Oral History Transcript — Dr. Herbert Friedman
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Hirsh:First if we would ask you about some things in your early life. We know you were born in New York in 1916, but we know very little else about your family. Could you tell me about your parents; what did they do?
My father was born in Indiana. The family gradually drifted East. His education probably never got beyond 6th or 7th grade. He went to work as an early teenager. He got involved with peddling pictures -- prints of various sorts of a religious nature -- and eventually reached the point where he could set up his own shop for picture framing. As time went on, his operation improved to the point where he did business with galleries like the Whitney Gallery, which was in the lower part of Manhattan. His shop as I recall, was on 9th St. near the old Wanamaker Building. The Whitney Gallery was a block or so away. He used to set up exhibits for many artists who at that time were penniless and often paid the costs of the work he did for them in IOU’s, and later became quite famous. Those were the WPA [Work Projects Administration, an agency of the federal government established during the depression of the 1930s] days. My mother came from Russia as a young girl. I think she came alone at age 17, and she had the typical immigrant experience in New York. She always was interested in education and languages.
When she came she spoke Russian and Polish. Later on in life, because the family was strongly Zionist, she learned Hebrew. She did this by having a Hebrew speaking young woman stay with us as a boarder who paid for her room and board by teaching my mother Hebrew. I was able in my early years in science to send her papers written in Russian and have her translate them for me. She retained that ability to the end of her life, even though she had nobody to speak Russian to. I would describe the family as middle class. They were never financially affluent. They sort of scraped by. My father was a very orthodox Jew, and the family adhered to his requirements. I had an older sister and a younger brother, and while my father was generous and lenient in most all respects, he tolerated very little conflict with his religious requirements at home. My mother had a liberal attitudes but she felt his needs were the highest priority, and so she went along with it. She maintained a kosher home. All of the children, myself included, broke away from that in the sense that we didn’t follow any pious activities., but we remain culturally strongly Jewish and strongly sympathetic with Zionism and Israel.
Hirsh:Can you tell me whether you read a lot in your childhood? Do you remember any specific books on science that you read?
Friedman:There were no scientists in the family as far back as one can trace the family tree. The tradition was scholarly but of a Talmudic type of scholarly activity, and so I went to Hebrew school before I entered kindergarten. I can’t remember much except that I couldn’t even see over the seat in front of me. I was that young and small. And I continued with that kind of a Hebrew education along with the public schools until I was well into my teens, through Hebrew high school parallel with the normal high school. I was always interested in reading, I also had some talent as an artist and the family recognized it. I went to a free art school. I think it was the Educational Alliance Art School which was on the Lower East Side of New York. It had a good staff. In retrospect I can’t remember very much-- that is. I wasn’t terribly stimulated. I spent a great deal of time doing the usual thing, which was taking classic busts and doing charcoal renderings of them and everything was very rigid -- a classical type of art training,
Hirsh:But science did not enter your life at that time?
There was no intimation that I would end up as a scientist trying to earn my living that way. I did well at school, beginning with elementary school. The result was that I was sent to Boys High School In Brooklyn. The Boys High School was sort of an elitist school. It specialized in mathematics, classics. The bright students in the city generally went to Boys High. I guess I liked math. It came easily. The in our financial circumstances, there was never any question of my going to a private school. The routine was to live at home and go on to free public college, and for those of us who lived in Brooklyn, it was Brooklyn College. If you lived in Manhattan you went to City College. And there, I had no direction to my work. I started out as an art major. I continued to take math because it seemed like an easy course, and I enjoyed it. By the time I had finished my sophomore year, I had decided that I really didn’t want to continue as an art major. For one thing, I was the only boy in classes that were otherwise all female.
The teachers were all women. I seemed lost in that environment and I felt very uncomfortable. I finally took required science -- a physic course -- and found I liked it very much. I decided in my junior year to take some physics electives. There was a very good teacher there, Bernhardt Kurrelmeyer. I latched onto him and took almost nothing but physics, with some math in the last two years. By the time I graduated I was a physics major. But I still had no idea of going on with graduate work. There were all told about ten physics majors in what must have been a school population between 10 and 20 thousand at that time. Physicists were in no demand. The best thing one could do was high school teaching as a livelihood. I had taken the education courses for that. But teaching openings were extremely scarce.
Hirsh:This was in ‘36 when you graduated.
Friedman:‘36. During the summer after I graduated, I hunted for a job in commercial art -- totally without success. I kept in touch with Dr. Kurrelmeyer and made application for graduate work at Johns Hopkins, which was his alma mater, and Cal Tech. I applied to Cal Tech because I had a buddy at that time, Martin Summerfield, who was another physics major in the same class, and towards the end of the summer I had about decided to go along with Summerfield to Cal Tech. And then Kurrelmeyer, I suppose, was influential in getting me an offer of a graduate instructorship at Hopkins. It was a typical arrangement where you got your tuition and were paid a small sum for teaching undergraduate laboratory. Well, the family made the decision for me. In those days it cost about $2.50 to go to Baltimore from New York. It cost $40 to go to California. My mother felt, if I ever got that far away, I'd never come back, so insisted I go to Hopkins. There was a difference. At Cal Tech I was offered a tuition scholarship, but had no provision for earning any additional money, and that was a factor too. Well, that's how I got to Hopkins.
Hirsh:How do you think your background in art might have affected your career as a scientist or you scientific thought?
Friedman:I remember enjoying laboratory courses very much and doing elegant drawings of laboratory setups every time I wrote a report. That is about the a closest connection. I did very well with work in microscopy because I could draw what I saw. I think I even earned some money doing this. The National Youth Organization in that time offered students some meager income for assisting professors in whatever work they wanted to give them, and I produced some drawings for various research projects. That’s about all the connection there was with the art.
Hirsh:When did you make the drawing of Einstein sitting behind you?
Friedman:That’s probably high school era, when he first came to this country.
Hirsh:Was there much discussion in your family about Einstein and modern science?
Friedman:Well, not science, but Einstein was a Jewish hero, of course. He supported the idea of Zionism. He was recognized from the time he first came here, but nobody understood just what it was he did. I often tell how my mother would describe what I did. When friends would ask “What does your son do?” – she'd say, he’s a physicist. "What is a physicist? "Oh, he does what Einstein does.
Hirsh:Do you remember whether there were people at Brooklyn College besides the professor whom you kept in touch with afterwards? Were there colleagues in physics, for example?
Friedman:The only one I kept in touch with was Summerfield. He was successful in the same sense that I was, that we managed to stay with physics and receive our PhDs and get into research and so remain in touch through the research world. I don’t know of any other student in my era who, let's say, made it in the straightforward way. They probably succeeded by getting into some form of technology in industry or taught in small colleges, but not in the research world. So when I look back now, I can hardly even recall names. With a struggle I can dig them up, but I can’t identify any of them with a reputation for research.
Hirsh:When you went to Hopkins what sort of life did you expect to lead as a scientist? You had obviously made a commitment now to enter a scientific career, I suppose.
Friedman:Without question., once I went into graduate work, it was with the understanding that I would get a PhD, although what I would do with a PhD after I got it was still very very vague. The only thing which was straightforward was teaching, and positions in the universities were still very very difficult to get.
Hirsh:Did you see yourself becoming an experimentalist, a theorist, a specialist in solid state?
Friedman:I didn't know. I enjoyed experimental work. Maybe that was connected with the artistic talent or whatever it was. I could design things elegantly and I liked doing that. I wasn't prejudiced against going into theoretical work, but the professors I became connected with were experimentalists. What I remember most vividly is coming into the physics department at Hopkins, the day I arrived., and identifying myself as a new grad student. The secretary took me down to see Professor James Franck. I hardly knew who he was at that time. He was a Nobel Prize winner and a truly great man. And he had a very fatherly look about him -- sort of a portly handsome man, smoked a big cigar, ashes kept falling on his vest, he was totally indifferent to it --but he was very relaxed, and talked to me for about two hours. I appreciated only later on what it meant to have two hours of James Franck's time and that kind of discussion with a new student. He tried to understand what my aptitudes might be, and to prescribe courses for me, and sort of generally indicate the direction I might take. I had never experienced anything like that previously. I had developed a strong personal relationship with Kurrelmeyer at Brooklyn, but that was just a strictly individual thing. At Hopkins, this kind of relationship with professors was the norm.
Hirsh:What did Franck tell you, as far as career directions?
Friedman:Well, he laid out a course of study, which was a basic grounding in physics at that time, and suggested that I look into various laboratories, to get a feel for myself of what looked exciting to me. There was no attempt really to make a rigid prescription. I got through my course work at Hopkins without any strain. I think one was Barnes and Noble.... I also remember Billy Minsky’s burlesque. When we lined up for registration at Brooklyn College, his representative was on hard to give us all free passes. It was directly across the street from the building in which we were registering. All of Brooklyn College was downtown in those days. Hopkins had a wonderful faculty in those days. Mathematicians: there was Zarisky, and Murnoghan, and Wintner. In the physics department we had Franck and Herman Pfund and R.W. Wood and Hertzfeld , Maria Mayer, Dave Inglis, John Hubbard and Joyce Bearden. We had about one graduate student per professor. So it was very comfortable and, very tightly knit group of students and faculty.
Hirsh:What was it like to be in grad school during the Depression? You wee there toward the end of the Depression, sure, but it was still a rough time.
Friedman:One of the faculty who was especially helpful to me was John Charles Hubbard. He worried about my personal situation, and got me a job as a proctor in the dormitory, so that took care of my housing and food for that first year. By the second year, I got raised to $40 a month, and that was enough so that I could rent a place with a couple of other graduate students, and get along very comfortably. One of the students who shared the apartment with me was Bill Beeman [William W. Beeman], and we remained roommates for three years, until we both got our degrees and left. I recall our room rent was something like $12 a month. On $40 a month, it was no financial strain. Also, we were totally absorbed in our work, so there was little question of money. None of us owned automobiles. We walked wherever we had to go. Life was filled up almost completely with studies .
Hirsh:Who did you latch onto as an advisor?
I decided to do my thesis work with Franck. At that time Franck had become very interested in photosynthesis. He was willing to take me on, and I was just about getting organized to start my research work with him when he moved to Chicago. They set up the Franck Institute there. However, there was no provision for fellowships for students in the new Institute immediately, and I just couldn't afford to leave Hopkins without some income. So I looked around and found an empty lab room in Bearden’s [J.A. Bearden] area, and asked Bearden if I could work under his direction. He was happy to have me take over that room with whatever equipment was in it. He didn't prescribe any thesis project for me. He just thought I would play around and then at some later point we could talk about it. The equipment in the room included a very high quality Geneva Society precision spectrometer, an instrument for making precise X-ray wavelength measurements. At that time there was a growing interest in solid state physics.
People like Slater at MIT were developing the theory of metal physics, the idea of Brillouion zones, conduction bands and so on. There had been some pioneering work done in X-ray spectroscopy of solids to try to understand the Brillouion zone structure as it was revealed by the structure of X-ray absorption edges. That seemed interesting to me, and with the prospect of having this fine spectrometer there for my use, I decided I would try to set up whatever I needed to make very high resolution studies of X-ray absorption edges. In those days, one made his own X-ray tubes, continuously pumped. For detector we used ionization chambers with electrometer tubes -- that famous or infamous FP54 electrometer tube -- which was the standard amplifier for an ionization chamber. It was a frustrating thing to try to make measurements at very low intensities, because typically with an ionization chamber electrometer, you try to count X-ray photons, or rather you try to see the current from X-ray photons, which are weakly ionizing. An alpha particle or a cosmic ray will come through and give the electrometer a blast. The pointer will slowly swing off scale and then drift back.. taking minutes to recover, and so the work went very very slowly.
I tried this just brief ly and realized it was not going to be a good way to work with very low intensities and with high resolution. Some work had been going on with Geiger counters at that times and I developed a counter which was ideal for X-rays. It had a re-entrant bubble--a very thin window at the front end -- and a long absorption path, say 10 or 15 centimeters. .... So that if it were filled with a high- pressure of a gas like argon, plus some quenching agents it would be very efficient for absorbing soft X-rays. I guess the trick there was to achieve fillings which permitted almost a full atmosphere of argon in the tube, and still get good counting, good quenching,, and have a short dead time.
Hirsh:These then were pretty innovative methods.....
Friedman:These were innovative at that time. Nobody had done X-ray spectroscopy with that type of detector. The other problem was electronic counting. Counting circuits were typically thyrotron circuits -- a ring circuit of the Winn-Williams type. We had to build those ourselves. It took a 1ot of tinkering, and I was not trained in electronics. It was a matter of making things more by instinct than by engineering design. So my effort in the research lab was to devise the counter and the electronic system to go with it, and then just go ahead and make measurements because the X-ray tube was there, the technique for pumping and so on was all developed, and this beautiful spectrometer was available. I found almost immediately that I could resolve structure in the absorption edge of the transition metals, and that I could theoretically relate that structure to Slater’s theories of the distribution of electrons in the valence conduction band, and in the bands of the inner shell electrons, so that I had a nice experimental proof of the predictions of the theory.
Hirsh:So you got onto your dissertation research partly because the equipment and all was there, and because of your own reading. Again you were not assigned a thesis topic?
Friedman:That's right. There was a room available in the X-ray laboratory. The equipment was there. I was offered the privilege of just going ahead and playing around with it, and chose this subject myself. Within a month I had enough data to write a thesis. It went very well. In fact.. almost before Beardon had a chance to discuss anything with me, I had it all there. About that time my roommate, Bill Beeman, had also passed his preliminary examinations and joined me in the same laboratory. We had the idea that if the absorption edge showed that structure, then the emission band should show complementary structure. We agreed we would look at the emission band as well as the as the absorption band, but we made no pre-arrangement about how we would use the research. It ended up where we completed another paper on the emission bands fairly quickly, and then tossed a coin to see who would get the first crack at a thesis paper. I won the toss and made an agreement that I would later work out the next paper with Beeman. So I got my PhD on the first paper -- the absorption edge paper --and Beeman on the second paper, although we published them both joint. Then we felt an obligation to do something with Bearden, so we wrote a third paper on alloyed materials. I think that was about it for the research at Hopkins.
Hirsh:So that first paper of yours was actually the thesis itself?
Hirsh:Do you recall the title of that?
Friedman:It was probably Beeman and
Friedman:, because for the privilege of getting the thesis first, I put his name first.
Hirsh:Was it this?
Friedman:That's it, yes. There were a couple. Then there should have been a
Friedman:and Beeman one on the emission structure.
Hirsh:That was “The X-Ray K-Absorption Edges of the Elements Fe(26) to Ge(32).” Let me ask about Bearden’s. influence on the thesis. He did not have very much influence on it. You came to him with the finished product ?
Hirsh:Did he did have other students ?
Friedman:Yes, he had other students. For years afterwards he had a whole string of students who did similar research on the structure of the absorption edges of the metals, alloys, gases and liquids. That kind of work still goes on today. I occasionally have somebody send me a copy of a thesis referencing that early work as though I were still doing it. There will be more of it, because synchrotron radiation from particle accelerators provides very strong X-ray continuum sources. It makes this work comparatively easy. You can do very high resolution work and study the absorption edge structure out to very great distances from the edge. It's become a popular subject again -- to study the effect of chemical composition on absorption edges.
Hirsh:What were you thinking toward the end of your career at Hopkins?
Friedman:Just "a job. " In those days hardly anybody specified what kind of job he wanted. Jobs were scarce, and you wanted a respectable job, which meant an instructorship at a university, or a job in an industrial research lab. We made applications in both areas. There was a lot of anti-Semitism in the physical sciences and engineering fields in those days. I found out almost immediately that I couldn’t even get an interview at places like Bell Labs or GE and Westinghouse.
Hirsh:Just because you were Jewish?
Friedman:Because, any other student could and I couldn't. And yet as far as the department rating went, I was probably close to the top of the list of graduate students. Hopkins had never had any difficulty in placing its students, because it was a great department and well respected all over the country. So I became sort of an embarrassment, as time went on when every other student got his job and I didn't. In the case of Bill Beeman, who is not Jewish, he suffered from association with me -- the combination
. People played it safe from the anti-Semitic point of view. If there was any suspicions, they would avoid asking to find out exactly who was Jewish. There was an instructor’s position open at MlT, but the question came back to Dave Inglis, at Hopkins, "Is Beeman Jewish?” (Beeman applied for the job.) He didn’t get the job. He was a very good student, and we had worked in this field that Slater had developed. There was a lot of activity at MIT. It was a natural place for one of us to go. And Beeman had been interviewed but hadn't been asked that question. The question came indirectly. Inglis's response was, "I really don't know, " and that was typical of him. It would have made no difference to him. He would never think of asking. Well, he said he didn't know, and that was perhaps taken to mean that probably Beeman was Jewish, so he didn't get the job.
Beeman was a General Motors Fellow at Hopkins. He had an understanding that he would go back to work for them, which he finally did. He worked for them for a year or two and then went to a position at Wisconsin, and he’s been there ever since. But I languished without a job. I tried to do some research at Hopkins that summer. Bearden had heard that one of the local companies, the Rustless Iron and Steel Company, which specialized in making stainless steel, was interested in the process of electrolytic polishing -- interested in scientific studies of what the mechanism really was. So I started to work on that problem, and Beardon got their people to come in and talk to me. They were very interested in following what I was doing, and I thought, well, now I've got a job. At the end of the summer they told me they had 30 chemists in the laboratory and no physicist. They really were not sure they had enough work to support a physicist full time. So that opportunity vanished.
Hirsh:Were you by this time getting bitter about it?
Friedman:I was getting a little bitter.
Hirsh:Do you think that the problem with the steel company had anything to do with your being Jewish?
I don't know. But I think they could have risked one physicist in a laboratory of 30 chemists. By this time Herman Pfund, with whom I had not done any research -- but I'd taken courses with him, and of course every professor knew every student -- was becoming rather irritated. The idea that a good Hopkins PhD could not get a job was an insult to the university. So he started to try to find positions for me. He thought he had found one at the University of Pittsburgh. That didn’t materialize. Pfund had put a lot of his students into industrial positions, places like Dupont. He was a consultant to many of these companies. He finally got me the job here at NRL [Naval Research Laboratory] because Dick Canfield, who was superintendent of metallurgy, was one of his former students. I think he called Canfield and said., "You give Friedman: a job," and that was it. Although to Pfund, that was still an indignity -- he thought working for the government was really a second class profession. I should have worked for Dupont. That would have been first class. Apparently, he wasn't about to get me in there.
So, I came to NRL. I should say that I applied to the civil service, and about that time, physicists were beginning to come to Washington. The Washington Navy Yard had a big program in de-gaussing. Roosevelt had leased the 90 destroyers to the British, and there was the big problem, how to protect ships from submarine attack. The major effort here was de-gaussing of ships. So I went to the Navy Yard and had an interview, and at the end of the interview I was asked, whom I was going to vote for in the Presidential election. I innocently replied "Roosevelt, and my interviewer turned cold. I didn't get the job.
Hirsh:I don’t think they could ask you that any more.
