Is there life on Mars?(4)

Spotting stromatolite-like layers in rocks will not, though, be enough on its own. Researchers will also need to consider the textures of the rocks concerned and the distribution within them of minerals and potentially telltale organic molecules. Confusingly, in chemistry-speak, an organic molecule is not necessarily of biological origin. The term just means that it is built around carbon atoms, so organic molecules can also originate inorganically, as it were. The biological nature of an organic molecule has thus to be justified by other evidence. As Kathryn Stack Morgan, a geologist who is the Perseverance mission’s deputy project scientist, observes, “This is exactly the type of thing that we do here on Earth to make a case for biosignatures in our own rock record, and for the very first time using our instruments we can do that on the surface of Mars.”