Oral History Transcript — Dr. Richard Bleach
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Interview with Dr. Richard Bleach
Richard Bleach; May 11, 1984
ABSTRACT: After describing his upbringing and undergraduate education in physics at Renesselaer, Bleach (b. June 7, 1944) reviews his subsequent enrollment in the PhD program in physics at the University of Maryland. He then discusses his work at Goddard while in the PhD program, including initially developing solid state detectors for cosmic ray experiments; moving to an X-ray astronomy group headed by Dr. Elihu Boldt; developing and testing proportional counters in balloons, rockets, and satellites; use of mechanical and modulation collimators in the counters; and interaction with other research groups. Bleach next describes his thesis on Cygnus X-1 and work at NRL after completing his PhD program, including initially building and conducting experiments with detectors for the gamma ray group under HERO, and subsequent move to the laboratory diagnostics area in which he still is involved.
DeVorkin:We're going to be doing an exploratory interview with you, Dr. Bleach, about your education, training, and the development of your interests. So first tell me when and where you were born, what your mother and father did, or do, and a little bit about your schooling.
Bleach:Okay. I was born June 7, 1944, in Fort Riley, Kansas. When I was born my father was in the Army. After he was wounded in the Philippines and discharged from the Army, we moved to New York state where he became a retailer of clothes, and after a while cars. That was because the area where I grew up was a resort area so in the summer time all of the business was associated with tourists coming up from New York City. He was in various businesses that dealt with the tourist trade. My way of making money for college, after I got out of high school, was doing work in the summer time associated with the resort trade up in that area. I started to go to college in 1962 at Rensselaer Polytechnic Institute in Troy, New York.
DeVorkin:Were you the first generation in your family to go to college? Did your father or mother have college training?
Bleach:My father completed three years of college and then went into the service and was sent overseas in World war II. So I'm the first one that completed college. I have a sister who went to nursing school and got her degree in nursing. My mother did not attend college.
DeVorkin:Was it acceptable in your family for you to attend college?
Bleach:This was very much encouraged, probably because of my half Jewish and half Italian heritage, and the environment where I grew up in Monticello, N.Y., a region in the Catskill mountains of New York, with about a 50% Jewish population.
DeVorkin:On which side?
Bleach:On my father's side. My mother's side is Italian; an interesting combination. Most of my generation — my uncle's and aunt's children, my cousins — went beyond high school and became lawyers or artists, but most of them had some higher education beyond high school.
DeVorkin:Can you pinpoint when you became interested in science or astronomy or physics in particular? What caused this?
Bleach:Yes. In my case, too, there is a story where I can say this is the first time I really got interested. Something happened and it sort of clicked in my mind. I met a man from my home town, and I don't remember whether it was through the Boy Scouts or through some other contact, but somehow I found out that this person had a telescope. Then one evening I went over and looked through this telescope at craters on the moon, and started reading about astronomy. I went to the local library and I read books about astronomy. That got me interested enough in science, so that I took the courses in high school which at that time were electives. This was in the late fifties — like '58, '59 to '62 — when basically you didn't have any earth sciences. You started out with general science in 9th grade, then in 10th grade you took biology, 11th grade you took chemistry, and 12th grade you took physics.
DeVorkin:Yes, that's standard. Did you make your own telescopes, join amateur clubs? Were there any to join?
Bleach:My high school class consisted of about 100 people, I had one other friend who also became interested in astronomy. What happened was, I got a small retracting telescope as a present from my grandmother, and he got a similar telescope, and together we used to try to take pictures of the sky through the telescopes. There were some hotels near Monticello, N.Y. that were high enough up so the trees didn't block the horizon. So in fact we made observations together by ourselves, but there wasn't really any official club.
DeVorkin:Were they Unitrons?
Bleach:He had a Unitron and I bought a telescope from Lafayette Radio. I don't think Lafayette Radio exists any more. I had, and I still have as a matter of fact, the three inch refractor. He had also a 3 or 4 inch refractor, but of course his was better constructed than mine and a lot more stable. What we did was to hook up cameras to the telescopes and take time-lapse pictures of eclipses of the moon. I remember once going up to the roof of the Concord hotel in the middle of the winter when it was very crystal clear and cold and we had some very good seeing. We did things like that because of our common interest in astronomy.
