You’re no doubt familiar with the dry, dusty appearance of Mars as it looks today, but scientists have found evidence of a vast ocean existing on the red planet’s surface around 3.5 billion years ago, which likely covered hundreds of thousands of squares. kilometers
This evidence comes in the form of distinctive coastal topography, identified through numerous satellite images of the Martian surface. When these images are captured at slightly different angles, a relief map can be constructed.
Researchers have been able to trace more than 6,500 kilometers (4,039 miles) of river ridges, apparently cut by rivers, showing that they are likely eroded river deltas or submarine channel belts (channels cut into the sea floor).
The floor of Gale Crater, near a region called Aeolis Dorsa, which researchers believe was once a massive ocean. (NASA/JPL-Caltech/MSSS)
“The most important and new thing we did in this paper was to think about Mars in terms of its stratigraphy and its sedimentary record,” says geoscientist Benjamin Cardenas of Pennsylvania State University.
“On Earth, we trace the history of waterways by looking at the sediments that are deposited over time. We call this stratigraphy, the idea that water transports sediments, and you can measure changes on Earth by understanding how they accumulate the sediments. That’s what we’ve done here, but it’s Mars.”
Using Mars Reconnaissance Orbiter data collected in 2007, the team applied an analysis of ridge thicknesses, angles and locations to understand the study area: the topographic depression known as the Aeolis Dorsa region on Mars.
It seems likely that so many years ago an important change had taken place in this part of the planet, explains Cárdenas. This is evidenced by evidence of substantial sea-level rises and the rapid movement of rocks by rivers and streams. Today, Aeolis Dorsa contains the most concentrated collection of fluvial ridges on Mars.
All this is linked to the search for life on Mars. One of the most fundamental questions scientists are looking at regarding the red planet is whether it has ever had conditions hospitable enough to support life.
“What immediately comes to mind as one of the most significant points here is that the existence of an ocean of this size means a greater potential for life,” says Cárdenas.
“It also tells us about the ancient climate and how it evolved. From these findings, we know there must have been a period when it was warm enough and the atmosphere was thick enough to support so much liquid water at once.”
The researchers don’t stop with the Aeolis Dorsa region.
In a separate study published in Nature Geoscience, some of the same researchers, including Cárdenas, applied an acoustic imaging technique used to map ancient seafloor in the Gulf of Mexico to a model of how water might have eroded the surface of Mars .
There are large areas of what could be river ridges all over Mars, and the team’s simulations are remarkably similar to the shape of the red planet’s landscape, suggesting that there was extensive water coverage at one time.
We’re seeing more and more signs that water was once abundant on Mars, and work continues to figure out what might have led to it and where the water is now, although looking back through billions of years doesn’t It’s easy.
“If there were tides on ancient Mars, they would have been here, gently flowing water in and out,” says Cárdenas. “This is exactly the kind of place where ancient Martian life could have evolved.”
The research has been published in the Journal of Geophysical Research: Planets and Nature Geoscience.