Friedman:No. He’d be in deep trouble if he asked me that today. But all of those things added up to a real frustration. Also, I wanted to get married at that point. I’d known my wife about two years. She was teaching at Brooklyn College, and until I got a job there was no question about that. So that added to the irritation.
Hirsh:So when you came here did you feel like this was a place of last resort? How did you feel about the job?
Well, when I came in I found people here like John Sanderson. There were a lot of Hopkins people here. Hopkins had been the major source of PhD for people who worked in the Washington area -- Bureau of Standards, Department of Agricultures, Naval Research -- and there were several people here who had Hopkins backgrounds and of course were very friendly to me as a Hopkins alumnus. So I felt comfortable in that sense almost immediately. They went out of their way to help me. On the other hand, the day I arrived, Canfield left., and while he was a very good physical metallurgists, and we had talked about what I might do generally in the new solid state physics, the man who replaced him -- I forget his name now -- F.M. Walters. He was the kind of person you easily forget.
He was an old fashioned what you would call cookbook metallurgists and I think he was worried about having a modern physicist come in, somebody trained., up to date, who knew metal physics. He really didn't know what to do with me, and wished I hadn't shown up. He put me in with Herman Kaiser, who headed up the nondestructive testing laboratory. This included all sorts of applications of X-rays and gamma rays. The Navy had pioneered in the development of gamma ray radiography, and it was very important, because we were getting into an intensive shipbuilding program. Failures in valves and castings could be costly and catastrophic. They needed nondestructive methods of looking at cracks in welds and that sort of thing. Like a good soldier, or sailor, I went to work on these things, and tried to devise more efficient methods of nondestructive testing. I had experience with Geiger counters, and I felt that X-rays and Geiger counters and proportional counters were a good combination for high speed nondestructive testing. I don't know whether we want to go into that at this time, but there were many many applications that came along rapidly which were practical, and where I could make a useful contribution. At that time, I was able to develop the laboratory setup for studying discharges in gases -- sort of a fundamental problem with gaseous detectors for ionizing radiation.
The situation in metallurgy was unpleasant because, while I was happy to do something useful, it was not very elegant physics, and I was looking for other things to do. About that time, electron microscopy had reached the point where RCA was ready to manufacture a commercial version of a microscope, and the laboratory was interested in getting possibly the first one that came off their production line. The plan was that it would go into chemistry. I'm trying to remember my dates right. And Dr. Borgstrom, who was superintendent of chemistry had gotten to know me through some of his people. I had struck up close friendships with a number of the chemists. They occupied the same building as the metallurgists -- were just across the hall. People like Bill Zisman who was as much a physicist as a chemist, and Pete King who was a very ingenious physical chemist, were good friends. So we talked about the possibility of my moving over into chemistry provided they got an electron microscope, and I would be responsible for the program in electron microscopy. Well, that was going very slowly. I heard that there was a possibility for a job at the Bureau of Standards which would truly be metallurgical research -- physical metallurgy.
I was interviewed there and they were willing to offer me a job. I remember coming back here and having lunch with Dr. Hulburt [Edward O. Hulburt] who was head of the optics division. I'd gotten to know him quite well as a former Hopkins man. And I used to enjoy the talks we had. He really was a great physicist. I told him that I was going to take the job at the Bureau of Standards. He didn't say anything at that point, but after lunch he went up to the director of the laboratory – the commanding officer – and asked permission to offer me a job, and in particular for the optics division to get the electron microscope and set up a branch of electron optics, and appoint me branch head. He got approval to do just that in this quick conversation after lunch, came back., found me, and asked me if I would charge my mind about leaving if I could work with him. I was of course delighted to do that. So it by the barest margin that I stayed on here at NRL and got out of metallurgy and into an entirely different kind of work.
Hirsh:How did you feel about the war in Europe in 1940? Did you feel the United States should have entered the war earlier? What kind of news was coming out of Europe?
Friedman:It was clear that we would get into the war. I recall that within the family at home, from 1933 on, we looked on the Hitler regime as the world’s greatest catastrophe, and it was clear in 1940 that we were moving towards war. The National Defense Research Council had been set up. In fact I neglected to mention a phase when I was still at Hopkins – after that first summer of working on electrolytic polishing. I got an NDRC job to work on the proximity fuse. Merle Tuve was the key person in that program. Bearden was heavily involved in it. There were three approaches: one was optical, the other was essentially a radar fuse, and the third was an acoustic fuse. I worked on both the optical and the acoustic fuse. Neither one of those ever became practical. And I got out of that program when I came to NRL.. It was clear from that time that the work on the proximity fuse, degaussing projects and so on, were all part of an attempt to prepare ourselves militarily to get into the war.
Hirsh:Did you ever think of enlisting as a soldier once the war began?
Friedman:I was here at NRL, and all of us thought about the problem of enlisting. Everybody felt a duty and obligation to serve the country then. It was the honorable thing to do. The war against the Nazis was something that the whole civilized world had to carry on. There was no question of what was right and what was wrong. The right thing to do was to do your part to beat the Nazis. Here at NRL the decision was made to put everybody into uniform. By ‘42, I was already involved in work which was being done with uniformed people. I was working with two naval officers who had the rank of lieutenant commanders. If I were to go into uniform, I would be an ensign because of my age. So the administration held off. I was one of very few people here who did not get into uniform because of the awkwardness of the situation -- my taking the rank of ensign and having to give instructions to officers two or three ranks higher. As a result, I never got into uniform. But I believe that 98 percent of the people of my age here did serve through the whole war in uniform at NRL.
Hirsh:What did it feel like to be working in obstensively a military organization during the war? Were there any censorship problem? Were you ever inhibited by the military?
No. It was an exhilarating experience, because problems kept coming in here from everywhere. These were problems of great practical importance for the war effort, and if you could see your way to solving one of those problems, you had the feeling you were doing something to justify your being here and not out on the front exposed to enemy weapons the way other young men were. There were lots of problems, and a surprising number of them were solvable technically and useful in the war effort. One which was most useful was the development of equipment to produce quartz crystal oscillator plates. When we got into the war, the Signal Corps had been using communications equipment controlled by quartz crystal oscillators, and all of the Army aircraft equipment -- all the various communications channels -- were controlled by crystals. But the Japanese had scooped us by going into Brazil before Pearl Harbor and removing all of the good crystalline quartz, all of the well faced quartz.
The procedure for making an oscillator plate in those days was to find the optic axis from the faces, and then make the cut relative to the faces and the optic axis. Then you put it into an oscillator and ran it through a temperature test in an oven, which could take one or several hours to see how the frequency deviated with temperature. What you wanted of course was a cut which was so precise that the frequency was relatively unaffected by temperature. But the procedure was to see how big the deviation was, pull the crystal out, polish the face to make a correction, put it back in the oven and run a test again. It was all terribly slow. We found that the only quartz available to us from Colorado, for instance, was generally poor grade, in terms of having large clean faces, and we were desperately in need of a method of making the orientations for cutting without having good faces to work with. When the problem was brought to us here, I thought immediately that I could do it with X-rays, and so I made a setup with a simple gonionmeter, a proportional counter, and X-ray tube, and showed that you could find the reflecting planes without having a good optical face and that one could cut the crystal with almost no error.
This procedure was then passed on to the various X-ray manufactures like Picker X-ray and GE and the Phillips Company. The only one that wanted to talk seriously to me about it was the Phillips Company. The others thought they could develop their own techniques and went ahead with ionization chamber devices. Phillips sent its people down here to see how we did it. The kind of proportional counter with a re-entrant bubble tube in it that I used was not a commercial tube, so we agreed to make several hundred tubes here if they would go ahead and manufacture the X-ray equipments, and the tubes which we supplied would be given to the Signal Corps and the Signal Corps would provide them to the industry. That worked extremely well. The total effort to set up a demonstration to prove the method took about two days, and in the end, I received a medal and a citation which said that this procedure had saved 50 million man hours of labor, which of course is a little absurd. We never would have had 50 million man hours, but to produce that many crystals with that precision with the old technique would have taken that much time.
Hirsh:Were a lot of these procedures published after the war?
Friedman:Yes. And it was adopted commercially everywhere. It still is used today. That is the standard method.
Hirsh:Did you patent that method?
Friedman:I didn't patent it. I didn't know about patents in those days.
Hirsh:I know you have a number of patents.
Friedman:I learned about patents afterwards. But during the war we didn’t think about those things . We never thought about it at the university. The government took rights to all the patents. The government was very liberal then. It gave commercial rights to the inventors, and if I had realized that this invention would have continuing commercial use afterwards, I undoubtedly would have made an effort to patent the invention. But I was very naive.
Hirsh:Did you hear about the new diffusion process for uranium?
Hirsh:When did you hear about that work?
Friedman:Well, the key people then were Ross Gun and Phil Ableson. And they were only one building away. And the story was around, that they were trying to develop a diffusion method to separate uranium isotopes. We did not know that that was connected with a bomb project.
Hirsh:Were you aware of the bomb-project, the Manhattan Project ?
Friedman:No. We knew of the Manhattan Project, the metallurgical Laboratory at Chicago, and Oak Ridge, but we didn't know what they were doing there.
Hirsh:So it really was a well kept secret.
Friedman:It was a very well kept secret.
Hirsh:But you knew of the people working on the diffusion process.
Hirsh:But again you didn't know what they were doing it for.
Hirsh:Did they know what they were doing it for?
Friedman:Ableson and Gunn did. But probably nobody else in the group.
Hirsh:After the war you did work on developing detectors for radiation, for bomb tests, isn't that right ?
Immediately after the bombing of Japan, we wanted to send in survey teams to map out the distribution of radioactivity from the epicenter of the bomb, and that team was headed by Shields Warren, a distinguished pathologist who died just a couple of months ago. (He was a Navy captain on duty at the medical center at Bethesda.) I had made a number of devices and actually published descriptions of them – of a portable nature, for exposure meters, for checking out the distribution of scattered radiation around X-ray and gamma ray facilities. Surprisingly, there didn’t seem to be any instruments of this type in the atomic energy project. They had all sorts of instruments for measuring radioactivity, but not portable battery operated devices. So Shield Warren and his group were directed here, and we put together some radiation devices, calibrated them, and equipped their team to make the survey of Hiroshima and Nagasaki. From there on, of course, the Navy had a great concern for radiation problems connected with atomic warfare. How to decontaminate ships and other facilities which had been exposed to atomic bomb attack, and generally how to monitor areas for contamination. The Bureau of Ships set up a program with us and we worked with them for many years developing a whole catalogue of radiation devices for different kinds of radiation. That became standard Navy equipment.
We were also interested in the bomb tests themselves. Hulburt and Sanderson and others in the optics division went out to the Bikini test to make various radiation measurements, and I suggested to Hulburt then that we could make radiation dosage measurements with glass. During the work on the quartz crystal plates, a technique was developed - not by us - for making final adjustments by irradiating the crystal. We found that you not only charged the frequency with a heavy dose of radiation., but introduced a coloration in the crystal. In crystaltine material that coloration remained fairly stable. In ordinary window glass or Pyrex glass, the sensitivity to radiation was high. The glass became fogged, blackened, but it would then return to its normal state in a few days. So I studied a variety of glasses, and I think silica glass -- vicor -- turned out to have a reasonable combination of sensitivity and stability, and so we made capsules with rods of vicor, which were exposed at the Bikini test, brought back here, and then you could simply make an optical transmission measurement to get the dose that the glass had received. We were also aware of thermo-luminescence effects, and as a result, other groups from the laboratory here, primarily under Dr. Schulman, initiated programs to develop especially sensitive phosphate glasses and thermo-luminescent devices for radiation dosimeters and those are standard radiation personnel badges these days.
Hirsh:I'm really seeing., by the way, how things are coming together, because some of those thermal luminescent phosphors were then used in space research.
Yes. In fact, that came first. It was known that calcium sulphate manganese was a thermo-luminescent material that could be activated by short wavelength radiation. Theodore Lyman had discovered that back around 1912, ‘13 and so it was thought that that might be used an dosimeter for shortwave radiation in rocket flights directed at the sun. Dr. Tousey’s group pursued that. Ken Watanabe was one of the physicists in our group here, and he undertook to make a thermo-luminescent dosimeter for solar radiation. Before we leave Bikini.... there was a major involvement in setting up a monitoring system for a Russian weapons test. We know that they were working on the development of a bomb and we received intelligence reports estimating where they were at any particular time. A group was met up in the Air Force – the Air Force Special Weapons Project, AFSW – to take the responsibility for developing a monitoring network . They had no laboratory, and so they couldn't conduct a program for developing such a system themselves, and they were directed to ONR. ORN sent them over to us, and we talked with them about possible ways of doing it. In the beginning, we thought of a lot of obvious things, like sending up balloons equipped with filter papers that would pick up debris in the atmosphere, using filter papers and blowers on the ground to pull air through and look for particulate debris from a weapons test. We had a lot of expertise here in filter paper work in the chemical warfare group.
Since I had a lot of experience with radiation detection., I undertook to devise various detectors that could be placed on the ground or in the air. The first approach was to see how large a bank – how sensitive a bank of detectors for typical gamma rays emitted by fission products – ,we could put together. We devised a unit which had Geiger counters about that long, two inches in diameter, in stacks of maybe a dozen, all bound together to make one very large sensitive counter. And we set those out around the laboratory just to see what normal conditions were like – what natural radioactivity was like. I decided to put a pan over one of these banks and let rainwater accumulate in it. We found that when it rained the signal went up very markedly, very dramatically. Clearly, rain was efficient In taking the natural radon, radim B, out of the atmosphere by scavenging it. It didn't take us very long to decide that was probably the most efficient method that one could devise. I went to my chemist friends then, Pete King in particular, and asked him how well a chemist could separate radioactive material from water– particulate material from water.
His off the cuff estimate was startling – the concentration factor could be something like 1018 with chemical methods. So we began to think seriously of what we might do. We went over to Dalecarlia. The standard method was a flocking technique; aluminum hydroxide placed in the water would precipitate all the particulate material in a sludge– flock. And they were using that technique at Dalecarlia. We took some of the sludge off the bottom of the reservoir and brought it back here. Dr. Gilbrandson was an expert on rare earth chemistry. We asked him to separate cerium and yttrium for us. He succeeded very quickly, and I put the separate under a Geiger counter. It went wild. So we had an enormous amount of radioactivity – fission products – in the sludge at Dalecarlia. Of course the water was perfectly clean, purified by the flocking technique. There was no danger from drinking the water. From there on, we went ahead very vigorously, and planned on setting up water collection stations at all the air weather stations. We did two things before that. We sent a chemist, Luther Lockhart down to the Virgin Inlands–St. Thomas– where they have a large rain collection reservoir, took material from there, and also went up to Kodiak, Alaska where they have large ponds of drinking water. In each came we found evidence for large amounts of fission products. From the ratio of cerium, yttrium and ruthenium, we could identify the kind of bomb. These were Bikini test fission products. We decided to go ahead then with what we called Project Rainbarrel. We bought Sears Roebuck corrugated roofing, and then arranged it so that the runoff would be collected in large 100 gallon drums, and each station was instructed when rain fills the drum, you put so many grams of the flocking aluminum hydroxide in, let it settle, drain it off, and send us a bottle of the floc which became a routine procedure.
We also set out our large banks of gamma ray detectors at each weather station, so they had both rainbarrel and the direct measurement of radioactivity on the ground. When the Russians fired their first shot, the jet stream carried it over the Aleutian Islands. We got a large signal on the gamma ray detectors on the ground. We knew immediately, that something very special had happened, and sent some of our people up to supervise the flocking . They brought back the material, and we established right away a high radioactivity in cerium, ruthenium, and yttrium. Luther Lockhart undertook to separate out plutonium – to see if they'd used plutonium. The plutonium chemistry then was a great secret, and supposedly it had taken an awful lot of research to develop it. Lockhart was able within two days to separate out plutonium, which is quite an achievement, and we could identify it as plutonium from the range of the alpha particle. We had the full story within a couple of days. There was a committee set up by the AFSWP to evaluate the evidence. Oppenheimer was chairman of the committee. We presented our results to that committee and Oppenheimer took them to Truman. He and the committee decided we had made a correct identification. Truman decided in his own wisdom that he was not going to reveal how it had been done. He wanted the impression left that we had spies all over Russia, and we knew that they had fired the bomb through espionage. And that's the way it remained. The work was classified, wasn’t declassified until some ten yea re later.
Hirsh:Do you think the Russians believed that? Americans may have believed it more than the Russians.
Friedman:It's hard to know.
Hirsh:Did you have any doubt., thoughts, about working on this testing project? I understand that you were not involved in actually making the bombs that were tested but rather the detection equipment. But still, did you have any thoughts, doubts about working on an atomic bomb program?
Friedman:Well as you say, I've never worked on development of a bomb. Since it existed, we had to live with it. In those days, the American stance was a very generous and honorable one. You know, the Baruch plan offered to put all of the weapons under United Nation control if the Russians would permit on site inspection and agree not to develop a bomb themselves. There were people in those days who thought we ought to solve the Russian problem right off before they had the bomb– by conquering them, making sure they wouldn't develop one–but the official government line was relatively altruistic, one of offering to put it all under international control. The Russians didn't go along with that. So on our part, as scientists, there still was no question about the need to preserve the American lead and to understand where the Russians were with their own development.
Hirsh:Do you recall what your reaction was when you learned of the bombing of Hiroshima?
Friedman:At that time I didn’t know that we had developed the bomb. And as the story came out, the feeling was one of very great horror. There was concern on the part of all scientists, I think almost immediately, that we had developed something terrible. On the other hand, as time went on it was clear that it was necessary for us to do it because the Nazis were working on it. You know later on, the cold war with the Russians developed. We had an enemy there, and there was no out from this situation. I think today the greatest threat to civilization is atomic warfare. Everything else we worry about, all of our environmental problems and the nuclear power plants and so on, is utterly trivial compared to the issue of preventing an atomic war.
Hirsh:Do you think we’re doing the right thing these days in the way we’re trying to prevent a nuclear war?
Friedman:I don't consider myself an expert on arms control and disarmament. I wish we were much further ahead in conventional weapons. I would like to be sure that we have a good stand-off with the Russians in conventional warfare so that we don’t have to resort to tactical nuclear weapons to make up for the discrepancy. I can't believe that we can ever fire a nuclear device– even a small one in a tactical weapon–without escalating very rapidly towards broader use of nuclear weapons and eventually strategic weapons. I can't believe any of these scenarios that say that we will conduct a war by shooting at military targets and hold it there. It will go immediately to civilian populations.
Hirsh:Can I ask you one last question on the war and then we’ll get into rocket research. After the war in Europe ended, of course there was terrible news still coming out of Europe. Do you recall your reaction to that news of the horrors of the war? Were many people aware of what was going on in Europe in the concentration camps during the war?
Friedman:I think in the general population, no. Amongst Jews, yes. In my own family my father thought the world had come to an end in 1933 with Hitler. He could only foresee the worst possible consequences for Jews in Europe. And we knew the story all through that period from ‘33 on. It's hard to believe that Europeans– those who wanted to know–could have been unaware of such details.
