Wolfgang Priester

Doel:

This is an interview with Dr. Wolfgang Priester, Director of the Institute for Astrophysics and Extraterrestrial Research of the University of Bonn. We're recording this on January 19th, 1987, in Dr. Priester's office in Bonn. Dr. Priester, I know you were born on the 22nd of April, 1924, but I don't know a great deal about your family, or about your parents. Who were they, and what did they do?

Priester:

Is this so important? My father was an architect. My mother was just his housewife. I have a brother who became a teacher of physics and mathematics and sports, and now he's already retired. And right after the war, I started of course to study physics, astronomy and mathematics, and got my PhD in Göttingen in 1953.

Doel:

I wonder if, before we get into your university career, we could talk just a little bit more about your life and growing up in Germany. Did you feel that your parents played a strong influence in bringing you towards science?

Priester:

Oh, I guess so, yes. Yes, my father was very interested, particularly in philosophy, not too much in physics, but my first book on astronomy, I came to find out, because I was ten years old, and each time I put a mark on with the date when I had finished a chapter, and I still have that old book. I saved it through the war.

Doel:

Do you remember the name?

Priester:

It was Bruno. It was a popular book on astronomy, which brought me into the interest in astronomy and physics, and of course, this was at the age of ten, and then of course, in high school, what we call gymnasium, I was lucky to have a famous high school which was already more than a thousand years old, and had this old tradition, and basically of course a tradition in Latin and ancient Greek, but of course, in mathematics and physics, so I had a good background, and right after the war, I got into Göttingen University to study astronomy and physics and mathematics.

Doel:

What was the program that you had in high school? How much physics and astronomy were you able to take?

Priester:

Astronomy, there was no special course in astronomy in high school in those days. It isn't even today. It's just incorporated into physics or geography, and — but mathematics was pretty good, and physics. But since I got my high school diploma in 1942, it was already during the wartime, and of course there was a reduction of everything, and the teachers, some of the teachers had to become soldiers already and so on. And then right after that, after finishing high school, I had to become a soldier too, and spent five years or four years in the war, but very luckily I survived it without major harm, and so, after the war, I started astronomy.

Doel:

What particularly led you to Göttingen?

Priester:

Oh, in those days it was very simple, because that was the, it was in the first place, a famous university for science, and secondly, it was the university next to my home.

Doel:

Were you living at home then during the time you were in Göttingen?

Priester:

No, no, of course not. That was 150 kilometers away, and one had to stay in Göttingen. I was lucky to get what we call a student room together with my brother. He studied physics and mathematics and sports to become a high school teacher, which he later did, and so we spent our time of studying in Göttingen together, and that that is —

Doel:

Who influenced you the most during the first years at Göttingen? What kinds of courses did you take?

Priester:

To get into the university in those days, there was something that we called which was much more severe than it is nowadays, and in particular, I missed, I came out of the war in November, ‘46, out of a prisoner of war camp, an American prisoner of war camp, and so I missed the first semester after '46, and so when I was back home, I took the train to Göttingen and tried to see one of the professors there, just to find out my chances and so on to get into it, and I took my diploma along, of course, and so I met the director of the Göttingen Observatory, a famous chair of Gauss 150 (50?) years ago, and the professor was and he was in solar physics, in those days. He had done lots of work in stellar physics and in particular globular stellar clusters, but this was all before the war, and after the war, he specialized in solar physics, and that's why I later then took my doctoral thesis in solar physics, and made observations of the center limb variation of the sodium D lines in order to find out the temperature variation in the solar atmosphere, and the entire physical state in the solar atmosphere.

Doel:

How much of his work did you know already by the time that you first met him?

Priester:

Of his personal?

Doel:

Of his research.

Priester:

His research, hardly anything. I had, in those days, a famous book by Sir James Jeans, what's the name? There's a German translation, “Stars, and Atoms," probably, I don't know what the English title is. I had the German translation of that. And —

Doel:

It might be THE MYSTERIOUS UNIVERSE, but we'll —

Priester:

— no, no, that's another one. This was not THE MYSTERIOUS UNIVERSE, it was another one. I don't know whether I — I probably have it at home, I kept it somewhere.

Doel:

We can check on that later. What other works had you read prior to the time that you came to the university? What influenced you?

Priester:

I did do some mathematics, but in astronomy, to get any information in astronomy basically was reading this kind of sort of popular books of a high level, like Sir James Jeans' books, and then, I had a German journal which is, well, it's a journal which is in the level above SKY AND TELESCOPE, because it had lots of equations in it and so on, but it was still considered to be a popular journal, and of course because of that high level, it never managed to get a large number of copies to be sold, so the journal died. I don't know when. Late in the late forties, after the war. It did not survive and doesn't exist anymore.

Doel:

Was it a journal that the astronomers would read as well?

Priester:

Yes. Yes, certainly.

Doel:

Were you certain already when you entered Göttingen that you wanted to work specifically in astronomy, or were you thinking about other choices as well?

Priester:

It's a little bit difficult to answer, because, right after the war, you must consider the situation in Germany, and to study a field like astronomy, which is sort of — I think that a very rare field and somewhat, most people think it's a little bit — so I wasn't really certain whether I could manage to stay in research in astronomy, the situation was so uncertain that I was — I said, OK, I study astronomy, physics and mathematics, and these three fields, actually, when I returned every semester then one had to re-enter the university, and the second semester I put, physics, astronomy, mathematics. In the first semester I put mathematics, physics, and astronomy. And so I wrote it every semester. But finally, when it came to start on the doctoral thesis and so on, it was very clear that I wanted to stay in astronomy, and by that time, I had established also a good relation with and other professors, Professor and Professor. He was already in his seventies in that time, and was a young man, and so, the doctoral thesis took me almost three years to finish it, because we didn't have computers then, and everything had to be done with a slide rule. It took a terrible long time to do the reduction of the data and so on. Actually, was very clever, in that I had, for my thesis, I had four students working under me on the data reduction, which you now do with a computer.

Doel:

That's interesting.

Priester:

Human computers, four students working for me, and they kept me busy all the time. I hardly could do my research, because I had to supervise their work, doing the reduction for my thesis.

