A Transistor Museum Interview

with Dr. George Ludwig

The First Transistors in Space - Personal Reflections by the Designer of the Cosmic Ray Instrumentation Package for the Explorer I Satellite


Curator’s Introduction

Explorer I, the first U.S. earth satellite, was successfully launched on February 1, 1958 (0348 Greenwich Mean Time) from the Cape Canaveral missile center.  The cosmic ray instrumentation package on this satellite was designed by Dr. George Ludwig, who was studying at that time at the University of Iowa in the Cosmic Ray Lab under the guidance of Dr. James Van Allen.  The Explorer I instrumentation payload used transistor electronics, consisting of both germanium and silicon devices.  This was a very early timeframe in the development of transistor technology, and represents the first documented use of transistors in the U.S. earth satellite program.  In this Oral History, Dr. Ludwig provides a very informative and highly readable account of the transistor electronics carried aloft in the Explorer I satellite, and the details of Dr. Ludwig’s work with these early semiconductor devices provides a truly unique perspective on these historic events.  In addition to the historic use of transistors, the Explorer satellite instrumentation package achieved another major scientific breakthrough – the discovery of the Van Allen radiation belts. [1]  [2]



Go To Ludwig Oral History, Page 2  


Ludwig Historic Audio Recordings


Curator’s Introduction


Copyright © 1958 by The Huntsville Times


Credit: ABMA. Courtesy JPL. 1958


The Explorer I satellite was launched from Cape Canaveral on January 31, 1958 (local time).  This historic event generated tremendous world-wide excitement, because the Explorer I was the first U.S. satellite to achieve earth orbit.  Shown at top (above) is the front page of the Huntsville Times, announcing the new artificial “moon”.  The Jupiter-C rocket was used to launch the Explorer I, and had been built at the Army Ballistic Missile Agency complex in Huntsville.  A 1958 JPL photo of the launch is also shown.



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