Mars may have had water a million years ago

Mars is thought to have had a watery past, but when exactly it transitioned to its dry and dusty present is up for debate. Now, though, a team of scientists studying the marks on a young Martian crater has found signs that waterlogged debris flowed down the Red Planet’s slopes surprisingly recently – within the last million years.

The findings, described in the journal Nature Communications, help to fill in an increasingly complex picture on the recent Martian water cycle and have implications for the possibility of life.

The team of European scientists looked at the mid-latitude Istok crater, which has so many well-defined gullies running down its steep sides that they overlap. Given that the crater is surprisingly young – 1 million years old at most – it means that whatever falling material carved these gullies was happening in the last million years.

But was the debris dry or wet? To find out, researchers used data from the HiRISE camera on NASA’s Mars Reconnaissance Orbiter to map out the gullies in three-dimensional detail and compared them with gullies carved on Earth.

They found that the debris flows likely would have had about 20 percent to 60 percent water content in them in order to carve the tracks that they did – and they did so frequently, with sudden slides happening every 10 to 100 years, said lead author Tjalling de Haas, an earth scientist at Utrecht University. That’s comparable with the rate of wet debris flows in dry areas on Earth.

“It’s a surprising result, but it’s really solid,” de Haas said. “It’s just what the evidence said.”

To make the tracks, the Istok crater would have to have been much wetter than previously expected for this time period, the researchers said.