[Cover of Sullivan's book 2009, Cosmic Noise]
Sullivan's Cosmic Noise, Cambridge University Press, 2009


NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES

Papers of Woodruff T. Sullivan III: Tapes Series

Interview with Cornell H. Mayer
At Naval Research Laboratory
September 30, 1971
Interview Time: 55 minutes
Transcribed for Sullivan by Pamela M. Jernegan

Note: The interview listed below was either transcribed as part of Sullivan's research for his book, Cosmic Noise: A History of Early Radio Astronomy (Cambridge University Press, 2009) or was transcribed in the NRAO Archives by Sierra Smith in 2012-2013. The transcription may have been read and edited for clarity by Sullivan, and may have also been read and edited by the interviewee. Any notes added in the reading/editing process by Sullivan, the interviewee, or others who read the transcript have been included in brackets. If the interview was transcribed for Sullivan, the original typescript of the interview is available in the NRAO Archives. Sullivan's notes about each interview are available on the individual interviewee's Web page. During processing, full names of institutions and people were added in brackets and if especially long the interview was split into parts reflecting the sides of the original audio cassette tapes. We are grateful for the 2011 Herbert C. Pollock Award from Dudley Observatory which funded digitization of the original cassette tapes, and for a 2012 grant from American Institute of Physics, Center for the History of Physics, which funded the work of posting these interviews to the Web.

Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event.

Part 1

Sullivan

30 September ’71 at NRL. Ok, we're talking about Ferrite switches.

Mayer

But even if you really broke your back to match everything, standing wave ratio of 1.02, or something like that, over the band of the receiver, it still is virtually impossible to get away from errors of 5° or 10° from your source.

Sullivan

Yes.

Mayer

And of course, the isolator, but even better, the circulator knocked that error way down. By a factor of ten or a hundred.

Sullivan

About what time was this that you saw this article and started working on it?

Mayer

About 1950, ’52, somewhere in there.

Sullivan

Oh, that early?

Mayer

Yes. In fact, the applicator, well then the obvious thing to do with the circulator is to instead of using a fixed magnet to switch it, and use it to replace the ferrite switch, which would give both the advantage of the impedance isolation, getting rid of this calibration error, but would also get rid of the dipper disk - almost always been used up until that time.

Sullivan

Right.

Mayer

Certainly it had always been used at short wavelengths or some artificial replacement for it. But that had all sorts of advantages, you could switch between two antennas or you could switch between anything you wanted to. That led to the development of this 3 cm radiometer which was used on the 50 foot in ‘56 and that radiometer was actually in development for two or three years but was held up by these eclipses and stuff. The ferrite switching stuff was actually done, I think, by 1952 or 1953 and just sat there for two or three years. Anyway, in 1956 we- this was I guess Haddock left somewhere in 1955 or something like that- and well, again, for various reasons, with Haddock leaving and with Hagen finally being saturated with eclipses, this made it possible for me to work full time on this radiometer and get it in the 50 foot. And immediately in putting that radiometer in, the first thing we did was look at Venus, and we asked for a month's time, because we wanted to look for phase effect.

Sullivan

Now...

Mayer

In other words we thought the sunlit side of Venus should be hotter than the dark side, and we wanted to see if we could measure the surface temperature of Venus. And also to see if the sunlit side was hotter than the dark side. The sort of thing you did on the Moon, you see, previously.

Sullivan

Right, but Venus had never been observed at radio wavelengths?

Mayer

No.

Sullivan

So this was just your idea that it should be observable?

Mayer

Yes, based on the infrared temperature of 300°.

Sullivan

And with, I guess, reasonably low noise at that time, 3 cm receiver. I'm just trying to get a feel; I guess the main thing was the large dish usable at short wavelengths that enabled you to do it.

Mayer

It worked out that the antenna temperature was of the order of 2° or 3° and just to do something like that and it would be observable. As I say, we asked for, I guess we actually asked for two or three months time, but they gave us one month, so we started out about a month before inferior conjunction, our time was up right at inferior conjunction. And the first day, we did pick up Venus, and it was not only farther from conjunction, but also farther from the Earth. It was- I've forgotten now, but probably 1° or less on antenna temperature. So right away it was apparent that if it was thermal radiation from Venus It wasn't 300°, it was 600°. The very first day that was apparent.

