NASA’s Curiosity rover has detected a diverse mix of organic molecules on Mars, including chemicals widely considered building blocks for the origin of life on Earth. The finding marks the first time a new kind of chemical experiment has been performed on another planet.
Curiosity rover has been dutifully probing Mars’ Gale crater and Mount Sharp since the robot plopped down on the Red Planet on Aug. 6, 2012. The car-sized Mars rover is now wheeling about in the Glen Torridon region of Gale crater, a place that scientists believe could have supported conditions that were favorable to supporting ancient life, if it was ever there in the first place.
While in the region, Curiosity recently utilized its onboard Sample Analysis at Mars (SAM) instrument suite, built to search for compounds of the element carbon that are associated with life and investigate ways in which these compounds are generated and destroyed in the Martian ecosphere.
Curiosity’s SAM instrument was able to use a chemical known as tetramethylammonium hydroxide (TMAH) to detect organic molecules in the region’s clay-rich sandstone. After years of lab work, the results are in: A rock that NASA’s Curiosity Mars rover drilled and analyzed in 2020 includes the most diverse organic molecules ever detected on Mars.
Confirmed molecules include methyl benzoate, dihydronaphthalene, naphthalene, benzothiophene, and methylnaphthalene. These molecules were liberated by the onboard tetramethylammonium hydroxide wet chemistry experiment. Diverse thermochemolysis products, including benzothiophene, methyl benzoate, and single and dicyclic aromatic molecules were released and detected by evolved gas analysis and gas chromatography-mass spectrometry.
Results indicate the experiment successfully released molecules preserved in ancient macromolecular or free organic matter within Martian bedrock despite ~3.5 billion years of diagenesis and radiation exposure. The discovery adds to the growing evidence that Mars once had the right conditions to support life, though scientists remain uncertain about how these organics got there or whether they are of biological origin.