Hirsh:I ask the next question because it affects me very personally. My family is a refugee family and lost a number of members in Europe. Do you think the war experience or the experience of being Jewish in America and being a survivor has affected your work, your life, or your thoughts?
Friedman:I think, very much so. You know, we talked a lot about anti-Semitism before the war. Somehow., the need to use everybody's talents without discriminating was so great during the war that the country made fantastic progress in overcoming these prejudices. By the end of the war, I could feel that I was never discriminated against as a Jew in my profession, that the question wouldn’t even come up. Even the situation in industry had changed almost completely. Of course there was great progress for blacks in the service. Jews were a step ahead of them. I think it was a successful war in the sense that we all knew what we were fighting, and we were all deeply committed and the whole experience helped us to realize how wrong racial prejudices were. We came out of the war a much cleaner country than we went in.
Hirsh:There were no second thoughts really after World War I., when people were arguing that it was the munitions makers who got us into the war.
Friedman:No. I don’t think we ever had any qualms about what we were doing, and although there was a horrible reaction to the death in Hiroshima and Nagasaki, we also realized that we would have produced that many casualties by conventional bombing and lost almost a comparable number of our own people invading Japan if we hadn't dropped the bomb. I think Truman's reasoning was honest and justifiable.
Hirsh:Can I start asking you about some of your space research. To start that off, maybe I could ask you about when you started thinking about space travel. Were you ever impressed with science fiction, with Buck Rogers for example?
Friedman:Not really. I think my orientation was more towards art and music and literature, and I may have had a subliminal fascination with beautiful devices. It was probably more an artistic stimulation than anything else. I don’t think I had thought of space travel, or even knew enough about physical research to realize what kind of excitement was ahead. I'd read Jules Vernes’ books. They were interesting, but I wouldn’t say they stimulated me towards a career in science.
Hirsh:I suppose then you didn't think much about life on other planets.
Friedman:No. I think I was excited by the exposure to scientific instrumentation in the laboratory in the first experiences I had, and by the beautiful experiments one could do in optics, for instance. They were artistically beautiful as well as being interesting scientifically.
Hirsh:So then how did you get involved in space research?
I had a close relationship with Dr. Hulburt. Hulburt interests were in – well, we us used to call them– natural science. He could get fascinated with the color of the sky, the blue of the sky, all of the phenomena that one sees in the sky: rainbows, rings around the moon, haloes around the sun, that sort of thing. And in particular he had done a lot of pioneering research in radio reception by reflection via the ionosphere. And it was a mystery how the ionosphere was formed because when you looked at the sun, you saw a 6000 degree black body, and that would not produce enough ionizing radiation . Hulburt very early thought there must be something like X-rays from the sun, although he didn’t have any idea how they could be produced, because only X-rays would have the right ionizing properties and the right absorption characteristics to produce an ionosphere at the right height.
And we used to talk about things like that. Once we knew that we could get German V-2 rockets excitement arose about the possibility of putting instruments on those rockets and making high altitude measurements. I was busy then with the atomic weapons problems, and Hulburt’s idea was that we could put laboratory spectrograph on a rocket, and somehow get it to look at the sun during the rocket flight and extend the known spectrum below the ozone limit. A group under Ernie Krause and Erik Durand and others formed a rocket sonde branch, to do various things with these V-2 rockets, and Durant and Oberly and a few others joined with Tousey and people in the optics division to try to do this optical measurement of solar ultraviolet radiation. They realized right away that trying to put this little Hilger instrument in was not a good approach. One had to design something specifically for the rocket. They contracted with Baird Associates build a suitable spectrograph. Somehow all of this came together in time to make one of the earliest experiments on the V-2 rockets in 1946 and they got a spectrum which extended down to about 2200 angstroms and showed the depth of penetration and absorption of radiation by ozone, and how getting above the ozone layer revealed the ultraviolet spectrum. I took no part in that. But I was motivated to try to utilize some characteristics I had observed in the Geiger counter, proportional counter work, where I could control the threshold of sensitivity in the ultraviolet, or use filters in combination with a gas, to get narrow band detectors in the ultraviolet and in the X-ray regions.
So I started to prepare a collection of detectors which would isolate what seemed to me the most interesting regions of the spectrum: I had detector which would concentrate on X-rays, and in the right wavelength range, to explain why the ionosphere is produced at 100 kilometers, and a detector which would isolate the Lyman alpha line of hydrogen, which could be the strongest ultraviolet line in the sun, and then another detector which would concentrate on longer wave lengths that are absorbed by molecular oxygen in the upper atmosphere. Then I waited for a chance to put theme on a V-2 rocket. That chance came in 1949 and it was a spectacular success. We got good signals in every range of wavelength that we selected, and could conclude that X-rays were a very, important factor in producing the E region of the ionosphere, that Lyman alpha penetrated to D region, and that absorption in what we call the Schuman-Runez bands of oxygen was very different from the simple theory of photochemical equilibrium, that molecular oxygen apparently persisted to much higher levels than one would predict from a simple diffusion separation model of the atmosphere. In a very simple experiment, we answered several of the classical questions about solar radiation and the upper atmosphere. Of course that was a great stimulus. From that point on I wanted to get rid of all the other things that were absorbing my time and concentrate on this. Since then, I have been largely able to do that.
Hirsh:The laboratory itself must have been quite easy to work in so that you could move from one field to another that quickly and easily.
Friedman:The laboratory then was a beautiful organization, in the sense that all you needed was a good idea, be able to explain yourself, and you could go up front and get approval and get the money to do it. There didn't seem to be any obstacles to doing something which seemed interesting, and to getting the tactical support of Navy facilities, to do it – to get ships and planes and travel to strange places and so on.
Hirsh:The money was not necessarily free for the asking, but relatively easy to obtain from the Navy?
Friedman:If you had a good story, you could get support.
Hirsh:Did this money come from ONR essentially?
Friedman:It came from ONR largely. The Bureau of Ships was very generous with us , because we had produced all of these radiation instruments for the Navy Radiac program. They were very indifferent to our sloughing off substantial amounts of money to do anything we pleased, and in fact looked at it as kind of subsidizing research which might benefit them down the road. Obviously what we had done previously had been very valuable to them.
Hirsh:Who do you think the military wanted from rocket research in the late forties?
Friedman:For practical purposes, we could say that we were trying to understand the ionosphere, and since communication was so fundamental to the military, improving our understanding is a very relevant research endeavor. It's true that out of those early years, we got a good understanding of the nature of the ionosphere, how it was produced, and how it varied with solar activity. We’re still in a mode where we’re looking at more and more refined aspects of ionospheric behavior because we can say that such understanding might prove useful.
Hirsh:You phrased that answer, "we could say this was the justification. " What was the justification in your mind?
Friedman:It was pure research. That was enough for my supervisor, Dr. Hulburt, when he was director of the laboratory. And ONR had a real commitment to basic research. That's why it worked so well with the universities. It looked for the best people in the country, and essentially said., "as a technological organization the Navy needs every new idea, every advance in science leads eventually to something of technical value to the Navy. So we’ll get the best people in the country. Let them do whatever they want to do, and we feel certain we’ll get a payoff.” That attitude fed into the laboratory here too. In those days, the laboratory effort was roughly 50-50 basic research and applied. The applied came from the operating commands, and the basic came from ONR. And 50-50 was considered a healthy distribution. Today, it's more like 20 percent basic, and one might question whether all of that is really basic. There’s been a great change.
Hirsh:Can I ask you about your relationship with a few other people here at the lab then?
Hirsh:Can you give me thumb nail sketches and your opinions of these people, such an E.O. Hulburt.
Friedman:I have the greatest admiration for Hulburt. I had it from the very beginning. I think he was a brilliant scientist. He’s still alive, but of course he is long retired. The man had a kind of innate modesty. He never pushed himself, so that he never seemed to get the recognition he deserved in the scientific community. He was never elected to the Academy of Sciences, for example. I think that's disgraceful on the part of the Academy. But the Academy is largely under the influence of academic types, and very rarely do people in government laboratories get elected.
Hirsh:Though you did get elected.
Friedman:I did. Tousey did. Isabella Karle and Jerry Karle are both members. They’re very distinguished for their work in crystallography. We have an older man, Sam Collins, who developed the helium liquefier, who still works here. He's in his eighties. And I think we have a number of people who are good candidates, if it weren’t so hard to get a government laboratory man in.
Hirsh:You mentioned Richard Tousey. Can you tell me something about him ?
Friedman:Our work, his and mine, have gone largely in parallel from the very beginning. He basically in a spectroscopist, and he's always been known for the elegance of his experimental techniques. He is the kind of man who concentrates on a particular area and doesn't wander. Mine is a wandering career. I have broad interest in physics, and I find it all exciting – science generally – and I don't find it difficult to pick up anything which excites me at the moment, if I have an opportunity to work in it. But he doesn't deviate, hasn't deviated, over his career. He decided he was going to study the solar spectrum. He stuck to it, and all through these years has essentially been in the lead and pushing that work. On the other hand, he has not been interested in solar terrestrial physics, for instance, the interaction of the sun’s radiation with the atmosphere. So, call him a purist. And in the field he has stayed with, he's essentially made the pioneering advances at every phase.
Hirsh:How about Robert Burnight? He was involved in early solar X-ray work.
Yes. He was a radio scientist when the V-2s came,, and he became part of rocket science team under Krause Durand and Gilbert Perlo. But let’s say he was a very subordinate. He really was not trained as a physicist but decided to move into the area. I might say that the idea that the sun produces X-rays was not a novel idea here. There had been theoretical work done by Edlen for instance which strongly implied that there ought to be X-ray emissions from the solar corona. In even the crudest idea of the sun, the corona was thought to be a very extended atmosphere of the sun. In order for it to be that extended, it had to be hot, because it had to compete with the pull of the sun’s gravity – hot enough to imply temperatures in the million degree range. And a million degree plasma will produce X-rays. The big question was, how intense was the X-ray emission? That's what we set out to do with the rocket work.
Now Burnight understood to fly packets of film. This was not a novel idea. The Air Force was sponsoring similar work. But I thought he went about it wrong. He used Schuman film which is what one uses for the ultraviolet because the gelatine in ordinary film absorbs the radiation, and very little gets to the emulsion itself. But Schuman film is very fragile because it has no gelatine binder. He wade up packets and flew them. When they came back, typically the film was fragmented and terribly damaged. He detected blackening on the film which I would have attributed to pressure blackening, because of the way he constructed his packets, but he claimed to have detected X-rays..... He gave a paper at a Physical Society meeting. This in unrefereed an oral presentation. He claimed blackening of film behind something like 30 microns of beryllium at a height of 40 kilometers, which he interpreted as a flux of about 10 ergs per square centimeter per second of radiation around 4 A. Now, we never see x-rays at 40 kilometers. You would have to put it up at 80 kilometers., and then Burnight’s figure would be about a million times what is normally observed. He claimed there was a solar flare early in the day, but we know that once the flare is over there is no enhancement of X-rays. So the whole thing was an improbable claim and a rather poor experimental performance.
Hirsh:But did you feel that way then?
Friedman:Yes., because I was preparing X-ray counters for flight, and Burnight was moving in a head of us . He would come down to talk to me about how to calibrate a film. I found that it was difficult to get him to understand what one had to do to calibrate a packet for X-ray sensitivity. Yet, because he was in the group that was flying payloads, he could simply slap one of these packets – several of them – on a rocket, fly them, and then came out with these absurd claims. I felt that until we flew the counters, there was no valid measurement of X-rays. In fact we know in retrospect that he could not have detected it. The exposure available on a spinning rocket with that kind of film was not adequate to show up any detectable exposure. Unfortunately his work has been quoted, and people who write reviews generally don’t go back to the original work to check it themselves. A lot of what appears in reviews is a kind of hearsay. I have a paper that was just sent to me for review. The same kinds of state is made: “Once rockets were developed., X-rays were detected from the sun by T.R. Burnight and studied in detail...”.
Hirsh:That will be worth a comment to the publisher.
Friedman:Well, I've suggested simply taking out the names, saying "detected by scientists at NRL, “but it’s kind of an embarrassment. I would have to say that Burnight was wrong from start to finish. I tried to imply it by avoiding saying it – just using a kind of statement like "the first quantitative measurements were made in ‘49."
Hirsh:Let me ask you for another personality analysis, of Hower Newell. Were you working closely with him?
Friedman:Newell started out an Krause’s assistant, primarily an editor for reports for reports in Krause’s branch. I thought, was a very inventive scientist/engineer, and a man with enormous drive who had a great ability to organize complicated expeditions and programs and get them done. Newell was basically a mathematician. He published, I think, only one paper while he was here, connected with the rocket work. It was a calculation of a geometry factor of a counter used in cosmic ray measurements. He did assume the leadership of the rocket-sonde program when Krause left. The Vanguard project was carried out under John Hagen. Hagen had the Vanguard project. Newell was superintendent of the atmosphere and astronomy program. They had a radio astronomy program which also came under his supervision. I don't know quite how to evaluate Newell. He was always on the administrative side rather than the. creative side. So, I had some tendency to diminish his contributions. He may have made considerable contributions from the administrative standpoint, but not as a creative scientist.
Hirsh:One more person, perhaps. I see a photograph on your wall inscribed by Werner von Braun. Of course he was involved with the V-2 project. Did you know him early on– in the late forties?
Friedman:I met him early on, in casual situations. I got to know him much better in his later years when we would serve on committees together and have a more substantial opportunity to talk to each other. At first, I resented him. I didn't get over my prejudice against Nazis – former Nazis or anyone associated with their war effort. Again in retrospect, it seems like he happened to be there at that time and probably most Americans in the some situation would have conducted themselves in the same way. At one point his life was in jeopardy for his failure to please Hitler and the higher ranking German military. So that he barely escaped. And in all of his work here, his motivation seems to truly have been the idea of getting a man into space, the fulfillment of a boyhood vision. While I don't think he ever really understood our kind of science, he was sympathetic towards it and would display enthusiasm when we talked casually about what might be done. But basically he wanted to put men in space. That was it.
Hirsh:Did some people feel uncomfortable or uncooperative with him due to his former work with the Germans?
Friedman:Not seriously, really. The German group went to Redstone. American groups developed the Thor missile. They didn't feel there was any unfair competition. Von Braun was recognized as a great leader, motivator, not even the best engineer in the German group, but he's certainly the most persuasive salesman for what went on. The Congress really loved him. And when you got to know him, in a way he was likeable for his enthusiasm.
Hirsh:You were talking about the first experiment you did in 1949, how exciting and what a great stimulus it was for you. What happened immediately after that? You said you were able to get out of some of your other work. Was that easy to do?
I was able to leave the other work to other groups in the laboratory and the idea then was to try to do a more elaborate version of that original experiment. Instead of using essentially three detectors, as we did the first time, we prepared a payload with, oh, 40 or 50 detectors. The rocket – another V-2 – blew up on the launch pad. We had a succession of disappointing experiences. We had an opportunity to instrument one of the early Vikings – I think, it was Viking 9 – and it was the occasion when they were attempting to stabilize the rocket by, de-spinning it. The rocket had a fish tail motor to guide it. The combination of that and the de-spin would give you a stable rocket. And so we instrumented it very heavily to look at the sun, on the presumption that the de-spin would work, and that we would end up with our detectors all looked on the sun for the full flight. Instead of that happening, the de-spin accelerated the spin of the rocket until everything tore loose inside. The centrifugal force just ripped everything apart., and we got nothing for it.
While we were doing these more grandiose attempts, we also got involved with the use of the Aerobee rocket. Jim van Allen was a very important scientist in the early development of the rocket research programs. He was involved early on with the V-2. Then he had the idea of getting a simple rocket which could be used for research. The problem with the V-2 was that there was so much space in it that everybody and his cousin wanted to put something in, and it was awfully difficult to manage a clean payload. Jim's idea was to have a small rocket which could be assigned to one experimenter – completely his own – to be used just as he wanted it to be used, and that was the Aerobee. The trouble with the first Aerobee was that it could barely reach some 80 kilometers. So as far an we knew, the only radiation from the sun that we would see would be the Lyman alpha line, which gets down to about 70 kilometers. It didn't look very attractive from that standpoint. But we decided that we would simply extend the fuel section, and with that additional two feet on the fuel tank, get enough propulsion to bring us up to the top of the ionosphere. When we did that, the rocket did get up to 120 or 130 kilometers. We were able to get all the Aerobees we wanted just for the asking.
The first contract produced about 20 of them. Nobody really wanted them because everybody thought if he could get on a V-2 he could get much higher, or on a Viking, still higher. So we had several years in which we had as many Aerobees as we could manage and did a lot of simple things which were really quite valuable. We were able to make the first attempts at astronomy, at putting small 4 inch or 6 inch mirror telescopes in Aerobees, and observing the fluxes of stars in the ultraviolet. We discovered the hydrogen geocorona of the earth from the Lyman alpha glow that surrounds the earth, and a lot of other experiments were done with mass spectrometers and various radio propagation experiments that told a lot about the details of the ionosphere. We were in that mode – working with Aerobees --until the Sputnik era came along.
Hirsh:Would you say that the Aerobee was almost a preferred vehicle for the 50s?
Friedman:We loved it because we had complete freedom. It was our rocket. We could do anything we pleased with it. And all you had to do was to get scheduled on the range and have a Navy crew there to launch it. There was no paperwork connected with carrying out an experiment. We would typically go out with three rockets and assume that if we had a failure on the first one, we could patch up the second one and try again, or if we succeeded on the first one, maybe make some improvised changes in the second one on the basis of what we learned. It was all very free and flexible. It was very nice. And they were inexpensive.
Hirsh:Your group made a lot of technical advances in using the Aerobees, isn’t that right? And because of some of those advances you could do ultraviolet astronomy and later X-ray astronomy. Can you tell me about some of the technical innovations that your group initiated with the Aerobee?
Friedman:We can't take credit for the engineering improvements, but we initiated some of those contracts and supported later work on stabilization systems, for instance, the 2 axis stabilizer was largely funded by the Air Force for solar work., but the stabilization of the entire Aerobee payload was developed sort of as a joint effort by all of the people who were interested in having stabilized payloads. We were always concerned with minor details, like the development of suitable parachute techniques, recovering payloads, various safety systems that we used, the techniques of tracking the rocket, the design of a transmitting antennas on the rocket, things of that sort.
Hirsh:In the early fifties, then, how would you classify your work? Were you concentrating on any specific spectral region?
The emphasis was primarily on the sun. The earliest experiments showed how the sun controlled the ionosphere under normal quiet sun conditions. Then the next step was to try to see how sola r activity influenced the behavior of the ionosphere. We therefore carried on a series of repetitive measurements over a solar cycle to see how the X-ray emissions followed the solar cycle and varied with sunspot activity. Then there were solar flares. That’s the extreme form of solar activity. I had the idea that solar x-rays were the prime source of radio fadeout. We knew that radio fadeout and solar flares were coincident. But the older idea was that the flare was a burst of ultraviolet light, and some simple theory showed that it couldn't be – it was impossible – but that if the flare produced x-rays in reasonable amounts with physically reasonable mechanisms, that the X-ray emission would be sufficient to produce a fadeout.