DeVorkin:Did you subscribe to SKY AND TELESCOPE or any other magazines?
Bleach:Yes. I probably did. Probably the first one that I subscribed to was SKY AND TELESCOPE, back when I was in high school.
DeVorkin:Did Sputnik make a difference in your life, in your career goals, in your interests?
Bleach:No, I don't think so. That was '59, right?
Bleach:Okay. At that time I may not even have experienced the story that I just told you about looking through a telescope. I read about Sputnik in the paper. At that time I may have been in 8th grade, or 7th grade, I knew about it, but it was a couple of years before I was ready to get interested in something like that.
DeVorkin:Why did you choose Rensselaer?
Bleach:Well, there was an economic reason for choosing Rensselaer. I attended a small high school and was close to the top of my class — in the top five. After applying to college, I was able to get accepted by three or four engineering schools. The two that I was most interested in were MIT and Rensselaer. MIT said, "Fine, you can come to MIT", and Rensselaer said, "Fine, you can come to Rensselaer and we'll pay your tuition." That made the difference. In New York at that time — and I guess still today — there were state scholarships. Also, since my father was a veteran of World War II, I qualified for the veteran's scholarships offered in New York state. Essentially a large part of my tuition and other expenses, except for some living expenses, were paid for by scholarships. If I had gone to MIT, I would have had to pay for everything.
DeVorkin:Could your parents have afforded it or would you have had to work?
Bleach:I would have taken a lot of loans. I still had to take out a small amount of loans for Rensselaer because we really didn't have that much money even to take care of the extra things. So for MIT we would have taken out a lot of loans and I would have been responsible for paying them back after I graduated and got a job. I looked at the courses at both places, and decided that I could get the education I wanted at Rensselaer.
DeVorkin:You mentioned all engineering schools. This meant you were interested in engineering per se, or were you particularly interested in science?
Bleach:I was interested in engineering at the start. As a matter of fact, when I went to Rensselaer, I told them that I wanted to major in chemical engineering. I don't know why, at this particular point. I was thinking along the lines of some kind of engineering. I wasn't thinking per se of physics. During the second year, there was one course in chemical engineering that I was able to take called Stoiceometry. This was a plumbing course, basically. You would put something in one end of a pipe — on a slide rule — and you would calculate to seven decimal places what came out of the other end of the pipe. After I got an A in the course, I walked up to the professor who was also the chairman of the department, and said, "Thank you, but I don't think chemical engineering is for me. I think I'm going to go into something a lot more general." Since I was in an engineering and science school, there weren't too many options. In the sciences there was chemistry and physics, mainly, so I went into physics. That's how I chose physics.
DeVorkin:1962 through '65, '66?
Bleach:In '62 I started Rensselaer. In '66 I graduated.
DeVorkin:Did you take any courses from Mayo Green or any other astronomers who were in the physics department?
Bleach:I didn't take any astronomy courses. There was one astronomer who is still there, I believe, who became my advisor. His name was Allan Meltzer. He became my advisor, because before I went into physics, I remembered the astronomy hobby that I had, and talked to him about going into astronomy. But they didn't have an undegraduate astronomy program, just a graduate astronomy program. So I went into physics and Meltzer was my advisor. I know I didn't take an astronomy undergraduate course, but I don't know if they had one or not.
DeVorkin:Well, they had a student's observatory.
DeVorkin:Did you ever use it?
Bleach:I walked in there and it was full of dust. The tennis courts were right below it then, and I looked around and I walked out. There was an astronomy club there, but somehow I never got involved in it. I think what happened was that I was so pressed for time that I spent all week long studying. At that time it was not coed. When I came I think coed was just getting started. They had about five women there. It was a very artificial life. All week long you spent your time either in study hall or some other place studying. You could have had other interests but it was mainly confined to campus. There were about 30 or 33 fraternities at Rensselaer and about three thousand students. The weekend was a great contrast to the week. Everything just turned into parties. Then Monday you went back into the other mode. It was strange. When I finished there and first came down to the University of Maryland, I saw all these women walking around campus. My friends and I who came to Maryland from Rensselaer used to sit on the steps just to watch, because for the past four years it had been like working in a cloister or monastery.
