Life On Mars? New Study Reveals That Red Planet Was Likely Habitable Precisely Where NASA’s Rover Is Now Searching

Microbes could have existed on ancient Mars and one of the best places to look for it is precisely where NASA’s Perseverance Rover is right now.

It’s been thought for some time that the red planet potentially had favourable conditions for the development of life for at least part of its history. However, a new paper published in Nature Astronomy today attempts to quantify this by modelling the interaction between the likely environment on early Mars and an ecosystem of methane-producing microorganisms.

These microorganisms are referred to as methanogenic hydrogenotrophs because they consume hydrogen and produce methane. Such microorganism are thought to be among the earliest forms of life on Earth.

The authors go further by predicting that the total biomass of these microorganisms could have been similar to that of the early ocean on Earth.

However, they also predict that the very existence of these microorganisms on Mars may have made the planet itself less habitable. That’s because the model presumes that the microorganisms lived within the Martian crust. Their existence would have triggered a feedback event, say the authors, cooling the Martian atmosphere by up to 40° Kelvin closer to the surface. This would have probably driven the microrganisms deeper within the planet’s crust.

Tantalisingly, the authors also identify three regions of Mars as the best places to look for traces of these early microorganisms. One of them is Jezero Crater, where NASA’s Perseverance Rover has been since February 2021 after its 314 million miles journey.

About 28 miles/45 kilometers-wide, Jezero Crater is thought to be a four billion-year-old river delta that may have once hosted a lake as large as Lake Tahoe more than 3.5 billion years ago. It was chosen as Perseverance’s landing location because it’s a promising place to find organic molecules and other potential signs of microbial life.

There’s no water there today, but it’s possible that ancient rivers flowing in and out of Jezero Crater carried organic molecules and possibly even microorganisms. The region is known to contain some of the oldest and most scientifically interesting landscapes on Mars, but it’s also home to clay, which could contain preserved traces of life.

Jezero Crater is on the western side of Isidis Planitia, a giant impact basin just north of the Martian equator that the authors also identified as being an ideal location to search for biosignatures of microorganism on Mars.

Perseverance’s core mission at Jezero Crater is to search for traces of ancient life on Mars. It’s analyzing rock and sediment samples to see if Mars may have had conditions for microorganisms to thrive—exactly as this paper predicts. It’s drilling a few centimeters into Mars to take core samples and putting the most promising into containers, leaving them on the Martian surface.

In August 2022 it was confirmed that some of the rock samples it’s already collected from the crater’s floor appear to have been geochemically altered by liquid water.

Could Perseverance detect the first evidence of the existence of life beyond Earth? It’s possible, but Perseverance is the largest, heaviest, most sophisticated rover ever sent to the Red Planet for a reason. Verifying ancient microscopic life on Mars carries an enormous burden of proof.

Despite its payload, only laboratories back on Earth would be able to prove definitively that Perseverance finds evidence of past life on Mars.

Cue the Mars Sample Return mission, which will see Perseverance deliver its cache of rock samples to a lander equipped with a rocket. This first-ever return trip to Mars in 2027 that will bring these very rock samples back to Earth in 2033 for study by astrobiologists.

Wishing you clear skies and wide eyes.