I proposed experiments which were specifically designed to see the spectrum of emission from a solar flare. The problem there was that you can't predict the onset of a solar flare, and the ordinary Aerobee operation at White Sands required that you put the rocket in the tower, scheduled well in advance, and you had to arrange the cooperation of all the facilities at White Sands for tracking and safety, countdown and so on. Half an hour was about the extreme holding time– waiting time– that was available to you. And that was obviously not a good way to catch a solar flare. So we thought of using Rockoon at sea,. where you hang a solid propellant rocket on a balloon, pen float the balloon at 80,000 feet, start early in the day, and if at any time during the day you have evidence of the beginning of a solar flare, you command the rocket to fire from 80,000 feet and it goes up above the ionosphere.
Hirsh:This was Project SunFlare.
Friedman:That was SunFlare, and was done in 1956. We succeeded in catching one flare which showed that the X-ray emission did predominate over ultraviolet, and it was of the right wavelength and the right intensity to produce a radio fadeout. I consider that one of the most satisfying experiments. It solved a classical problem in solar terrestrial relationships. In the course of that series of Rockoon flights, we also got evidence of an extra-terrestrial X-ray flux. The detectors were scintillation counters which had no directional sensitivity so we couldn't tell from where the X-rays came. It’s just that the intensity which was observed increased with the height of the rocket. In other words, we were detecting something above the absorbing atmosphere, and it was inconsistent with what we knew about the direct radiation from the sun. It couldn't be solar radiation. With hindsight I realized later that was the first detection of galactic X-ray emission. I thought then it was a possibility, and reported it as such but with great reservations because we had nothing in sound theory to lead us to expect that we could find that kind of a galactic X-ray flux.
Hirsh:How did you report that?
Friedman:In 1958 there was an IAU and IGY meeting in Moscow, and in a session where van Allen reported upon his discovery of the radiation belts, I reported these results, and suggested the possibility that we were seeing a cosmic radiation. I also published it as part of a chapter in a book on the upper atmosphere which was edited by Ratcliffe, again with an iffy statement that this could be evidence of cosmic radiation.
Hirsh:I’d love to get those records.
Friedman:I can give you them.
Hirsh:So that was then the SunFlare project.
Yes. That was part of SunFlare, and it was a serendipitous type of observation. I felt sufficiently excited by the idea – actually, at that time, almost all of my colleagues tended to put down – the idea that it was a cosmic radiation. At a meeting here in Washington, Jim van Allen suggested that energetic particles in the radiation belt were expected to generate X-rays when they were dumped in the atmosphere, and possibly very likely I was detecting the X-ray emission generated by dumped particles, and I couldn't say yes or no to that. But the obvious thing was to try to design an experiment then to get more conclusive evidence. It is interesting that about that time, Gold and Hoyle were proposing their continuous creation theory – and in that theory, the particles created were neutrons. The neutron decays to a proton and an electron with very high energies. If you characterize the energies by a temperature. the temperature would be in the range of 108 or 109 degrees. So if their the theory were true, there would be a background radiation – a diffuse X-ray emission – and 108 or 109 degrees would produce the spectral range that we were observing, which was around 50 to 200 KEV. In, let’s see – I guess it was spring of 15 – I went to Cambridge University to deliver the Scott Lectures on space research, and I had the opportunity then to spend some time with Fred Hoyle.. and I asked him what he thought of this evidence for background X-rays, whether it was consistent with his theory.
We spent a night trying to make a back of the envelope calculation, and it came out that we were about a factor of 50 too high. In retrospect again, the problem was that we used a value of the Hubble constant, which we now know was several times too high. Well, anyway, he started out being rather excited by the idea that we might have experimental verification of his theory, and then the fit was not good enough for him to make any claim. We left it at that. Again in retrospect, I wish he and I had published a note, at least making that comparison. Instead, I went back and tried to schedule an Aerobee rocket flight, and assumed that if we were really measuring galactic X-rays with a thermal spectrum and seeing a detectable emission at 100 KeV, if the flux would be enormously greater at lower energies. So we flew a detector with a rather small window, about half a centimeter diameter, Mylar window which would transmit very soft X-rays, and I had hopes that we could see galactic X-ray emission. In that flight in, let’s see, let me get the dates right...
Hirsh:SunFlare was July, ‘57. Is that possible?
Maybe we called that project, Project Rockoon. SunFlare was the beginning of the IGY in ‘57, and we were using two stage rockets then from San Nicolas Island. The observation I've been talking about was made with a Rockoon in ‘56, and I guess by ‘57 I had scheduled an Aerobee rocket with this small detector. It also had a variety of ultraviolet telescopes on it. The object of the ultraviolet telescope work was to get fluxes of stellar emission in the ultraviolet, and the results seemed to indicate a surprisingly large halo of ultraviolet emission around the star Alpha Virginus. This was very hard to explain. Also, my X-ray detector showed a modulated X-ray response. The detector had no collimator on it, it was looking at the broad sky, but with each revolution, there was a modulated signal. The flight was in ‘57. We were in the process of analyzing data in early ‘58. I had scheduled an eclipse expedition in ‘58 for the South Pacific and took off with a group of our people a t that time. While we were gone, the transition of people to NASA took place in a flood. There were three people here – Jim Kupperian, Jim Milligan and Al Bogges who were especially interested in the ultraviolet stellar part of the experiment. They three decided to go to NASA and took all the telemetry data with them.
When I got back, we had nothing to work with. There was a lot of tension then. People were finding it very difficult to decide whether to go to NASA., move with this new tide – this great new organization – or stay with NRL and worry that we would not continue to have a program. While I wan the Pacific, the laboratory director wired me and asked if I would accept the superintendency of the new division of astronomy and space science, with the guarantee that they would allow me to replace all the people who left for NASA, and they would provide continuing and enhanced support for a program here, if I agreed to run it. I replied with a yes, I would stay at NRL, but the people who were back here felt that all the brand new opportunities would be with NASA, and most of them left. So when we got back, it was difficult for us to pry out the information from the 1957 Aerobee.. We also had a feeling of some responsibility for the ultraviolet results, because the publicity that went with this apparent ultraviolet halo around Alpha Virginus was rather great, and we weren't sure that it was a correct result. We wasted valuable time trying to repeat that part of it – to prove it right or wrong. In 1958 we flew again, got negative results on Alpha Virginus, and we never could quite explain what produced the illusion on that first experiment. We didn’t move as aggressively as we should have for the X-ray work. We did in fact repeat the small counter X-ray experiment, got a negative result. In retrospect again I think that what we saw the first time was the large flux from Scorpius X-1 and the galactic center region, and the next time, that region was below the horizon, and we didn't see it. In ‘59, I became ill, underwent some serious surgery, which essentially put me out of business for half a year, and I think I was still very much alone trying to push the X-ray work, even against my own colleagues.
They were more involved with the ultraviolet. We had good clean signals of ultraviolet stars, a nice field to pursue – whereas nobody could quite believe to begin, with that one could do X-ray astronomy, and they were skeptical of those first tentative results we had. I had to recover from my illness, get back into the swing of things, and then try to push the program once more in the direction of X-ray astronomy. I did it by trying to make a very large X-ray detector, to give us more sensitivity, and while we were preparing for that experiment, the group at American Science and Engineering got off their flight. They had a program which was sponsored by the Air Force to look for fluorescent X-rays from the moon. At first they reported their results as positive evidence of lunar fluorescence, and then when Bruno Rossi and Riccardo Giacconi looked more carefully at their results, they realized that the centroid of emission was displaced from the moon. They thought it was close to the galactic center, and they reported the discovery of extra-galactic X-rays from the galactic center region. I think it was three or four months from the time they reported their results at the end of ‘62 to the spring of ‘63 when we flew our big detector, and that showed clearly that there was a strong source which we called Scorpius X-1, we gave its position with what later turned out to be an accuracy of about half a degree. That was about 20 degrees away, I think, from the galactic center. The other source we found was the Crab Nebula, and that one we were ready to believe. I myself had written in a SCIENTIFIC AMERICAN article that if we were going to find an X-ray source., the most likely one to look for was the Crab.
Hirsh:Because it was so unusual?
Friedman:Yes. It had a strong synchrotron spectrum, and the spectrum looked continuous, and it was not unreasonable to project it into the X-ray region. Well, there has been great competition in the X-ray field since those first discoveries. After we found the Scorpius X--l source, the AS&E group claimed that was really what they had discovered. In their first experiment they had flown a counter with no collimation, so it saw a steradian in the sky, and I think they were looking at the whole complex of emission from Scorpius X-I and the galactic center region, and not resolving any of it, of course. They certainly deserve credit for having recognized and made a clear statement of their discovery of extra-galactic X-rays, but I think in all fairness we were the first ones to actually identify discrete sources. We went ahead and did an experiment on the occultation of the Crab, which gave a precise position for the source in the Crab. There was a lot of discussion by then about the nature of these X-ray sources . The fact that we had found the Crab was consistent with the theory that a supernova leaves a neutron star behind . And the neutron star theoretically would have a surface temperature of maybe 10 million degrees and radiate X-rays in a detectable intensity. The issue was. could we prove that we had a point source, or were we looking at synchrotron radiation from the diffused nebula, the occultation experiment in principle could answer that.
Hirsh:May I ask you if we could perhaps hold off on that experiment for a moment? Can I backtrack a couple of minutes and ask about your work between ‘57 and ‘60. You said you were concerned with this observation perhaps of an extra-galactic X-ray source, but you were doing lots of other things as well. You were working on Solrad 1 and then OSO satellites, I think as well.
Friedman:No we didn't get OSO 1, but we were almost every other OSO from then on. As part of the split between NRL and NASA, John Lindsay went to NASA. He was part of our solar X-ray team. We already had in mind a SolRad type of experiment, and he immediately became the manager of the OSO program in NASA and naturally wanted to go ahead and do a solar type of X-ray experiment. In that interim,, we flew a Bragg crystal spectrometer on an Aerobee rocket, and actually observed X-ray emission lines in the wavelength region from a few angstroms up to about 25 angstroms. That was the first successful detection of X-ray emission line from the sun, and it was an obvious next step to put it on a satellite. Lindsay decided to do just that. He flew the first spectrometer of that type. We flew the second one. And we sort of alternated opportunities on the OSO program. We had also discovered the Lyman alpha geo-coronal glow, and did several follow up experiments on that to define the shape and establish the origin of it. I believe we did the first experiments on the heights of the ultraviolet air glow and the phenomenon of horizon brightening of the air glow, and the possibility of using horizon measurements for stabilization – for giving the orientation of satellites. In that period, we also made the first attempts at infra-red astronomy from rockets. We set out as our objective the detection of the cosmic background radiation– the 3 degree radiation– which had just been discovered in the radio spectrum, and in theory should have a black body distribution. We wanted to measure that distribution, at around 1 millimeter and that required the use of a liquid helium cooled telescope, which was a really difficult technology to try to develop for rocket flight. We never really succeeded in a good experiment, but in a sense. we did very well overcoming a lot of the technological difficulties– of actually developing a cryogenically cooled mirror system and the proper detectors.
Hirsh:How were you involved in the Vanguard program– the program to launch the first satellite?
Friedman:There was a plan, you know, for a scientific series of space experiments and we had the first payload,, which was dedicated to looking at one X-ray and one ultra violet channel (Lyman alpha and the 8 angstrom region of X-rays) to monitor this emission from the sun. We never got of successful flight. We did finally, late in the series, have a successful launch, but we were overwhelmed by Van Allen Belt radiation. It's quite clear that we would have duplicated his experience if we had had a successful flight the first time. The counter would have been choked by Van Allen Belt radiation just the way his cosmic ray counters were. When we finally did get up, we were overwhelmed, counters were choked the way his were, but he had already had that experience and analyzed it properly.
Hirsh:That's why they're not called the “
Friedman:Well. I don’t know whether they ever would have been. Van Alien has a more lyrical quality to it.
Hirsh:What was your reaction to the news of the Sputnik launch in 1957?
Friedman:It was a shocker. We had been having a meeting all week, over at the National Academy– an IGY meeting with the Russians– in which we were describing our two programs, and trying to get the Russians to accept frequencies which we had chosen for the Vanguard program, which they did not agree to do. And the debate went on, in the sense that we were ready to launch and they were not. And yet they were giving us signals that we just didn’t appreciate. They were about ready to go. By the end of the week of that meeting–I think it was a Friday night– the news came through that they had succeeded in launching Sputnik, and it really took us completely by surprise. We could look back on that week afterwards and realize that they were telling us that they were about ready to go, and we just were not reading the message.
Hirsh:Do you think that the semi-hysteria in this country was justified? Congressmen and the public just went bananas almost. First of all, that wasn't the same type of reaction you had, was it?
No. I felt that we had the capability, that we for instance were developing the ballistic missile capability. The country was terribly frightened by the idea that the Russians might have that capability and that we did not have it. And knowing that they had the hydrogen bomb, this was plenty of cause for worry. And the fact that we were so ignorant of where they stood. I went to Moscow in ‘58 for the IGY-IAU meetings, and they had an exhibit at their Industrial Fair on the outskirts of Moscow in which they showed Sputnik I and Sputnik 2 by that time and the instrumentation that went into them. It surprised all of us who were there to actually see all of this, because back home we were just guessing, what kind of technology did they have, and how had they put all of it together? And there it was, spread out right before our eyes. One of the components in the Sputnik 2 was a Geiger counter. We were working at that time on what we called low voltage counters, counters which operated at 200 or 300 volts, instead of 1000-2000 volts, and that was the kind of counter they were using on Sputnik. I was especially interested in that because I had been trying to make them in our own laboratory. Before I left Russia, I visited Leningrad, and on the Nevsky Prospect there was a store that looked like Central Scientific Instruments Company. It had all sorts of educational materials. And in the window was the counter that I had seen in the Sputnik. I was there with John Simpson of the University of Chicago.
We both decided we would go in, see if we could buy a counter. So we went in and got across the message, “we were interested in the counter in the window” and the girl went to a catalogue, turned the pages, and asked if that catalogue item, which we could see the picture of and so on, was what we wanted. There were two counters, one small one, one bigger one. Each of us bought a sample of each counter at something like a ruble a piece, and we took them home. In my case, I just wondered, would they let me take it out? And so I stuck the counters in my coat pocket like two cigars, and thought I would just – in a blase manner – walk through. And it worked. They were very relaxed at that time, and they didn't frisk us. I got home. It wasn't long before one of the intelligence people came in to talk to me about my experience there and I had the counter on the table, and I casually mentioned, this was the Sputnik counter. I could just see the shock in his response. They formally asked to borrow them, and we agreed to let them have it. They promised to return it undamaged and so on. Months later it came back to us, this time classified secret.
Hirsh:That’s great– especially since you could just walk into a store in Moscow and pick it up.
Friedman:I've often used that story to emphasize how much we learn by scientific contacts, compared to the normal route of intelligence people. They could have spent millions of dollars to get those items in a typical, espionage manner. And here it was so easy.
Hirsh:What did you think about the organization of NASA? There is of course the big debate after Sputnik– how we should reorganize the space program in this country– and there was a debate on how to set up NASA– whether it should be civilian or military. How did you feel about that debate? Did you contribute to that debate?
Friedman:The idea that we have a purely civilian space agency was very appealing. Because NASA was populated by so many alumni of NRL we felt very comfortable. We felt we would have no trouble working with them even though we were military and that we could do unclassified projects with NASA. We believed our former colleagues would be very sympathetic and helpful to us, and it certainly worked out that way. We had very good relationships with them. I myself turned down subsequent offers to come to NASA. I was invited to come to Goddard as chief physicist there. But I liked the free and easy way of working here, and I liked to work in simple things with a minimum of administrative problems and I thought we still could go a long ways in that mode. As time went on,, of course.. space science became big science, and you just cannot spend tens of millions of dollar a on a mission anti not have it organized in a rigorous engineering WaY4 with full accountability for everything you do. So I guess I was becoming sort of old fashioned and out of tune with the times, by continuing to do what was a kind of individualistic kind of program here.
Hirsh:What was the cost of some of those experiments that you did with Aerobee?
Friedman:Oh, the Aerobee costs varied from slightly over $10,000 to finally about $20,000 for the rocket period. A few thousand dollars usually was enough to cover a payload. When you used something as sophisticated as the biaxial pointing control, it became maybe a $20,000 type of payload.
Hirsh:It was comparatively cheap then?
Friedman:Yes. And we could specify all the Aerobee experiments we wanted to do and get funding to do them. At the peak of our program, we might have done as many 16 Aerobees in one year, and had no trouble covering that.
Hirsh:And again most of this money before NASA came from ONR and from some Bureau of Ships?
Friedman:Primarily ONR money.
Hirsh:What happened when NASA came on the scene? I know there was some funding that you received from NASA even from the early days.
Friedman:NASA supported us very heavily on the solar research, and we got into, I think, OSO 2, OSO 4, OSO 6, 7, 8, and so on. They also began the OGO series, the Orbiting Geophysical Observatories, and we got into almost every one of those. Typically, to prepare a payload for one of those cost, one to several million dollars, and NASA funded us generously for those payloads.
Hirsh:Did you still have to make proposals and go through the standard procedure, or was it less formal than that?
Friedman:It was much less formal, and one of the nice things about it was that the proponents would debate openly the merits of their proposals before the reviewing committees. And they could criticize each other's experiments. It was all out in the open. And it was, in a way, an enjoyable competition. If you liked to compete, it was the right kind of environment. We enjoyed it, and we succeeded. We had a very high success ratio in getting funded for what we proposed. Now, as time went on, it all became much more complex. The program became much more expensive, and NASA established rules for proposals, rules for review, conflict of interest positions, and one of the things that has bothered me for years in that you don't have the straightforward opportunity to come before the selection committee and answer their criticisms face to face, or criticize your competitor's approach and debate with him before a committee. Everything is done sort of second hand.
Friedman:Yes. And you never have a direct debate. And people get hung up on the gamesmanship of how you make proposals, how you win payload space. We lost many because of our old characteristic of trying to do things simply to get at an essential question in a minimal way. We would lose to a group who would propose a very much more elaborate approach, costing very much more, and not really answering the question any better than we thought we could with a simple experiment, but somehow they'd be more attractive to the reviewers. It looked as if they knew more about what they were going about, because they proposed a more elaborate approach. So you turn around then and try to get into the mainstream, and you end up playing games instead of doing it the way you conscientiously believe is the most cost effective and scientifically effective way of doing things. And I don't know how we solve that problem.
Hirsh:I imagine you were pretty pleased with the original emphasis of NASA – namely for space science. How did you feel when the emphasis changed somewhat, in ‘61, when Kennedy said “We will go to the moon” and NASA essentially was given a new goal of getting a man to the moon by 1970 ? Do you think that affected space science emphasis of NASA?
