Planetary Science: Revisiting Mars’ Red Hue

A recent study published in Nature Communications challenges the long-held belief that Mars’ red color is due to the presence of hematite, a form of iron oxide that forms under dry conditions. The research suggests that the planet’s distinctive hue is instead due to ferrihydrite, another form of iron oxide that requires water to form. Led by Adam Valantinas, researchers from Brown University and the University of Bern utilized data from the European Space Agency (ESA) and NASA, along with advanced laboratory experiments, to recreate Martian dust. Their findings indicate that ferrihydrite mixed with basalt more accurately matches the mineral composition observed on Mars. This discovery implies that Mars had a wetter and colder past, as ferrihydrite forms rapidly in cool water. The findings challenge the previous assumption that Mars’ red dust formed under dry conditions. Future missions, including samples collected by NASA’s Perseverance rover, will help to further confirm these findings and advance our understanding of Mars’ history.