GS Paper - III

Mars today is a cold and barren desert, but this was not always the case. Increasingly, new evidence suggests that water flowed on the Martian surface once upon a time. This means that a thick atmosphere would have had to envelope the planet, to keep this water from freezing.

What

• Then, some 3.5 billion years ago, the water dried up as the carbon dioxide-rich atmosphere dramatically thinned.
• Just why this happened is the central question for scientists seeking to understand the history of the Red Planet.
• A new study published in the journal Science Advances on 24 September 2024 might have some answers to this question.
• Geologists Joshua Murray and Oliver Jagoutz from the Massachussets Institute of Technology suggest that the water trickled through certain rock types on the Martian surface, and set off a slow chain of reactions that progressively drew carbon dioxide out of the planet’s atmosphere and converted it into methane.
• Methane is a form of carbon that can theoretically be stored for aeons on the Red Planet’s clay surface.

Trapped in folds

• The two geologists formulated this theory based on their research on Earth. In 2023, they were working on a type of clay material known as smectite, which is known to be a highly effective carbon trap.
• Grains of smectite each comprise a number of folds, within which carbon can sit for billions of years.
• The MIT researchers found that if left exposed to the atmosphere on Earth, smectite can draw and store atmospheric carbon dioxide over millions of years, enough to cool down the planet.
• Soon after this finding, Jagoutz happened to look at a magnified map of the Martian surface, and found the same smectite clay he was studying.
• Except, he was not sure how it got there. On Earth, smectite is a product of tectonic activity, but it is well-established that Mars does not see such activity.

Role of water

• The two scientists thus began to research alternative ways in which smectite could have formed.
• The answer to this question lies in how Martian water reacted with olivine, a ferrous rock known to be abundant on the planet’s surface.
• Using available data on the existence of olivine and the presence of water, as the existence of a thick CO2-heavy atmosphere, the scientists came up with a computer model to simulate how the three would react with each other, over a billion years.
• They found that in this vast time frame, oxygen atoms in water would slowly have bound to the iron in the olivine (this is also what gives the planet its red colour), freeing the hydrogen which would then have combined with the carbon dioxide to form methane.
• Over time, the reaction with water would lead the olivine to turn into smectite which, in turn, absorbed the methane.
• This knowledge has utility beyond scientists and researchers. With humanity looking to send missions, and perhaps eventually colonise the Red Planet, methane trapped in the Martian surface can potentially be an invaluable resource.
• This methane may even be used as an energy source on Mars in the future, the researchers suggest.