DeVorkin:When you switched to physics, what kind of physics did you specialize in or were you most interested in?
Bleach:You didn't really specialize in any particular area of physics, as I remember, in undergraduate school. There were, first of all, four semesters, or two years, of this Resnick and Halliday physics course. It has become a classic, I guess, or at least the books have. We were, I think, some of the first students to use those volumes. They had probably not been out for more than a year or two before that. So I took just basic physics through the sophomore year. In the junior and the senior years, you could get somewhat specialized, but it was only through the laboratory courses. For instance, for senior laboratory I remember I had to do an experiment in solid state physics, where for half a year I spent time in the materials lab growing single crystals or lead and conducting experiments on the Meisner effect. We spent half a year paying attention to one single experiment. That, you could say, was specializing in something. I don't remember specializing in any other way.
DeVorkin:What were your interests like, though? Was there one type of physics that interested you more than another?
Bleach:Once I got into physics I always had in the back of my mind that somehow I would couple the astronomy interest with physics. In other words, I never got to the point where I said I'm going to be a nuclear physicist or a solid state physicist, even though I did the solid state experiments. So when I applied to graduate schools, I was looking for schools where they had either an astrophysics or an astronomy focus. I was attracted, for instance, to departments called "department of physics and astronomy". That's how I wound up applying to graduate school at Maryland. I said, "I haven't found a love for any particular kind of physics, so I'd like to look into something that explores astronomy and astrophysics. AIt relates to the Apollo program because, at that time, astronomy and astrophysics was just beginning to involve rockets and satellites. That astrophysics observations made above the earth's atmosphere was just beginning to bloom.
DeVorkin:Were you still reading SKY AND TELESCOPE to find out about these things, or were you reading more professional journals?
Bleach:I think it was still at the SKY AND TELESCOPE level that I was hearing about these things. Really, in the media too. I heard about what was being done in connection with astronomy that could be done from space. I began to hear about experiments that were planned by NASA. I would learn something that NASA was about to do in the way of sending up a satellite or a project or Explorer, OSO, whatever and that's what kept my interest. I tried to learn about these projects in order to see what was happening and what I could be doing. I remember also there was a woman who was a graduate student in physics or astronomy at Rensselaer. She had worked for someone at Goddard Space Flight Center before coming to Rensselaer. She told me about the work that she had done in lasers at Goddard in the early sixties.
DeVorkin:Do you recall her name?
Bleach:Yes. Diane Tilson. I think she's principal of a school here in Maryland right now. That was her maiden name. When she told me what she did at Goddard, I said, "That would be an interesting thing to do for a summer." I remember asking her, "Should I just write to someone to get a summer job?
DeVorkin:You were aware of Goddard and its programs?
DeVorkin:Other than Diane Tilson, how were the interests of your colleagues, fellow students, cohorts, developing? Was there a general interest in getting involved in space activities?
Bleach:No. I don't know if they really had a special interest then. Let me put it this way. When you graduated at that time with a bachelor's degree in physics — I guess the same thing happens now — your advisor would tell you that there is very little you can do with a bachelor's degree. This is what would be told to you. So what choice do you have? Either you go and take a job in something related to physics or you go on to graduate school. It wasn't like engineering. In the mid-sixties all the engineering companies would come around to Rensselaer and other engineering schools and recruit. You could instantly get a job with a good salary and go right to work out of undergraduate school with your bachelor's degree. That wasn't the case for physics. So you had to decide. I decided — also because of the war situation in Vietnam at that time — that I was going to go on to graduate school and get the next degree. If there had been a job offered to me that looked very attractive, I might have had second thoughts. But there wasn't anything much more attractive than these two options. Either you go into another field or go on to graduate school. The next step was, after you got a master's degree, you couldn't do much with that degree until you went and got your Ph.D. So in fact, when I was in graduate school (this may be jumping ahead a little bit) I never got a master's. I just found a way to bypass the master's degree and get the PhD.
