Pressure inside the 2,300 m³ enclosure was raised to a few dozen pascals above atmospheric pressure, then lowered in the same proportion like in a breathing exercise.
The cocoon's synthetic skin passed the test, which guarantees that no leak or uncontrolled air intake, however small, will alter the quality of the atmosphere inside the structure.
In order to protect the lower cylinder from mould or corrosion, the air inside the cocoon will be kept circulating and maintained at a constant 38 percent humidity.