High-altitude balloon
These balloons are launched into what is termed "near space" , defined as the area of Earth's atmosphere between the Armstrong limit ( above sea level ) , where pressure falls to the point that a human being could not survive without a pressurised suit , and the Mesopause ( above sea level ) , where astrodynamics must take over from aerodynamics in order to maintain flight . 
<triplet> near space <subj> Earth's atmosphere <obj> part of <subj> Mesopause <obj> followed by