Imagine catching a “Monster Wave,” and then imagine you are Surfing on ancient Mars! “I can imagine that surfing on Mars would be quite photogenic, but probably quite a bit easier,” Don Banfield, a planetary scientist at Cornell University, says. “The waves would be bigger for a given wind speed, and they’d move slower, so a surfer would look more heroic and the photographer would have more time to line the shot up well.”
There is no question that surging would likely have been a more epic undertaking on The Red Planet than it is on modern-day Earth because of the possible existence of giant, slow-moving waves. Researchers believe these big waves could have carved shorelines into Mars long ago. They speculate that studying these shorelines could shed light on the ancient Martian climate and whether the planet had seas long enough for life to develop.
Today, Mars is too dry and too cold for liquid water to survive on its surface for very long, but there is compelling evidence that much of the Red Planet was once covered in rivers and seas. The existence and extent of ancient Martian seas are still highly debated by researchers, especially because we know so little about what the ancient environment was like.
“If you could identify a wave-cut shoreline on Mars, then we could tell you the minimum wind strength that must have occurred when that open-water sea existed on Mars,” Banfield, who led the study, notes. There is also a link between wind strength and atmospheric pressure.
“This could go a long way to better constraining the ancient history of Mars’ climate,” he adds.
The strength of waves depends on the strengths of winds blowing on the water, which depend on the thickness of the atmosphere. At present, the atmosphere of Mars is very thin. But that does not necessarily mean it always has been. In computer simulations, Banfield and his team modeled atmospheric pressures of 6, 60, 600 and 1,200 millibars, ranging from the current atmosphere to slightly more than Earth’s. They also modeled wind speeds that were between 11 and 44 mph, similar to the ones we see on Mars.
Because the gravitational field of Mars is only 38 percent as strong as Earth’s, waves would more easily rise on the Red Planet. The scientists discovered “that even at very low atmospheric pressure like on Mars now, you could generate waves if you could keep a liquid surface around,”
The Martian waves would probably look pretty close in shape to what we see on Earth, “but they would move significantly more slowly on Mars than on Earth. Because water waves move forward due to the force of gravity, and the surface gravity is smaller on Mars, the waves on Mars would move about half as fast as they would on Earth.” This slower speed would allow the waves to build to higher heights.
Of course, even if no shorelines are ever discovered, we cannot conclude that Mars never had waves. But it’s exciting to think that new answers could be on the horizon.