So, what should happen to definitively confirm that these are real signs of previous life on Mars? NASA has a process in seven stages to determine if something can be confirmed as an extraterrestrial life. This is known as the cold scale, for the confidence of life detection. In this case, the detection of these spots on a Martian rock represented only the first of the seven stages. Among other stages, scientists must exclude any non -biological possibility and identify other signals to have confidence in life outside the world – solving the problem called “false positive”.
For example, “sulfur isotopes analyzes can be used to retrace the geochemical and biogeochemical pathways that have formed sulfate and sulphides,” wrote Janice Bishop (Seti Institute) and Mario Parente (University of Massachusetts Amherst) with a view to support. “Such analyzes would be necessary to determine whether the old microbes participated in the redox reactions which formed these minerals on Mars.”
Michael Wong, an astrobiologist at Carnegie Science who was not involved in research, told Ars that he appreciated the care of Hurowtiz et al. Not to have overlooked their conclusions and think they have shown a convincing case. Unlike biosignatures on distant exoplanets, he thinks that scientists can have confidence in March data. “We are against the rocks, we take specters of things with which we can get closer,” he said.
The delicate part lies in the interpretation of this data. “I think this is consistent with a potential biosigrance,” said Wong. “I would not be too excited, of course, because there could be interesting geological mechanisms to create these phenomena that we have not yet thought.”
The chemically reduced nodules of greenish materials containing mineral vivianitis are integrated into a matrix of red and oxid brown clay minerals. The more complex characteristics of “leopard spot” contain vivianitis with a mineral sulphide.
Credit: J. Hurowitz et al. 2025
Still cause of skepticism
That said: “I would like to know a little more about organic products and in what abundance,” said Wong. “If you can watch the distribution, for example, amino acids or lipids, these constituent elements of life, which can be a really important clue to know if it is really the life that was responsible here. Preferentially absorbs lighter isotopes than heavier isotopes.”
