Methane on Mars: a key to solving the planet’s ancient mysteries

The mystery of the disappearance of Mars' atmosphere could find a solution: up to 80% of the ancient atmosphere, composed of carbon dioxide, could have been transformed into methane and trapped in the clays of the Red Planet

Mars, millions of years in the past, was a very atmospheric planet, replete with a lot of water on its surface. Yes, you read that right. That dusty desert we observe today through telescopes was once much more like Earth. That glorious past now remains as some water trapped underground and an atmosphere reduced to less than 1% of Earth’s. The big question now is: where did the rest go?

For a long time, it was theorized by scientists that most of the atmosphere on Mars has simply escaped to space. However, new findings are offering a shocking theory: perhaps up to 80% of the ancient Martian atmosphere-whatever it was made of-mostly carbon dioxide-may not have been lost at all. Instead, it could be buried in rocks.

The atmosphere and methane: a seasonal mystery

Aside from the disappearance of its atmosphere, Mars poses another mystery: methane. The gas has long perplexed scientists, as it follows a seasonal pattern of appearing and disappearing, shifting with changes in temperature and pressure. Perhaps this methane is somehow related to the ancient atmosphere? A few billion years ago, some speculate, atmospheric carbon dioxide could have been able to go through a chemical reaction whose end product was methane being deposited into clay-rich rocks like smectite.

When Mars was covered by water-yes, it had oceans! -, minerals such as olivine oxidized and produced hydrogen. This hydrogen, upon contact with the carbon dioxide dissolved in the water, formed methane. Then this methane got captured by the clays of the planet; a process that still continues on Earth today. Calculations suggest that the huge amount of Martian clays may have trapped up to 80% of the ancient carbon dioxide.

In other words, much of the atmosphere of Mars could have been “preserved” as methane, sealed deep within the rocky layers of the planet.

Methane: a potential resource for human missions

And that puzzle of this latest research may well solve one of the biggest mysteries on Mars and simultaneously open up fresh opportunities. As Professor Oliver Jagoutz from MIT explained, methane can turn into a valuable resource for future human missions to Mars someday. Perhaps sometime, astronauts will find a way to convert this gas into energy, transforming what is now a scientific enigma into an indispensable way of survival for humans on the red planet.

Source: Science Advances – MIT