You’re no doubt familiar with how dry and dusty Mars looks today – but scientists have found evidence that a vast ocean once existed on the surface of the Red Planet about 3.5 billion years ago.
This evidence comes in the form of distinctive beach topography, identified by numerous satellite images of the Martian surface. When these images are taken from slightly different angles, a bump map can be created.
The researchers were able to map more than 6,500 kilometers (4,039 miles) of river ridges, apparently carved by rivers, indicating that they were most likely eroded into river deltas or channel belts (channels carved into the seabed).
“The big and new thing we’ve done in this paper is to think of Mars in terms of its stratigraphy and sedimentary record,” says geologist Benjamin Cardenas of Penn State University.
Using data from the Mars Reconnaissance Orbiter 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.
Cardenas says it seems likely that there will be a great deal of change in this part of the planet all these years ago. This is evidenced by evidence of large increases in sea level and rapid movement of rocks by rivers and currents. Today, the Aeolis Dorsa contains the most concentrated group of river ridges on Mars. And all this is related to the search for life on Mars. One of the fundamental questions that scientists are looking for regarding the Red Planet is whether it has conditions hospitable enough to be able to support life.
“What immediately comes to mind as one of the most important points here is that an ocean of this size means a higher possibility of life,” Cardenas says. “It also tells us about the ancient climate and its evolution. Based on these results, we know that there was a period when it was warm enough and the atmosphere was The atmosphere is thick enough to support that much liquid water at one time.”
In a separate study published in Nature Geoscience, some researchers themselves applied the acoustic imaging technique used to map ancient deep seas in the Gulf of Mexico as a model for how the surface of Mars was eroded by water.
There are vast expanses of what would be river ledges all over Mars, and the simulations run by the team remarkably resemble what the landscapes on the Red Planet looked like – suggesting that there was extensive water coverage in ancient times at one time.
We’re seeing more and more evidence that water was once plentiful on Mars, and work continues to figure out what it might lead to and where that water is now – although looking back through billions of years isn’t easy.
The research has been published in the Journal of Geophysical Research: Planets and Nature Geoscience.