Answer the following question given this paragraph: 

Not so fast. The mesosphere is the least known layer of the atmosphere. The mesosphere lies above the highest altitude an airplane can go. It lies below the lowest altitude a spacecraft can orbit. Maybe that's just as well. If you were in the mesosphere without a space suit, your blood would boil! This is because the pressure is so low that liquids would boil at normal body temperature.


Q: What atmospheric layer lies above the highest altitude an airplane can go and below the lowest altitude a spacecraft can orbit?


A:
mesosphere