The Curiosity Rover had been searching signs of water in Mars and was successful in doing so, as far as flowing waters are concerned. However, searching for large bodies of water was quite a challenge for the robotic rover since its landing in 2012. Not until today that scientists from the California Institute of Technology(Caltech) have stumbled upon evidence that the red planet used to have a vast ocean.

Mike Lamb, coauthor of the paper and assistant professor of geology at Caltech, have confirmed that the scientists have long believed that the northern plains of Mars might used to be an ocean. However, they never had any substantial evidence to support this idea.

Almost a third of the planet’s northern hemisphere is flat and a lower than the southern hemisphere which is similar to Earth’s ocean basins. The boundary between the plains and the ridge would have been the shoreline.

In order to prove their hypothesis, the Caltech team used the latest images captured by the Mars Reconnaissance Orbiter (MRO), a multipurpose spacecraft designed to explore Mars from its orbit. The scientists analyzed the 100 sq. km-long shoreline as well as previous images of the Aeolis Dorsa which is about 1,000 km away from the Gale Crater where the Curiosity Rover is located at the moment.

The scientists believed that the ridge-like features in the images might be gravel and cobbles washed away by an ancient river. Over time, they had become today’s ridge-like features.

The inverted channels of the images suggest three things: they might have been drainage systems in which waters from the streams and creeks flow down, they might have been from a single river which branches into different directions, or it is a part of delta sending waters to the ocean.

The scientists recreated the scenarios by taking more images in various angles to determine the planet’s landscape. They were able to measure the slope to reveal the direction of the water flow in which they concluded that the inverted channels were indeed part of a delta.

The scientists concluded that a third of the Red Planet used to be covered with water and have an ocean of about 100,000 sq. km in the Aeolis Dorsa region. They will continue their research to further strengthen this discovery.

The paper was published in the July 12 issue of the Journal of Geophysical Research.