Interview with Frank Drake on 7 August 1978
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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.
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Sullivan
This is talking with Frank Drake at URSI [International Union of Radio Science] in Helsinki on 7 August ’78. Now could you tell me when you first came in contact with radio astronomy?
Drake
I first came in contact with radio astronomy when I went to Harvard in the summer of 1955. I had been in the Navy three years; I had, nevertheless, been accepted in graduate school. I went to Harvard expecting to study optical astronomy, but when I got there, I discovered I'd been assigned to the radio astronomy project on the basis of my background in electronics and having been an electronics officer in the Navy. That turned out to be very good luck. The radio astronomy group at Harvard was a very lively, good one, and this can be attributed entirely to the efforts of Bart Bok who went to very great effort to create a strong research atmosphere, to provide support, and particularly to get people to interact. The people produced in that era at Harvard have played a major role in radio astronomy in many, many places. They included Bill Howard, Campbell Wade, [T.] Kochu Menon, May Kassim, Dave [David S.] Heeschen, Ed [A. Edward] Lilley, Nan [Nannielou H.] Dieter, Bob Davis, and some others, and we were all a very close knit group both in research and socially. As I said that can be greatly attributed to the work of Bok.
Sullivan
Were you in close contact with the other optical astronomers besides Bok at Harvard?
Drake
No, there was contact, but the contact was not nearly so good because then, as now, the senior scientists at Harvard very much isolated themselves from the students. So there was much less contact than one might have hoped.
Sullivan
Bok was an exception to that?
Drake
Bok was, and still is, an exception to that situation. A very important figure in all of that at the time was also Dave Heeschen, who had gone away for a year to Wesleyan and come back and was instrumental in giving good guidance to the group but also, in working with Bok to get the money to build the 60 foot antenna, a project which commenced just about then. That money came primarily from a normally anonymous donor, one member of the Agassiz family, who gave a great deal of money to Harvard Observatory about that time. Bok succeeded in obtaining from her money for the 60 foot.
Sullivan
Why was it Heeschen that was working with Bok? Was he sort of the senior graduate student or what?
Drake
Heeschen had gotten his Ph.D. in 1954, along with Ed Lilley. They had been the first two radio astronomy graduates at Harvard. They had both gone away. Ed Lilley had gone to NRL. Dave Heeschen went to Wesleyan but after a year, Dave Heeschen came back to Harvard and took over the radio astronomy group and gave it a great deal of strength. In fact, that continued until Dave went to NRAO, which was a serious blow to the group because about that same time, Bok also left for Australia. The result was that the group was taken over by Tommy [Thomas] Gold and Kochu Menon, both of whom had great skills, but not the skills of holding the group together in a congenial atmosphere that had existed previously.
Sullivan
And that was now 1957 or something like that?
Drake
That was 1957 when both Bok and Heeschen left. Now, Dave went to NRAO where he was the galvanizing force for at least the next five or six years, despite the fact that it wasn't until about 1962 that he was formally director. Nevertheless, before that time most of the guidance and decisions were really made by him, despite the fact that other people were director and so forth.
Sullivan
He was the senior radio person, certainly. I mean, Otto Struve was the director, but...
Drake
That's right. Dave was the senior radio person. And at various times we had Lloyd Berkner as a director. He, in fact, did a good thing in that he set very high standards of quality with regard to instruments, people- the way things were done. And I give him a plus for that. He got NRAO established on a very firm basis. Later, Otto Struve came. Through both of these regimes, though, Dave was really the senior radio astronomer, and the one everybody depended on for decisions. Struve was pretty much lost. He came almost because he felt it was his duty to astronomy to help out this struggling young observatory, but in fact, because of his very limited background in radio astronomy, he found it very difficult to make decisions and he primarily deferred to other people.
Sullivan
He must have somewhat of an enlightened attitude towards this upstart field, though, to have been willing to do this at all.
Drake
Oh, he realized that the field was quite important. It had a tremendous potential for playing a key role in astronomy. He was excited by the results that were obtained, but he felt very uncomfortable when discussing the techniques and terminology. Things like flux density and various frequencies were things that were not comfortable to him. I remember very early after the construction of the first 85 foot telescope, I did a map of the galactic center with very much higher resolution than had been possible before and showed that Sagittarius A source resolved into a number of components. And Struve looked at that and was very thrilled by it. He said, "That one map justified the entire cost of the telescope."
Sullivan
Let's go back to- we're getting a little bit ahead of ourselves. Let's go back to Harvard. When you were a graduate student, how was it decided what you would work on?
