科学素养与现象阐释·英语30篇（6）
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Iron Oxide Surface Chemistry: Why Mars Exhibits a Predominantly Red Hue
氧化铁表面化学：为什么火星呈现红色
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Mars’ surface is extensively covered by fine-grained regolith rich in nanophase iron oxides, particularly hematite and nanophase maghemite.
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These minerals form through billions of years of oxidative weathering driven by solar UV radiation and trace atmospheric oxidants.
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Unlike Earth, Mars lacks plate tectonics and liquid water circulation, so oxidation proceeds slowly but pervasively across exposed surfaces.
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Spectroscopic data from orbiters like Mars Express confirm strong absorption features near 860 nm, characteristic of Fe³⁺ in crystalline oxides.
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Dust storms lift and redistribute this oxidized material globally, creating the planet’s uniform reddish appearance from space.
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The red hue intensifies under low-angle sunlight due to Mie scattering from submicron particles suspended in the thin atmosphere.
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Laboratory simulations replicate the spectral signature using irradiated olivine and pyroxene under Mars-like conditions.
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Surface missions have detected perchlorates that accelerate iron oxidation even at subzero temperatures and low humidity.
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While some regions show bluer or greyer tones—indicating fresher, less-oxidized basalt—red dominates over 90% of observable terrain.
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This coloration is not pigment-based but emerges from mineralogical composition, grain size, and radiative transfer physics.
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Long-term climate modeling links current oxidation rates to past aqueous episodes and episodic brine activity.
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Thus, Mars’ redness encodes a multi-billion-year record of surface-atmosphere redox evolution.