Does metal corrode or rust in space?

Essential knowledge for long-term spacecraft upkeep. 

5th September 2017
Does metal corrode or rust in space? (Getty)

Asked by: Brian Hope, Birmingham

Surprisingly, yes. Earth’s atmosphere still contains oxygen up to about 700km altitude (the ISS orbits at 400km). At that altitude, oxygen exists as single atoms, rather than O2 molecules, and it is more reactive. Aluminium and stainless steel form a protective oxide layer and won’t corrode, but silver and iron corrode quickly in low orbit. In deep space, however, the lack of oxygen means that corrosion does not occur. 

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