Microbes from Mars may have been able to live deep beneath the planet’s surface

Humanity is super excited about the idea of ​​finding signs of ancient life on Mars. So excited we keep sending more and more advanced machines, like NASA’s Perseverance rover, to look for evidence. A new study suggests we may need to investigate the matter further.

A research team led by Rutgers University planetary scientist Lujendra Ojha has been examining a puzzling problem when it comes to the habitability of Mars long ago: the weak young sun paradox.

The sun wasn’t always the lively ball of light and heat we know today. “About 4 billion years ago, the sun was much weaker, so the climate of early Mars should have been freezing cold,” Rutgers said in a statement Wednesday. This is a bit of a mystery because we also see a lot of water signs in Mars’ past.

Research in recent years has indicated liquid water long ago on the Martian surface and also the presence of wild animals megafloods.

If it were hot and humid, Mars could have been habitable for microbial life. But how do you get meltwater with a faint young sun? The paper by Ojha and his colleagues, published today in the journal Science Advances, addresses this problem.

“My co-authors and I propose that the feeble young sun paradox can be reconciled, at least in part, if Mars had high geothermal heat in the past,” Ojha said. This is a phenomenon observed on Earth where decaying elements produce heat that can melt ice sheets from below. If Mars had experienced similar conditions, this could explain liquid water despite the weak sun.

The study shows that ancient Mars would have been ripe for this type of warming 4 billion years ago, but the planet’s surface would not have remained very friendly to liquid water thanks to a thin atmosphere and ever colder temperatures. . “Therefore, life, if it ever originated on Mars, may have followed liquid water to progressively greater depths,” Rutgers said.

“At such depths, life could have been sustained by hydrothermal (warming) activity and water-rock reactions,” Ojha said. “So, the subsoil could represent the longest lived habitable environment on Mars.”

Our knowledge of Mars and its water ancestry has expanded rapidly. Recent studies have indicated hidden ponds of brackish water under the Martian polar ice.

Rovers will continue to scour the Martian surface for clues to ancient life, but someday we may want to peer deeper under the planet’s skin to fully understand its history of habitability.