November 27, 2021

I, Science

The science magazine of Imperial College

What do organic materials detected by the Mars rover reveal about the potential for ancient life on the Red Planet?

mars imageNASA’s Curiosity rover recently discovered a ‘methane spike’ in the Martian atmosphere and organic materials after drilling in a rock named Cumberland in the resource-laden Gale Crater.

On November 26, 2011, Curiosity was dispatched to Gale Crater on Mars, which scientists believe was once a lake billions of years ago. The rover was dispatched to this region specifically because of the composition of the rocks, which likely preserved any deposited organic materials, molecules composed of carbon chains. While these molecules are considered the chemical building blocks of terrestrial life, they can form from non-biological processes.

As Professor Roger Summons of the Massachusetts Institute of Technology notes, “Organics are important because they can tell us about the chemical pathways by which they were formed and preserved. In turn, this is informative about Earth-Mars differences and whether or not particular environments represented by Gale Crater sedimentary rocks were more or less favorable for accumulation of organic materials.”

During the span of 20-months, Curiosity’s Sample Analysis at Mars (SAM) laboratory observed a two-month spike of methane in Mars’ atmosphere. This spike represented a dramatic increase, with readings roughly ten times the average of the other measurements.

According to the University of Michigan’s Sushil Atreya, “This temporary increase in methane – sharply up and then back down – tells us there must be some relatively localized source. There are many possible sources, biological or non-biological, such as interaction of water and rock.”

Along with discovering methane in the Martian atmosphere, Curiosity also detected organic materials in Cumberland. Scientists were initially unsure of the molecules discovered in Cumberland. It was found that some of the detected samples were actually transported from Earth to Mars by the rover itself. John Grotzinger of the California Institute of Technology and Mars Science Research Laboratory expressed less concern after further testing. “At the time we first saw evidence of these organic molecules in the Cumberland sample it was uncertain if they were derived from Mars; however, additional drilling has not produced the same compounds as might be predicted for contamination, indicating that the carbon in the detected organic molecules is very likely of Martian origin.”

Curiosity’s findings are a crucial piece in determining the habitability of ancient Mars. It is unknown whether these organic molecules formed through biological or non-biological processes, though the findings are indicative of potentially habitable conditions billions of years ago. “The challenge now,” Summons says, “is to find other rocks on Mount Sharp that might have different and more extensive inventories of organic compounds.” Curiosity will further pursue its mission on the Gale Crater by collecting data from a crystal-rich rock dubbed ‘Mojave’.

Image: Wikimedia commons