DeVorkin:Okay, is there anything else we should talk about in your Rensselaer years to understand your career and its development, or shall we go on to Maryland?
Bleach:I think that pretty much tells you the ideas that I had in mind. The only other significant thing involves getting into a graduate school. Certainly what happened to make me come to Maryland affected the rest of my career. So I'll briefly tell you why I applied also to three or four graduate schools, including Rensselaer. I knew I needed financial help, so I applied to schools where I thought I'd be able to get a teaching assistantship. I think I applied to MIT, to Cornell, to the University of Maryland, and maybe to one other school. I was accepted at the University of Maryland first. That was exciting to me because they advertised both physics and astronomy programs. Then I was told that I wouldn't be able to have an assistantship for the first year. I persisted and made a lot of phone calls. By luck, I happened to call one day when someone else turned down their assistantship. There were about three or four phone calls back and forth that day. Finally they called me back and said, "We have an opening for you with a teaching assistantship."
DeVorkin:You say you did apply or write to Goddard for a summer job, or you didn't?
Bleach:I did, and I didn't get a favorable response. I got, "Thank you, we'll keep your name in the file."
DeVorkin:Did the presence of Goddard have anything to do with convincing you to come to Maryland?
Bleach:Yes, although I only knew Goddard by name. I hadn't met anyone associated with Goddard except this one lady, Diane Tilson, and all I knew was that she did work in lasers. I didn't really know all of the astronomy that was going on at Goddard.
DeVorkin:Was the assistantship NASA supported?
Bleach:No, I don't think so. It was just a teaching assistantship that the University of Maryland funded from their own internal funds.
DeVorkin:Had you applied for one of those NASA assistantships or traineeships?
Bleach:No. That all came at the end of my first graduate year at Maryland. There was a bulletin board in the physics building at Maryland that offered summer jobs at Goddard working for Frank McDonald. So I called out there and I may have sent a resume out there. The school year was approaching an end — I also had the possibility of going back to New York and working for the State Highway Department designing roads and airports. About a week before I was supposed to leave to go to New York, Frank McDonald called me at home one night, and said, "Would you still be interested in having a summer job at Goddard?" I said, "Yes, and I went to Goddard to talk to him. He told me about a group needing help in designing solid state detectors that were going to be used to measure cosmic rays. What I'm describing is what started the interaction with the Goddard group there, as far as a summer job goes. So Frank McDonald had me meet the scientist in charge of the cosmic ray project; do you want names?
Bleach:Bonnard Teegarden. He was doing cosmic ray experiments, and he was developing solid state detectors along with electronics for his satellite — I don't know whether it was IMP or OSO or whatever. My summer job was to work with these solid state detectors used for measuring cosmic rays and test them out in the laboratory at Goddard. There were a number of other people I found out, once I got there, that had similar kinds of jobs. In other words, Frank McDonald at that time — and this is the summer of 1967 — was getting graduate students from the University of Maryland involved in some of the NASA work. So as far as I can recollect there was money flowing from NASA to Maryland in '67, and probably a few years before that.
DeVorkin:Okay. Could you describe the major types of courses you took in your first year of graduate work and what helped you and trained you for this summer work?
Bleach:Okay, I can't really say that it was all focused towards training me for the summer work, because this kind of thing is serendipity. There was a classic set of courses, I believe, a semester of quantum mechanics, classical mechanics, thermodynamics, electrodynamics; basic graduate physics courses that were required to be taken. That was the total background. There weren't any specialized courses in astronomy.
DeVorkin:Still no astronomy at that time?
Bleach:That's right, and you'll find that up to the point when I was actually working at Goddard, I did not have an astronomy course that I could list saying "I am a trained astronomer" because I took a course. And that's true.
DeVorkin:Was that typical of the students at Maryland?
