About the Author Slides from the Lecture Presidential Lecture 1992 - James A. Van Allen

Figure 2. The scientific payload and its two part protective shield of the first successfully launched American satellite (31January 1958). Note the one-foot ruler for scale. The centrally located cylindrical object about one inch in diameter and six inches long is the Geiger-Mueller tube whose output revealed the existence of the inner radiation belt of the Earth. The radiation detection system was developed and built at the University of Iowa.


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