Sullivan

Really, you had no doubt about the alleged signal, shall we say, that time, you mean?

Mayer

We didn't have any real doubt, of course we had all sorts of doubts because everybody told us and all the books told us that this was impossible. And so we had all sorts of doubts. We had no doubts about our equipment because that equipment was very thoroughly designed, Every individual component had been thoroughly tested. Overall system was thoroughly tested the calibrations very well checked, the thermal sources, we felt very assured about what we were measuring, but we couldn't feel very sure about Venus being at 600° because all the real smart astronomers said this couldn't be so.

Sullivan

Yes.

Mayer

And so, well, in fact, [Wilt?] had worked out that there would be a greenhouse effect assuming there was carbon dioxide as they thought there was, but he set an absolute upper limit of 400° for the possible temperature. So even with that assist from [Wilt?] on the greenhouse, it was still impossible. Anyway, we continued to measure Venus up to inferior conjunction, and we saw this downtrend in the brightness temperature as it got toward inferior conjunction. And of course, as Venus got closer, the antenna temperature went up like it was supposed to and so forth. About that time, we got tossed off of the dish. And we couldn't follow it through on the other side of inferior conjunction.

Sullivan

But you said the brightness temperature was falling?

Mayer

The antenna temperature was going up, as it should.

Sullivan

Right.

Mayer

But of course, not as fast as it should if the brightness temperature was falling.

Sullivan

Right.

Mayer

Anyway, we couldn't do anymore, we got kicked out. Then we begged and pleaded that we be allowed to put the 9 cm radiometer on to check to see if another thermal spectrum. So Hagen gave us two days on a weekend about a month later. So we worked all night in a thunderstorm to mount that huge radiometer which is in a box about this big and weighed a ton up on the back of the 50 foot dish, run 10 cm waveguide this big all the way up to the focus. The next day measured Venus. That measurement wasn't awfully good because it was still too close to the Sun at that wavelength and we had some side lobe troubles. But he gave us one day a month later to try it again, and we went through the whole procedure again. And this time we got some fairly marginal measurement at 9 cm, which could have been improved, of course, with a few days time, but...

Sullivan

Yes.

Mayer

But it did indicate a thermal spectrum.

Sullivan

Was the dish being used 100% of the time now or was this, once again, that he just wasn't willing to give you time?

Mayer

Oh yes, it was being used - mainly for the hydrogen line. I think that may have been about the time that Lilley and Barrett were looking for OH, and they were screaming their heads off that we shouldn't waste time on the valuable antenna looking at Venus. In fact, we had a terrible time getting on the antenna at all for that reason.

Sullivan

Now do you know if that experiment came out - they just didn't have enough sensitivity to find OH?

Mayer

I never understood why they didn't find it. When asked, their answer was that they didn't know the frequency well enough, but I've never understood that answer. Maybe that's right, but it seems to me that, well…

Sullivan

Let's see now, the Venus stuff was published most certainly, and that was in ApJ?

Mayer

Yes.

Sullivan

Now what about the phase effect?

Mayer

That came later, but before that another thing that we had in mind to do at 3 cm was to try to detect polarization on the Crab Nebula. And we wanted to have some kind of comparison source anyway, for the Venus measurements. So we looked at the Crab Nebula and Venus all day long every day during this two month period - all the way across the sky. Of course, this inferior conjunction was in June- 23rd I think. So Venus and Taurus were practically in the same part of the sky - all through the whole experiment. But anyway, we looked at both Venus and the Crab Nebula all day excepting right before [?] one to the other. So we had this data on the Crab Nebula, linearly polarized feed all day long, [paralaxic?] angle at that declination rotated like 120°, I think it was. And after the first month, we rotated the whole radiometer 90° so we could fill out the other part of the curve and verify if it really was a polarization effect or whether it was some other kind of systematic effect during the day. And those curves, in fact, did show that for one, I can't remember which one now, but I guess horizontal polarization during the day that the thing looked like this. The vertical polarization went down like this. As it should for polarization.

Sullivan

So what percentage was it approximately?

Mayer

Hmm, yes I remember, 8%, I think.

