Transistor Museum Oral History George Ludwig Explorer I Transistors Page 4

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

Oral History – George Ludwig

(Continued)

What was your first exposure to transistor electronics?

It was not until 1955, when I started designing the satellite instrument. My undergraduate work took only three years because I had a year’s credit for my studies in the Air Force. During that time I worked on balloon and rocket instruments. But those all used vacuum tubes. Our mainstay was the very tiny Raytheon tubes that were designed for proximity fuzes. Van Allen had played quite a role in developing them during the War. Among other things, he worked with Raytheon in designing the filament so it could withstand the acceleration and shock of being fired in a shell. [4]

There is a long story about how the International Geophysical Year and the Vanguard program were put together to launch a satellite. But Van Allen was instrumental in getting both programs started. In a competition between scientists, who put in about 33 proposals (presented at a meeting in Ann Arbor, Michigan on the 23^rd of January, 1956), four of the experiments were chosen for development for the Vanguard satellite. A fifth one was added somewhat later. Ours was one of those.

Oral History – George Ludwig

(Continued)

So, I was just getting my Bachelor’s degree at that time, and was ready for a graduate project. Also, at that time, of course, I had had more electronics experience than anyone else, as a hobbyist in my 'teens, then in the Air Force, and then in my work in the Cosmic Ray Lab.

I started serious design work on the satellite instruments in April 1956. The first thing I had to do was to learn about transistors, because I had never even seen one before then. We knew we had to use transistors – the whole instrument package that ended up being flown on Explorer III took far less power than simply lighting the filament in a single vacuum tube. That instrument package occupied a portion of the severely limited 23 pound total capability for orbiting a satellite with a Jupiter C launch vehicle. My instrument package in Explorer III was a cylinder about 6 inches in diameter and about a foot long, and that whole package weighed between eight and nine pounds, including its batteries.

Go To Ludwig Oral History, Page 5

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