Explorer 2

Explorer 2 was the second spacecraft of the Explorer program, which was the first and most comprehensive program of satellites and space probes of the United States. The flight was to be a repeat of the successful mission of Explorer 1 essentially. However, the fourth stage of the Juno I launch vehicle did not ignite, so that the satellite failed to reach orbit.

Explorer 2 was equipped with, among other things, to measure cosmic rays with a Geiger counter, and an apparatus for detecting micro- meteorites.