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Oral History – George Ludwig
(Continued)
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So you
worked on a series of Explorer satellites?
Well, I worked on this
package originally for Vanguard. Then after Sputnik was launched in October, 1957 there was a
big flurry of activity, and approval was given to the Army for going ahead with a launch with the Jupiter
C. Again, there is a
long history behind this. Even before the Sputnik launch, Van Allen and I had worked with the
people in Huntsville Alabama in designing a version of our instrument that
would fit onto the Jupiter C launch vehicle. When Sputnik was launched and the Army finally received the go-ahead,
then I switched our instrument to the Army’s program. Well, they wanted
an initial launch that was extremely high reliability, with absolute minimum risk, the greatest redundancy, and so
on. So we extracted a part of my instrument,
combined it with two continuously operating beacons and some micrometeorite
detectors, and put those on
Explorer I. That satellite did not have a device
for recording the data in orbit, and so we depended on only the data as the
satellite passed over the network of ground stations (most of them were roughly along 85 degrees
west longitude). That signal carried data from my electronics, the data from two micrometeorite detectors, and three different
temperature measurements.
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Oral History – George
Ludwig
(Continued)
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To back up, I had designed the full cosmic ray
package, including its onboard tape
recorder, for Vanguard. Then the switch was made to the Army. We
made a simpler package using part of my
electronics for Explorer I,
and then flew the full
package in Explorer III. Actually we
attempted to launch it as Explorer II, but that one did not go into orbit..
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. (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).
Go
To Ludwig Oral History, Page 6
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