Free Astronomy Magazine January-February 2023

9 JANUARY-FEBRUARY 2023 ASTRO PUBLISHING the intracellular matrix. The information stored in DNA is only accessible because it can be uncoiled, read, repaired, and recombined in the fluid chemical environment within the water-filled cell. Liquid water, by the fact that it is not frozen into a crystalline lattice of ice, also provides the medium within which all of these small, biologically rele- vant molecules can come to be in close proximity and com- bine to make larger, biologi- cally relevant molecules. This is why the several recent dis- coveries of salty subsurface pockets of liquid water on Mars are specifically exciting to astrobiologists – simply ex- isting in a liquid form means chemical processes can be oc- curring that are otherwise im- possible in solid ice, even if the salt content and still ex- tremely cold temperatures significantly impact the rates and di- rections of those reactions. The book describing all we currently know about the chemistry of life and the transition from simple mol- ecules to the simplest organisms is dwarfed by the many volumes that could be written about those things S ample tube number 266 was used to collect the first sample of Martian rock by NASA’s Perseverance rover. The laser-etched serial number helps science team identify the tubes and their contents. [NASA/JPL-Caltech] we currently do not know about that same transition. It may come to pass that the books describing the things “we do not know that we do not know” may eventually be larger still. With all that said about the chemistry of life on Earth, we return to the issue of simple organic molecules on the sur- face of an ancient, frozen, and barren planet unpro- tected for billions of years from solar radiation of all wavelengths. The samples from Wildcat Ridge are unique among all previous finds on Mars because of the high concentration of organics detected by the SHERLOC (Scanning Habitable Environments with L eft, this sealed titanium sample tube contains Perseverance’s first cored sample of Mars rock. The rover’s Sampling and Caching System Camera (known as CacheCam) captured this image. Right, Perseverance’s first cored-rock sample of Mars rock is seen inside its titanium container tube in this image taken by the CacheCam. [NASA/JPL-Caltech]