On November 11, 1935 35,000-40,000 people gathered to watch Explorer II, a helium-filled balloon, launch from the Stratobowl, as reported by South Dakota Public Broadcasting. Explorer II was an improvement of the previously launched Explorer I, which was a hydrogen-filled balloon launched in 1934.
Explorer II reached a height of nearly 14 miles, which was nearly three miles higher than Explorer I’s top height and set a 21-year altitude record. During the flight, information on high-altitude atmospheric conditions was gathered and photos which revealed the curvature of the earth were captured for the first time.
To learn more about the 1930s balloon launches from the Stratobowl, visit the Black Hills Knowledge Network resource page. For historical photos and documents of the Stratobowl, visit the Black Hills Knowledge Network's digital archive.