Project Manhigh was an experimental program begun in December 1955 to study the behavior of a balloon in an environment above 99% of Earth's atmosphere and to investigate cosmic rays and their effects on human beings. Three balloon flights to the edge of space were made during the program:

 

• Manhigh 1 to 29,500 meters, by Captain Joseph Kittinger on 2 June 2 1957
• Manhigh 2 to 30,900 meters, by Major David Simons on 19-20 August 1957
• Manhigh 3 to 29,900 meters by Lieutenant Clifton McClure on 8 October 1958.

 

Including pilot and scientific equipment, the total mass of the Manhigh 2 gondola was 748 kilograms. At maximum altitude, the balloon expanded to a diameter of 60 meters with a volume of over 85,000 cubic meters.