New research suggests that Mars was once not only a perfect holiday destination (if you’re willing to overlook the radiation exposure and absence of food sources) – but also had the right conditions for alien life. Why? The discovery of ancient sandy beaches on the Red Planet suggests that a large liquid ocean once spread over the northern part of the planet.
The research team behind the study, from China and the US, say that this ancient shoreline is the clearest evidence yet that the red planet was previously habitable.
“When we look back at where the earliest life on Earth developed, it was in the interaction between oceans and land, so this is painting a picture of ancient habitable environments capable of harbouring conditions friendly toward microbial life,” said Benjamin Cardenas, assistant professor of geology at Pennsylvania State University, in the US, and co-author on the study.
Four billion years ago, these beaches would have been the best kind: sun-soaked and sandy with softly lapping waves.
“We found evidence for wind, waves, no shortage of sand – a proper, vacation-style beach,” said Cardenas, whose study was published in the Proceedings of the National Academy of Sciences (PNAS).
To find this out, the researchers used the China National Space Administration’s Zhurong rover to probe up to 80m (260ft) below the Martian surface, in an area of northern Mars called the Utopia plain, using radar imaging.
At 10–35m (33–115ft) deep, they discovered 76 hidden structures. Sadly, this didn’t turn out to be a mysterious alien infrastructure (we can dream), but rather sedimentary deposits resembling those found around Earth’s coastlines.
The structure, thickness and length of the Martian deposits indicated that they were not formed by rivers, wind, lava or ice melting, but rather by a stable ancient ocean. In fact, they were almost identical to those in 21 locations on Earth, including the Bay of Bengal.
Specifically, the formations, called ‘foreshore deposits’, slope down towards the ocean at a 15° angle and are formed by tides and winds carrying sediments like sand and gravel.
“This stood out to us immediately because it suggests there were waves, which means there was a dynamic interface of air and water,” Cardenas said. This interaction, which also happened in Earth’s early history, is important for the beginnings of life.
The discovery suggests that, for tens of millions of years, Mars had a warm and wet climate.
“We tend to think about Mars as just a static snapshot of a planet, but it was evolving. Rivers were flowing, sediment was moving, and land was being built and eroded,” said Cardenas.
“This type of sedimentary geology can tell us what the landscape looked like, how they evolved, and, importantly, help us identify where we would want to look for past life.”
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