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Scientists find subtle clues ancient Mars had rainy days, too

时间：2025-06-13 23:21:35 来源：不由自主网

For the past four years,关键字1 NASA's Perseverancerover has rambled over a region of Marswhere scientists say a strong river once emptied into a crater, creating a large delta.

But for that to have happened, a lot of waterwould have gushed — something difficult to explain if the Red Planet were always frozen.

Computer simulations show that ancient Mars likely experienced regular rain and snow, which helped shape vast networks of river valleys and lakes. The distribution of these land features lines up better with precipitation models than merely the effects of melted ice caps, according to a new paperpublished in the Journal of Geophysical Research: Planets.

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The research, performed by geologists at the University of Colorado in Boulder, argues that our planetary neighbor, on average 140 million miles away in space, was warm and wet billions of years ago, challenginga long-held belief that early Mars was mostly cold and icy.

Most scientists agree that at least some water existed on the surface during a period about 4 billion years ago, but where the water came from has been up for debate, said Amanda Steckel, who led the studyas a doctoral student.

"We see these valleys beginning at a large range of elevations," Steckel said in a statement. "It’s hard to explain that with just ice."

SEE ALSO: A NASA rover just exposed something on Mars that eluded orbiters Viewing Mars' topography from space

NASA's Mars Global Surveyor spacecraft created this topographical map of a region near the planet's equator with its Mars Orbiter Laser Altimeter. Credit: NASA

The researchers created a digital version of part of Mars and tested different climate scenarios. In some computer simulations, they added widespread rain or snow. For others, they only tried melting down polar ice. Then, they used the software to simulate what would happen if that water flowed for thousands of years.

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Their goal was to determine whether ancient Mars may have had a more Earth-like climate, at least for a while.

The results showed when precipitation was part of the climate, valleys and streams formed in many different regions at varying elevation points. When water came only from melted ice, the valleys mostly formed in the highlands, in close proximity to where the ice caps would have been.

The team compared the simulation data to real images from NASA spacecraft that have observed Mars from orbit. The patterns created by rain or snow more closely matched what is actually seen on the Martian surface.

Observing Mars' valley networks from space

Mars' oldest terrains appear to have eroded into branching valleys, similar to regions of Earth where rain and snow have caused runoff. Credit: NASA / JPL-Caltech / Univ. of Arizona

"Water from these ice caps starts to form valleys only around a narrow band of elevations," Steckel said. "Whereas if you have distributed precipitation, you can have valley heads forming everywhere."