Doel:

And these people were hired by…

Priester:

They were hired by the Institute, yes, and paid by the Institute. Most lucky. Not everybody was lucky in this respect, but it might be that it was the research project that I was working on was very much interesting to himself, and so. And later on it turned out that this, — got quite a jump in solar physics, because then we realized that the temperature profile in the solar atmosphere is different in different wavelengths, so to speak, and that of course depends on the up and down streaming of the gasses in the solar atmosphere, that makes the temperature profile, which you derive in different wavelengths, becomes a function of wavelength. Sounds very strange if you look at it this way, but it was just due to the upstreaming, downstreaming, and now the whole problem in the solar atmosphere is what people are working on still since now almost 30 years, and it's still a very interesting field, and there are big telescopes to be built, and German solar astronomers just built a very big huge telescope, solar tower in the island of and there was even an inauguration last year. The King of Spain, and Deutches Bunde President, the King of Sweden and the Queen of the Netherlands, and — the Queen of England wasn't there; it was the Duke of Gloucester who replaced her, because the Queen of England is not on good terms with the King of Spain, since about 500 years. It's just because of, but, whatever it was, and then there was the King of Denmark, so there was a whole big inauguration ceremony for this solar tower, the European telescope, two years, it's already two years ago now. It was in '85.

Doel:

You jumped ahead just a bit. In 1950 then would have been the time that you began doing your doctoral research.

Priester:

Yes.

Doel:

Who else were you working with? I would assume primarily with

Priester:

Yes, but of course there were assistants in the Institute. It was who later, after in 1960, took a job at the Einstein Tower in Potsdam, in East Germany. And —

Doel:

That's unusual.

Priester:

Yes, it's very unusual. He had this offer, and in those days we were still hoping that there would be a United Germany some time, and so he just took his chances, and very unluckily, I would say. He's retired now and I've never seen him again since that time. He did his research with the Einstein Tower, but he never managed to make the jump back into the Western world. Even in 1961, that was before the Berlin Wall was erected, he was in West Germany, actually he attended the IAU meeting in Berkeley, but then he decided, during that time the Berlin Wall was built, and then he decided to go back, despite the fact that he had family in the West.

Doel:

Were you in contact with him at that time?

Priester:

Oh yes, of course. We were good friends. But I've never seen him really because I never went to East Berlin or Potsdam after the Wall.

Doel:

Who else in addition to were you working with? Was there a sense of community in solar physics?

Priester:

Quite a few people. For instance, there was who used to be the president of the Max Planck Society, now is director general of the European Space Agency. He worked on his thesis at about the same time, and his wife, Dr. [???], worked — they were not married in those days, they married after they both got their PhDs — and she worked in solar physics in those days, and Liszt took his doctor's, his thesis with at the Max Planck Institute in those days, and I ought to know, the — it's difficult to remember now who else was there. He's now in the States, at Ann Arbor. I've forgotten. It's a long time, thirty years ago.

Doel:

Were there other students at Göttingen at that time that you came to know very well, who had an influence on your career?

Priester:

Oh, I met my wife there, of course. She studied astronomy too.

Doel:

Tell me about that.

Priester:

Actually, to get into the astronomy in 1946 in the first semester, when I went to [???] he told me, "I have 19 applications and I will take, because of the numerous classes, a number small against ten, " that was his absolute, it turned out to be four, two boys and two girls. One of the girls is my wife now.

Doel:

That's interesting. When were you married?

Priester:

We were married in 1950. I was still working on my thesis, and she had given up after the financial situation in '48, when all our money went down the drain, the old money, and we got this new money, and so, her father was a high ranking man at the Karl Zeiss Company in East Germany, in Jena, so he couldn't manage to support her anymore, so she got a job, at the Karl Zeiss factory in Göttingen, in the laboratory as a laboratory assistant, and so she supported the family. Actually it was very nice. I didn't have any money either anymore. My parents had died very early, and so this was the way we managed it.

Doel:

How difficult was it to get any kind of fellowship support in those years?

Priester:

Oh, there was no fellowship support. The only thing I got, I got a free luncheon every day. That was the support I got. In the free luncheon, actually, most of the time even for lunch time and in the evening. It was the fellowship, you know.

Doel:

How much contact did you have with [???]? Did you meet him also after?

Priester:

Hard to know all these details, because — oh, it was much more contact than it is now with the students here, much more. There were about, at that time, five or six people working on the diploma of physics or the PhD, and usually once in the semester we were invited to his home, and so, for an evening social, and actually I saw him in the Institute. I saw him every day, because at 8:05 in the morning, he came swooping into the offices and said, "Hello, what kind of new research have you done during the last night?" and you'd better have an answer. Of course, it was also possible to say, "There's nothing new to report on, " but — it was his way of life, at 8:05 he started to go around, so you'd better be there on time. Of course, when I went to the solar tower, then we had to start very early in the morning, because right after sunrise, this is the best time to do solar spectroscopic research, because then the air level is rather quiet and you can, for the center limb observation, you have to do it at 5:30 in the morning in the summer time, and so we went walking up to the mountain every morning, it was half an hour's walk. We didn't have a car and there was no public transportation, so we started at 4:30 or something like that to be there on time. Of course then he couldn't come in at 8:05 and ask us, because we were up on the mountain.

Doel:

In 1953, after you'd finished your doctoral research, you became a research assistant at the Institute for Theoretical Physics at University.

Priester:

Yes. This was an agreement between [???] who was basically of course an observational solar physicist, and Processor Albrecht who was the famous astrophysicist, theoretical astrophysicist, and talked to Umsalt about my future, and so he suggested that I should, after my Ph.D, take a fellowship of the which he had asked the Kiel for me, but to carry it out, at the Institute for Theoretical Physics at University under Umsalt. It was an excellent idea certainly, and so, my wife and I, we changed to Kiel, and with the 370 marks per month salary, but very luckily there was another Zeiss Company in Kiel and so she was just transferred from the laboratory in Göttingen to the laboratory, the Zeiss Company in Kiel, and so she got a job there and I got a job, so we managed.

Doel:

What were you doing? Your job of course was at the —

Priester:

She did laboratory work in the factory in Kiel. The factory in Kiel made movie machines and things like that.

Doel:

How was the experience at Kiel compared to Göttingen? How was it to work with Umsalt?

