Did the Space Shuttle crew have to worry about monatomic oxygen?

Question

Comments below this answer tell us that the Space Shuttle always remained in Earth's atmosphere. When it visited the Hubble Space Telescope or the ISS or Mir it was still in the thermosphere and simultaneously the ionosphere.

Above the turbopause the oxygen component of Earth's atmosphere changes from diatomic (O2) to monatomic (O), while nitrogen remains mostly diatomic. The most noticeable effect of this is the "knee" at about 100 km altitude where the scale height doubles, i.e. the exponential rate that the density decreases with height drops to about half, i.e. the scale hight increases significantly, because O is lighter than O2.

• Why does Earth's atmospheric density have a big "knee" around 100 km? Is there a good analytical approximation?

Believe it or not, monatomic oxygen is the primary constituent of the atmosphere between about 175 and 450 km!.

Monatomic oxygen is a drag.

Of course the crew of any spacecraft in LEO will need to understand the impact of atmospheric drag since it has a continuous and significant effect on orbit altitude and phasing, and spacecraft attitude and tilt of solar panels can have a significant impact on that.

• How are the orientations of the ISS' eight independent solar arrays optimized?

Question: But what (if anything) were crew taught about monatomic oxygen and its interaction with the Space Shuttle besides the increased drag? Did they have to worry about spacecraft erosion due to the chemical activity? On long missions it "eats" spacecraft parts, especially things like plastics, organics, things that can oxidize and will suffer from it. Were there any materials on the outside of the shuttle, or of space suits, or of any other equipment or items used that were vulnerable to monatomic oxygen such that the crew needed to be aware of it?

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See Why does Earth's atmospheric density have a big "knee" around 100 km? Is there a good analytical approximation? and U.S. Standard Atmosphere 1976

note: the three thin lines are simple scale-height plots with $h_{scale}$ of 6.5, 7, and 7.5 km, bottom to top, just for reference.

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Volume fraction of the main constituents of the Earth's atmosphere as a function of height, based on the MSIS-E-90 atmospheric model.

Source

Answer 1

Obviously, @Digger can provide a first-hand crew experience answer, but in general no.

Atomic oxygen (commonly called just AO) is a designer's problem that manifests primarily in the restriction of materials that are used on the exterior of the vehicle. This is a much bigger deal on ISS than it was on Shuttle. In general the erosion rate for most spacecraft polymers is measured on the order of tens of microns per year at ISS orbit altitude. Interestingly, silver erodes at a rate one to two orders of magnitude higher than, e.g., Kapton. This is why you never see silver or silver-plated materials directly exposed to the space environment in LEO.

Put another way -- for AO to become a crew concern would imply a serious, fundamental engineering failure in the design of the spacecraft they're in.