This NASA image shows a preserved river channels on Mars, with colour overlaid to show elevation (blue is low, yellow is high). The range of the height in the snapshot is approximately 115 feet (35 meters).
Mars was wet, and then, suddenly, it was not.
Scientists have long seen, dry riverbeds, slashed across the surface of Mars as proof that water once flowed freely on the planet. And in 2012, NASA’s Curiosity space rover sent back images of smooth, round pebbles from the bottom of a such riverbed, their lack of rough edges-evidence that water had once flowed over them. Now, a new study published today (27 March) in the journal Science Advances catalogs that rivers and the reports that their waters probably flowed heavily in the last period, before Mars is completely dry.
“It’s hard to explain, rivers, or lakes on the basis of the information that we have,” Edwin Kite, a planetary scientist at the University of Chicago and lead author of the study, said in a statement. “This makes it a difficult problem even more difficult.” [7 Most Mars-Like Places on Earth]
If the rivers were short, or was only a part of the time, it still would have been challenging to tell about their existence. But scientists just don’t know where all the liquid water came from the formation of these heavy flows.
Mars is cold and predominantly dry, with only a thin atmosphere on the surface. In the distant past, it seems that the weather should be even colder because the sunlight reaching the surface of the planet would have been dimmer. And yet, billions of years ago, the water seems to have flowed strongly and freely on Mars, in the rivers, which were sometimes broader than those on Earth. These waters seem to have flowed so hard that she would have been in movement the whole day, and not only at the peak sunlight hours or in thin trickles.
Scientists just don’t know what kind of weather on the Red Planet would have made of these rivers, but the study showed that the strong stream of water existed for more than a billion years, in the beginning of Mars history.
That implies at least that Mars had a strong greenhouse effect than the back to absorb the energy of the limited sunlight on the planet and melt the water — which then ran out in the river channels. [‘4-Billion-Year Old’ Mars Fly-Over Shows Water and Blue Skies | Video]
Kite said that this work implies that there is something in the current science of the planets and the early solar system is wrong, because everything scientists know suggests that the rivers on Mars must be small and temporary, if they existed at all. The long-term, heavy flow for the duration of millions of years, just do not fit in the current scientific knowledge.
The research also shows that as the Red Planet got colder, not slowly dry up. Instead, at the end of the march wet season, the rivers became narrower, but still carried heavy drain for — and almost immediately — to disappear.
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Originally published on Live Science.