James Van Allen, the nuclear physicist who discovered the belts of radiation encircling the Earth that now bear his name, died today at the age of 91.
In 1958, Van Allen designed instruments that were placed aboard Explorer I, the first American artificial satellite. These included a Geiger counter for detecting cosmic rays. Over South America, the Geiger counter registered 0 counts per second instead of the expected count of around 30. It was hypothesized that the counter was being overwhelmed by a belt of very strong radiation. The experiment continued with Explorer 3 (Explorer 2 having failed to make orbit) later the same year, and confirmed the hypothesis. The discovery of the Van Allen radiation belts is considered the first scientific discovery of the space age.
As a point of interest, Van Allen is thought by some "moon hoax" conspiracy theorists to have been part of the conspiracy, because he originally thought that the Van Allen radiation belts were too deep and too intense to be traversed successfully, but subsequently came to believe otherwise. (In typical moonbat fashion, of course, the assumption appears to be that no scientist would ever change his mind, and therefore his first statements must be the Really True one.)