Friedman:A lot of scientists thought that that would be the death of space science, that we would get locked into manned programs which were terribly expensive, and we would compromise the way in which we did experiments. I never felt that sharply about it. I think I rationalized that to support a big space program– an expensive program– you had to do the things which were politically motivated, and which also caught the imagination of the public. And certainly there’s nothing comparable to man in space for those considerations. I felt we just had to find a way of doing our science in that environment. So there were prominent people in the science area– Jim van Allen for one– who criticized severely the coupling of science to the manned program, and other people like myself who felt we should find a way of going along with it. I reasoned that the public was not going to buy an expensive space program just for science itself. They couldn’t understand it. I think the way it's worked out, the compromise has been reasonable .
Hirsh:You say that NASA supported a lot of the solar work that you were doing here. How about some of the non-solar work? You were doing non-solar ultraviolet astronomy very successfully from ‘56 on, and then you were getting into non-solar X-ray astronomy.
Friedman:Well, we were treated, I think, somewhat shabbily in the non-solar areas.
Hirsh:Ultraviolet as well?
Friedman:Ultraviolet, yes. You see, we had some personality conflicts. The group that went over to NASA had been doing ultraviolet astronomy. They were involved then in generating the OAO program, and that was not offered to an open competition. The three OSA’s, were assigned to their principal investigators internally without a full outside competition. We never had a chance to bid on any one of those, even though we had made the only ultraviolet photometric measurements proceeding them in the rocket program. So as a result, we never pushed to get into the NASA ultraviolet astronomy program. We felt we didn't have a fair chance there. In the very early days of the X-ray program, the possibility came up of assigning an Explorer satellite to X-ray astronomy, and we were asked if we would propose on it at the same time that American Science and Engineering was asked. I was certainly interested, but our internal facilities were tied up with programs to such an extent that we could not engineer the spacecraft. We were prepared to provide the science and to do the scientific analysis, but we couldn’t build a spacecraft. NASA insisted that if we got the Explorer for X-ray astronomy we would have to do the whole thing. In the end they gave it to A S and E, but with APL building the spacecraft. If the offer had been to have APL build the spacecraft and we do the science, we would have been very enthusiastic on it, but we didn’t get that opportunity. So there too the chance to do the first satellite experiment was given to AS and E and wasn’t an open competition really. It wasn't a fair competition in the sense that we weren’t allowed to look for a subcontractor for the satellite.
Hirsh:That Explorer was the UHURU, the first Small Astronomy Satellite (SAS-1)?
Hirsh:Let me ask you a general question about scientists and rocket research, rocket and satellite research. In the early days, in the late forties and fifties and into the sixties I think there were very few astronomers involved in rocket and satellite research. You certainly were not trained as an astronomer and yet you were doing astronomy. Does this say something about astronomers or other scientists in general?
Friedman:It certainly does. It says that the astronomers were trained along classical lines, and very few of them could see the possibilities of space research. The very few were very good ones– men like Lyman Spitzer and Leo Goldberg–but the vast majority of astronomers just saw their careers the way they'd been trained in classical astronomy. They were not motivated to get into the new way of doing things. The people who got in were primarily physicists who were comfortable with this kind of experimentation.
Hirsh:Most of those physicists in X-ray astronomy at least seem to have been nuclear or cosmic ray physicists.
Friedman:Certainly in the X-ray astronomy, the technology was what you use in a laboratory in nuclear physics work. So that was easily understandable.
Hirsh:Did you have any early predisposition toward one cosmological model over another? You talked about the steady state constant creation model. I don't think you have talked yet about the Big Bang theory, but did you have any predisposition toward either?
Friedman:I was influenced by Einstein’s intuition that the universe was closed, and that– I guess intuitively–it would seem more attractive than an infinite universe which was a one shot universe which expanded forever, and that was it. As a result, I became intrigued with the first evidence we gleaned that X-ray astronomy might give us a measure of the total mass of the universe– that the diffuse background radiation could come from material in inter-galactic space– and that in a simple way we could calculate what that mass was. There again, if we attributed all of the originally observed background to hot gas, it turned out that it gave the critical density for a closed universe. I would say today I am comfortable either way. I'm not trying to prove open or closed. The interesting thing is that we can pursue the evidence and find out which it is.
Hirsh:Did the steady state theory appeal to you at all at any time? You said you talked to Hoyle who is of course one of the founders of the theory.
Friedman:I was never comfortable with the idea of spontaneous creation of matter. It was attractive in the sense of having a universe which is infinite in all directions– infinite backward in time and infinite forward in time. That is philosophically attractive. I think it’s awfully vain of scientists to think that they can ever get the definitive answer to questions like that. But it’s a great adventure to try to pursue the evidence.
Hirsh:In the late fifties, you were elected to the National Academy of Sciences, correct?
Hirsh:You were a member of the Space Science Board earlier, weren't you?
Friedman:I mentioned I was very sick in ‘69 and could do very little, but as soon as I began to recover from that, I got involved with the Space Science Board. I believe I had 13 consecutive years on it, which is a record. The policy now is for three year term.
Hirsh:So I take it you were not on the board when it was discussing ways to compete with the Russians in space. In 1957 there were discussions there about what we should do in space?
There wasn't a Space Science Board then. There was a Space Research Panel in the Academy for the IGY, and I was a member of that, and that panel tried to identify the projects that deserved NSF funding, for instance., for the IGY. It was a rather simple kind of operation. There weren't many people. Typically the people who had been doing rocket work for the past decade were involved, and they were simply proposing expanded support for their work. There is some interesting background there. I conceived of this eclipse expedition to try to identify the location of X-ray sources on the sun as an IGY project, and the panel that considered that proposal was chaired by Fred Whipple. Homer Newell was the laboratory's representative on that panel. My proposal was turned down, and as I learned from Whipple in later years, largely on the basis of Newell’s comments that he thought I was stretching the technology a little too far. He believed we really were not capable of doing that kind of an experiment with the existing technology. Well, true, it was risky. I was proposing to use a two stage rocket , which was still developmental, and to go all the way out to the South Pacific with the idea of launching six of those in rapid succession. It was sort of a gamble.
In a sense Newell killed the project by his comments in this Academy committee, and what brought it back was Sputnik., because immediately after Sputnik everything loosened up. I went to ONR and talked to the chief of naval research then, Admiral Bennett, and told him what I wanted to do. We needed a Navy ship. And I thought it would cost about $70,000 to carry out the expedition. He said., “You've got the money, go and do it.” He assigned a ship to us. This was sort of overnight. So we were able to go ahead independently, and we did the experiment and it worked very well. I shouldn't criticize Newell too severely because in our own groups I had one key man who panicked over it. He should have been right in the middle of that experiment and he just couldn't conceive of our going out and trying this. He thought we would have total disaster. It got to the point where he almost had a nervous breakdown over it, and we left him behind. He didn’t go out. Some people are comfortable with taking a certain amount of risk and hope they get away with it, and others can agonize over it.
Hirsh:Can we go into some X-ray astronomy now? You were anxious to get there and I”m anxious too, but I thought I should ask you some questions about NASA and its creation. But you told me that you were in the process of building a large counter, when you received word of A S and E’s discovery in 1962. Was this a counter that eventually went up on your first experiment?
Hirsh:Now, wasn't that being built by Stuart Bowyer here? I know there was one that he was building and one that was patented under his name in fact.
Friedman:Yes. Stu Bowyer's role was essentially that of a technician. The counter was designed by Talbott Chubb. I’m not sure now. I think the one that Stu Bowyer patented was still different, and that one was also given to him. It was a design that had been developed before he came. It was a tray counter with parallel wires. It was essentially a multiple wire counter, and those were completely described in work that I published years earlier. So I can never understand how he patented that version. I really don't think that he has any creative role in the early work. The same thing would have been done by any of the technicians who normally worked in the program.
Hirsh:Was that the first counter that was used in your first experiment? I thought it was the one with the honeycomb columnators.
Friedman:The one with a number of small end window counters with needle anodes was developed by Talbot Chubb. And the idea of getting large area was to calm those counters which we essentially had in hand, put a bundle of them together to give us the area. The tray counter was a more efficient way of doing it, but had to be built and tested and so on. So that came second.
Hirsh:But this other one, the combination of a number of smaller counters, was being designed even before you knew about A S and E’s work?
Friedman:Oh yes. It used to take pretty close to a year to put together a rocket payload. And we had decided to go bigger than the small half centimeter window areas because we had not succeeded in reproducing that 1957 result. I thought we had to have substantially greater sensitivity. So what we finally flew was about 10 times the area of the A S and E counter. It's interesting there too that the A S and E counter came from Anton Electronics and was essentially a counter that we designed as part of the Bureau of Ships program. In fact, all of the know-how for counters built by Anton Electronics came from contracts with the Bureau of Ships and were based on counters of our design. The counter that van Allen flew was one of our design, built by Anton for Bureau of Ships and also for van Allen
Hirsh:Were you terribly surprised or disappointed when you learned of AS and E's discovery of a sours?
Friedman:Well, all of those things. I did not know that – well, I did know that AS and E was looking for lunar X-rays. I felt that was a futile effort. I didn't believe that was possible. And I guess I didn't realize that if they continued to do that, they would automatically stumble on the galactic X-ray detection. So it was a surprise when Giacconi reported that result. And the only important reaction we had was– well, let’s go ahead and do what we were planning to do– that if the AS and E result was a true detection of galactic X-rays, we would do better with a bigger counter. And that's the way it worked out. From then on our effort has been progressively to go to bigger and bigger counters. We used flow counters because we wanted the thinnest windows, and we couldn't make them vacuum tight. Our judgment there was a correct one – that the X-ray flux would rise steeply to the lowest energies, and that one would gain by making the thinnest possible windows.
Hirsh:Obviously since you were interested in galactic (non-solar) X-rays since '57 from that first hint, there must have been some reason why you thought that the discovery of an X-ray source would be a rather exciting or important thing. What was the significance of the discovery of a source
Friedman:Let's say first of all, I had a general philosophy of looking into any region of the spectrum which had not been explored. I had just the gut feeling that there were surprises everywhere one could look,, and it was a mistake to ignore any part of the spectrum. And trying to rationalize that in any quantitative way for X-rays , we couldn't really make a good case. The only X-ray source we knew of was the sun, and to look for solar type stars was rather futile. On the other hand, one could speculate that the surprising objects that had been found by the radio astronomers might also be surprising in the X-ray spectrum–the Crab in particular. Radio galaxies were becoming much more prominent subjects of discussion amongst astronomers. So in that kind of diffuse way, we felt that it would be a great mistake not to take a look. We had marginal detection already, then it was an easy step to go a factor of 10 or a factor of 100 beyond that, and it seemed very worthwhile.
Hirsh:Did you essentially drop or postpone other work or concentrate more on X-ray, after ASE made the announcement?
Friedman:You see, our next flight came so quickly and the result was so spectacular that we just had to give that the highest priority from then on. The idea that we might have detected a neutron star was a terribly exciting prospect.
Hirsh:I noticed that the popular magazines did not report the first discovery of an X-ray source until after your announcements which seems to indicate that you people sealed the lid on the existence of X-ray sources.
Friedman:The fact that we had pinpointed two sources and that we had especially pinpointed the Crab source, and that we emphasized the importance of trying to identify the X-ray emission as a neutron star – that’s what got people excited. I remember giving a colloquium at the Princeton Institute for Advanced Studies, and Oppenheimer sat through the colloquium, and he was terribly excited by the idea that maybe we did finally have a handle on neutron stars, which he had predicted back in the mid-thirties. I think it was the neutron star concept that grabbed the imagination.
Hirsh:Did you have much to do with the AS and E group? Did you communicate with those people there?
Friedman:No. We didn’t know anything about each other, really.
Hirsh:After the first experiments, though, did you start calling up each other or comparing notes? Was there a competitive attitude?
Friedman:There was a very strong competition. All scientists are highly competitive. But the AS and E group, I think was particularly so.
Hirsh:Why do you think that to so? Because of Giacconi perhaps? Became of you?
Friedman:Giacconi has that reputation. He’s a very aggressive type of scientist. He's awfully good at getting things done, and he’s been a very successful promoter of the field. But along with that aggressiveness is this extreme competitiveness and a desire to get on top of it. We were involved in so many different things simultaneously that we were much more relaxed about any one particular aspect of our rocket science program. I don't know, maybe I'm making my own case look good – for being less competitive. I think fundamentally you don't make any progress unless you are strongly competitive. An exciting field just runs away from you if you don’t push it very hard.
Hirsh:There was a third group involved in X-ray astronomy from very early on, namely Phil Fisher's group at Lockheed. He had a lot of bad luck, it seem. Was it just bad luck when he started out? I know he had a couple of early experiments that just didn’t work out or that the scientific community just didn't accept his results.
Friedman:His results were fuzzy and he had a fuzzy style which was not very persuasive. I think undoubtedly he would have gotten good results if he had continued. But up to the point where the AS and B group succeeded, and where we got discrete sources, he hadn't convinced anybody that he really had anything. One step further on, he would have been right in the main stream. Things went wrong with his program, I think largely because of his own personal difficulties. I don't know what they were, but he's disappeared from the scene. He corresponded with me, in an informal way, as a friend, trying to get my support to credit him for what he had succeeded in doing, feeling that he had a better chance of getting a sympathetic response from me than he had from Giacconi. But all of his correspondence was in a very strange context, of somebody who's rather seriously disturbed. I really don't know the details. It way have aggravated his condition that he came so close and that the community didn't give him any credit for having just missed it.
Hirsh:Can you tell me about some of your colleagues? On practically every paper in the first ten years of your work in X-ray astronomy, it goes alphabetically, Byram Chubb,
Friedman:, and in the early days Boyman would get in there first. Can you tell me something about Talbot Chubb and Edward Byram?,
Friedman:Well, I have the greatest admiration and affection for Talbot Chubb. He really is a brilliant mind and an awfully good physicist He has very good intuition, and I’ve enjoyed every minute of partnership with him. He deserves a lot of credit for everything we’ve done. Byram is an engineering type, and we are indebted a great deal to him for details of the technical operation. He solved a lot of the instrumental problems very well. But he's not a physicist in the sense that he doesn’t take the results and interpret them. I still give him a lot of credit for the success of the experiments.
Hirsh:And how about Bowyer. He was here as a graduate student wasn’t he?
Friedman:We had a program which we called the Hulburt Center Program which was financed by the National Science Foundation, and it was designed to allow graduate students, pos t-grads and faculty on sabbatical, to come to work with us for one, two, or three year terms. We had the kind of a program where you could achieve results in a year’s time, and move in and out very easily. And Bowyer came in as a graduate student in that program. Now, I can't think back to anything he did while he was here, which was, let’s say, creative on his part. He was essentially fitting into things that were going on and which had been designed and conceived by other people. In a sense he had the good luck to be alphabetically at the top of the list, and perhaps a lot of people give him credit for having made a senior contribution,, but that is not so. He’s very ambitious. I don’t know whether you know him personally?
Hirsh:I've talked with him for about an hour.
Friedman:He's very ambitious, very hard working, very aggressive, wants very much to succeed, and he has succeeded in large measure in Berkeley where he is now but he wanted very early on, right here, to be promoted to some position of leadership, and I felt he just wasn't superior in stature to several other people in the program and would not move his ahead of them. When it became clear that his future was not going to be a quick rise to the top here, he decided to move on. He was not popular here with his colleagues, and --
Hirsh:Was that because of his personality?
Friedman:Yes. The amount of push he had. And his willingness to take an idea from any source and run with it.
Hirsh:You tell me that one of the things that got people excited about X-ray sources was that you had early on associated them possibly with neutron stars. How did you hear about neutron stars? How did you get involved with them? Why were they so appealing?
Friedman:One of the people here wan Don Morton, and Morton had one his thesis at Princeton on neutron star structure. Another scientist who had been writing about neutron stars was Hong-Yee Chiu. And he knew of his work. I think the fact that Morton knew about neutron stars, and somehow brought it to our consciousness, and was able to call our attention to Hong Yee Chiu, was very helpful. Not having come out of the astronomy field or the field of stellar structure, I probably would not have thought of neutron stars, if not for the contact with Morton and Hong Yee Chiu’s publications at that time.
Hirsh:How did you go about trying to detect a neutron star? I know you had your very famous and classical Crab occultation experiment. Maybe you can tell me how you decided to do that experiment.
We had detected emission from the direction of the Crab. We knew the synchrotron model of the Crab radiation, so that it was possible the emission came from a nebula (the nebula). We also knew the theory that supernova collapse would lead possibly to a neutron star and that the neutron star model called for a surface temperature of 10 million degrees and a radius of 10 kilometers. If you put an object of that size at that temperature at the Crab Nebula, you would see the flux that we had observed. So the issue was to prove somehow that what we had measured came from a point source or came from the Nebula. Since we didn't have a telescope capable of resolving the point source, we had to think of some other way of doing it. And I guess it was early in January of ‘64 , I had a note from Cornell Mayer, who was directing our radio astronomy program in the same division, that he had a listing of occultation of radio sources by the moon, which our radio astronomers wanted, because they were using the occultation technique to identify positions and dimensions of radio sources. And right there in the list was the Crab Nebula, with the information would be occulted that year; and this was a once in nine years event. So it was sort of an instant recognition of the fact that an opportunity was coming up in a time frame which we could respond to. The occultation was in July. This was January. But what we were not sure of was whether we could stabilize a rocket well enough to be able to hold on the Crab while the occultation took place. There was under development the ACS system, the automatic control system for the Aerobee, but it had had more than half a dozen tests and it had failed each one. Something went wrong each time. So the question was, should we gamble on an as yet unsuccessful stabilizer in a very difficult operation, to get a rocket off in a matter of a fraction of a minute, at White Sands and point it accurately at the Crab and hold it there for the duration of the occutation? I decided, yes, I thought it was worthwhile and would take the gamble. Again, in those days failure was not a disaster.
We could get the Aerobee. We could get the support for new experiments, and laying all of that against the once in nine years occulation, we thought we shouldn't miss that opportunity. So we went ahead and built the payload for it. It's interesting that in the Spring of that year, I got a letter from Shklovsky, the Russian astronomer, a very friendly letter in which he was terribly excited about our X-ray results, and wanted to point out to me that there was an occultation of the Crab coming up, and didn’t I think this would be a great opportunity to do it? He was sort of saying "I know you can do it, but our Russian colleagues aren’t ready to do anything like this." Well, that was great encouragement to follow though. I think Shklovsky may feel that he actually proposed and got us started on it, but in truth we were building it from the January date on for a July flight.
Hirsh:And then of course the experiment went off. The technology worked very well. The ACS worked got the rocket off precisely the right time.
Friedman:Everything worked. The rocket went off just as scheduled and the ACS worked for the first time, and the data came through and showed that the occultation was gradual, not abrupt. We could only conclude that if there were a point source there, it could not exceed 10 percent of the total intensity. It turned out that the point source contributes less than 10 percent of what you see.
Hirsh:Why did you not find a point source ?
Friedman:We couldn't detect the 10 percent increment on the flux we were observing . Our statistics weren't good enough. We could see the gradual decline of emission across the nebula and convert that to the size of the X-ray source, but to see the 10 percent effect right at the center was beyond the statistics of the measurement.