Drake
The decision as to what people would work on were made by the people themselves, but there was pretty much a roster of possible ideas available, mainly generated by Bok. And these were just a little roster of ideas was the sort of thing that a very traditional astronomer would produce. That is, his would have subjects- study the distribution of hydrogen between galactic longitudes 20° and 40°, that would be a subject. Now some of the students actually just adopted such subjects even though there was no prime scientific question to be addressed. Others either invented their own subjects which happened to be subjects of interest. For instance, Campbell Wade decided he wanted to study the hydrogen distribution around HII regions and found a very symmetrical [???] and did that one. Nan Dieter decided she wanted to give a try to external galaxies and so did an M33 thesis. In my case, I was very interested in star formation, and I knew that stars were formed in a young clusters and OB associations and so because some other students were working on OB associations, I worked on hydrogen galactic clusters.
Sullivan
I was just wondering, did you get the same education, so to speak take the same courses as the more traditional astronomy students at Harvard?
Drake
Yes. At Harvard all of the students took the same courses, so everyone had the same coursework.
Sullivan
Does this mean that the other students were getting two or three radio courses at that time, also? Even if they were not going to do anything with it?
Drake
At that time, there was only one course in radio, and looking back on it, it was an extremely trivial course, but then that was very early in the history of radio astronomy. But there was just the one course and otherwise, all of the other courses you took were much more traditional- Radiative Transfer and Galactic Structure and Quantum Mechanics and...
Sullivan
Celestial Mechanics?
Drake
Well, there was no Celestial Mechanics, but there was... when Gold came, there were some plasma physics.
Sullivan
Who taught this one course?
Drake
Dave Heeschen taught it the year I took it and after that, Kochu Menon taught it. I think one year Alan Maxwell taught it.
Sullivan
So you did your thesis, then, on these galactic clusters, [???] and so forth, the obvious bright and big ones, with this 60 foot dish?
Drake
Yes, it was done very early after the 60 footer went in operation.
Sullivan
About the 60 footer, was that, did it come into operation very smoothly? There were no troubles with it or was this a step that required quite a bit of...
Drake
The 60 footer came into operation quite smoothly. But then the standards weren't high. Our receiver was a simple mixer receiver; there was no low noise amplifier and we had had much experience with that kind of receiver on the old 25 ft. antenna.
Sullivan
These are the Ewen Knight...
Drake
These were the Ewen Knight receivers. But the telescope itself, we were very relaxed about the surface quality. When I look back on it now, I think we were almost unaware of really how accurate a surface must be to produce a certain gain. That thing was just thrown together and we used it, and it seemed to work, but there was no study done. Similar to the receiver, there was no great effort made to improve the noise temperature, which was about 1000° at that time. The two things that I remember that we considered something new was first, the pointing it turned out did have to be carefully calibrated because we were down to, believe it or not, a 36 minute or 48 minute of arc beam width, which to us was really a narrow beam. And so for the first time, we did a very careful pointing calibration, which I did and I was very proud of.
Sullivan
Using strong radio sources?
Drake
Using strong radio sources and I discovered such things as gravitational deflections and particularly backlash - the fact that the telescope flopped as it went over the zenith which was zero hour angle, something we'd never even thought about in the old dish.
Sullivan
Did you tie in with the optical by mounting a camera at all or anything like that?
Drake
Only in the initial alignment of the polar axis was done that way, but for all the pointing calibration, we used radio sources.
Sullivan
I gather you also weren't using, looking at antenna journals to find out how they calibrated things.
Drake
No, we weren't even aware of antenna journals. The other thing that was troublesome on that telescope was that we soon after it was put into operation, we experienced an enormous amount of interference, which developed was coming from a radio ham who was about a mile away with a beam antenna which was normally beamed right at our telescope. And he was broadcasting right on the IF frequency, on the ten meter band and we had to go to an enormous effort to eliminate that interference, because it turned our signal noise ratio into our IF was about 200 dB and we had to invent all kinds of filters and grounding straps and shields and so forth.
Sullivan
There was nothing you could require him to do?
Drake
No, he was quite legal and he wasn't very cooperative. He liked to transmit for many hours each night. He was a (?).
Sullivan
The absolute worst sort of situation to be in.
Drake
He beamed that antenna right on us, blasted thing. A kilowatt of power into a ten [?].
Sullivan
So the 60 foot got going, what year would this be, 195...
Drake
The 60 foot was finished in late 1956, if I remember right.
Sullivan
And you began observing these clusters. What did you find out in the clusters?
