Stratospheric balloons

Humans had reached heights up to 6 miles before, and uncrewed balloons were used to reach greater heights. Piccard built a sealed aluminum gondola with a normal atmosphere and ascended to 10 miles to study the ionosphere and cosmic rays more intimately.
 Auguste Piccard Switzerland 1931 Stratospheric balloons

Humans had reached heights up to 6 miles before, and uncrewed balloons were used to reach greater heights. Piccard built a sealed aluminum gondola with a normal atmosphere and ascended to 10 miles to study the ionosphere and cosmic rays more intimately.