Hirsh:So most of the X-ray radiation indeed comes from the rest of the nebula?
Friedman:Yes. It's true that when the Crab pulses, the energy in the pulse is about, I think about 30 percent of what comes from the nebula. But the duty cycle is small, so that on the average, the contribution of the pulsar to the total flux is just a few percent.
Hirsh:Were you terribly disappointed not to find a neutron star there?
Friedman:I was very disappointed. The whole goal was hopefully to find a neutron star, and prove its excellence. That was balanced somewhat by the fact that we had done a very tricky experiment and it had come off so well.
Hirsh:And after that it seems, according to me, being an outsider to the field and just studying it, that interest in neutron stars died off for a couple of years. Was that the case?
Friedman:That was the case because although I think everyone knew you could build an X-ray mirror, the technology was still rather far off, and we sort of put it on the back burner. Somebody would build a mirror. In those days I was talking with Giacconi, and he was already pushing hard, he and Rossi, to build an X-ray mirror, and I was content to say, “You go ahead and build a mirror. We’ll try to build bigger and bigger counters.” And I guess the interest in the neutron star then burst forth again when pulsars were discovered in ‘67. Shortly afterward, we looked at the Crab and found that the Crab was an X-ray pulsar. Everything has moved very fast since then.
Hirsh:Did you have any well articulated research program when you got into X-ray astronomy, after the first, your first detection of the Scorpius source and the Crab source? Did you have any plan ? Did you sit around with the other members of the team and say, “This is what we should do in the long run”? Or were you just going from experiment to experiment?
Friedman:I myself was convinced that the X-ray astronomy was the most important thing we could do. At the same time, I guess I'm not a tough administrator. The people who were doing ultraviolet work or infra-red work or whatever were terribly immersed in what they were doing, and they would have been unhappy if I had pulled them off. I made the attempt with one man but didn't succeed. So I decided we would go ahead with our basic team, which was Chubb, and Byram and myself, and gradually add new people to the program, which we did. But we never built up a large X-ray astronomy group as the people at AS and E did. Before long they were ten times our size. Within the first two years – by 1965 – we had a catalogue of about 30 sources. I knew we could build much bigger counters and go a great deal further with that technique on a rocket, and I was satisfied to pursue that for a while. I mentioned the possibility of doing a satellite – the kind that led to UHURU – but we got shut out of that, and there was no obvious other opportunity. In 1965, we had a Space Science Board meeting at Woods Hole in which we were trying to project the next packet of experiments. By that time the country was into the Apollo program, and the program was rich enough so that it was possible there would be a fair amount of Apollo sized hardware left over. The people at Huntsville, in particular Ernst Stulinger who wanted to try to develop a scientific payload for post-Apollo mission. His idea was that these would be manned experiments that would use the whole Apollo system, and at Woods Hole we discussed what might be done. There too Giacconi emphasized the telescope, and I thought that on the Apollo hardware we could carry 100 square feet of X-ray detector – a very extravagant idea but technically it seemed reasonable. Stulinger thought it was reasonable. He even went so far as to make a mockup of this 100 square foot detector down at Huntsville. That led to the HEAO concept, the first mission of the HEAO program would have a very large array of X-ray detectors, and the second one would have the Einstein telescope.
Hirsh:The concept of using large area detectors led to the HEAO program.
Friedman:Yes. The idea of using a man was the first thing that disappeared from the program. It was called the EMR program then, the Electromagnetic Radiation program. But we continued with the concept of HEAO no longer as a Saturn launch, but an Atlas Centaur launch mission, in which we could have about 60 square feet of X-ray detectors backed by phoswiches for higher energy X-ray. Now, that program got to be too expensive for the times. We were already over the peak and were sliding down the slope. And so it was suspended and then brought back into the program in the present HEAO for
Hirsh:Can I postpone discussion on that a little too? I do want to speak about that, but I have some questions on the earlier work in X-ray astronomy. As far as a research program developed early on, was it building bigger and more sensitive counters and doing surveys?
Friedman:The motivation was still largely survey. One of the exciting things that came out early was evidence for X-ray galaxies. It was not a surprising– let’s say not terribly surprising– to find the possibility of X-ray emission from supernova remnants, but the X-ray galaxy was a great surprise. The first one we found was M-87, a spectacular optical and radio galaxy, and it was even more spectacular to find very strong X-ray flux from it. We had early indications of X-rays from 3C273, just about the time that quasars were discovered, and even from Centaurus A. So while we were still working with rockets, we were sort of getting a feel for the wide range of types of sources that exist in the X-ray spectrum.
Hirsh:Did you have an eye to identifying these sources with optical sources?
Friedman:Well, the M-87 was an obvious candidate. It's so spectacular. Even though the precision of our positioning was a matter of a couple of degrees, nobody would question the fact that there was nothing else within a couple of degrees of M-87 that would be that spectacular. In the case of 3C273, the detection was more marginal, but then again, it was nice to believe that the nearest and brightest quasar shows up as the first quasar in X-ray emission.
Hirsh:What was the reaction to the optical identification of Sco X-1 in ‘66?
Friedman:That was quite a surprise to find that a 12th magnitude blue star was the X-ray source, but it also stimulated people to think of a binary star model, and the possibility that secretion processes in such a system could produce intense X-ray emission.
Hirsh:There were a number of new groups that entered the field after ‘64. For example new groups formed at Wisconsin, at Berkeley, at Lawrence Radiation Lab, San Diego and so forth. Do you think any of these groups especially innovative in the sixties? Were there any that you worked with closely?
Friedman:I wouldn't say that any of them were especially innovative. They followed the track that had been laid out. Of course each group contributed some special expertise.. Improving the instrumentation for the particular observations they carried out. But I think the leadership remained with NRL and with Giacconi’s group. The Wisconsin group for instance concentrated on studies of diffuse background. We had made probably the earliest comments on diffuse background radiation before 1960, because on the basis of that 1957 experiment, we could set up the limits on diffuse X-ray background. George Field was interested in the question of intergalactic gas, and recognized right away that he could set limits on the gas density by using the limits we had on X-ray emissions with different wavelengths.
Hirsh:You were talking about the diffuse background .
Friedman:Yes. We continued to work on that. One of George Field's students, Dick Henry, had worked on it at Princeton and continued to work on it here,, and at one point, we thought we had defined the soft X-ray background to the extent that we could publish a paper claiming that if this were truly intergalactic radiation, it indicated a closed universe. Up to that point, I think we were pretty much alone assuming this, and then the Wisconsin group made a major effort in this direction, and others as well.
Hirsh:That report, by the way, really got wide publicity, because it would have been the first demonstration that there is enough intergalactic mass to close the universe. I remember seeing an article with a picture of Henry in TIME MAGAZINE. What happened there? Was it a premature report ?
Friedman:No. With more definition, we came to realize that the emission was not intergalactic, but comes from our own galaxy. There's enough diffuse radiation n that soft energy range within our own galaxy. The Wisconsin group did a good experiment in which they looked for an absorption effect in the in the Magellanic Cloud and found a negative result, which showed that the radiation was between us and the Magellanic Cloud and essentially within our own galaxy.
Hirsh:Why wasn't that experiment definitive? In retrospect it does look very definitive, and yet for years afterwards, people were saying, that there could be local clumping of gas. There were a number of ways of getting around that, and people could still say that there was enough mass or X-rays were extragalactic, and due to intergalactic matter.
Friedman:I think the strongest argument was that there could be just enough emission from the Magellanic Cloud itself to compensate for what it absorbed from deeper space. Instead of getting a hole, the hole was just filled up by the emission from the Cloud itself
Hirsh:Would that have been a likely effect? It certainly is a possible effect.
Friedman:It's a possible effect. Now we appreciate that it is a very likely effect– that the soft X-ray emission is essentially galactic. Each galaxy has its own contribution to make.
Hirsh:Here are two cases in which you not necessarily jumped the gun, but you were speculative. You speculated about neutron stare as X-ray sources, and you speculated, with some basis, on intergalactic mass enough to close the universe. You discounted one of them almost immediately, and the other there is some doubt about. Does it bother you to make these speculations and sometimes find that they are not right?
Friedman:Well, you know, you can't win all the time. And if you sit back and say, "If I’d only done such and such at such a time, it would have broken the field wide open and I would have received great praise and recognition for it.” That’s kind of futile. It happens to lots of scientists all the time. It's a large measure of luck. The failure to find the neutron star in the Crab in the occultation experiment was compensated, to a large degree, by our finding the X-ray pulsar in the Crab just a few years later. We had planned to look at the Crab, and I think, my own colleagues tell me, I was the only one, when we actually flew it, who thought we would find the pulsar and the X-ray emission. But even before the radio pulsars were known, we had planned to do this intensive study of the Crab. The pulsar signal was so easily found when we did it that if we had been a yea r earlier, let’s say, we probably would have discovered pulsars by the X-ray emission from the Crab. The timing is that close. We could not have looked at the Crab with that instrument, really, and not have seen the pulsar.
Hirsh:But time resolution really was not a major thing until pulsars were discovered, isn't that right?
Friedman:Well, for instance, we had enough time resolution in this payload, which had been designed before pulsars were discovered, and before 30 milliseconds was a criteria, that it was entirely adequate to show the pulse profile of the Crab. And I think the story came out around November of ‘67, and we flew our experiment around April, and found it immediately, when we first looked at the record, we found the Crab pulsar. So if one wants to complain about bad luck, we could say, if we had been one year ahead in doing that Crab experiment, it would have popped right out at us.
Hirsh:In the late sixties yow wrote a number of popular articles in which you stated that it would be unlikely for new X-ray sources to be discovered using rockets. Why did you say that? Do you recall saying that?
Friedman:I'm not sure.
Hirsh:You said the next step would have to be satellites.
Friedman:In the late sixties?
Hirsh:Yes. At this time there were about 30 to 40 sources known.
Friedman:Oh. yes. We had reached the point where it was obvious that you couldn't fire enough rockets to give you an adequate enlargement of the catalogue of X-ray sources . It would take too long to do it that way. And we had had the opportunity to think of an Explorer satellite. As I say, we would have been very happy to go that way if NASA had allowed us to team up with APL. We just couldn't do it on our own. I guess I was talking in those terms, that if one could go satellite, that was really the way to do it. Also we’d had that 1965 Space Science Board study, and it strongly proposed the HEAO type of program.
Hirsh:So when did work start on HEAO? You were not involved at all, at first., with UHURU?
Friedman:No. We had no connection with UHURU.
Hirsh:But you were anxious, I imagine, to get some satellite experiments up. Was HEAO-1 the first opportunity?
Friedman:We made some feeble tries while we were doing the SolRad program. We tried to put an X-ray detector on one of the SolRads. The one occasion we had was an a SolRad which had its spin axis pointed at the sun, and spun rather rapidly, and the detector was on the periphery of the spinning disc, so that it swept out great circles in the sky. But we never got anything spectacular out of it. We saw the strong sources, but with a spin rate of something like 6/10 of a second, you have great difficulty superimposing successive spins to build up statistics. It just didn’t work out. And UHURU was doing very much better.
Hirsh:Then was HEAO-1 your first opportunity?
Friedman:HEAO-1 was our first real opportunity.
Hirsh:Can you tell me how the whole HEAO project got going?
Friedman:It goes back to that ‘65 Space Science Board study, and I made the push for the large area detectors. As I say, Giacconi pushed for the mirror. And we went from the EMR manned concept, away from the Saturn rockets, to an Atlas Centaur, and then reduced it once more.
Hirsh:Why did the astronomy community support the HEAO project so much?
Friedman:by that time, we had the UHURU results, which were really spectacular: the d1scovery of binary X-ray sources, and transient sources. There was obviously enough there to say that here we had a field which could become as productive as radio astronomy had been, starting from similarly inauspicious beginnings .
Hirsh:And then of course in early 1973 the whole HEAO program was scrapped. Can you tell me something about that?
Friedman:You mean the cancellation o f the HEAO?
Friedman:Well, that was a real disaster. The space program seemed to be going into a deep slump, and we just barely avoided having the HEAO program cancelled. Having it suspended was what saved us, because we could then continue the design phase, but scale it down, to where the price was cut in half. It was acceptable to OMB and Congress. If it had been cancelled at that point, we all felt we wouldn't get it back in. And there was nothing else on the horizon for high energy astronomy.
Hirsh:Did you lobby for the reinstatement of the program? Did you go up to the Hill for example or go over to NASA and talk to people there?
Friedman:I've never gone up to the Hill, but I've always had some access to OMB people and talk to them directly. My form of lobbying was to reach key people in the scientific community and enlist their support, so that the President's Science Advisor would be sympathetic and get the message from important people in the scientific field– people not necessarily with a conflict of interest. I also used the approach of writing about it, lecturing about it and so on. Some of the people who’ve been associated with the whole program, like Frank McDonald, feel that I probably had a major role in initiating the program and keeping it alive through that period. I don't know whether that is so, but I certainly tried hard.
Hirsh:Do you think these cutbacks were reasonable when you consider the politics of science these days?
Friedman:I'm a strong supporter of science in space. I believe, in spite of the expense, that it's been very worthwhile, and that as time goes on, the science per dollar keeps going up, in spite of the fact that the costs go up, because the information retrieval goes up orders of magnitude with each now generation that we try. If you try to translate what we've learned from UHURU and HEAO to what it would cost to do it shot by shot with rockets, it's just absurd.
Hirsh:Right. So how long were you working on HEAO? When were you able to start building the detectors? The experiments went up in '77.
Hirsh:So when did you actually get a contract from NASA?
Friedman:It was roughly two years earlier. And it was really too short a time frame. We needed more time. We were terribly pressed in building the HEAO payload. We wished we had had more time. We would have done better testing. We would have come out with a better performance in the end. On the other hand, what worked produced very beautiful results. I think we still have several years of data analysis ahead of us, that may turn out to be very interesting – a tremendous amount of data in hand that we haven’t looked at yet.
Hirsh:What disappointments occurred when you launched the satellite?
Friedman:We lost detectors. We had seven modules of large detectors. We lost them one by one. In the ern we had two that were working well, two that were working partially well, three that were totally defunct. We feel we solved a number of technical problems which were considered handicaps. See, these all were thin plastic window detectors and required flow systems, and people had never built detectors that large with flow counters. They criticized us for taking a chance, but it turned out that in no case did we have a serious window leak problem. We think we know the sources of difficulties, in that one major source was corrosion of the points at which the w ires were soldered to the connectors. In the process somebody had used an acid solder and hadn't thoroughly cleaned it. That is one supposition. We had electronic failures that could have been avoided or minimized with better testing programs and a chance to select better components for final flight. We had one major disappointment in that we have difficulty getting spectral information out of it. We thought we were designing it to get good spectral data but one of the technicians charged a component from the design. It got by us. In the rush testing that we did, it looked as though the energy discrimination was there. It turned out we were testing with a relatively strong sources. When we had to discriminate the energy spectrum at very low fluxes, this charge in circuitry ruined the performance of that element. If we had an adequate test program, we would have discovered it. Then we would have gone back and looked at the details and found that a change had been made that got by our engineers. It would have been a very simple thing.
Hirsh:Do you think some of these problems, and lack of enough time were due to the stopping of the HEAO program for a while, and the restructuring of it?
Friedman:Yes. Once it was restructured, the desire was to get on with it very quickly. Unfortunately there was no money available to begin work, up to that point. So we got locked into a very tight schedule. And it was all done on an austerity basis. There was no free and easy money at any time in the HEAO program.
Hirsh:Having told me about some of the disappoints, maybe now you can tell me about some of the achievements of the HEAO-I., your HEAO-I experiment?
Our basic mission was to produce a map of the sky. When UHURU was finished, it had about 300 sources. Other missions like the British Aerial added some to the catalogue. We hoped we would get 1000 sources and a fairly uniform coverage of the sky. It looks as though we'll come out with that. We are ready now to put out the first part of hie catalogue– of about one -third of the sky– and there are about 350 sources in that third of the sky. Now, it's not merely increasing the number, but each source position is better. We have smaller error boxes, so that when we try to make optical identifications, it will be a lot easier to do it with the HEAO catalogue than with preceding catalogues. We've also had a fast timing capability and as a result, we have been able to see characteristics in the black hole candidates, Cygnus X-I., for instance, GX-334-9. I forget the identifications. Circinius XR-1. We see the sporadic character of the emission with much higher time resolution than previous observers and I think when we’re through analyzing that information, we’ll be able to relate it more significantly to the black hole model than has been possible before.
We have one burster source in which we are quite confident now that we see a 12 millisecond periodicity. That's interesting in the sense that the model which is most popularly proposed for bursters is a thermonuclear ignition over the surface of a neutron star. It implies that the neutron star is old, that it's spun down, that its magnetic field has decayed and so material accrete relatively uniform all over the surface and gradually builds up to ignition. 12 milliseconds is not consistent with that picture. On the other hand, if you have a black hole and an accretion disc, the period of rotation at the inner edge of the accretion disc would be about 12 milliseconds, if you had a 25 solar mass black hole. We’re very much intrigued with that result. Unhappily it to sort of marginal. We've done an enormous amount of statistical testing to see if we can set a proper statistical criterion on the credibility of the result. I think it's probably correct.
Hirsh:There's been a lot of debate, of course, about whether black holes do exist or not. Are you of the opinion that they most probably do exist, as in Cygnus X-1 and a few other sources?
Friedman:Cygnus X-1 fits the theoretical requirements very well. It’s an awfully difficult thing to believe. We know that if you keep piling mass on a compact object, it can't sustain it beyond the neutron star limit. On the other hand, can you believe that it then collapses to a singularity or must it somehow in the collapse tear itself to pieces before it can reach a singularity, as a black hole? I don’t know. But the Cygnus X 1 model is possible to test in many detailed ways. There are predictable characteristics of the accretion disc which we can look at. And you can look with higher and higher resolution that makes the evidence more and more credible. For instance, in Cygnus X-1, the emission has been described as “shot noise”, with a typical time characteristic of about 300 milliseconds. We find not only that pattern but we find a pattern down around 3 milliseconds, as though there were a family of pulsations in that range, and that would be consistent with the idea that these are blobs of plasma ripping off the inner edge of the accretion disc. Again, around a 10 solar mass black hole, it would have a periodicity of the order of 3 milliseconds. It’s the lifetime of material which is failing into the black hole from the inner edge. It’s that kind of detail that we would like to develop more and more. It’s very popular to answer all of the problem in astrophysics with black holes these days.
Hirsh:You can get nice books out of it, too.
Hirsh:Did you have anything to do with the design of HEAO 2, the Einstein Observatory?
Friedman:No. We have no part in that. Of course, we are guest observers. We make requests for the use of it, just like anybody else, but not really in the design.
Hirsh:What do you think the next step is in X-ray astronomy?