Drake
Well, I found bodies of neutral hydrogen associated with the clusters. In fact, there was more hydrogen, with the younger clusters, such as [???]. In retrospect, I'm not sure that these observations are very sound, because at that time, we were not aware of the very complex cloud structure of the interstellar medium. At least some of those clouds which I attributed to the clusters were, in fact, fortuitous coincidences with the clusters.
Sullivan
Well, I was going to ask, what was your evidence that it was the cluster?
Drake
There are two forms of evidence - one was a discrete cloud whose size and position coincided with the stellar cluster. That's the type of evidence I now realize is pretty shaky. The other was that in some of those cases, the clusters have very large peculiar velocities. One did find a cloud that had precisely the peculiar velocity of the cluster. The best case of that is in the Pleiades, where there's a peculiar velocity of about 25 km per second. And it’s very near the anti-center so that the differential galactic rotation does not give large velocity offsets. In that case, there's a cloud that's bang on the Pleiades in velocity and in position. Some of the other clusters, those correlations really weren't so good and I think that they were over-interpreted.
Sullivan
Okay, bringing up the subject of over-interpretation, it seems to me looking at the work that came out of the Harvard group in the late '50s that there were some other cases of these bumps and base lines that proved not to be real. What was the basic reason for this over-interpretation. I mean, allowing in some sense that...
Drake
Yes, there was a great...
End of Tape 111B
Sullivan Tape 112A
Drake
There was a great deal of over-interpretation and it had several roots. One was that the standards as to what's an acceptable statistical certainty were much lower. At that time in radio astronomy, it was quite acceptable to publish results that were only two or three sigmas, which we would never do now. That immediately led to a lot of spurious results. The other was that, in a way, psychological, and that was the need to get a positive result because you were a student. The Harvard receiver then had one channel and to get signal and noise ratio, typically, one scanned the spectrum very slowly with this one channel. The typical observation took a half hour to an hour. This meant the rate of production of data was very slow. And as a result, people wanted very much to find positive results in their data and were influenced to give credence to bumps which were in fact the result of noise. That was particularly true of the extra galactic work, which I think in retrospect, is almost entirely erroneous. That included some of the work on M33 and probably almost all of the early results on hydrogen emission from clusters of galaxies.
Sullivan
Oh, yes, that's definitely way too high. So what you're saying then, is that the fact that you had to get a project done in a couple of years that would look good to the thesis committee, it was a large part of it?
Drake
It was a combination of that with the low standards, which allowed you to get away with accepting two or three sigma bumps as a genuine result.
Sullivan
But do you think that this was common in radio astronomy as a whole? In that era? Two or three sigma results?
Drake
It was common all over - the standards were somewhat different at different places. The standards were higher in Holland and in Australia, but at that time the standards were even worse in England. One sigma was considered a good result. That’s how we got the 2C and 1C catalogues.
Sullivan
Well, that was not really statistics. Well, it was statistics but it wasn't just noise statistics. Do you think it would be fair to say that Bart Bok with all his enthusiasm, did not really have- he would be the one to pass on these theses ultimately I would suspect and he didn't really have the feel for what you could have happen?
Drake
As a person who hadn't done much radio astronomy, as had none of us, he didn't have a good feel for what was statistically reliable as any of the rest of us. So these things slipped by.
Sullivan
Okay. Looking at your publications here, I don't see, did you work on any other projects while at Harvard?
Drake
Yes. There was one project I worked on which turned out to be, in fact, accurate. And that was a map of Cygnus X.
Sullivan
Right, at 21 cm. continuum.
Drake
That was continuum and at the time that was very controversial and a mystical subject, because Cygnus X was thought to be a single, very large extended continuum radio source in exactly the direction of the spiral arm. There were all kinds of mystical, exciting interpretations about it. What I did that was accurate just because we had high signal noise ratio- we weren't being fooled- was to observe with the 60 foot and show that it did resolve into- I think we saw something like a dozen radio sources which correlated extremely well with emission nebulae visible on the Palomar-Schmidt plates, and so clarified the nature of that object.
Sullivan
Right. Now I notice you gave this paper at the Paris Symposium. Did you attend the Paris Symposium?
Drake
Yes.
Sullivan
That meeting always fascinates me, it's sort of the last time that you could get virtually all of the radio astronomers in the world together.
Drake
Virtually all of the radio astronomers in the world were together and the thing that was most memorable about that occasion was not only that, that is you discussed, all the radio astronomy in the world in a week quite successfully, but that there was a vicious row between Ryle and Mills that reverberated throughout the whole thing.
Sullivan
Reverberated throughout the following five years also. This, of course, was not your field so as a more or less objective, although young viewer, how did you see it? Can you remember?