Priester:

Oh, I guess it was pretty much the same, except the attitude of the two scientists was completely different. I can tell you a little story. [???] was always very careful. He said, "If you get a scientific result, you can never be certain that this is the final answer to everything, so when you put it in writing, you always put it very very carefully that you, let's say, even to leave a little door open in case of uncertainty. "And Umsalt was just the opposite. He said, "Once you have realized that some result is the best thing you can do, and you really believe it's true, then you stick out your neck and say, this is it." So these two poles of , I don't know how to put that in English — so in my career I switched back and forth between the two kinds of attitudes toward science, but I must say that I am more inclined towards Umsalt’s attitude, to stick out the neck, when you realize that this is the best way to do it.

Doel:

You mentioned to me that your father was interested in philosophy. Were you also very interested in it?

Priester:

Yes, my father read Emanuel Kant and Schopenauer and all these great philosophers, but I myself never really went into it. I had a relation with Emanuel Kant because I was born on the same day exactly 200 years after him. But I was also born in the same day as Robert Oppenheimer when he was 20. Of course by that time we didn't know. We knew about Emanual Kant but we didn't know about Robert Oppenheimer.

Doel:

True. Can you tell me a little bit about the research, how you got into doing radio astronomy when you were at Kiel?

Priester:

Yes, of course. I started out first to read lots of stuff, and then we had already a technician in Dr. [???] who did the electronic work, and — Dr. Franz [???] — at the Institute, and I was responsible for the program and for the reduction and so on.

Doel:

Umsalt had suggested that you do radio astronomy.

Priester:

Yes, he suggested it to me by saying, "OK, when you come in from Göttingen, you are new in the Institute," and if I would like to do it, and of course I said I would like to do it, except that I don't know anything about it really, but to read 150 papers, it didn't take me too long because one learns to read them diagonally. Umsalt usually said to read a scientific paper, to report on it, should take you less than 20 minutes. I thought it was a joke, but nowadays really you don't have time more than 20 minutes, except for the very few you really read very very carefully, of course, so one shouldn't make a joke, shouldn't emphasize that joke too much really.

Doel:

He may have been ahead of his time. How did you come to the research that you began doing? How quickly did you find the area of research that you wanted to do in radio astronomy, or had Umsalt suggested it?

Priester:

No, I realized, from the very beginning, that the only really good thing to do with that five times five meter telescope we had, it was a quadratic device, to do a survey of the entire sky, and I tried to make it an absolute calibration, and just make a survey of the entire sky, and this turned out — because there was already a survey going on in Australia for the Southern Hemisphere made by C.W. [???] and Colin S. Gamm. Gamm died unfortunately in an accident in the Swiss Alps in the later fifties. They had made a survey with a similar telescope of the Southern Hemisphere, and so it was very natural to extend it to the Northern Hemisphere, and in the overlapping area, which is a huge overlapping area of course, to fit both together, and this then became the first whole sky survey in radio astronomy, and the frequency was 200 megahertz, we call them hertz in the States, megacycles per second, megahertz, and so this was l.5 meter wavelengths, and this is one of the three we have on the wall up there. There are three nowadays, all sky surveys. On the left side is my old one, together with von [???], and of course with Colin S. Gamm's part in the Southern Hemisphere, and then in the seventies, who sits next door here in the Max Planck Institute, did it with together at 850 megahertz, and then came the real famous survey in '8l, with the 100 meter telescope, and the Australian 64 meter telescope, at 408 megahertz, which was made by Hazlem and his entire group and of course it's all done on a computer. In my old days, I had to do the data reduction all by hand and even the convolution integral by hand, so to speak, without computer, but I managed to do it. Nowadays you have much more detail, so much detail that you don't see the structure for the details anymore, so it’s —

Doel:

I understand. Who, what people did you consider to be most active in radio astronomy at the time? Who did you have the most contact with, both within Kiel and outside? Priester; In Kiel we had a very small group. This was just Dr. [???] and myself really, and the [???], who is now here and manages our 100 meter telescope, and Umsalt of course was interested, but he was occupied writing this very very big book on physics of stellar atmospheres, the second edition, and it took him practically 48 hours per day, I have to put it that way.

Doel:

Did he talk to you a lot?

Priester:

Of course, we had social contact also, on the research projects, but since he was so much occupied with writing his real famous book, which is a marvelous book still, that we really couldn't rely upon him on all details. He wanted to see the results and that was it and no details please.

Doel:

You learned how to condense material very well.

Priester:

Of course, during that time we did some other radio astronomy with observation of the solar eclipse which happened to go through Kiel, the shadow area went through Kiel in those days, of course, and we managed to calculate the energy distribution in the solar corona. The resolution was not so good because the moon has the same size in the sky as the sun so the resolution was not good enough really that one can make use of it later on, but in those days it was interesting. But nowadays it's completely outdated, except for the all sky survey, it is good still, if you really want to have the gross structure, then you can still look at it and see what's going on there.

Doel:

Right. It was in 1955 that you became part of the University Observatory here.

Priester:

Yes.

Doel:

How did that come about?

Priester:

The research project I had in Kiel was of course a time limited project, and I stayed here for a little bit more than two years, but by that time, the director of the Bonn Observatory, Professor Becker, he died last year at the age of 85, and he had decided to start radio astronomy in Bonn, besides the optical observatory. The optical observatory, the [???] in Bonn, was built, let's see, about , at that time a hundred years ago by [???] who made the famous Bonn [???] of the sky with 320,000 stars, which is still used in the Smithsonian stellar list nowadays, but nowadays it's all on computers, you can take it from the Smithsonian computer. But this was entirely optical observatory, up till about early fifties, when Becker decided that there should be a place in West Germany besides the little effort we could afford at Kiel in radio astronomy to, in those days, the financial situation here in Bonn was much better than it is now, I'd say — and so he decided to build a radio telescope. And so he was looking for a radio astronomer, and since I was one of the two radio astronomers in Germany in those days, in West Germany — in East Germany, at Berlin in East Germany was a large installation under Otto [???] who, in 1961, when the Berlin Wall was created, he lived in West Germany and worked in East Germany, so he couldn't go back to his office anymore, so we got hold of him and got him into Bonn. But this was not so in the fifties. And so we built a 25 meter telescope and started radio astronomy, and the main project in those days was the 21 centimeter line of hydrogen, and so we had lots of work in the hydrogen distribution in, the first place of course, in the galactic spiral arms, and then of course also in extra galactic objects. Of course there you can, with the 25 meter telescope, you usually can only get the entire spectrum, and you can't go into the details. This had to be left then to later development. This was in the fifties. It was, when I came, on the very first days I took office in Bonn, we went out to the Mountain to find the place where to put the telescope, and so Becker and myself, we looked around in that area which was available to us to site and said, "This is the place where to put it, " and that's where it is now. And actually, a little bit and more than a year later, the telescope was ready and working. It started working in '56, '57 really.

