Scientists have discovered that the organic molecules found in a martian meteorite were formed from interactions between water and the rocks from Mars itself about four billion years ago.
Don’t get too excited now – when we talk about organic molecules, we’re not exclusively talking about life on Mars, we’re actually talking about more formative compounds. This is mostly carbon and hydrogen, but often also includes oxygen, nitrogen, sulfur and other elements.
The meteorite is called Allan Hills (ALH) 84001 and is considered one of the oldest projectiles to reach Earth from the red planet. It was discovered in the Antarctic in 1984.
Now, after analysis, scientists have figured out what is behind the organic molecules found inside the Mars rock. It opens windows into how we might one day colonise Mars and shows how geochemical processes could have occurred in forming the Earth we know.
“Analysing the origin of the meteorite’s minerals can serve as a window to reveal both the geochemical processes occurring early in Earth’s history and Mars’ potential for habitability,” says Andrew Steele from Carnegie Science. He’s also a member of the science teams for both the Perseverance and Curiosity rovers.
Steele’s international team of researchers used a wide array of analysis techniques, including nanoscale imaging, isotopic analysis and spectroscopy. Using these methods, they were able to come to a conclusion over the organic molecules.
The organic molecules of the meteorite have been debated for years with many origins hypothesised. An idea put forward was that it was caused from volcanic activity. Another idea was an impact event on the Mars surface. A less likely origin was, of course, the possibility of ancient Martian life or contamination when crashing into Earth.
“These kinds of non-biological, geological reactions are responsible for a pool of organic carbon compounds from which life could have evolved and represent a background signal that must be taken into consideration when searching for evidence of past life on Mars,” Steele Added.
“Furthermore, if these reactions happened on ancient Mars, they must have happened on ancient Earth and could possibly explain the results we’ve seen from Saturn’s moon Enceladus as well.
Well, now we know that it was formed from water and Mars rocks coming into contact with each other some four billion years ago. Less climactic, sure, but it tells us some interesting things about Mars.
The evidence uncovered from the meteorite indicate similar interactions between water and rock to that which has been observed on Earth. The samples also demonstrated that Martian rocks go through two important geochemical processes.
The first is serpentinisation, when iron and magnesium-rich igneous rocks meet circulating water and produce hydrogen as a chemical reaction. What then happens is carbonisation, when carbonate minerals are formed from rocks and slightly acidic water including dissolved carbon dioxide.
“All that is required for this type of organic synthesis is for a brine that contains dissolved carbon dioxide to percolate through igneous rocks,” continued Steele.
“The search for life on Mars is not just an attempt to answer the question ‘are we alone?’ It also relates to early Earth environments and addresses the question of ‘where did we come from?’”
You can read up on Steele’s findings on the organic molecules from Mars in the journal Science.