Mars Rover to Test for 'Handedness' of Organic Molecules

For decades, Martian exploration has confirmed the presence of organic molecules across the Red Planet. However, simply finding carbon-based compounds does not equate to discovering life, as non-biological geological processes can also produce them. A critical differentiator, however, is chirality, a property describing the spatial orientation of molecules, often referred to as "handedness."

Organic molecules with chirality can exist in two mirror-image forms, much like a left and right hand. Abiotic processes typically create these forms in roughly equal proportions, resulting in a racemic mixture. In stark contrast, life on Earth exhibits a strong preference for specific chiral forms – for instance, using exclusively left-handed amino acids and right-handed sugars. The detection of a significant imbalance in one handedness of organic molecules on Mars would therefore serve as strong evidence for biological activity.

While previous Mars missions, like Curiosity, possessed chirality-measuring capabilities, they were limited by the complexity and integrity of the organic molecules encountered. The Rosalind Franklin rover, slated for a 2030s launch, will carry the highly sensitive Mars Organic Molecule Analyzer (MOMA) instrument, designed to overcome these limitations and perform on-site analysis without the need for sample return.

Recently, a specialized version of the MOMA instrument underwent a rigorous test using the Murchison meteorite. Researchers aimed to detect pristane and phytane, compounds found in petroleum and stable degradation products of chlorophyll. Their findings revealed a racemic mixture, suggesting the meteorite may have acquired these molecules from Earth's fossil fuels during atmospheric entry, rather than from extraterrestrial biological sources. Nevertheless, this test successfully demonstrated MOMA's advanced capability to analyze chiral organic molecules.