Was There a Large Ocean on Mars?

New data from ESA’s Mars Express reveals strong evidence that an ocean once covered the northern hemisphere of Mars. The evidence is based on signatures of ocean floor sediments in an area within the boundaries of what has thought to have been an ancient shoreline on Mars.

Deployed in 2005, the MARSIS radar has been collecting data that was recently analyzed by Jérémie Mouginot (Institut de Planétologie et d’Astrophysique de Grenoble). Mouginot’s analysis revealed that the northen plains of Mars are covered in low-density material.

“We interpret these as sedimentary deposits, maybe ice-rich,” says Mouginot. “It is a strong new indication that there was once an ocean here.”

Scientists have long suspected the presence of martian oceans in the past. One piece of evidence supporting the theory of a wetter martian past are features that closely resemble shorelines on Earth. According to some researchers, Mars may have actually had a large ocean during two seperate time periods. The first, around four billion years ago, and the second at around three billion years ago.