New Study Reveals How Rain Reshaped the Surface of Mars

New Study Reveals How Rain Shaped the Surface of Mars

Valley networks on Mars show evidence for surface runoff driven by rainfall. Credit: Elsevier

A newly published study from the Smithsonian Institution and the Johns Hopkins University reveals that heavy rain on Mars reshaped the planet’s impact craters and carved out river-like channels in its surface billions of years ago. The study shows that changes in the atmosphere on Mars made it rain harder and harder, which had a similar effect on the planet’s surface as we see on Earth.


But in the new study, geologists Dr. Robert Craddock and Dr. Ralph Lorenz show that there was rainfall in the past — and that it was heavy enough to change the planet’s surface. To work this out, they used methods tried and tested here on Earth, where the erosive effect of the rain on the Earth’s surface has important impacts on agriculture and the economy.

Valley networks on Mars show evidence for surface runoff driven by rainfall. “Many people have analyzed the nature of rainfall on the Earth, but no one had thought to apply the physics to understanding the early Martian atmosphere,” said Dr. Craddock of the Smithsonian Institution.



“By using basic physical principles to understand the relationship between the atmosphere, raindrop size and rainfall intensity, we have shown that Mars would have seen some pretty big raindrops that would have been able to make more drastic changes to the surface than the earlier fog-like droplets,” commented Dr. Lorenz of John Hopkins University, who has also studied liquid methane rainfall on Saturn’s moon Titan, the only other world in the solar system apart from Earth where rain falls onto the surface at the present day.



The new study is published in Icarus.

Study: Robert A. Craddocka and Ralph D. Lorenzb, “The changing nature of rainfall during the early history of Mars,” Icarus, Volume 293, 1 September 2017, Pages 172–179; doi:10.1016/j.icarus.2017.04.013

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