual cycle water cycle of a current issue. Geophysical Research Letter. Their computer simulations show how water vapor overcomes the cold air barriers in the middle of Mars and reaches higher atmospheric layers. This may explain why Mars, unlike ground, has lost most of its water.


Billions of years ago, Mars was a planet rich in water with rivers, and even an ocean. Since then, our neighboring planet has changed dramatically. Today, only small amounts of frozen water exist in the earth; In the atmosphere, water vapor only occurs in traces. All in all, the planet could lose at least 80 percent of its original water. In the upper atmosphere of the sun, ultraviolet radiation of the sun splits water molecules into hydrogen (H) and hydroxyl radicals (OH). The hydrogen escaped from there irregularly. Measurements by spot probes and space telescopes show that even today, water is still lost in this way. But how is this possible? The middle atmosphere layer of Mars, like Earth's trappings, should actually keep the rising gas. After this, this area is usually so cold that water vapor would turn to ice. How does the Martian water vapor reach the upper air layers?

In their current simulations, Russian and German researchers find a previously unknown mechanism reminiscent of a type of pump. Their model comprehensively describes the entire gas flow around Mars from the surface to a height of 160 kilometers. The calculations show that normally freezing medium is permeable to water vapor twice a day – just in a certain place, and at a certain time of year.

** New water cycle on Mars discovered

Vertical distribution of water vapor on Mars in the course of a March year, shown at 3:00 local time. Only in the summer on the southern hemisphere can water vapor reach higher atmospheric layers. Credit: GPL, Shaposhnikov et al.: Seasonal "Water" Pump in the Atmosphere of Mars: Vertical Transport to the Thermosphere

The orbit of Mars plays a role in this. Its way around the sun, which lasts about two years, is much more elliptical than that of our planet. At the point closest to the sun (which roughly coincides with the summer of the southern hemisphere), Mars is approximately 42 million kilometers closer to the sun than in its furthest point. Summer in the southern hemisphere is therefore noticeably warmer than summer in the northern hemisphere.

"When it is summer in the southern hemisphere, in certain times of the day, water vapor can rise locally with warm air masses to achieve the upper atmosphere," says Paul Hartog of MPs, summarizing the results of the new study. In the upper atmospheric layers, air flows along the longitude to the northern pole, where it cools and sinks again. However, part of the water vapor escaping cycle: under the influence of solar radiation, water molecules disintegrate and hydrogen escapes into place.

Another Martian peculiarity can fortify this unusual hydraulic cycle: huge dust storm that spans the entire planet and repeatedly frosts at intervals of several years. The last such storms occurred in 2018 and 2007 and are comprehensively documented by space probes orbiting Mars. "The amount of dust swirling through the atmosphere in such a storm facilitates the transfer of water vapor into high air layers," said MPs Medvedev.

** New water cycle on Mars discovered

Time and again, Martian dust strangles the entire planet, as here in June 2018. The image was taken by the NASA's Rover Curiosity. Storms of this kind can facilitate the transfer of water in the upper atmosphere of Mars. Credit: NASA

The researchers calculated that during the 2007 dust storm, twice as much water vapor reached the upper atmosphere as during a radiant summer in the southern hemisphere. As the dust particles absorb sunlight and heat up, the entire ambient temperature reaches up to 30 degrees. "Our model shows with unprecedented accuracy that dust in the atmosphere affects the microphilic processes involved in ice-water transformation in water vapor," Dmitry Shaphnikovich of Moscow Institute of Physics and Technology, first author of the new study, explains.

"Apparently, the Martian atmosphere is more permeable to water vapor than that of the Earth," Hartog said. "The new ever-growing water cycle found to massively mass" improves water loss. "


Dust storms linked to gas escape from Martian atmosphere


More information:
Dmitry Shaposhnikov et al. Seasonal water pump "Mars": vertical transfer to the thermosphere, Geophysical Research Letter (2019). Du: 10.1029 / 2019 gl 0882839

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New Water Cycle on Mars Discovered (2019, May 10)
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