Based on my previous reading, I was under the impression that the atmosphere would be negligible until the perigee dipped much lower than the initial orbit. (Ob

Based on my previous reading, I was under the impression that the atmosphere would be negligible until the perigee dipped much lower than the initial orbit. (Obviously, if you keep lowering the perigee then eventually it becomes important.) That's consistent with your second quote, but your first quote suggests I was wrong and the atmospheric effects are detectable even now. Thanks for the correction.