Sullivan

And was this the first radio astronomical polarization detected? And I guess it was [Iosef Samuelovich] Shklovskii that first proposed synchrotron radiation. No?

Mayer

No.

Sullivan

Had that been proposed -did you have any idea of where this polarization was coming from?

Mayer

Oh sure. Oh sure. That was why we looked for it.

Sullivan

Then who was it then?

Mayer

Well, synchrotron radiation as an explanation for celestial radio sources was first proposed by [Karl Otto] Kiepenheuer for the galactic radiation and by [N.] Herlofson and [Hannes] Alfvén for radio sources. Discrete sources.

Sullivan

Can you tell me approximately where and when these proposals were made?

Mayer

I can give you the references. In fact if you look at our polarization paper, they’re in there.

Sullivan

Okay, fine.

Mayer

And this was in about 1950.

Sullivan

And they were saying that this was for Cygnus A also for the extragalactic?

Mayer

I don't remember whether they specified particular sources; they were just suggesting this as a possible mechanism for explaining this radiation, which by this time everybody agreed couldn't be thermal. So there were these two independent suggestions of synchrotron radiation. And somewhere along in that same period of time but I think even the Russians admit later a whole bunch of Russians proposed things like this, notably I guess [Vitaly L.] Ginzburg and maybe Pikel’ner and a bunch of guys proposed synchrotron radiation, and maybe independently, maybe they didn't even know about this outside of Russia, I don't know. What Shklovskii did as far as I know, anyway, he's not the first guy that proposed synchrotron radiation for radio sources at all. Not even in Russia. By my understanding, what he did was to propose that not only the radio radiation from the Crab Nebula was synchrotron radiation but also the optical, and that was done about 1953, that proposal.

Sullivan

I see.

Mayer

And as a follow-up on that proposal of his, a couple of Russians looked for optical polarization and found it.

Sullivan

And found it?

Mayer

Yes.

Sullivan

Before your radio polarization?

Mayer

Yes.

Sullivan

So you did have that to go on, at least?

Mayer

Yes.

Sullivan

So that optical polarization was pretty strong proof, well, not proof, but weight on the side of synchrotron in the radio...

Mayer

On the optical, yes.

Sullivan

The radio, just about clinched it for radio.

Mayer

Yes. And that they were, in fact, the same process.

Sullivan

Right.

Mayer

And also, I guess independently, [Jan Hendrik] Oort claims independently, Oort and [?] looked for optical polarization and I think they didn't know about the Russian results, which in fact though had already been gotten. And they found polarization, actually made a polarization map, a crude one, optically. And then according to Oort, Baade was over there and he showed Baade and this and Baade went back and took these famous photographs with the 200 inch, which show the different sheets of polarization, which showed the polarization very definitely and then [Lodewijk] Woltjer of course took Baade's photographs and analyzed them and got these very high resolution polarization pictures by analyzing Baade's photographs.

Sullivan

Now I suppose this polarization measurement, maybe the Venus, too, is an example of the earlier equipment work that paid off in the late ‘50s.

Mayer

That's right. So anyway, as a result of that what we thought was a definite detection of polarization, but we wanted to confirm it better, so then we built a rotating feed radiometer, and I don't remember when but I guess the next year, and we confirmed it with the rotating teed and got better data and stuff and published it. And then somewhere along in those same years, I don't remember where, we also looked at Mars and Jupiter and we, of course, looked in this period, we looked at the strong radio sources and got what appears to be good data and flux as anybody ever had, but we didn't ever present it that way or publish it that way.

Sullivan

In any of these projects you haven't really mention other people as competitors or anything; was NRL just pretty much on its own or did you feel pressure from anyone else?

Mayer

There weren't any competitors at these wavelengths because we had the only 50 foot dish.

Sullivan

That must have been a nice position to be in.

Mayer

Yes. And your other question about weren't astronomers clamoring to come to NRL and look at stuff, I don't think they were although even if they were, I might not have known about it, because they probably would have come to Hagen.

Sullivan

Yeah.

Mayer

But I don't think in general that astronomers were clamoring to do anything with any radio astronomy stuff; they were still taking a strictly hands-off attitude.

Sullivan

Yeah, yeah.

Mayer

And looking down their noses.

