Combining stellar occultation observations probing Plutos atmosphere from 1988 to 2013 and models of energy balance between Plutos surface and atmosphere, we conclude that Plutos atmosphere does not collapse at any point in its 248-year orbit. The occultation results show an increasing atmospheric pressure with time in the current epoch, a trend present only in models with a high thermal inertia and a permanent N2 ice cap at Plutos north rotational pole.
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