Friedman:I don't like to identify one step. Einstein has been very successful, and so it makes sense to say, let's go to a bigger one, and a bigger one can be substantially bigger. It would be twice the aperture with maybe eight nested mirrors instead of the four on Einstein, and much longer focal lengths so that you could observe higher energy X-rays. Einstein really peters out between 3 and 4 KeV. And you might be able to go as high as 7 KeV with the next generation, which is called AXAF, the Advanced X-Ray Astronomy Facility The trouble with that is, it's going to be terribly expensive. It will probably end up costing as much as the Space Telescope. And if it does, the people in the X-ray astronomy community feel there just won't be any money for any other approach. I think there is so much intrinsic science in the timing experiments that I would like to see a large effort go into what we would call timing Explorers, where you could actually point a large area detector at a particular source, like a burster, and enjoy the luxury of waiting for it to burst, and then getting very good timing information on it. Or we could look at binary systems of pulsars and study them pulse to pulse and get all sorts of refined details. So, we have a very competitive science requiring very different kinds of instrumentations. It's a shame that one excludes the other.
Hirsh:Do you think that NASA or government in general, has let down X-ray astronomers by not providing funds as easily as in the sixties?
Friedman:Well, of course we'd like to get more money and do more things. Right now, it’s very fortunate that Einstein is apparently going to run three years, instead of the originally planned one year, but when it runs out, there will be nothing up there for X-ray astronomy. We do have an approved gamma ray observatory, and we're very pleased with that, but it might not get launched till 1985-6. Other than that, we don't have anything.
Hirsh:Do you feel let down because of that? Do you think the community will feel let down ?
Friedman:I think so. You can't sit back and wait five, six, seven years for another round to get generated. There is a lot of data in hand, a lot of material for people to work on, but a large community that is motivated to do something new, something better – they're the ones who can't tolerate this sitting back and doing nothing. They may drift out of the field and look for something more active and more readily fundable.
Hirsh:So what role will NRL play in the next X-ray astronomy experiments? You mentioned AXAF, and you mention now, you're playing a guest investigator role on Einstein. Is that the way it’s going to continue?
There are going to be opportunities in the space shuttle program. One in a small extension of rocket work. We proposed this and pushed it and NASA is supporter it now. It's what they call the experiment of opportunity, where you take a rocket type payload, and put it in a box which is released from the shuttles and operates freely, with a preprogrammed pointing system, and then is recovered by the shuttle after it is out a day or two days or a week. In terms of rockets, it's worth hundreds of rockets, and it's cheap. It can be used over and over again like a recoverable rocket body. And NASA has essentially bought this idea to the extent that we're working with Goddard on a demonstration test. If it works well, that will provide a lot of people with a lot of opportunities at comparatively low cost to try ideas. If NASA funds a timing Explorer, we will bid on it. I don't know that we'll be successful. In a sense, I think we are the originators of the large detector approach to timing. It may turn out to be a disadvantage.
The feeling may be that we've had our chance, now somebody else should have a crack at it. So you don't necessarily get credit for being an originator and having demonstrated something. It can work in the reverse way. We have also proposed, unsuccessfully so far, to develop a telescope based on the use of a mask in carrying out a Fourner transform, the transform telescope. In its simplest version, the pinhole camera is a transform telescope. You can increase its sensitivity by putting many pinholes in the mask. That gives you a confused image, but the original image is recoverable by doing the proper transform. So we think that that is a mode which will permit working to much higher energies. The limit is the transmission of the opaque portions of the mask. One should be able to work up to maybe 8o KEV, whereas a mirror like Einstein is only good to 4 KEV, and the next generation maybe to 7. With a transform telescope, one can go to 80 KEV. The resolution depends on the separation of the mask and the detector. If you’re limited to the dimensions of the shuttle, you end up with resolution of the order of minutes of arc. But in principle, you could separate the mask and the detector by a kiloseter.,and you could achieve resolutions of if thousandths of a second . So we would like to start in this direction, demonstrate something on the shuttle, and look eventually towards a very expanded system with very high resolution. We're into the gamma ray observatory. We have one of the basic experiments on that. That's funded. It's an approved program now, and it will keep many of our people very busy for eight or ten years.
Hirsh:What's been the ultimate excitement of X-ray astronomy to you and members of your group? Why have you been so heavily involved in this for the last 20 years?
Friedman:It really is a new astronomy. We see things very differently and what we see relates to very exotic processes, like supernova collapse, formation of neutron stars, and black holes. I can't think of more intriguing problems in astronomy.
Hirsh:You talk about astronomy, yet you have a physics background. This is interesting because you've crossed disciplinary boundaries. Did you ever find that crossing difficult or a problem with colleagues? At lunch you told me you don’t mind drifting where the interesting problems are. How have other people thought of that in your case?
Friedman:I'm treated very well by astronomers, even though I never had a course in astronomy. Probably that’s a handicap for me. I might have progressed much more efficiently and faster if I came out of a thoroughly coached background in astronomy. But maybe I learned my astronomy after the fact; I'd come up with a strange observation, it needed a new interpretation, then I leaned what I needed to learn. But I think the best astronomers have welcomed all of these new discoveries very warmly, and I’m very comfortable with the relationship around the field.
Hirsh:How do you think, in general, astronomy has changed in the last 20 years? Some people have called it a revolution in astronomy. Would you go that far in describing it that way?
Friedman:I think it’s fair to describe it that way, when you think of where all the observing and theoretical emphasis is today. Classical astronomy has been greatly reinvigorated by the need to make the classical observations of these X-ray and radio and infra-red sources. It’s given new life to the whole classical field of astronomy. And you really have to put all the parts together in order to understand the objects you're looking at. No one type of astronomy seems to be entirely adequate to give you the correct models. The pulsars, the neutron stars, the black holes, the quasars, the Seyfert galaxies, the BL-Lac objects – these are all objects discovered and recognized in the last 20 years. We still have all of the classical problems, like the true value of the Hubble constant, and the evolution of galaxies, all of which are benefitting from the new observational capabilities.
Hirsh:I should have asked you earlier when I was asking you about your experience in going from physics into astronomy if someone were to ask you what you do, how do you classify yourself as a scientist, what would you say?
Friedman:I would call myself a journeyman physicist. Basically I’m, still a physicist, and I tend to look at any work I’m interested in from the viewpoint of a physicist.
Hirsh:Let me get a picture of how you work as a scientist. You've been head of the X-ray group for its entire life. You seem to have had the ideas for the major programs and major experiments. But how did you translate those ideas into actual experiments? There were other people of course working. How did you delegate authority?
Friedman:In the earlier years, I spent most of my time in the laboratory. I made the detectors myself. I interpreted the data, largely on my own and took the records that came off an Aerobee flight and rolled them out on the table and measured signals on them and so on. But as time has gone on and the experiments have become more complex, the group has become bigger. I find myself spending most of the time in an office, reading and writing. I visit everybody and see what’s going on and keep informed, but we have younger people now who are very comfortable with computers and do their own programming. I can’t take a record off HRAO and look at it the way I could an Aerobee record. It goes through a very complicated massaging in the computer facility. I still take part in generating the new programer in close discussion with all of the younger people. They're very good. They have their own ideas. I think they look on me as the person with some senior wisdom, who knows whether what they're proposing is likely to be looked on with favor by reviewers. They look for my advice on how to develop a proposal and ask me if something will sell well, and so on. At this point in life, I have kind of senior status. They depend on wisdom of past experience to help them, and I look for many of the younger people to show qualities of leadership and creativity. I'm very pleased when I find it in them. Fortunately we have several who will do very well over the years.
Hirsh:Who are some of these hot young people?
Friedman:In the X-ray astronomy group, we have Kent Wood, who is very able, and Seth Shulman. In the gamma ray work, Jim Kurfess an Neil Johnson are really first rate. In the radio astronomy infra-red area, we have Phil Schwartz, Ken Johnston, Doug McNutt and Kandy Shivinanda. In the ultraviolet, we have George Carruthers, who’s really outstanding. He already for many years has been generating all of his own ideas and programs and carrying them out very successfully. In the solar work, Gunter Bruckner is probably the best instrumentation man in the country in his field. He's designed the best spectroscopic experiments and carried them out very successfully. George Doschek and Urey Feldman are right at the front edge of their field in solar spectroscopy. There is a substantial number. These are all people under 40.
Hirsh:During the last 20 years when you were working in X-ray astronomy, I know you were also involved in other programs. You were superintendent of the Atmosphere and Astrophysics Division since 1958, so therefore I suppose you were supervising lots of other types of research too. Did you take as much interest in some other fields, like radio astronomy, ultraviolet and so on as you did in X-ray astronomy?
Friedman:I've been interested to the extent that I want to know what they do. I want to understand the relationship of X-ray work to work going on outside and perhaps offer some advice and be able to defend it. Our radio astronomy group has been self contained. I don't honestly think that I have given them any impetus for any special scientific problem area. It's come out of their own – they've generated it themselves. On one or two occasions, I suggested that they try things, which they did not, which later turned out to be really quite important and exciting, but the problem is that I was not enough expert to really push very hard.
Hirsh:Can you give me an example of that?
Friedman:Well, the search for water vapor in radio astronomy. Our group had been doing work in which they could see the absorption band of water vapor at 13 millimeters and I asked them, “If you see it so prominently in absorption, couldn’t you turn around and see if you can find emission features in various parts of the galaxy from water vapor”? This was at a time when hydroxyl had jut been discovered. They didn't follow through, but Charlie Townes and his group did and almost immediately, with even simpler instrumentation than we had available, were able to pick up water vapor, and it’s been a major component of the observing program ever since– the water vapor masers.
Hirsh:Am I right though in assuming that X-ray astronomy was the main thrust of your intellectual activity for the last 20 years or so?
Friedman:I think that’s right. I remain rather closely involved with solar work and solar-terrestrial physics, but for me the real excitement has been X-ray astronomy.
Hirsh:Can you tell me, generally, how things worked administratively here at NRL through the years? You've told me a number of time how it was so pleasant in the old days. Things worked out very smoothly. There wasn’t a lot of paperwork. How has that charged, and how has it changed as you've moved into different administrative position here?
Friedman:I've always dragged my feet in response to paperwork administration. I've been very fortunate in having an administrative assistant, Dr. Manges who is very very good at that. And we've had a partnership in which he absorbs practically all the pain and leaves me largely free. In spite of that, there are demands that I can't escape, such as frequent presentations of programmatic material for approval at different levels at ONR, over at the Pentagon., and so on, There eat up a lot of time. They are kind of a ritual performance and I wonder whether they're really necessary. But it's a trend that grows progressively worse. The number of times one has to defend programs and budgets, the amount of paperwork that goes with promotions of personnel, the difficulty in making new hires, trying to sustain a lively healthy vigorous atmosphere in a rather large division, by infusing it with fresh young blood – it becomes so difficult and so fatiguing to try to continue that. It gets to be discouraging. The system doesn't allow for a good flow-through. Your personnel get older and older., but stay on., and the ceiling points remain fixed or keep decreasing, so we don’t get young people. I solved the problem years ago by working out this arrangement with the Science Foundation to support the Hulburt Center with roughly a million dollars a year.
Hirsh:I'd like you to tell me about that.
Friedman:Well, that was at a time– goes back to 1963– when the space program was expanding and we had already established a very good reputation. We had the kind of a program, in contrast to NASA of a lot of small experiments. It’s very easy for a man to come in, connect himself with our programs and maybe leave even within a year with a piece of research that's publishable. I had one PhD Candidate who did his thesis within a year. Generally people came for two years. Some stayed an long as three years We had the atmosphere of a graduate school and I had the opportunity to discover– " the best ones in any year's group and would try hang onto them. The best young people I have now, came out of that program. Now, when the Vietnam War came along, and Senator Mansfield got into the act with his Mansfield Amendment, trying to separate the military and the academics, the Science Foundation got cold feet about this program. Even though we were not using any of their money to support the salaries of our own people, or our own hardware – all of that money was going to the visitor program – they pulled out of it. For a while NASA supplemented about half of what it cost. Then they got out of their program of institutional support and found it awkward to continue giving us money. ONR tried to pick up some of it, and that gradually faded away. In the end, we use all sorts of makeshift arrangements now and are lucky if we have one or two people who are in this fresh new category at any time. So that’s a very disappointing loss. I think it's essential to maintain the creative vigor of a program– to get bright young people in it.
Hirsh:So is that what the Hulburt center was?
Friedman:The Hulburt Center was the name we gave to the visitor program., but it gradually got the connotation of identifying ail of our research work with the Hulburt Center, and we still publish that way. We still try to bring people in as Hulburt Center appointees. But the money doesn't exist. It has to be scratched up by AJA sorts of devious means.
Hirsh:Aside from contracts to do work like on HRAO, did NASA provide any other types of fording? You said there was some funding also for the Hulburt fellows.
Friedman:That's right. And that was permissible at a time when NASA had its institutional support program. When they abandoned those, we had to be out off too. There have been Presidential interns and other temporary program of one sort or another . Whenever something comes along, we grab it. We have our own postdoctoral program, with the National Research Council. We try to use that, but that's not as good as the NSF program because the choices are made by a committee in the Research Councils, whereas with the Foundation, I was pick my own candidates. I feel I was able to do much better than to accept somebody else's judgment who to send down here.
Hirsh:What new duties did you take on when you became superintendent of the Atmosphere and Astrophysics Division in ‘58?
Friedman:It was primarily having oversight over activities with which I was not directly associated previously– like the radio astronomy program. We also had an aerology program, essentially an atmospheric science program in "which was a branch of the division.. And that w as a bout it. Everything else I was intimated with and very familiar with. So in a sense, it broadened the scope of the total activity I was concerned with. So in a sense., it broadened the scope of the total activity I was concerned with. The administrative responsibilities in the beginning were, oh., almost nil – very easy. I could make a rough budget estimate. I didn't have to do it myself. It was my associate who drew it up. The budget would go to the director, and I could almost count without any uncertainty that we would get what we asked for, and I wouldn’t have to make any interim justifications during the course of the year. My responsibility was to see that we lived within our budget to the end of the year, and in fact at the end of each year, there were year end funds that were always tagged for us and made life very comfortable. Nowadays your budget is followed on the computer day by day, and every item down to the $100 level, you have to be accountable for, or somebody in the division has to be accountable for. That is a very tedious burden.
Friedman:I don’t think we've been especially repetitious.
Hirsh:No. I think it’s going really well. In 1960, you were elected to the National Academy of Sciences. Can you tell me what kind of work you’ve been doing with the Academy?
Friedman:I have been involved with various Academy studies rather heavily all through the years. I mentioned I had 13 years on the Space Science Board. I chaired a study in 1970 on the next ten years of space research, which I think had a rather profound impact on the subsequent NASA program. For instance, one of the things which JCL lobbied for very strongly was called the Grand Tour – a mission to visit all of the planets, an unusual configuration which supposedly would be coming up about now. That report said that we shouldn't do the Grand Tour, that we should reconfigure a planetary exploration program, dedicated to some more specific things. It turned out to cost about half as the Grand Tour, and I think the scientific returns have been much richer than would have come out of the Grand Tour. That report also put heavy emphasis on high energy astronomy and supported the Space Telescope work, so the results were very gratifying to me. I'm happy that I was involved in a key role in that study. I've chaired other studies in the area of solar-terrestrial physics which, let's say, helped shape programs for a decade. I'm doing another one now, sort of a decade later, and we’ll, see what impact that will have. I've served on the Committee on Atmospheric Sciences and on the Climate Research Board. I've chaired the Geophysics Research Board. I've chaired the Committee on Solar-Terrestrial Relationships. I've served on the Committee on International Programs. I was the American vice-president for COMPAR. for five years, and that’s run out of the Academy. I could go down a long list of these things. I was on the NASA SPAC committee, that's their top advisory committee, for a few years while Jim Fletcher was the administrator. I think that may be the only NASA committee that I was directly affiliated with. There are others but not terribly important.
Hirsh:Those are a lot of committees, obviously, and you’re still heavily involved in them. How do you balance this committee work with your own work – your own research and planning?
Friedman:The committee work is really very interesting. You sit with distinguished colleagues. The discussion is usually sharp and bright and has to be interesting. I enjoy that mechanism for keeping abreast of good science, getting involved with a lot of things in which I'm not personally doing research, which are intrinsically very interesting, and sort of let it rub off on me through this committee procedure. I find that well worth the effort put in.
Hirsh:Tell me about your activities as a member of the President’s Science Advisory Committee in ‘71 and ‘72. How did the committee work; what input did you have in the committee?
Friedman:There were a number of interesting issues that came up during that time. In the space category, there was the question of Viking. Viking had escalated enormously in cost, and there was a serious question, should it be out off or escalated still further and carried through? And the decision was made to support it in spite of the extravagant cost. There was the question of a supersonic transport, and I was involved as having some expertise on the question of the ozone problem – nitric oxide emission from the supersonic transport. My own opinion offered then was that we really didn't understand the problem well enough to say which way the effect would go. At the same time, another panel of PSAC did a study of the economics of the supersonic transport and came out very negatively, and that report was leaked. Essentially it was what got President Nixon discussed with the committee. It was his committee. He wanted a supersonic transport. We had leaked information which was killing it. It was the period in which the space shuttle concept was being developed. I chaired a panel for the space shuttle in which we came around to the present concept. The original idea of a fully recoverable system launched from the ground was going to cost over 13 billion dollars and Nixon said he wanted us to come back with something closer to six billion, so a shuttle in which you dispose of the fuel tanks and bring back only the orbiter was the concept which we reached. Given the constraints of the time, we configured a program which was approved and which went ahead. We never got into details like the tile problem. I don’t know where that surfaced but it never came up in the discussions of our committee. Wells that was the sort of thing that went on in PSAC at that time.
Hirsh:Did you find that Nixon was responsive to recommendations of PSAC?
Friedman:If they were politically convenient.
Hirsh:Did you ever have problems in working for Nixon?
Friedman:We sat down with him one time, when the issue of the war on cancer came up, and the opinion of all the scientists was, that's not the way to do cancer research. We though that you support basic research and the solution to the cancer problem would fall out of good research. When we explained our attitudes to him, he agreed with them. And then when Kennedy came out with his proposal for a war on cancer, he turned right around. He had to make the war on the same basis to match him politically, so he had a war on cancer. That’s the sort of thing. When he was crossed on the supersonic transport, he abolished the committee.
Hirsh:That’s when you left.
Friedman:Yes. We all got our friendly letters saying we had solved all of the scientific problems of the country, and that he appreciated it, and he could release us now.
Hirsh:That's a nice way to dismiss people. Can you tell me something about your activity on the General Advisory Committee for Atomic Energy? You were on that committee from ‘69 to ‘74.