Bleach:Yes, I can say that for people who went to Goddard to do summer work in astrophysics. I can't say that for people who remained at Maryland and stayed within the astronomy department per se. There was an astronomy department, and I believe Dr. Gart Westerhout, who's now the director at the Naval Observatory, was the head of the department back when I was there. People enrolled in that department took graduate astronomy courses. They had undergraduate degrees in astronomy and did graduate thesis work making observations and performing theoretical analysis. That was separate from the people that I worked with and the people that I knew, who worked at Goddard. The people I knew were from the physics department.
DeVorkin:So there was a school or department of physics and astronomy?
Bleach:That was the name of the department.
DeVorkin:And then there was also an astronomy department?
Bleach:I don't know if you would call it another separate department, but there was a head of the astronomy program. I know there was a head of the physics and astronomy department, because that's who I dealt with. I believe Westerhout was the head or director of the astronomy program. Maybe it wasn't called the astronomy department, maybe it was the astronomy program within physics and astronomy. Something like that.
DeVorkin:So there were different tracks and you were on the physics track.
DeVorkin:Okay. How did your interests and career goals change, if you can identify them, after your first summer at Goddard? Would you say that was a turning point?
Bleach:Yes. I'd say that was the turning point, because I realized then that there was a possibility for getting involved in a thesis project. By the end of the summer I met students doing thesis research who had been there the summer before, and who stayed on after the summer job as research assistants. At that point I hadn't formed any idea of what area I was going to specialize in for my thesis. So I asked Frank McDonald if I could stay and do a thesis project at Goddard. He said, "Well, the group that looks like it could use some graduate students and where there might be possibilities for doing graduate research leading to the thesis, would be the X-ray astronomy group." I took advantage of this opportunity. I transferred out of the teaching assistantship, into the research assistantship. I spent 20 hours a week at Goddard doing whatever they needed me to do. That paid roughly enough to support myself. The rest of the week I spent doing course work at the University of Maryland. Half of my time was supposed to be spent at Goddard, helping the scientist whom I worked for do research. That scientist was supposed to be aware that I was being trained to do some kind of thesis project.
DeVorkin:How well would you say that worked?
Bleach:Well, it actually worked the same way as I see it happening now. Graduate students wound up doing a lot of work in connection with projects that were ongoing. In the X-ray astronomy program at Goddard they had a rocket program. So they needed detectors and electronics built. They had enough money then for a sufficient number of technicians and equipment to support graduate students, so I was lucky. They had people that built the hardware for me, but as far as testing it goes, it took a lot of my time to test it. Another fortunate thing for me was that they already had at least one rocket flight, or at least there was data available from rocket or balloon flight. So what I quickly got into was analyzing data. Here's another thing: I never took a computer course. However, in order to analyze the data you are forced to use computers. So I started learning about computers and programming by having to learn how to analyze this data. That first year at Goddard I saw what experiments were done, learned about the field of X-ray astronomy which was very young then, four or five years old, and learned enough to see what next experiments could be done in rockets. I got involved by sitting down with the people in the group there and deciding what I could do in the way of experiments that would lead to thesis material.
DeVorkin:Let's identify a few things about this group: who ran it, what their budget was, how work was done, and what the general atmosphere of the group was. Who was in it, first of all?
Bleach:Okay. The X-ray astronomy group at that time consisted of three scientists. One had been there for several years, and the youngest member of the group had been there maybe a year before I came in. The head of the group was Dr. Elihu Boldt. Dr. Steve Holt was the newest member of the group having just come from Columbia University, with a background in doing neutron measurements from balloon flights. The third person was Dr. Peter Serlemitsos, who graduated from the University of Maryland, I believe. That was the group that was doing extra solar, X-ray astronomy. There was another group at Goddard, which I wasn't aware of much at that time, that was measuring X-rays from solar phenomena such as flares. I don't recall total budgets, but rocket experiments were costing a total of about $100,000 per shot then, including launch and vehicle costs.
DeVorkin:You were sending up X-ray detectors in Aerobees?
DeVorkin:Also balloons or just Aerobees?
Bleach:There was one balloon flight in 1968, I believe, that I tested out a camera on. Steve Holt, I remember, was out in Page, Arizona, launching a balloon experiment on which I tested a camera that was later used to determine where X-ray detectors on rocket experiments were pointing. After that it was all on the Aerobees.
