Before revision: Instead of moisture and oxygen acting as the primary corrosion causes, the materials exposed to outer space are subjected to vacuum, bombardment by ultraviolet and X-rays, charged particles (mostly electrons and protons from solar wind), and electromagnetic radiation.
After revision: Instead of moisture and oxygen acting as the primary corrosion causes, the materials exposed to outer space are subjected to vacuum, bombardment by ultraviolet and X-rays, solar energetic particles (mostly electrons and protons from solar wind), and electromagnetic radiation.