Low Earth orbits

Catalytic etching, 41 359, 383-384 definition, 41 360-361 in low earth orbit, 41 414—415 models, 41 359, 360-362 plasma etching, 41 407-414 thermally generated free radicals, 41 406-407... 

SC 1-5 Uncertainty in Risk Estimates SC 1-6 Basis for the Linearity Assumption SC 1-7 Information Needed to Make Radiation Protection Recommendations for Travel Beyond Low-Earth Orbit SC 9 Structural Shielding Design and Evaluation for Medical Use of X Rays and Gamma Rays of Energies Up to 10 MeV SC 46 Operational Radiation Safety... 

Surfaces of spacecraft in low earth orbits (200-600 km) often undergo damage (253, 254), the severity of which is a function of the type of material. Organic polymers and carbon surfaces are the most severely damaged and may even disappear altogether. Some metal films, such as osmium, are also known to disappear, whereas others, such as silver, are severely oxidized. Painted surfaces lose gloss and become pitted (255). 

Atomic oxygen is a highly reactive species that can pose serious problems for spacecraft in low Earth orbit due to degradation of materials of construction. In the case of siloxane elastomers and coatings88,89, it has been shown that surface oxidation occurs to give a silica layer which then protects the bulk material from further oxidation, with the result that little loss of physical properties occurs. 

Radiation Protection Guidance for Activities in Low-Earth Orbit... 

---