Sullivan

And there were very few people that you could really call radio astronomers at that time.

Mayer

That's right. In fact, the Venus measurement, the only real astronomer who paid much attention to it and certainly the only one who gave us any support, was [Gerard] Kuiper. And guys like [Donald H.] Menzel just poo-pooed it and said they didn't know what we were doing wrong, but we must be doing something wrong. And did we really know what we were measuring, did we really know what we were doing- all that kind of nonsense, you know. But Kuiper was not only right away receptive to believing that people other than astronomers could do things, too, but he also was not so blind to the possibility that maybe they didn't know all about Venus and maybe it could be 600°. And he somewhere along in there started Carl Sagan working on this, who was his graduate student in Chicago.

Sullivan

I see.

Mayer

And Sagan was trying to explain the high temperature by greenhouse effect basically.

Sullivan

In general, was there trouble in publishing radio astronomy papers in things like the Astrophysical Journal in the early 1950s?

Mayer

Not as far as I know.

Sullivan

So they were accepting to that extent?

Mayer

My impression would be that there may have been some trouble but we certainly never encountered any real trouble. Maybe radio astronomers thought there would be trouble and didn't really try sometimes when they should have.

Sullivan

Yes. But there's still, you've hinted a lack of acceptance by most of the optical astronomers.

Mayer

Well, a lack of enthusiasm and acceptance. And there's always been a great reluctance for astronomers to accept NRL on any perspective.

Sullivan

Why do you think that is?

Mayer

It's partly snobbery and partly that universities don't like competition from government installations.

Sullivan

That's interesting. Do you think that applies for the Naval Observatory also?

Mayer

Yes. As far as research is concerned, they're perfectly happy to have them do ephemerides so they can use them. I think so. I don't have any information on that, of course, but I think so. I think it's still true today.

Sullivan

Well they certainly look upon an academic post as being a more favorable or exalted position or what have you than a civil service post. There's no doubt there's snobbery to that extent.

Mayer

Yes. I think that's always been the feeling - only second grade people would work with government, that sort of thing. If you're any good, you'd be at Harvard.

Sullivan

Yes. Well, that covers up to the 84 foot. Did you work on the 84 foot at all?

Mayer

No, or very little. Worked some on it and we tried to make some polarization measurements, well, we did make some polarization measurements at 10 cm. Well, that leads into all this follow-up work on the planets and the polarization. I mean we looked for even in the first measurements, we obviously looked for polarization on the other strong radio sources not just the Crab.

Sullivan

Yes.

Mayer

And... that may not be entirely true. I don't think we did look at Cygnus until 1961. I don't remember why that was. But anyway, all these things led to other things. For example, we couldn't understand why we didn't see polarization in Cas A; you obviously should. And there were only two possibilities: one was that the magnetic field- well, three I guess, now synchrotron radiation could be a possibility- the magnetic field was entirely disordered or it was symmetrical. And that was the basis for the experiments a few years ago with the 140 foot, map of polarization of Cas A.

Sullivan

I see.

Mayer

To find out - was it disordered or was it ordered? It turned out to be ordered. And so on.

Sullivan

At what point did the Radio Astronomy Branch become such devoted to radio astronomy almost?

Mayer

Oh yeah, well, there was something like 1954, ’53 or ‘54, it became the Radio Astronomy Branch and it still wasn't entirely devoted to radio astronomy, but it was called then Radio Astronomy Branch. And at about that time, Hagen became Division Superintendent. And what was the Division called then? I don't remember.

Sullivan

A and A?

Mayer

Well, I think he renamed it A and A [Sullivan: Atmosphere and Astrophysics]. I don't remember what it was called before.

Sullivan

Who became the branch head when Hagen moved up?

Mayer

A guy named [Sullivan: Warren] Ferris who had been Assistant Branch Head - he's the guy that Hagen got from RCA, he was a middle-aged fellow and I was never quite clear why he got in or why he came here - he had no interest in anything that was being done. He's a tube man. And he certainly had no interest in radio astronomy. But he had been Assistant Branch Read for a long time and also obviously, again, you don't have to repeat this, but obviously Hagen had in mind that as Division Head, he was still going to run this branch, because he was still interested in radio astronomy.

