Mars’s Red Dust May Mark Ancient Wet Times, Not Just Desert Rust
A 2025 Nature Communications study argues Martian dust’s red color is largely ferrihydrite, an iron mineral that forms in cool, liquid water, linking Mars’s hue to a wetter past. By matching spectra from orbiters and rovers with lab mixtures of ferrihydrite and basalt, the authors show ferrihydrite could dominate the dust, implying extensive aqueous alteration and a planetary history of water even as Mars dried. The finding strengthens the habitability case but requires returned samples for confirmation and does not prove life.