Doel:

How much trouble was there to obtain the funds?

Priester:

For that telescope, it was pretty easy, because it was, in we had a Secretary of State, that's a different term than your Secretary of State — secretary for research in the Ministry, Ministry of Economics, and he was very much interested in promoting science, and actually he was very vital. He , let's see — a nuclear research installation in [???], and he built the Society for Mathematical Research in Bonn and many other places, and also he got funding for the radio astronomy installation, so to get the 3.5 million marks for the 25 meter telescope was really pretty easy, as compared to the situation nowadays. But the more difficult thing was to get enough positions in the new Institute, scientists and so on. Of course, this basically had to be done all by what we call, the money you can get outside the university budget from NSF, so to speak, National Science Foundation, which is the But that means you have to apply every year, every two years, for new money and have time limited jobs and so on. Nowadays we have the time limitation to five years absolutely maximum, because the union's regulations don't allow having a time limit more than five years, because then you have the right to have a permanent job, and since nobody has permanent money or knows it in advance, all these jobs have to be terminated after five years. It is just absolutely disastrous for research.

Doel:

An incredible amount of turmoil and turnover.

Priester:

It's incredible, but we haven't found any way out of it. We tried very hard since twenty years and haven't succeeded.

Doel:

Are there any other positions that you were thinking to go to, outside of Bonn, at that time? Or was that your first choice?

Priester:

Let me see. As a matter of fact, when I got the offer from Bonn. I also got an offer from Umsalt in Kiel for a permanent assistantship, because he had got an offer to become director of the Munich Observatory, so he was going back to Munich, and back to Kiel, that is, whether to go to Munich or to stay in Kiel — so he, in Munich, he will get two or three openings for assistantships, but if he would stay in Kiel, he also would get openings there, but by that time, I had gotten this offer from Bonn, and I was in Bonn just for deciding whether I stay here and so on — I got a telegram from Umsalt right after I had decided to go to Bonn. So , but I never regretted it, because the situation in Bonn was, from the financial point of view, was much, much better than in that rather small theoretical institute, so from that point of view, it was a good decision.

Doel:

By the time you got your [???] in 1958, you were already working in a number of different fields.

Priester:

Oh yes. That's another story. Starting radio astronomy, but the telescope really became effective in the middle of '57, really, and then all of a sudden, on the 4th of October, '57, the Sputnik came out, and in our radio installation… In '57, when the radio installation was ready for starting working, on the 4th of October, '57, the first Sputnik went into the air, and in the radio laboratory was an engineer who had just, at the very first moment he got it from the news, very early on the next morning, had already the beep, beep of the first Sputnik on tape when I came into the office at 8 o'clock in the morning. And he jumped at me and said, "There's a satellite in the air!" And I said," I can't believe it. The American satellite is due in December." "No," he said, "it's the Russian satellite, of course." That was even more exciting, from that point of view. So we looked into it and then got this beep, beep and then realized that, what can we do with it — just to listen to it is nothing for a scientist, so you have to decide, what can you do with it? And so first we just tried to figure out the orbit of the satellite, and in the very early days, we figured out how to install — to measure the Doppler shift, when the satellite comes over and the signal, we get the Doppler shift — so what we had, the information of course was from the newspapers, from the Soviet Tass agency, that the satellite was moving around the earth and so on, in a circular orbit at a height of 900 kilometers above the earth's surface, and that it took it 96.2 minutes for one orbit. So we tried to figure out, to test this, and from the signal we could receive, because it was overcast, there was no chance to see the satellite. The entire October was cloudy in Bonn and was no chance to see it. And, but after two or three days, we realized that there was something fishy with the orbit the Soviets had released, and in particular there was then — actually the satellite started in the night, from Friday and Saturday, I believe, 4th of October, so on that Saturday morning when we started getting the results, and then on Monday, Tuesday, we started to install a Doppler effect measurement device, but on that same Monday...

Doel:

Resuming again after a brief interruption.

Priester:

The story in the first days after the launching of the first Sputnik, with a circular orbit of (height of) 900 kilometers, that Tass made the science community believe. So when we started with the Doppler Effect measurement on Monday, we got the news already from Cambridge, England, that Martin Riles, the famous Nobel Prize, he died unfortunately a couple or two years ago or so, and his group had already achieved Doppler effect measurements of the satellite, and found out that when the satellite passed over Cambridge, England, that the satellite was only 300 kilometers high. So 900 kilometers in the first day, according to Tass, and on Monday, 300, so the satellite came down very very rapidly, and actually we also believed the satellite will come down within this week, and this was the time when we made all Doppler effect measurements, and then also figured out what the orbit of the satellite was, and realized, there was no seeing of a circular orbit. It was an elliptic orbit with a perigee height of 230 kilometers, and the apogee height a little bit above 900 kilometers, but it was only the apogee height which Tass had released, and so this fooled the entire world, and actually the implications were very very severe, by saying, OK, the Russians are able to put a satellite of 84 kilograms into a 900 kilometer orbit, starting at 900 kilometers, with a rocket which brings it up to 900 kilometers — this was outrageous, and all the military were very much anxious to know a little bit more about that, of course. But then we immediately realized that the launching height, the perigee height, was only 220 kilometers, and so, there was nothing really very strange about the whole launching, and so the next day we got in the newspapers, because Moscow also had announced the satellite will not come down in this week, and then we gave the explanation, and so we got a headline in the German newspapers, "Bonn And Moscow Agree the Satellite Will Not Come Down." Which brought us really into satellite research of course. Then after, we immediately realized that there was a braking effect in the orbital motion due to the air drag acting on the satellite, and so one could use this drag in order to derive the density of the upper atmosphere, which , in that area, about 200 kilometers, there was no observational information on it before at all.

