Swiss-Belgian physicist Auguste Piccard (1884-1953, right) and his assistant Paul Kipfer in the pressurised gondola designed by Piccard during training for its first flight. On 27th May 1931 the balloon and gondola carried the men to a record altitude of 15.781 metres, making them the first people to enter the stratosphere. In order to reach the stratosphere Piccard had designed the gondola to be airtight, with pressurised air inside, and used a very large balloon, that didn't require to be fully inflated for take-off. During the flight they were able to gather substantial data on the upper atmosphere and measure cosmic rays.