At orbital velocity, roughly 1/32 Atmosphere would cause any spacecraft
Ooops.
Well that's what happens when you use the rule of thumb of air pressure halving every 5.6Km.
In fact https://www.avs.org/AVS/files/c7/c7edaedb-95b2-438f-adfb-36de54f87b9e.pdf
Suggests its more like 72 millionths of a Psi.