Stromatolites are layered structures created by the trapping, binding, and/or precipitation of sedimentary particles by microbes. They are among the oldest known fossils, with the earliest known examples being the Dresser Formation located in the Pilbara region of Western Australia, dating back over 3.5 billion years. These ancient structures provide valuable clues about the early history of life on Earth and may hold key insights into the potential for finding life on other planets, such as Mars, based on a study published in the journal GeoScienceWorld Geology.
In recent years, there has been renewed interest in the search for evidence of life on Mars. This has been fueled, in part, by the discovery of stromatolites on Earth and the realization that these structures could potentially be found on other planets as well.
Mars Inhabitability
A report published by NASA explains that the search for life on Mars is challenging due to the planet's harsh environment. Mars has thin atmosphere, low temperatures, and intense radiation, all of which make it difficult for life to thrive. However, the discovery of stromatolites on Earth shows that life cannot only survive in these conditions but also thrive and flourish.
One of the key instruments used in the search for evidence of life on Mars is the Mars Science Laboratory (MSL), a rover that was launched in 2011 and has been exploring the Martian surface since then. The MSL is equipped with a range of scientific instruments, including a drill that can collect samples from the Martian surface and a spectrometer that can analyze the chemical composition of these samples.
On the other hand, following a study published in the Cambridge Core, the MSL mission has identified several potential sites on Mars where stromatolites could exist, including ancient lake beds and shallow marine environments. This provides new hope that stromatolites, and potentially other evidence of life, could be found on the red planet. Furthermore, due to recent weathering, the Dresser Formation stromatolites have been mostly replaced by hematite. While this makes organic geochemical investigations unfeasible, it is extremely important for the hunt for life on Mars.
Hand sample of Dresser Formation stromatolite, showing a complex layered structure formed of hematite, barite, and quartz, and a domed upper surface
ALSO READ: NASA's Perseverance Rover Finally Lands on Mars
Stromatolites Formation
The fact that the Dresser Formation stromatolites offer evidence of ancient life does not make them the planet's oldest life. That (possible) accolade might belong to stromatolites discovered in 3.7 billion-year-old Greenland rock or to microfossils discovered in Canada that could be as old as 4.29 billion years. However, because it is difficult to differentiate living organisms from non-organic phenomena in these very ancient rocks, these and other comparable results remain contentious.
London's Natural Museum paleontologist Keyron Hickman-Lewis believes that the techniques employed to investigate the Western Australian stromatolites might be valuable in the search for life on Mars, especially if Mars specimens can be returned to Earth.
Sedimentary rocks on Mars's surface have been exposed to comparable ubiquitous oxidation, and their top centimeters to meters are largely iron oxides. In this light, the Dresser Formation stromatolites may be particularly useful in informing us of the precise manner of biosignature preservation that may be predicted on Mars. As the Mars 2020 Perseverance rover explores the Jezero crater, we should look for morphological manifestations of life similar to those seen in the Dresser Formation and prepare for sophisticated multi-technique investigations when Martian samples are finally returned to Earth.
RELATED ARTICLE: NASA's Big Move to Search for Life on Mars - and to Bring Rocks Home
Check out more news and information on Space on Science Times.