The highest rocket which had measured it directly went up to about that height, but there were only one or two rockets really which had measuring devices, and one location on the earth, and now you really could measure the behavior of the upper atmosphere, and so this really started an entirely new group in that institute, and then we found out that the upper atmosphere is breezy. According to solar activity , and it's also that , what has come a little bit later, that the atmosphere is of course being, even the upper atmosphere is being heated by the absorption of the solar [???] extreme ultraviolet radiation, and so this lifts up during daytime the entire atmosphere, and so the lines of constant density, the isobars, go up by , at a high range of 200, 300, 400 kilometers, go up by 50 or more kilometers every day, reaching a maximum height at 2 o'clock in the afternoon or even a little bit later, and then when the sun goes down it settles until at night it settles even more, but rather slowly. This was a very strange effect. And then next sunrise it goes up again, and all these interesting findings we published in that time, most of it we published in German, because our English wasn't good enough. It's still not good enough. But interestingly enough, the Royal Aircraft establishment in England always translated our publications into English, and I've just given them permanent permission to do so, and on the condition that they send us 200 reprints. Until I discovered that this was done by professional translators, and so when we discovered the atmospheric bulge, this blowing up in the afternoon, and we called it in German" which is literally translated" air bearer, "it should be atmospheric bulge, and when I discovered that, and there was another thing — the flux density of radiation in German is [???] , and that was translated as radiation current, so that the whole thing was very silly. From then when I discovered these two very bad mistakes, then I decided we'd rather learn English. Even with broken English, with the correct terms, it's better than perfect English with bad translation of the scientific terms.

Doel:

The physics of the atmosphere research you were doing was primarily based on your observations of the satellite.

Priester:

At that time it was the only information we had, in 1958 and '59. And then came the mass spectrometer measurements with rockets, in addition to it, and later on the mass spectrometers direct measurements on satellites, and we have , in Bonn we have in the Physics Institute Professor [???] who is one of the inventors of a special mass spectrometer which became very very vital for this kind of direct measurement, and — but by the time of 1960, early 1960, there was the first COSPAR meeting in Nice, and actually, I wasn't really so eager to go there, but then there was a famous geophysicist in Göttingen, Professor [???] whom I had known from my time in Göttingen, of course, and so he called me up and said, "There's this COSPAR meeting going on in Nice in early January, 1960, " I believe is correct here, and I said, "I don't know anything about COSPAR. Anyway what should I do there?" "Anyway, this is a scientific meeting," he said, "and I am the chairman of the German group, and I want you to be there." "Yes," I said. "Yes," he said, "OK, I have already asked the [???] of the research foundation to pay your travel expenses and so on, so you go." "OK," I said, "if you want me to go, I go." It was very very important for me that I went, because then I met Robert Jastrow, the director of the Theoretical Division of Goddard Spaceflight Center. By that time, Goddard Spaceflight Center at Greenbelt didn't exist, of course. It was all above a shoe store in Silver Spring, Maryland. On the second floor of a department store in Silver Spring, Maryland. But I met him there, and we became friends and talked about science, of course, and then he said, "Why don't you come over to NASA and do all that research there? We start to get a first IBM computer, and 7090, one of the first bigger computers, "and so this was of course an exciting offer in any case, so I said, "OK. Send me the invitation in writing and we'll see." So I had to get leave of absence here and so on, and it took another, it took almost another year. We left in March, '61, and this was exactly when we arrived, in the middle of March, '61, at the time when the first building of Goddard Spaceflight Center was inaugurated. Of course Goddard himself had died already, but Mrs. Goddard was there, and the big bosses of NASA for the inauguration. I'll never forget that day, because from Silver Springs we went out to Greenbelt by car, and I had thought, it was a beautiful day but freezing cold on the 16th of March, and I thought, this is an inside affair, and didn't take an overcoat, and then the whole thing was outside, and I was almost freezing to death during all this inauguration talks, but I didn't catch a cold.

Doel:

Most of your time was up at the Goddard Spaceflight Center in New York.

Priester:

Yes. When I arrived at Greenbelt in March, I was told, "Don't unpack all your belongings too much, because the Institute, the theoretical division is being divided into the theoretical division which stays at Goddard and a new Goddard Institute for Space Studies which is going to be built in New York City, in Manhattan, right next to Columbia University, sitting like a spider in the net between Princeton, Yale," what else there? Princeton, Yale and Harvard — Harvard is a little bit further off, but sitting right there. Everybody who comes into the United States has to go through New York, unless he lands in Logan Airport. Whatever, this was a marvelous idea of Jastrow's, and it worked out very well indeed. He got Alistair Cameron and [???] and [???] and Patrick and all famous names in astronomy. So after being two or three months in Goddard, we moved to New York City, and this was really the most fruitful time of my life and also the most interesting time of my life. We enjoyed staying in New York. At first I was a little bit shocked about all the dirt in the streets of New York, but after you really realize what kind of city New York is, it's a way of life in New York City in those days was very exciting. We went I guess 15 times to the Metropolitan Opera , in those years, but also, the research in that institute was very interesting, because most of the people, I was one of the very few married people there. Most of the scientists were still in their young times, in their late twenties and early thirties, most unmarried, so there was research done throughout 24 hours a day, I would say. Some came in late in the morning but then they stayed until 2 o'clock next morning.

Doel:

Was that Jastrow's policy, to hire young up and coming scientists?

Priester:

Yes, it was his policy in general. He used to be with the Naval Research Lab in Washington, and realized that all the bright youngsters in those days in physics tried to get into nuclear physics or elementary particle physics, and he said, and he actually, just to himself, of course, the famous Jastrow potential, the hard core potential of the product — but he said, "Now we have space research and so we have to get out of this pool of bright young fellows, we have to get , we have to make some interested in space research, " and so he did a lot of that in that respect, really, he was very efficient, and then of course he also had set up to have guests in that institute, like Harold Urey or even going up, Tommy Gold, Fred Hoyle, Geoff Burbidge, whoever, was there, I can't remember all the names right now. And so, then he arranged interesting meetings, and I still have lots of photographs from these meetings, and you see people you know are really top scientists in the field.

