Certain people (me) will have hours of fun in the Transistor Museum website. Who can resist stuff like this: Historic Germanium Transistors; General Transistor/General Instrument (5MB pdf)?

I found there a book review of Opening Space Research; Dreams, Technology, and Scientific Discovery, Ludwig, George H., American Geophysical Union, Washington DC, 2011. (478pp), ISBN: 978-0-87590-733-8.

There I saw these photos, including a thanks for the transistors! note from James Van Allen to Texas Instruments. I believe these particular transistors are silicon, but it got me wondering:

Question: The first transistors in space: Germanium or Silicon? What about in orbit?

below x2: from the Transistor Museum's book review of Opening Space Research; Dreams, Technology, and Scientific Discovery.

enter image description here

enter image description here


The first transistors in space (and in orbit) were likely germanium, and they were aboard Sputnik-2 in 1957, though Sputnik-2 did use vacuum tubes as well.

The first all-transistor satellite was Explorer 1, as explained by George Ludwig:

Was the Explorer I the first earth satellite to carry transistor electronics?

In my original interview I said that it was. Since then, I researched the question and found that, although the Soviets did not use transistors in Sputnik I, Sputnik II, launched in November 1957, did use a few transistors in one of its instruments. Of course they had a much larger launch capacity and could carry vacuum tubes and their required batteries. The Explorer I launch occurred on January 31st local time, which was actually February l Greenwich time, of 1958. It was the first all-transistor satellite.

Explorer 1 used a combination of germanium and silicon transistors.

Sputnik-2 and Explorer 1 were the second and third satellites to orbit Earth, respectively.

The first computer in space (and first computer in orbit) was the Gemini digital computer, built by IBM, which first flew in 1965. It was IBM's first completely silicon semiconductor computer.


  • $\begingroup$ Ah, so do you think "When did the first silicon transistor orbit the Earth?" is answered clearly here or is there room for it be asked separately? $\endgroup$
    – uhoh
    Jun 14 '17 at 16:23
  • 1
    $\begingroup$ The first three satellites were Sputnik 1, Sputnik 2, and Explorer 1. It was established here that Sputnik 1 had no transistors and Explorer 1 had both germanium and silicon transistors. We do not know for sure what transistors were on the Sputnik 2, and we are unlikely to come by that information given the note on George Ludwig's interview: "(Curator’s note: See reference [5] for a more detailed discussion of Sputnik 1 and 2 - there is a reference to the use of semiconductor triodes on Sputnik 2, although there is not much published information on Soviet early transistor technology)." $\endgroup$
    – called2voyage
    Jun 14 '17 at 16:25
  • $\begingroup$ I've squeezed out a follow-up question I have a hunch you know the answer already. $\endgroup$
    – uhoh
    Jun 14 '17 at 18:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.