Drake
It was clear that both of them were partially wrong, that the truth was about midway between. It's very clear Ryle was missing in his studies the extended radio sources, which was Mill's criticism of him, and at the same time, Mills was missing the small radio sources and the double radio sources which was Ryle's criticism of him, so they were both wrong in that respect.
Sullivan
But this is not later on that you're coming to this view, you thought you could see that right at the meeting.
Drake
It was apparent right at the meeting and I think everybody but Mills and Ryle had the same consistent feeling.
Sullivan
Were there any other highlights that you remember about that meeting?
Drake
No.
Sullivan
That's a good answer. I notice that you gave several papers at AAS [American Astronomical Society] meetings in the late '50s and I know that other people in Bok's group did, but was this an exception of radio astronomers going to AAS meetings or were you talking to other radio astronomers or was it just only the hydrogen line group at Harvard that went to these meetings?
Drake
No, the hydrogen line group was strongly encouraged to go to meetings and to give papers. That was one of Bok's philosophies- everybody should give papers everywhere. And the result was that a lot of papers were given. I might mention, you just reminded me of something, I think there were some papers done on a source called the Gamma Cygnus source.
Sullivan
Yes, that's right. That was a paper in 1959.
Drake
That fell out of the Cygnus X study because Gamma Cygnus source is part of Cygnus X. The thing I remember there was that I did a map of Cygnus X and the brightest source was both very small and when placed on an optical map, was right on top of a bright star, the F8 star Gamma Sigma. At the time there was a solid dogma that a star could not be a radio source, but I didn't know that, I was naive. So I went out and spent a great deal of time using Harvard 61 inch to photograph that region, both in broad band optics but also with the new H alpha interference filter. Those turned out to be exceptionally good photographs, I didn't realize it at the time, but we were competing quite well with Palomar, and that was simply by a result of spending many nights and taking five hour exposures and going to great efforts to guide. The thing that came out of that was that right, very closely adjacent to that star was an extremely bright emission nebula which if the star weren't close to it, would be well known as one of the brightest emission nebulae in the sky. It's like the Orion Nebula, and the anecdote that goes with that is that when I wrote to [Rudolph] Minkowski at Palomar and told him it was there and told him, "Why don't you take the plate with the really good telescope - that we were using this crummy 61", and about two weeks later, I had a plate back which said in essence, "Pooh-pooh, young man - there is no nebula near Gamma Cygnus, forget it." Subsequently there have been many photographs taken of it.
Sullivan
You took a shorter exposure or less sensitive one and didn’t found it.
Drake
He never observed it at all. He was assuming that since he hadn't seen it on the Palomar...
Sullivan
Oh, he looked at the sky survey, I see.
Drake
That it wasn't there and an upstart couldn't [?]. I think that's still an interesting nebula because I suspect that particular nebula is associated with a star and it's excited by the solar winds, the problem is that a nebula that bright should not be excited by an F8star. I suspect that it really is the solar wind, not the star.
Sullivan
But why is it, is it the star is so bright that you have dynamic range problems, is that why you don't see it?
Drake
Yes. The star is a first magnitude star and on everybody's plates, the lights scattered from the stellar [???] which is right in, it's about 2 minutes of arc from the star, which turns out to be too much, too close.
Sullivan
But now back to the business about going to AAS meetings, were there other radio astronomers than the HI people at these meetings?
Drake
At that time the number of radio astronomy groups was very small, the only other one that came to meetings were the NRL [Naval Research Laboratory] people, who were all engineers and felt fairly out of place.
Sullivan
But they did come?
Drake
They did come. And the only other group was DTM [Department of Terrestrial Magnetism] and there one had Bernie [Bernard] Burke. Bernie Burke used to come to the same meetings and that was sort of the other source of hydrogen line papers and they were very good. DTM was considered the competition to Harvard.
Sullivan
In fact, it was the only other HI in the U.S.
Drake
Yes, the only other HI in the U.S.
Sullivan
There was, of course, quite a bit known in Holland and Australia. Even some at Jodrell [Bank].
Drake
In Holland, though, all they had at that time was the Würzburg, so that, in fact, we were ahead of them in instruments for quite a while.
Sullivan
But, no, Dwingeloo.
Drake
Dwingeloo came along...
Sullivan
1956-7? Yeah, 1957, maybe 1956. But it didn't have line work at first, it did continuum and [Gart] Westerhout's survey. And then they got into line with the galactic center and absorption, [Lex] Muller and...
That finishes part one of the interview with Frank Drake. We obviously need to get his time at NRAO until he went to JPL [Jet Propulsion Laboratory] in ’62 in a second session.