Sullivan

Yes.

Mayer

But anyway, Hagen only remembered Division Head for something like a head, and then he took on this post as head of Vanguard at which time Newell became Division Head. And Newell was Division Head then for two or three years until he left with the crowd that went to NASA.

Sullivan

And that's when Friedman took over? And who followed Ferris as Branch Head?

Mayer

Well, Ferris, I know, only remained as Branch Head for a year or two, he found the situation untenable. He went to University of South Carolina and McClain became Branch Head and that was in about 1956 or somewhere around there.

Sullivan

Had McClain acquired an interest in radio astronomy?

Mayer

Oh yes. I guess I skipped that - I said...

Sullivan

You said he started off with zero.

Mayer

When I said he was not the least interested, in fact he didn't want to do this at all - he was working in the Doppler navigation system, which he was interested in. But when they pointed the thing at these radio sources, he got mildly interested, I think. But then when they found this hydrogen line absorption thing, he became very interested. I converted him. But anyway, to answer your question, for a few years, along in that period, probably still only about half the branch was working on radio astronomy. It would have been at least until these people left or came or something - it would have been a group, in the ‘55, say, ‘56 era, it would have been Hagen and Haddock and McClain and Sloanaker and McCullough and Gibson and I've forgotten some, but that's basically it. And then a few other guys like Corbett.

Sullivan

There's another thing that we haven't mentioned is the maser collaboration.

Mayer

I haven't gotten that far yet.

Sullivan

We're still...

Mayer

We're about there. Anyway, what you should also have somewhere in your records is that shortly after the detection of Venus, Gibson and McEwan, who was a technician at that time here- Scotty, maybe you've even heard about him, I don't know. They measured Venus at 9 mm and they found the lower 400° temperature at 9 mm. So actually, if you're wanting to accept the very marginal 10 cm result, the spectrum of Venus essentially as it’s known today was found here in about 1956, ‘57.

Sullivan

Was that published - the 9 mm?

Mayer

Yes. That in the Paris Symposium if I remember correctly. Then that was extended further by Grant, I think, who measured Venus at 4 mm using the 10 foot and got still lower temperature, 300° or something. Anyway, the spectrum of Venus was very well delineated at NRL. And of course, about 1957 or 1958, NRAO got their first 85 foot and Drake right away went on Venus at 10 cm.

Sullivan

Yes, that was 1958. That was the first time you had any competition. So is the next step…

Mayer

Well the Townes maser, that was a collaboration or set up, I guess, initially in talks between McClain and Townes. Townes had graduate students building masers and he wanted to apply them to radio astronomy and the 50 foot dish was the best place to do it. So he contacted McClain and we worked with him first of all on the 3 cm measure on the 50 foot and next I guess it was the 21 cm measure that I know Penzias built and that was on the 84 foot. And then I guess next was Bill Rose who built a 10 cm maser and that was used on the 84 foot. I don't think I've forgotten any.

Sullivan

Was there anything particularly troublesome in adapting these things as radiometers?

Mayer

No. Not really, I mean there were troubles, of course, but nothing basic.

Sullivan

Nothing so they had to operate upside down or things like that?

Mayer

Operate what?

Sullivan

Upside down and out in the elements.

Mayer

Oh, no. [?] problem. Of course, an alt-azimuth mount is not such a bad problem, but just mounted at 45° so you could cope with the zenith down to the horizon.

Sullivan

Let's see. The other thing that comes to my mind that you've been involved in is you know, very recent, namely the Townes collaboration with the water and ammonia lines.

Mayer

Yes.

Sullivan

Of course I know some of that myself, but I was just wondering if you would talk about just how that collaboration was set up. The way I know is simply that Townes was looking for a bigger telescope, and since he'd worked with NRL before, it was natural for him to give you a call.

Mayer

Yes. Well, let's see, as best I can remember it, he called and said they'd detected ammonia, and that he thought it would be really good to look at it with higher resolution and so forth. So we were planning to try to get something together and do this and a couple of weeks later he called and said they'd found this water - which looked a lot more interesting...

Part 1

Modified on Tuesday, 23-Dec-2014 14:30:20 EST by Ellen Bouton, Archivist (Questions or feedback)