A new study suggests that icy clouds over early Mars could have provided the heat to enable flowing water on the Red Planet.
US researchers used a computer model to predict that icy clouds in the atmosphere of Mars may have caused a greenhouse effect. Earth is also experiencing a greenhouse effect, which occurs when gases in the atmosphere trap the sun’s heat.
Today Mars enjoys a cold desert climate. All existing water is believed to be in the form of ice due to the extremely cold temperatures on the planet. However, there is a rich amount proof suggesting that rivers, lakes, and even oceans once existed on Mars.
In fact scientists announced in February they had created a new map to identify the best sources of water ice on Mars.
Scientists have long tried to explain what made it possible for Mars to have the great rivers and lakes that they believed existed in the planet’s ancient past.
Researchers involved in the latest study were interested in coming up with a possible explanation. They created one three-dimensional, or 3D, model of Mars’ atmosphere.
The study was led by Edwin Kite, a professor and planetary scientist at the University of Chicago. He said the research resulted in an important discovery – that ice on the surface of Mars likely caused global warming. The study was recent published in Proceedings of the National Academy of Sciences.
When water or ice on the surface of a planet evaporates – what happens when it changes from solid form to one vapor – it creates moisture. Humidity is created when there is a high level of water vapor in the atmosphere. The vapor helps to form clouds.
The researchers say that high cloud cover has more of a warming effect than low cloud cover. High clouds would have formed sooner if only small areas were covered with ice, such as the poles or on mountain tops. They think this was the case on Mars.
Kite said previous studies had considered similar theories, but the research was based on ideas related to the behavior of our own planet. “In the model, these clouds behave very unearthly,” says Kite said in a statement.
“Building models based on the Earth” just won’t work, he said, adding, “This is nothing like Earth’s water cycle, which moves water quickly between the atmosphere and the surface.”
Kite said his team’s model suggests that once water got into the early Martian atmosphere, it likely lasted much longer. “And that creates the conditions for long-lived clouds at high altitudes.”
The team said it hopes the new theory can help scientists resolve a huge “gap” between existing evidence about water on Mars and the ability to back it up with physics and chemistry.
Kite added that NASA’s Mars explorer Persistence should be able to test the theory in different ways. For example, small rocks can be collected and explored in an attempt to simulate past atmospheric pressure on Mars.
The latest study and future research into how Mars gained and lost its heat could help scientists identify others as well habitable worlds, Kite said. “Mars is important because it’s the only planet we know of that had the ability to sustain life – and then lost it.”
I am Bryan Lynn.
Bryan Lynn wrote this story for VOA Learning English, based on reports from the University of Chicago and Proceedings of the National Academy of Sciences. Caty Weaver was the editor.
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Words in this story
three-dimensional (3D) – adj. have or appear to have length, depth and height
vapor – n. small drops of liquid in the air
habitable – adj. able to sustain life