Doel:

I'd love to see those.

Priester:

So this was very very vital in those days, with that institute, sitting at Columbia University like a spider in the net. That was his idea and policy, and it worked out very well indeed. So this was an exciting time, and we had computer facilities, and I worked still with Isadore Harris who stayed at the theoretical division at Goddard, so we did most of the joint work on FTS line, but of course, we came together. We worked separately and jointly, and each time there was something, then either I came over to Goddard or he came to New York, and we finished up our joint papers. Sometimes I kept saying, "OK, you write the paper and I'll write another paper." Sometimes he said, "OK, we have now joint papers, this was written by Izzie and Wolf has never read it," and vice versa.

Doel:

But both your names were on them.

Priester:

This is like the famous paper, alpha, beta, gamma paper of Gamov, you know that story, certainly. Hans Bethe never did anything to that paper, but just because it's a Bethe.

Doel:

Alpha, Bethe, Gamov.

Priester:

He was quite a guy, Gamov. Fantastic man. Unfortunately he died in '68, the same year as Robert Oppenheimer died. Both were only 64 years old when they died.

Doel:

How well had you come to know Gamov?

Priester:

I met him only at meetings. The most interesting meeting was in, when was that, in '67? I believe — it was the Texas Symposium for Relativistic Astrophysics, in the Hotel New Yorker, in New York City, in Manhattan, and he was chairman of the afternoon session. And you know he was sort of an alcoholic. At luncheon he had, I don't know how many drinks, but after that he was chairman, and he was almost drunk, but very bright still, but he couldn't organize himself too well, so Alistair Cameron was standing behind him and telling him everything he had to do as a chairman. It was an interesting time. There was a big discussion between Peter [???]from Moscow and Stirling Colgate about the fluor in the sun and so, he was accused to put all the fluor in his toothpaste. Ginsberg and Colgate had a long discussion about the fluor.

Doel:

That's a good story.

Priester:

Lots of interesting things happened in those days.

Doel:

How did Jastrow organize the institute? What was it like to be a resident member there?

Priester:

It was a loose organization. He tried to cover certain fields of interest with a man responsible for it. And then of course we had this kind of fellowships, and with lots of applications, and each time a new application came in, or he collected four or five or six, and then, — six, let's say, leading men of the institute were called together, and then he said, "Look into it, there's a fellow coming in from Italy and there's one from California," and so on, "now let's see what can we, do we want to have him or not?" And this depended basically on whether his research proposal was such that one realized he was scientifically with the idea self-supporting. He doesn't fit on somebody's neck. He knows himself what to do. Then of course immediately he was welcome. But if there was an application where you had the impression, here is somebody who comes to do research but he wants to know everything what he is doing, to be told, then we rejected him. This was the attitude, you know. Somebody who has his own ideas and is pushing it, even if it would be outside of the general field, in the general field but outside of the special interests of somebody of the senior scientists. And so this worked very well in those days. But of course, the computing facilities were absolutely marvelous for the time being.

Doel:

How close were the connections to Columbia University?

Priester:

Jastrow was teaching there, and [???] was teaching there, and [???] was teaching somewhere in Long Island, wherever it was, and Cameron was teaching there. I didn't teach in those days, with my bad English anyway. I was teaching at the Summer Institute for Space Research. This was also a very interesting setup, with 60 students, 40 Americans and 20 foreigners, selected out of 400 applications. Quite a selection. And I remember, what was it, '64, yes, this was when I wrote with Isadore Harris a very big paper on the theory of the upper atmosphere physics, a continuation of that... But in the summer school, I had taught radio astronomy, on synchrotron radiation and quasars and, pulsars were not discovered then, so, out of the student bodies, we had then money for one month or six weeks after that to hire one of the students to write up the lecture notes, and I got Johann Rosenberg from Utrecht. He volunteered to stay there, and I said, "How is your English?" And he said, "Good enough,"— my English was bad but his was absolutely excellent, and so he wrote up my lecture notes on extra-galactic radio astronomy, which then becomes a sort of a best seller in NASA. I don't know, 3000 copies were supplied all over the world, on the synchrotron radiation, in the early days — now you have famous books by [???] and things like that. But I still use this basic concept for my lecturing nowadays in German, and he wrote it up in four weeks, out of my handwritten notes, you know, which were not too well organized. Of course, it was a tape going along, but all the text in between had to be filled in and checked upon and everything, so he did it, right at the time when I was sitting with Isadore Harris writing a paper on upper atmosphere physics. So this was a time when it came about by saying, neither one has written the papers, or joint papers that were written by the other one.

Doel:

Right. Many of the people who became involved at the Goddard Institute for Space Studies had had long experience in physical science, particularly in physics. Did Robert Jastrow attempt to bring in people who were trained outside of physics, to the institute, or was that part of his?

Priester:

Well, physics was really a requirement. Actually if you want to do research in space research in any respect, it has to be either a physics background or whatever, what else, geophysics background.

Doel:

Geophysics or geology?

Priester:

Geology, yes, but I hardly remember anyone who did not come from physics or especially astrophysics, like Cameron, he started out as a physicist but became an astrophysicist, and Richard Stoddard, who is still there, is an astrophysicist from the very beginning, and Steve Marin, I don't know whether you know him, at Goddard, an old friend of mine, he was a student in those days, now he is a big [???] at Goddard, and he used to check upon my English in my publications. We are good friends now. And — I lost my line now.

Doel:

You were given a chance to stay in America at the Goddard Institute, weren't you?

Priester:

Yes, of course. I got the offer and I got from the, what is this, NASA, grant from the National Research Council. I got my money from Washington, DC, from the National Science Foundation or National Research Council. What all this is, double heading, I never found out about, but I was there to have lunch with the leading administrator from that and so on, but I've forgotten the details of it.

Doel:

Would you have considered possibly staying in the United States?

