Michael Rowe and Kathleen Campbell (University of Auckland) with collaborators (Universidad Nacional de La Plata, NASA Jet Propulsion Laboratory)
The possibility of life on Mars has fascinated lay people and scientists for decades. More than just a science fiction theme, knowing whether life exists or existed on the red planet will help us better understand life on our own.
In 2007, the Mars Exploration Rover Spirit detected opaline silica and sulfate-rich soils at Home Plate on Mars, which are like those from hydrothermal systems on Earth. On Earth, these systems host micro-organisms and develop living stromatolite structures.
With missions intended to return Home Plate to collect samples from this deposit, understanding the chemical relationship between living things and the silica sinter will be needed to understand if there are specific chemical signatures of life identifiable in these deposits.
Samples of sinter from Chile and New Zealand were collected from active hydrothermal systems and were analysed together with samples from ancient sinter deposits. The X-ray Fluorescence Microscopy (XFM) beamline was used to rapidly scan these large samples for chemical variability and representative metal signatures to identify signals associated with microbial filaments, the remains of living things.
The XFM scans highlighted biostructures present in sinter with enrichment of Ca, Ga, Fe and Mn in microbial filaments. This signature was found in both recent, modern sinter and in preserved sinter from the Jurassic Medeado Massif, revealing that geochemical signatures from these microbial filaments can survive tectonic activity for many millions of years.
Mars has had a very different geologic history to Earth. However, the discovery of preserved microbial filaments in sinter and their geochemical signatures, shows that deposits like that of Home Plate can preserve biostructures and signals. These signatures can survive through geologic time on a planet with a much more active geosphere than that of Mars. This opens the possibility that biosignatures from Martian samples would be detectable with current techniques.
Such a discovery would represent one of the most significant scientific milestones in Planetary Science, Geology and Biology since the acceptance of plate tectonics or evolution.
Reference:
Nersezova EE, Rowe MC, Campbell KA, Langendam A, Tollemache C, Lyon B, Galar A, Guido DM, Teece BL and Hamilton TL. 2024. Trace metal and organic biosignatures in digitate stromatolites from terrestrial siliceous hot spring deposits: Implications for the exploration of martian life. Chemical Geology 661(5). https://doi.org/10.1016/j.chemgeo.202422194
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