Was Young, Wet Mars Once Close Enough to the Sun to 'Dance' with Venus?

By Nola Taylor Redd, Space.com Contributor | September 4, 2018 07:00am ET

Billions of years ago, liquid water flowed across the Martian surface. As the Red Planet lost its atmosphere, it also lost its ability to hold on to that water — or so most theories propose. Now, a new model suggests that Mars would have started off warmer and wetter if it had begun closer to the sun and slowly moved outward.

"Mars starts off on top of Venus; then it dances outward towards Earth," Cole Brown, a researcher at Penn State University, told his colleagues. Working with planetary scientist Darren Williams, also of Penn State, Brown modeled an early solar system where Mars started off in a warmer place. He found that the process was unlikely, but possible — just over 10 percent of the worlds starting out this way successfully worked their way out to where Mars orbits today. He presented the results in June at the 232nd meeting of the American Astronomical Society in Denver.

"After Mars would escape Venus, that's where things would get interesting," Brown said. [How Did the Solar System Form?]

"A Mars cannon"
The Martian surface is gouged by river-like features and spreading deltas, all of which seem to suggest liquid water once sat on the surface. At almost 4 billion years old, these features are almost as old as the planet itself, hinting that liquid water was short-lived on the Red Planet.


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