'Iron oxide containing water': Scientists discover the real reason behind Mars' reddish appearance
Produced by Tarun Mishra
Produced by Tarun Mishra
New research challenges the long-held belief that Mars' red colour emerged under dry conditions. The study suggests that the planet’s signature hue is due to ferrihydrite, an iron oxide containing water, which formed when Mars was a cool and wet world.
Earlier theories linked Mars' red colour to hematite, an iron oxide that forms in arid environments. The new findings, published in Nature Communications, indicate that the red dust likely originated in Mars' wetter past.
Researchers analysed data from ESA's Mars Express and Trace Gas Orbiter, as well as NASA's Mars Reconnaissance Orbiter. Additional data from NASA’s Curiosity, Pathfinder, and Opportunity rovers helped build a detailed picture of Mars’ mineral composition.
Scientists recreated Martian dust in a laboratory using a grinding machine to match the dust’s fine grain size. Their analysis confirmed that ferrihydrite, rather than hematite, is a better match for Mars’ red dust.
Ferrihydrite forms quickly in cold, wet, and oxidising conditions. This implies that Mars experienced periods of liquid water and active chemistry before transitioning to its current dry state, refining the timeline of its potential habitability.
The presence of ferrihydrite indicates that Mars may have had environments suitable for microbial life. The study raises new questions about the planet’s past habitability and the conditions that shaped its surface.
ESA’s Rosalind Franklin rover and the NASA-ESA Mars Sample Return mission are expected to offer more insights. Samples collected by NASA’s Perseverance rover, including dust, will be analysed on Earth to further investigate Mars’ red hue and its history with water.
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