Explorer 1 Was Launched 65 Years Ago


The first US satellite was launched 65 years ago. In 2008, George Ludwig, who built the instruments for Jim Van Allen that detected the Van Allen belts, attended the 50th anniversary of Vanguard 1. He talked about this during the question-and-answer period. Here’s part of the transcript.

Member of the audience, Bob Whitlock: Perhaps one of the most famous experiments of that time was the Van Allen radiation belt experiment. Were there any tie-ins between Van Allen’s work and in the Vanguard program? Marty, maybe you might be the one to address that.

Mr. Martin J. Votaw: The Van Allen experiment was scheduled at the beginning of the Vanguard program as the second scientific satellite to be flown and the transmitter group that I had had the job of building transmitters that would– high-powered transmitters. The high-powered transmitters would have 125 milliwatts. And the high-powered transmitter would provide enough energy to carry telemetry signals, complicated telemetry signals, as well as to do the tracking. And they were necessary in order to get the telemetry of the Van Allen experiment to the ground.

So when Van Allen decided to move his satellite to the Army program, he talked to them about the transmitter and we had already built a 125-milliwatt transmitter for his satellite. But we took it out of the package that had his satellite in it and he took his satellite home. And when he talked to the Army about transmitters they said, “We’ve got a 10-milliwatt transmitter,” and he decided it wasn’t going to have the signal-to-noise ratio sufficiently wide to handle the data that he had. So, there was a phone call to me and they asked, “Can we have the transmitter that you built for us?” And I said, “Yeah, I guess so.”

We didn’t need it; we already had under construction, that we had finished the transmitter for the Lyman-Alpha experiment for Dr. Friedman, and we had two more under construction for the last two Vanguard satellites. So, I didn’t need it, so, I said, you can have it.

So, we sent Ed Dix down to Alabama, and he took the transmitter and soldered it back into the package that Van Allen had provided for the Army launch. And that was the last we heard of it. It worked well, it did fine. Van Allen had good data and everyone knew about it. It was an NRL transmitter and it was built on government money for the IGY program and Van Allen was part of the IGY [International Geophysical Year] program; no reason why he shouldn’t use it…

Member of the audience, George Ludwig: I built Van Allen’s instruments.  A comment and a question. The comment is, there was a reference to Orbiter just a moment ago, and I want to remind people when Orbiter, the initial Orbiter proposal was put together, it was a joint, collaborative effort between the Army and the Navy here at NRL. It was only some months later, when they sent that proposal out to JPL, that JPL got on board with the Orbiter proposal. So, just that little bit of correction.

The question has to do with the beginning of work on Vanguard 1. I started developing the cosmic ray instrument in the spring of ’56. And it was not much after that the 20-inch configuration became set in concrete and, not long after, that we received the first prototype shell. And I can remember very well receiving the first shell out at the University of Iowa and fitting our package into it and, lo and behold, it fit.

The question is, during all of that time I never heard of the six-inch diameter satellite. We always talked about the 20-inch satellite. And, furthermore, in reviewing the minutes of the meetings of the working group on internal instrumentation, which Van Allen headed, which did the work in sifting the proposals and arriving at a decision as to which satellite experiments would be flown, I found no mention whatever of the six-inch diameter satellite. So, my question really is, when did the work, that you mentioned, on the six-inch satellite really begin?

Mr. Alton E. Jones: Anybody who knows that answer, why I’ll give it to them.  I can speculate. I think that the reason why you only saw 20-inch satellites is because that was what the SLVs were supposed to carry. The six-inch satellite, I think, was only born after we decided to try for an orbit as an instrumentation mechanism and it was never intended to be a part of the IGY satellite program. I don’t know that’s true, but I’m just speculating.

Member of the audience (George Ludwig): I guess the key question is, was the work on Vanguard 1 started before Sputnik 1?

George Ludwig: When did the TV, the small satellite development start? Was it before Sputnik 1?

Another audience member: Before the 4th of October?

Dr. John W. Townsend: Oh, it must have been after.

Mr. Alton E. Jones: I think it started before. The satellite didn’t show up in any of the IGY papers, because it wasn’t part of the IGY program it was part of the NRL development of the Vanguard launch vehicle and it was intended, in the beginning, just to demonstrate by measuring its orbit, what the launch vehicle had accomplished. But the idea that it would have temperature measurements in it and two transmitters, those were all developed by Roger during the construction program after it had been carried on for a while.

Audience member (George Ludwig): Your comments lead me to believe that the actual work on some of these decisions that were made and some of the questions that Roger asked, were begun well before the 4th of October ’57.

Mr. Roger Easton: Oh yes, I am sure it was. The man who suggested putting the small satellites on the test vehicles, Col. Gibbs [an] Air Force colonel who was our Air Force representative on Vanguard. And he said, “If we are going to all this trouble, why don’t we put a satellite up,” and he sold it. And, so, then we started working on a better six-inch satellite.

