Just to get this out before it spirals into anything else—no, it’s not alive, and it likely doesn’t count as NASA’s long-sought-after evidence of life on the Red Planet, whether current or past. Despite these, however, this landmark discovery by NASA’s Curiosity rover makes a splash in the community, as these organic molecules hadn’t been found on Mars before. The NASA research team was led by Goddard Space Flight Center and Georgetown University astrobiologist Maëva Millan, and their study was published in the journal Nature Astronomy.
In truth, the study had been in progress for quite a while; Curiosity, the Mars rover that arrived on the Martian surface back in 2012, had actually detected these molecules from odd rock samples it managed to collect from a rock drilling mishap it experienced back in 2016. The rover had been drilling into rock at the base of Mt. Sharp (Aeolis Mons), a Martian mountain that forms the central peak of Gale Crater. (To note, Curiosity itself actually landed pretty close to the base of the mountain back in 2012, and had designated Mt. Sharp as its primary science target.)
Curiosity was supposed to grind up rock samples for analysis back in 2016. Problem is, the drill got stuck, and the scientists back on Earth were unable to process the rocks obtained further by drilling. Instead of stopping, though, the team decided to instead pass some Martian sand collected from an area called Ogunquit Beach through the rover’s on-board Sample Analysis at Mars (SAM) Wet Chemistry Experiment instrumentation.
SAM was designed to identify the composition of items placed inside its chamber. Thing is, it does this analysis mainly by heating the samples obtained. Heating the rocks would immediately destroy any organic molecules it may have locked within; to address this concern, NASA also included a secondary option which included the use of solvents to first dissolve the organic compounds, then pass them through an apparatus, in a process known as gas chromatography.
Thing is, SAM only carried with it nine cups of solvent, a liquid needed to let reactive components that would be otherwise sensitive to heat—like organic molecules—be detected first before any damage can be made. Each solvent can only be used once, meaning the Curiosity team had limited resources to work with in their experimentation.
It was the application of solvent that led Curiosity to its discovery of organic compounds like ammonia (NH3) and benzoic acid (C6H5CO2H), with some of these compounds having never been identified on Mars before.
Said Millan: “This derivatization experiment on Mars has expanded the inventory of molecules present in Martian samples and demonstrated a powerful tool to further enable the search for polar organic molecules of biotic or prebiotic relevance.”
The findings may not be the tantalizing evidence of extraterrestrial life that we’ve been looking for—far from it—but it does present a tantalizing opportunity for the Curiosity rover to examine for more biosignatures and chemical oddities even if the drill is broken.
It would take the NASA team another year before they could fix the drill; NASA, on the other hand, is planning a mission to Mars in the 2030s to possibly retrieve the samples laid out by the Curiosity rover.
Alongside the Curiosity rover is its younger sibling, the Perseverance rover. “Percy” has been the star of various updates in the sciences as of late, which included the new rover obtaining the first “pristine” Martian rock, as well as Percy giving the team reason to believe that Jezero Crater was once flooded.
References
- Cassella, C. (2021, November 5). Nasa rover has found previously unknown organic molecules on mars. ScienceAlert. https://www.sciencealert.com/curiosity-finds-new-organic-molecules-on-mars-in-an-unexpected-place
- Millan, M., Teinturier, S., Malespin, C. A., Bonnet, J. Y., Buch, A., Dworkin, J. P., Eigenbrode, J. L., Freissinet, C., Glavin, D. P., Navarro-González, R., Srivastava, A., Stern, J. C., Sutter, B., Szopa, C., Williams, A. J., Williams, R. H., Wong, G. M., Johnson, S. S., & Mahaffy, P. R. (2021). Organic molecules revealed in Mars’s Bagnold Dunes by Curiosity’s derivatization experiment. Nature Astronomy, 1–12. https://doi.org/10.1038/s41550-021-01507-9
