Free Astronomy Magazine January-February 2023

11 JANUARY-FEBRUARY 2023 ASTRO PUBLISHING T his annotated map shows the locations where NASA’s Persever- ance Mars rover collected its first witness tube and filled its first six samples. The name that the Perse- verance science and op- erations teams used to define a rock target on the Martian surface ap- pears at the top of each inset image. Also indi- cated is the Martian day, or sol, of the rover’s mis- sion and whether the image shows a target that has been abraded for proximity science or from which a core sam- ple was taken. Before collecting a sample, Per- severance uses its drill to abrade the upper few millimeters of the rock surface close to the in- tended coring target. Those inset images anno- tated with the word “abrade” were captured by the rover’s WATSON imager. Those with “core” were taken by the rover’s CacheCam, which visually inspects a sample tube after a coring event takes place. [NASA/JPL-Caltech/ASU/MSSS] no relevance to life whatsoever. This is certainly one of the key reasons why astrobiologists are eager for sample return missions from Mars, enabling us to subject every mole- cule within a given sample to the complete array of spectroscopic tools science has to offer to deter- mine exactly what, how much, and how complex each unique chemical species might be. If all goes well, the NASA Mars Sample Return mission hopes to make this eager need a re- ality as early as 2033. The irrefutable discovery of life any- where else in the solar system, be it extant or extinct, would be the most important discovery in human his- tory – rivaled only by the discovery that some organism or some species much more intelligent was attempt- ing to contact humanity. Further- more, this greatest discovery in our own stellar backyard need not be complex, intelligent life – “simple, stupid life” would be just as revolu- tionary. With this first discovery, we would go from being the only planet we know of on which life arose, to being the second planet in our own solar system to also qualify, dramatically changing the percep- tion we have about the uniqueness of life in the universe. If this discov- ered life were found to share the same means of genetic information storage (DNA) and retrieval (pro- teins), we would then have to have the further debate over whether “these seem to be the molecules that, under the conditions of our solar system formation, became the means to life” or “such a similarity almost necessitates that it all started on one planet and found its way to the other.” That all said, organic molecules are virtually everywhere we look and exist in abundance in locations, such as Titan, that we suspect are inca- pable of substantiating, much less sustaining, life as we know it. The leaps from simple organic molecules to complex macromolecules to en- capsulated macromolecules in sim- ple cell-like structures to whatever the first unicellular organisms might have been are wider than the 3,000 km wide Valles Marineris – the solar system’s largest canyon – also on Mars. We’ve little more than strong chemical identifiers for simple or- ganic molecules in limited collected samples and our own understanding of how and where life has existed here on Earth to guide our search for hard evidence for or against life, or even chemical complexity hinting at biological process, on Mars. !