Friedman:Yes. I look back on that period with great regrets. I don’t know what we could have done. But all of the problems that have come along since then were obviously there in those years. The safety problem was one. We were going to conduct a test on a reactor meltdown on a modest scale. It was called LOFT, the Lose of Fluid Test Experiment, and it had been on the books for many years and just wasn't getting anywhere, and during the six years I was on the committee, it still never got anywhere. That was sort of unforgivable. We recognized problems of reliability. The obvious thing seemed to be that we should standardize on all of the hardware and each atomic plant ought to be close to a carbon copy of every other. And instead, each plant was a mix of parts supplied from different manufacturers, very different in its basic assembly and that didn’t seem to make sense, but we never got anywhere in changing that. It was clear that the management of the program was centralized in Washington, whereas the leaders of the national laboratories were not given very much freedom to conduct their programs. Everything had to be approved from Washington. The directors at Argonne and Oak Ridge and so on were bitter in their criticism of the Washington management of everything they did. We couldn't change that. There was a lack of support for basic research in all aspects of the atomic energy program, and we couldn't see to do anything to cure that. And you can go on with this litany of things that should have been done, problems which were obviously there and crucial for the future, and the General Advisory Committee couldn't seem to make any impact.
Hirsh:Why was that? Why were you unable to make an impact? Were there people on the committee that were difficult to work with?
Friedman:Well, the response had to come from the Commission itself, and the Commission and all of its bureaucracy had been very well protected by the Joint Committee on Atomic Energy, who felt they owned the atomic energy program in the country. Maybe the blame can be traced all the way back to them. They sort of had this basic feeling that atomic energy was a great boon. It was cheap power, and it was going to get there, was going to prosper, and they weren't concerned about criticism of potential public reaction to the waste problem, for instance, and not doing anything about it, or to these safety issues which were being raised. They just felt it was not a public issue. And it became an overriding public issue.
Hirsh:Were these people mostly nuclear engineers?
Friedman:Yes, and lawyers.
Hirsh:Do you think there is a difference in the way scientists might see problems having an impact on the public, and the way engineers might see them?
Friedman:Nowadays, certainly, scientists are very conscious of the social impacts. I’m not sure they were then. It was a form of arrogance. We knew nuclear power was good, and it would work out, and there would not be any great public outrages.
Hirsh:Jane Fonda hadn't been around yet.
Friedman:The leadership, I feel, during Schlesinger's term, for instance, gave all of his energy to the legal problems of regulation, siting, and so on. And he ignored the technical problems which were so obvious to the General Advisory Committee. Dixie Lee Ray came in. That was towards the end of my term. I had to chair a study on basic research within the National laboratories. She asked for it. When we got it done, I think she just put it the bottom drawer of her desk. Probably she never read it. She was a very political animal and felt that her job was to appear on TV and calm the fears of the public just by telling them everything's OK, that sort of thing.
Hirsh:Why did you leave that committee in ‘74?
Friedman:My term was up. A year later the commission was abolished. A new structure was set up.
Hirsh:Let me ask you a question that might involve your modesty. You've won a number of prizes – from that first prize in 1945, the Distinguished Civilian Service Award to the National Medal of Science and lots in between. How do you feel as a scientist in receiving awards like that? Is there a sense that perhaps scientists should not be given public awards like this or what?
Friedman:Well, it's very nice to receive an award. It implies that your colleagues think well of you. That’s probably the most important aspect of it. Most of these awards are the decisions of committees of your colleagues that have looked over the field and decided you ought to get it. I suppose that’s a mixture of their appreciation of your work, and whether they like you personally or not. It's also nice for your family. In fact, the family generally doesn't understand what you're doing. They just know you work awfully hard and you don't give them as much time as the family thinks it ought to get. If you get an award and the circumstances are pleasant, like getting an award at the White House with all of the fanfare that goes with it, it’s a morale boost for the family. But there are lots of awfully good scientists that somehow don't get picked.
Hirsh:Do you think there might be a Nobel Prize given for work done in X-ray astronomy?
Friedman:A few years ago I would have “no” because the Nobel Prize is not given for astronomy. But they have given it now to Ryle and Hewish in radio astronomy, so maybe the precedent is there. I would think that since they've done that for radio astronomy, one of the exotic astronomies or space science generally justifies such an award.
Hirsh:Do you think there are people bucking for the award, in the field?
Friedman:I suppose there are. I hear that comment made about the original group at AS and E. They feel strongly it’s worth a Nobel Prize.
Friedman:Yes. But I don't know. There was a time when I thought that Jim van Allen would very likely get the prize for discovering the radiation belts. It never happened. It might still happen.
Hirsh:Yes. Sometimes it does take a long time. You were telling me a little bit about your involvement in planning the space shuttle. Do you think the shuttle has been a wise decision, considering the political and technical problems?
Friedman:I believe it was a wise decision to go ahead with an advanced transportation system. Whether we designed the right system or not is still very questionable. It may work out that the tile problem is fixed, the engine problem is fixed,, and sometime next year it will fly. And it will be used for some time, but by now, there’s a strange feeling in the engineering community that they wish they could do it differently. I don’t see how we can have an aggressive space program without a transportation system like that. A lot of things in the details of how it's designed, and how it's to be used, that I am not happy with, but we always think about it as a first generation approach, and that the country will support it and will get into a second generation, in which a lot of the faults will disappear.
Hirsh:Do you think the engineering problem that have been delaying the shuttle the last couple of years are going to affect space science research?
Friedman:It has to, because the science is getting all backed up now. We really don’t know what that impact will be, but it’s bad. I believe the military must make the decision to restore the conventional rocket production lines. We just can't risk getting held up with the shuttle. If the shuttle has really serious future problems, we might have to resort to conventional rockets.
Hirsh:What happens if the shuttle follows the example of the first Vanguard and blows up on the launch pad? What do you think that would do to the space program?
Friedman:It would be traumatic. I don't know whether to describe it as disastrous in the extreme. It is hard to know what the mood of the country is. I have a feeling that our troubles are bottoming out, and the country is going to get going to get going again. We’ll achieve a new level of prosperity. There will be a general revival of spirit of doing things. But whether that will come soon enough to save us, if the first flight of the shuttle is a disaster – I doubt. It’s going to take up five years to get on the upswing again.
Hirsh:You think that if the shuttle were to fail on the first mission, it would set back the entire space program quite a bit from the political standpoint?
Friedman:Yes. I think the crinita of the technology would be so severe that we’d go through a very serious phase of re -evaluation, maybe restructuring the whole program. I really don't know how it would come out, but there would bound to be delays of several years, to get it going again. I think the practical answer would be to return to the individual rocket launches for military purposes, and the public will be satisfied that our miliary posture isn't damaged.
Hirsh:Whereas the space science posture may well have been damaged. Have you had anything to do in committees or otherwise with the Space Telescope?
Friedman:I've been working with one of the university consortiums – the USRA group – the 52 university consortium which has specialized in work for NASA in space related problem areas. They've made a proposal for the Space Telescope Institute, and I am, in the proposal stage, serving as chairman of the steering committee for science on the Space Telescope. If their proposal wins, they propose to put it at Princeton, and for a number of years, I would probably serve as chairman of that steering committees advisory to the director. So I do expect to be fairly close to the telescope. I won't be doing my own research on it. Probably, I hope, some of the people here will get an opportunity to use it. But I'll enjoy what science comes out of it.
Hirsh:That's a wise decision then? It's a good project in principle?
Friedman:Oh yes. If it works the way it's designed to work, it will produce an enormous amount of very interesting science.
Hirsh:Why do you think it's taken so long to get up? And of course it’s not there yet .
Friedman:Well, the problem is the shuttle. The development of the telescope is on schedule.
Hirsh:But it is a scaled down version, isn't it. It’s a 2.4 meter telescope. First the designs were for over 3 meters.
Friedman:That’s a was a matter of cost, plus some technical problems. 2.4 meters is considered conservative and guaranteed to fulfill its specifications. 3 meters is pushing the state of the art. So, considering the cost and the desire to be fully successful, the wise decision was to cut back. It brought the cost within an acceptable range, although it is still a half billion dollar mission.
Hirsh:In general, do you think that these space observatories, these national space facilities, are good ideas?
Friedman:They work very well. The National Radio Astronomy Observatory is very successful. The operation that it runs in Soccoro with the VLA, is very good. Kitt Peak and Cerro Tolelo are very good operations. It has to be the way to do it, because everything is too expensive for an individual university to manage. And the concept, that they are to serve the whole nation, is fully recognized by the directorship of each one, and they've done it.
Hirsh:So you think that a similar type of organization for space observatories could work out.
Friedman:That’s why this has been proposed, and why NASA is willing to go along with this.
Hirsh:So in the long run it might be ultimately cheaper and serve more people than an individual experiment.
Friedman:Well, it's just too big a thing for any individual university to handle. It has to be a consensus type of operation. You have to get input from the best talent in the scientific community. You have to have an outstanding director and be able to replace him with similar caliber people on a routine four or five year term or whatever. The yearly operating expenses are going to be very high, maybe 50 million dollars a year. It has to be done equitably and efficiently.
Hirsh:What do you think will be the role of ground-based observatories for the future of astronomy?
Friedman:There’s a strong move towards initiating some very large ground-based observatory programs now, in large measure because people are worried about the space program. Suppose the shuttle doesn't go and that we don't have the Space Telescope? We haven't gotten any large new ground-based telescope because we've been given the Space Telescope. So astronomers right now are studying the possibility of 10 to 15 meter ground-based telescopes for optical and infra-red. The Palomar is only 6 meters, so the new concepts are very much larger, very much more powerful, and believed to be technically feasible. But to build a 15 meter telescope on the ground would cost a hundred million dollars, and it would be a project that would come to fruition in the 1990's. But there's a very very strong interest in trying to do that.
Hirsh:What large program would you like to see NRL involved in next?
Friedman:I mentioned that we're in the gamma ray observatory program and that's a large program for us. It's something which will run maybe 12, 14 million dollars over eight years. That's a big program for us. I mentioned some of the ideas for timing Explorers, and a transform type of telescope. We'd like to do things like that too. They would be compatible with the kind of staff we have – not too big but essentially pushing new frontiers. We’d like to do things in the submillimeter range. We have some good ideas, not too expensive, and we hope we’ll be able to get to them before too long.
Hirsh:May I ask you a couple of perhaps miscellaneous questions?
Hirsh:How have you felt about popularizing astronomy and physics? I know you've written so many articles for lay audiences. Why do you do that and why do you enjoy talking so frequently to lay audiences?
Friedman:I do enjoy it. The science is exciting. It's a challenge to see if you can transmit some of that excitement to a lay audience. I think it's really disappointing that there isn't more of that done by good scientists. It takes time. It's time away from your creative research. But I often find, until you try to explain something to a layman, you can’t be sure you really understand it yourself. It's a good challenge. And in a sense, it pays off. It reflects back in the kind of support we get. The fact that our work is well known outside of the scientific community in large measure I think due to the fact that I write a lot, in places that the nonprofessional will read. It gets to the bureaucracy and the government. It gets to Congress and Congressional staff. It gets to scientists in other fields who are happy to get an easy reading version of what's going on, something they know is exciting but outside the field. They don't want to give it a lot of time. And the net result is that you build up support for your program. We have a lot of ups and downs, in support from the administration and DOD. There have been some depressed times. There have been occasions when we might have been wiped out. But the fact that we’re so generally known in this broad community, has given us a kind of support that’s protected us.
Hirsh:So you think there's a link between your popularizing and the level and consistency of support?
Friedman:I think so. I've been told there definitely is. I wrote a popular book for the NATIONAL GEOGRAPHIC, and they're in their third printing now, and some of the people over in the Pentagon say “well, that’s done more to support and protect your program than the technical papers” that we send over to them.
Hirsh:That's THE AMAZING UNIVERSE.
Hirsh:Well, that's direct proof.
Friedman:I think it's got to be true.
Hirsh:Another miscellaneous question. I’d like to ask you about what do you think are the contributions of scientists who are on the fringes of discipline or sub-discipline – people not necessarily involved in the concerns of one field, people who might just come in, do an experiment or write a theoretical paper and then leave. Do you think people like this have made major contributions to the field? If you want to take X-ray astronomy as an example, please do.
Friedman:It's hard for me to think of people who just moved in to treat a particular problem, publish their work on it, and then moved out again. Usually if a field is exciting, once you get into it, you just tend to get in more deeply, and I think that has been the pattern of most people who moved from outside X-ray astronomy into it. They stay with it.
Hirsh:But then there are people like Richard Henry who’s worked with you for a while, and gets more involved now in ultraviolet astronomy and in the general question of intergalactic matter.
Friedman:He actually did some ultraviolet astronomy here an well as the X-ray astronomy, and it's a problem of the program over at Johns Hopkins. They have special skills in the ultraviolet which win them funded proposals, so they stay with it. If they were competitive in the X-ray astronomy area, I'm sure he’d be happy to be involved with the X-ray astronomy. He has students who come over here and work on our HEAO data, so he does remain connected. There are always these practical problems: what can you do where you are?
Hirsh:Do you think there’s a correlation between aging and creativity in science?
Friedman:I'm sure there is. Simply the matter of physical vigor. Young people who are productive and very successful really work very hard, and as you get older, you just don’t have the stamina to do that. It soon becomes a problem to last through an 8 hour day, whereas you could easily go 14 or 16 hours when you're intrigued with something, and young. I think it is more of that than anything else, just declining vigor.
Hirsh:Another random question. Because of the financial cutbacks and problems physicists and astronomers encounter, fewer people are entering scientific fields as PhD's each year, and as a result, communities of disciplines are getting older, on the average. What effect do you think this is going to have on science?
Friedman:It's bound to have a bad effect. The science leads the technology, and if we don't have creative science, we won't have productive technology – innovation (a good word we all use now) – and you don't get creative science unless you have a flow of fresh young minds into the field. It’s a very serious problem.
Hirsh:Do you see any way of remedying the problem?
Friedman:There has to be better support for scientists. As a profession, scientists are paid much more poorly than doctors, lawyers, other professionals. If you don’t offer them the opportunity of freedom of research to compensate for lower salaries, there's not much to persuade people to go in the field. It used to be you’d say, “Well, I don’t care what I earn because I have so much fun doing what I want to do.” But if you don’t do w hat you want to do and don’t get w hat you need to do it, then why go into it?
Hirsh:Now for really broad questions. What contributions do you take most pride in when looking back on your career?
Friedman:I have mixed feelings. I've gotten a big kick out of a number of things. When I look back, some of the practical things gave me as much pride as some of the basic scientific discoveries. During World War II, any time you could make a contribution which you felt really helped win the war. A great feeling of pleasure came for having been able to do that. Solving that crystal problem in a couple of days was a great satisfaction. Discovering the Russian test with a relatively simple technique gave me great satisfaction. Firing that first V-2 rocket and getting all those answers out of a very simple experiment was very exhilarating. Doing a Crab occultation experiment, going out to the South Pacific and firing six rockets which hadn't really been tested before from the deck of a ship, and having everything go off well and getting all the answers you wanted provided a great sense of adventure, The adventure component is a big factor in how good you feel about it.
Hirsh:And you I’ve had a number of adventurous --
Friedman:Yes, we’ve taken gambles and have come off pretty well.
Hirsh:What benefits do you think people will derive from these contributions?
Friedman:For the contributions in the practical area., the answer is obvious. They were valuable and maybe very valuable. It's hard to put a price tag on them. In the research field, I think as long as you work on the threshold, on the frontiers of the most interesting science, you're bound to ultimately contribute to very beneficial effects because that's where the new applications, new technologies, will come from. I think it is a mistake to get stuck in a worn out field and simply add the next decimal place to a result which is already well understood. The good people somehow find the frontier fields. You can’t keep them down. They’ll come up with something brand new.
Hirsh:I am through with my questions. Are there any things you think I missed or that you would like to have on record as being important.
Friedman:I think there are great advantages to working in a multi-disciplinary laboratory which applied missions as well as a basic research component. I didn’t select young people because they said they would like to work on military problems. I brought them in because they were intrigued with basic research, and wanted to work in astronomy. But in every case, I found that when an opportunity to translate scientific experience in support of a practical problem has come up, these people have been very pleased and very gratified to be able to do that. There was no snobbery about tackling a practical problem. The reverse benefit is that we have so much high technology all around us that it helps greatly in the conduct of the basic research. It is freely available to you if you learn how to live with your engineering colleagues here. There is a lot to be said, then, for doing basic research in a laboratory with mixed missions of this sort, instead of in an ivory tower.
Hirsh:Have you ever regretted not taking a teaching position, a university position?
Friedman:I really haven't. My life here has been very busy. The connection with committee work outside has given me all the exposure I could get in a university community including the friendly relationships with a large number of people with academic backgrounds. I’ve tried to spend some time teaching at various points. This has turned out to be more of a burden than a pleasure. It's a lot of work. I find the young people I have here have been more stimulating than the graduate students I've talked to when I've been in a teaching mode. At some early point in life I thought that I might finish my career in an academic role, but have no desire for that any more.
by W. Beeman and H. Friedman, Physical Review 56 (1939): 392.
The Navy Distinguished Service Award, 1945.
Richard Tousey, later head of the rocket spectroscopy group.
Office of Naval Research
J. Robert Oppenheimer
10 October 1946.
29 September 1949.
Bengt Edlen. See, for example, his paper, “The Identification of the Coronal Lines.” Monthly Notices of the Royal Astronomical Society 105 (1945): 323-33.
See T. R. Burnight, “Soft X-Radiation in the Upper Atmosphere,” Physical Review 76 (1949): 165.
Homer E. Newell, Jr., “Geometric Factors Underlying Coincidence Counting with Geiger Counters.” Review of Scientific Instruments 19 (1948): 384- .
See J. E. Kupperian and H. Friedman, “Gamma Ray Intensities at High Altitudes,” Proceedings of the Fifth CSAGI Assembly, Moscow, July 1958; H. Friedman, “Information about the Gas Density in Space Derived from Radiation Measurements,” presented at AGARD Conference, Paris, May 26-28, 1959, AGARDograph 42; and H. Friedman, “The Sun’s Ionizing Radiations,” in J. A. Ratcliffe, ed., Physics of the Upper Atmosphere (New York: Academic Press, 1960), p. 202.
In June 1962. See Riccardo Giacconi, Herbert Gursky, Frank R. Paolini, and Bruno Rossi, “Evidence for X-Rays From Sources Outside the Solar System,” Physical Review Letters 9 (1962): 439-43.
See S. Bowyer, E. T. Byram, T. A. Chubb, and H. Friedman, “X-Ray Sources in the Galaxy,” Nature 201 (1964): 1307-8.
See Herbert Friedman, “Rocket Astronomy,” Scientific American 200 (#6, 1959): 59.
Orbiting Solar Observatory.
Orbiting Astronomy Observatory.
launched 12 December 1970.
Admiral Rawson Bennett.
J. Robert Oppenheimer
Having missed making the first discovery of a non-solar X-ray source, that is.
Attitude Control System.
Josef S. Shklovsky.
For details of the experiment, see S. Bowyer, E. T. Byram, T. A. Chubb, and H. Friedman, “Lunar Occulation of X-Ray Emission from the Crab Nebula,” Science 146 (1964):912.
An optical mirror telescope. Einstein is the name given the second HEAO satellite that carried the telescope in 1978.
High Energy Astronomy Observatory.
in the early 1970s.
See R. C. Henry, G. Fritz, J. F. Meekins, H. Friedman, and E. T. Byram, “Possible Detection of a Dense Intergalactic Plasma,” Astrophysical Journal 153 (1968): L11-L18.