Audience member: George, you didn’t tell your story about where you were on Explorer 1 for the launch?

George Ludwig (audience member): Well, I was with Jack Townsend in the Russian embassy. We were drinking cocktails. You were talking about the Explorer 1 watch. Well, I would like to tell that story, because it’s a very interesting story.

When the decision was made for the Army to go ahead and launch, based on a Jupiter C, it just so happened, by no accident, that our instrument at Iowa fit on both the Vanguard and the Jupiter C. And that was the result of Van Allen’s knowledge from clear back in ’56 of the potential capability of the Jupiter C. We talked this over at great length and made the decision that we would go with a six-inch diameter package, which would fit on Jupiter C and as well would fit within the canister of the Vanguard.

Anyway, after the launch of Sputnik 1, the Army got the go-ahead and the JPL people came out to see me at Iowa and we worked out the arrangement, right at the very beginning of how the instruments would be handled. So, we came to the conclusion that that could only really be brought about if I went out to JPL with all my designs and instruments and help them do the repackaging necessary to get it into the Jupiter C configuration. So, I did that and the time for the launch of Explorer 1 came up, and I was tied up with JPL to the last minute because I was having trouble calibrating the Geiger counters.

So I appeared down at the Cape on the day, actually the countdown was underway for the first launch attempt for Explorer 1. Well, I got there, and I found out that there was no space made available for me to monitor the launch, monitor the instrument signal. So, I found a place by the roadblock, out with the general audience, to listen to the Cape squawk box at the countdown.

By the next day, I had checked with Roger and Marty and they had said they had modified their receiver at Hangar S to receive the signal from Explorer 1. They invited me to come to the hangar to monitor the launch of Explorer 1. And I did so for the second attempt. The three of us stood there at the bench, sat on stools listening to the signal coming from the transmitters on the satellite and, of course, that was scrubbed, too.

And, then the third attempt, I was back in Hangar S with my two very good friends, friends forever, Roger and Marty, listening to the signals. I remember that there was not even anybody else in the room, it was just the three of us there by that receiver. And the launch came about and I was recording in my notebook the switching of the tone on one of the subcarrier oscillators, which indicated the counting rate from the Geiger counter.

And, so I monitored that during the countdown and, then, during the ascent. So, that is where I was. By the time of the Explorer 2 and 3  launch, which carried the complete package that I had designed for Vanguard, I had a proper place in the blockhouse monitoring this signal. But the first one carried a much-abbreviated package, just the Geiger counter and a simple scaler and high-voltage power supply. Anyway, that’s where I was for that launch.

George is in back just to the right of the rocket in this 2008 photo taken at the 50th for Vanguard 1.

Published in Science & Technology
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There are 5 comments.

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  1. tigerlily Member

    If I counted right, there are 30 guys in that photo who are probably all either an engineer or a physicist. Of the thirty it looks like all thirty are wearing a white dress shirt, twenty-eight are wearing a suit coat, while twenty-four are wearing a necktie, three are wearing bowties, and three are tieless. That seems about right for professional men at work in 1960.

    Sorry Richard, but that aspect of the photo touched my fancy.

    • #1
  2. Percival Thatcher

    Great stuff, Richard.

    • #2
  3. Douglas Pratt Coolidge
    Douglas Pratt

    George Ludwig was the guy you wanted for a friend if your record player kept breaking down.

    • #3
  4. kedavis Coolidge

    tigerlily (View Comment):

    If I counted right, there are 30 guys in that photo who are probably all either an engineer or a physicist. Of the thirty it looks like all thirty are wearing a white dress shirt, twenty-eight are wearing a suit coat, while twenty-four are wearing a necktie, three are wearing bowties, and three are tieless. That seems about right for professional men at work in 1960.

    Sorry Richard, but that aspect of the photo touched my fancy.

    I’m thinking they just dressed up for Picture Day.

    • #4
  5. Douglas Pratt Coolidge
    Douglas Pratt

    Obligatory book plug: Van Allen and Ludwig’s adventures are described in great detail in Ambassadors from Earth, from interviews with both (Van Allen shortly before he passed on). Wonderful stuff, like Van Allen on a Navy ship launching sounding rockets when Sputnik went up, and calculating its orbit based on watching how fast the radioman had to turn the knob to keep the signal strong. Or Ludwig trying to get a data recorder to work when the Jupiter C spun up its payload section. Or the guys at the tracking station in Australia getting annoyed about how they wouldn’t get a look at the pictures of Mars coming in from Mariner, so making their own pictures with graph paper and pencils as the data came in. Or the lady at JPL, looking at Voyager pictures of the flyby of Io, exhausted and blurry after a 10 hour shift, and suddenly thinking, “is that a volcano?”

    PM me if you want an Audible freebie.

    • #5
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