Atomic Oxygen Erosion of Spacecraft Materials

Orbit & Material

Altitude 400 km

Ram-facing skin material

Mission clock speed 0.5 yr/s

Mission Readouts

Mission time

0.00 yr

AO flux

–

Fluence

Erosion depth

0.0 µm

Remaining thickness

100%

Mass lost

0.0%

How it works

In low Earth orbit, residual atomic oxygen (O) formed by UV photodissociation of O₂ slams into a ram-facing surface at ~7.8 km/s orbital speed — energetic enough to oxidize and chemically strip organic polymers one surface layer at a time. Recession depth follows the standard erosion-yield model used by NASA materials labs:

Fluence   F(t) = ∫ flux(h) dt        [atoms / cm²]
Depth     d = Ey · F                 [cm], Ey = erosion yield [cm³ / atom]
Flux(h)  ≈ F₀ · exp[-(h - 200 km) / H],  H ≈ 60 km scale height

Erosion yield Ey is a material property: reactive polymers like Kapton (~3.0×10⁻²⁴ cm³/atom) recede fast and visibly darken and pit; PTFE resists via a fluorocarbon surface; a silicone or SiO₂ coating suppresses Ey by roughly two orders of magnitude; bare aluminum barely erodes because its native Al₂O₃ oxide is already fully oxidized and self-protecting.

Altitude slider — sets the AO flux hitting the coupon via the exponential density falloff above; low orbits see far higher flux than high ones.
Material dropdown — swaps the erosion yield Ey and the coupon's visual response (color shift, pit density).
Mission clock speed — how many mission-years of exposure play out per real second, so multi-year degradation is visible in seconds.
Pits on the coupon face and the shrinking thickness bar both track the same depth number in the readouts — when remaining thickness hits 0% the coupon is flagged BREACHED.

Real-world relevance: this exact mechanism drove NASA to replace early uncoated Kapton multi-layer insulation with SiO₂- or silicone-coated variants after Shuttle and ISS blankets showed measurable AO thinning within months of exposure.

⚠ COUPON BREACHED

Atomic oxygen stream Remaining thickness

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