Priester:

Not in the beginning. There was this kind of fellowship, and the grant from the National Research Council. They also paid travel by ship or by air for my family, very generously, and also paid, which was even more important, because housing in New York City in those days was terribly expensive, and as a matter of fact, when we were at Goddard, for the first three months, Jastrow asked me whether I would like to come over to New York, so I flew over to New York with Eastern Airlines Shuttle and then tried to find a place to stay in New York, and looking at those buildings which looked so dirty from the outside when I saw it, I didn't even dare to go inside, really, and after a while I told Jastrow, I'm sorry, I guess we have to stay at Goddard, at Greenbelt, because I don't see how we can find housing here for my wife and myself. And he said, "Just a moment." He was very quick. He went on the phone, and so he said, "Let's go out, jump in my car." He had a car parked, it was towed five times because it always was parked somewhere — OK, so we went, and went on Riverside Drive at 87th St. right at the corner, and there was an apartment hotel, and so he said, "Let's go up . They have a nice apartment, one bedroom and one living room and a kitchenette." The boy was still a baby in a crib. And I said, "OK." Overlooking the Hudson — of course I said, "This is fantastic. But what is the price?" Jastrow said, "Yes, that is the problem $420 a month." In 1961. Imagine. With maid service, including maid service.

Doel:

That's still quite a price.

Priester:

$420 a month! He said, "OK, it's clear you can't pay that out of your grant, so you are supposed to pay $160 by yourself and the other is paid by an allowance from National Research Council." I said, "Under that condition, it's easy to find a place, and here we are." That was it. And we enjoyed it very much indeed, of course. The first thing we did, we cleaned the windows, until we discovered we couldn't (open them?)... We moved in on a Sunday afternoon from Washington. I had a car rented. I didn't have a car in those days and in New York City it's crazy to have a car. And put everything in a big station wagon and moved into that on Sunday afternoon and my wife said, "The first thing we have to do is to clean the windows." We could have asked the manager for a general cleaning and they would have done it. But so —

Doel:

Quite a lot came with the —

Priester:

11th floor, cleaning the window on Sunday afternoon, and people sitting out in the park and looking up, what are these crazy people doing on a Sunday afternoon? Lots of fun. Oh, the time in New York was absolutely extremely efficient and extremely important. Of course, and then I went back and forth, later on, fifty times I crossed the Atlantic, 51 times now, I'm still counting.

Doel:

And this is beginning in 1965, the temporary appointment.

Priester:

This was — the temporary is easy, consultancy actually started in '67, and then I came back and forth, and sometimes for money I had from my own resources, whatever the program really needed to be in those days was not so difficult to get travel support. Nowadays it's very very complicated. You have to ask for at least three months or four months in advance, if you want to have travel money and so on. In those days it was much easier.

Doel:

And of course at this time you were already director of the institute?

Priester:

No, no. I was, in '62 I became, let me see, I had a permanent position.

Doel:

You became professor in 1964 at the Institute.

Priester:

Yes, full professor. I became director of the Institute in '64. Let me just remember it. I was in New York when I got an offer from Bonn that would be, professorship for astrophysics, an opening, and I was number 1 on the list, so I got a letter from the Ministry of Science, from the state of [???], and of course, I told to Bob Jastrow of that, and Jastrow — yes, Jastrow offered me an exempted appointment from NASA, a sort of a counter-measure to make me stay there permanently, and so now I had two offers, what did I want to do ? And by that time, there was the second COSPAR meeting in Florence in '64, so I went to Florence, and on the way back I paid my visit to Bonn, of course, for some time, and also to the Ministry of Science, asking about the situation, and I said, "The only chance to get me back from New York, I have this beautiful offer from NASA with quite a bit more money than a professorship carries in Bonn, only when I get an Institute for Astrophysics and Space Research, because I have this little group of scientists even here working on upper atmosphere physics and I can't leave them in the open, if I am to accept a professorship, I have to have an Institute." So the Institute was created on my request. And of course that put me in the position that I had to accept the offer automatically, and Jastrow said, "OK, I understand the situation, but why don't we make you a consultant to Goddard, and then you can come back and forth and have the advantage of both places, and spread the ideas all over across the Atlantic." It worked very well in those days, and each time between times I spent a couple of weeks or months in New York, and then I came back for teaching here and doing research with the group here, and doing research with the group there, and this was the high time in my life.

Doel:

What direction did you set for the Institute here? What type of research?

Priester:

Oh, you can read it outside; it's stated on the board. No, actually, when I made my agreement with the Ministry of Science, I had set up a two lines, columns, there, the astrophysics and the space research, and the astrophysics is on this floor, and the space research is on the second floor where Peter Blum's office is and Professor Hans’s office. Professor Brimmer is on this floor now, and so, I really made a plan for the astrophysics doing, of course, basically radio astronomy, quasars and of course later on neutron stars came in. Oh, the discovery of the neutron stars, this is also an interesting story which happened when I was in New York. This brings me a little bit out of context here, but it might be an interesting anecdote. In July, '64, there was a time when the moon passed over the Crab Nebula. Of course, it was known that the Crab Nebula is an extended radio source of about three minutes diameter and so on, and in the Institute was Dr. [???], I don't know whether you know him. He got his PhD with Hans Bethe and Tommy Gold in Cornell, and after that came to the Institute for Space Studies, and he had worked on the theory of neutron stars, and of course, it was the idea that inside supernova remnant there had to be a neutron star as a leftover, but of course everybody agreed there was no chance to see that star, because it would be 10 kilometers in diameter and no chance to see it. That was our general idea, of course. And then Herbert Friedman at the Naval Research made his rocket measurements, the X-ray from the Crab Nebula, at the moment the moon passed over, and it was a very critical four minutes, and Honkey was on the phone, right next day, asking Herb, "What did the X-ray, how did it disappear? Did it disappear slowly or did it disappear suddenly?" A neutron star is such a tiny speck, it would — but it disappeared slowly, and the diameter of the X-ray source was about one minute of arc. So, Honkey was very disappointed at that moment, but then we were sitting and everybody else, it was scientifically not very difficult, were sitting saying, "OK, even if there is a neutron star, but the radiation, the radio radiation of the Crab Nebula is done synchrotron radiation from relativistic electrons, and they have to be produced somewhere, and of course a most likely source is a neutron star, with magnetic field around and producing those electrons, and so if the spectrum of the relativistic electrons is such that this spectrum extends up to the l0 to the 12 electron volts, and then of course, you would expect to get X-ray radiation from those electrons which have left the neutron star already, and you can just , with the known magnetic fields you can just calculate what the diameter of the X-ray source should be with that magnetic field, and knowing that the spectrum is just being extrapolated down to l0 to the 12 electron volts, " and it turned out that this would mean that they have a lifetime of only ten years, and since they are spiraling, they could move out just for about one light year, and this is just, see, one minute of arc source. So it still pointed towards a neutron star.

