Project Stargazer was an early balloon-borne project to carry out astronomical studies at very high altitude. It involved only one flight. On December 13–14, 1962, Joseph Kittinger and William White, an astronomer, flew a gondola suspended beneath an 85-meter-diameter Mylar balloon to a height of 25,000 meters over New Mexico. In addition to obtaining telescopic observations from above 95% of Earth's atmosphere, the flight provided valuable data for the development of pressure suits and associated life support systems during a 13-hour stay at the edge of space.
The balloon that supported the Stargazer capsule was a 280-foot diameter sphere of Mylar film; however, at launch only a comparatively small bubble of helium gas occupied the top of the balloon with the remainder of the balloon envelope dangling beneath. As the balloon rose, the gas expanded, filling the balloon until at maximum altitude, it was completely filled and reshaped the envelope into a sphere. The gondola was supported below the balloon on a cable giving a total height at takeoff of approximately 400 feet.