NASA’s Mars Perseverance rover mission might just have found a strong evidence of the presence of microbial life on the planet. The scans of some rocks in an ancient river -bed showed the present of small nodules and reaction fronts which are rich in minerals that might have formed due to chemical reactions catalyzed by microorganisms.
Where did they found the evidence ?
The perseverance rover had landed on the top of Jezero Crater’s rim. Jezero Crater was once flooded with water and fed by rivers that now have dried up. The valleys created by these rivers still remain. Near one of such river-beds there is a rock, named as “Cheyava Falls” . Instruments on the Perseverance have found that the rock contains organic molecules.
The photographs of the rock showed that there are small dots on them which appear to be formed due reactions catalyzed by microorganisms. The reaction fronts may be caused by dispersion of the catalyzing agents spreading around the centre where the microbes were situated. I am avoiding the use of the term “enzyme” here, because we am not sure what actually have caused the reaction fronts.
What are the nodule and reaction fronts made of ?
PIXL, the X-ray lithochemistry instrument on the Perseverance found that the nodules are enriched in iron, phosphorous, and zinc elements as compared to the surround rock parts.
PIXL identifies the elements by focusing X-rays on the rock surface. It also collects back the reflected light from the rock. Certain elements will reflect back a different wavelength of light, a phenomenon called fluorescence. Specific elements would emit specific wavelength of light, which makes the instrument identify them.
From the properties of the nodules the scientists have determined that the nodules contain iron phosphate minerals; vivianite, metavivianite, ferrostrunzite, phosphoferrite, and santabarbaraite.
The spots observed in Cheyava Falls rock do not appear to have been deposited as grains. The reactions fronts are probably enriched in sulphur, iron, nickel and zinc.
Why they are so important?
The nodules in the rocks could have been formed due to biological reactions. The minerals enriched in the nodules indicate a reduction reaction of iron and sulphate which could have yielded small amounts of energy for the microorganisms. If confirmed, this would be our first confirmation of an extraterrestrial life. If life could originate on two nearby planets, then it is likely that a lot more of other planets than previously thought might be harbouring life in some form.
Did microbes really produce those spots?
The researchers also proposed another mechanism by which these nodules could have been formed. However, those types of reactions require high temperatures of 150 to 200 degree Celsius. No evidence of anything reaching those temperatures is found yet.
Mars is far away, and we have limited technology available to analyze samples there. Until we have another mission that would bring back the samples back to earth, we have to wait for detailed analysis. Or, may be the Perseverance would find some other, more clearer evidence, of what actually formed those spots on the martian rock while it is still exploring the area.
Reference: Hurowitz, J.A., Tice, M.M., Allwood, A.C. et al. Redox-driven mineral and organic associations in Jezero Crater, Mars. Nature 645, 332–340 (2025).