Doel:

What I'd like to ask you, we're going to have to bring this interview fairly quickly to a close — you’ve remained here at Bonn, at the university.

Priester:

Yes.

Doel:

Let me ask you to comment on any major area of research that you would want to briefly mention. What do you feel has been the most important contributions?

Priester:

I'd have to give it some thought. I'd just mention the fields of interest. Of course, in the Institute, I have four, five groups under five professors now. There's the astrophysics section under Professor [???] who sits here on this floor, and my own interest now has shifted since about four years back into cosmology. I wrote my doctor habil thesis in '58, right in the satellite time, on the cosmology of radio sources, and so, I came back to that field about four years ago, and with Hans Blum, I'm writing papers on cosmology. But then, [???] has an interest in astrophysics, and right now it's concentrating on the jets from stars, in the making, very young stars make jets, and even of course the quasars make jets, and the jet phenomenon in astrophysics is right in vogue right now, isn't that so? And of course he's also interested in this strange object, the SS 4 CC, and all these very interesting objects which have very strange energy conditions. And then in the space research section, there is Peter Blum. He is more interested in the upper atmosphere, in the connection to the middle atmosphere and lower atmosphere. Then there is Max who is now editing or chairman of the group for the next COSPAR International Reference Atmosphere, which covers the entire height range from 30 kilometers up to 2000 kilometers, and I was editor of the 1965 edition of COSPAR. There was one in 1961 under the chairmanship of the late Hilda Carman, and I was already in that group, and then in '62 we started with the Harris-Priester series for the upper atmosphere, for the COSPAR International Atmosphere which came out in '65, and then I stepped down from the chairmanship of that group, and turned it over to my good old friend Luigi [???] at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, and he made then the next edition under his chairmanship of the COSPAR International Reference Atmosphere, 1972. I have to look into the library to remember all of the dates. And there was then, since now, almost 15 years, there was no other edition, and the COSPAR group now under the chairmanship of Ken Champion from Air Force Cambridge and Max Planck from his Institute, they have succeeded now to finalize the new COSPAR edition, the COSPAR atmosphere, after 15 years, with all the new data, but there are so many more details now available that it is very very difficult to combine that into one basic model of the upper atmosphere, which should be based partly on theory and mostly on observations, and to mix all this together with all these details, because now the behavior of the upper atmosphere, at heights above 100 kilometers or so, ionosphere, is so complicated, it's like weather on earth, you know. In the early days, we had smoothed it over long areas, over hours and minutes, and of course, the smooth behavior, that is known now and very well known, how it behaves with solar activity and how it behaves with the hour of the day and how it behaves with latitude and longitude and so on. But the details now are so complicated that it will be probably a very big book. But this is being done, partly the editing here at this Institute, and this international group, Americans and Russians and British and from Belgium and whatever. I remember — no, I don't tell the story, with the FBI.

Doel:

It might be better if you do.

Priester:

It doesn't matter. Nowadays I could tell it. It concerns the Russian fellows. But, I can tell you at lunch time. Yes, and then Hans is doing the interplanetary connections, the solar wind connection with the interstellar matters, the [???] charged change processes which take place when the solar wind collides, you see, with interstellar matter outside the solar system, and this is about the general field of physics.

Doel:

One final question I'd like to ask you. You talked in particular about your early research and what you did —

Priester:

I'm getting old now.

Doel:

— your early, a lot of experience — but also what you were doing at the Goddard Institute, and in the early sixties. Is there anything that you would like to add to the tape that we didn't cover, anything you feel is particularly important?

Priester:

In the seventies?

Doel:

In the sixties or seventies that you would want to mention.

Priester:

I was most of the time chairman or president or something like that, president of the Astronomical [???], which is the German Astronomical Society. That means the Astronomical Society of the German Speaking People, because it also covers the German part of Switzerland and Austria and so on. But , and then I was dean of the faculty and all this kind of management which was sort of, for my own personal research, sort of a bad time, I would say, because it kept you away from your area of research, and it's only in the last years that I really went back into it by getting interested in cosmology, particularly now in the possibility that the quantum field vacuum might play an important role in cosmology, and — but this is all still in the making, and I don't think we should really put that on tape.

Doel:

We can save that for a later time. How much time proportionally have you been spending in administration?

Priester:

It was different in different years. When I was dean of the faculty, that meant that almost all my time was spent in management, and the president of the Astronomical Society didn't take too much time, but all this — and then sitting on all these commissions at the Ministry of Science for deciding priorities for research money and so on, to build a certain meter radio telescope, on the peak of [???], and so on, to decide about the [???], in these groups, they have priorities of all the big spending in money for nuclear or elementary particle research, the installation at Hamburg, the big nuclear elementary particle research installation, and all, even to send up a new satellite probe like Helios or so, which is very expensive, and all this had to be decided by commissions, and there were many many meetings, and all even to get the money for the Rosa [???] satellites, the [???] telescope, which is now in trouble because of the Challenger catastrophe. So in the, I would say in the seventies, yes, the seventies, for research, my own research, was a bad time, because I have to look into my notes, whether I did something to speak of. I couldn't remember anything in the seventies. Is anything said about that? Is this all I sent you?

Doel:

It certainly was a very administratively busy period.

Priester:

Yes, it certainly was. Let me see, now. OK, there is nothing really important in the seventies. It's only now that I really get back into research by doing cosmology. A couple in the last four years or so.

Doel:

Unfortunately we've run out of time in this interview, but I'd like to thank you very very much, Professor Priester, for the time for this interview, and I would like to add, and put this on tape, that you will be receiving the form from the American Institute of Physics covering possible access to this interview, and you will of course retain full editorial control of the contents and access to it. We'll have that sent to you.