DeVorkin:What was the driving factor in the group? What were you after, technology, improved detectors, or specifically astronomical problems?
Bleach:Specifically, since the area was five or six years old, by the time I really got involved in the first rocket flight, we were after two things relating to astronomical problems. At that time, there were maybe several dozen discrete sources known in the sky, as well as an isotropic diffuse background. You could survey regions of the sky and hope to just find new point X-ray sources, as well as observe the background. The other problem, which gets into the central problem, was understanding how discrete X-ray sources were formed and evolved and understanding the nature and causes of the diffuse background.
Bleach:Richard Hirsh's book, was "Glimpsing an Invisible Universe." A central problem was that very early on, X-ray astronomers saw not only point sorces in the sky, but they saw a glow from the whole sky, an isotropic X-ray background. Because that was seen early on, theories began to appear attempting to explain what generates this isotropic X-ray background. The discrete sources and the diffuse background were the two parts of the X-ray sky; those were the problems at that point.
DeVorkin:Were you convinced that there was an isotropic background?
Bleach:That was measured. That was measured in the second rocket flight. AS & E sent up an initial rocket flight in 1962. I don't know specifically, but the data probably showed even in that rocket flight that there was a glow from the whole sky. You can imagine the experiment as putting your detector here on the earth and measuring the internal background. Then you send it up in a rocket and when you scan a certain portion of the sky, you may see a discrete source, but you also see a much higher background, when you are off the source, than what you see on the ground.
DeVorkin:I thought there was a time when they thought it was just due to the very poor angular resolution in the early detectors, and they thought that it could have been a collection of discrete sources.
DeVorkin:Had that been solved by the time you were in?
Bleach:Yes, by probably 1966, '67. X-ray astronomers were sure that there was an isotropic background. What they had done was to place mechanical slit collimators in front of the proportional counters. This narrowed the field of view thereby increasing the angular resolution so that they knew that a strong discrete source they originally found wasn't in the field of view. Looking away from a strong discrete source, X-ray background rates were still much larger than the internal background of the counter measured on the ground.
Tatarewicz:These two problems that you mentioned, the discrete sources and the background, were there members in the X-ray group who concentrated on one or the other?
Tatarewicz:What group were they in?
Bleach:Even within the Goddard group, Elihu Boldt — who still to this day has spent most of his time on trying to understand the isotropic background — was interested in mechanisms to explain how the background was generated. His idea was, there is material that's filling up the whole universe that generates, by interactions with other particles, the background. Until recently, this problem remained unsolved. Only out of the recent HEAO, the Einstein experiments, came evidence that the background could be accounted for by a collection of unresolved discrete sources. In other words, if you have a detector that doesn't have enough sensitivity to detect emission from discrete sources far away, these unresolved discrete sources would look like an isotropic background. It looks like discrete sources can finally explain the background, but we needed more X-ray surveys. Einstein has only sampled about 5 or 10 percent of the sky, but it saw deep enough to detect weak discrete sources. That's really where this problem stands. We don't have a complete survey of the sky with the sensitivity of Einstein. If you extrapolate over the whole sky, you find out that in fact 90% of the isotropic background can be explained by discrete sources. They've got about another 10 percent to go. Still, Elihu Boldt has his own theories for gas which generates the background that still can't be disproved. So in fact, there may be some part of the background — maybe the extra 10 percent that is generated by diffuse gas from clusters of galaxies — that may be the result of Boldt's efforts. He may have found 10 percent and Einstein found 90 percent of the background. But I consider that understanding the diffuse background is also a central problem, rather than just understanding what compact discrete objects that emit X-rays are.
DeVorkin:I see. That's very interesting.
Tatarewicz:Were you in contact with other groups who were also working on these kinds of problems? To what degree during your work with the group at Goddard, did you become exposed to the wider picture of space research and high energy astronomy?
Within the X-ray astronomy community there was (I can't say off the top of my head) a hundred or two hundred active astrophysicists, probably more like a hundred. So you knew all these people, and all the reprints and all the discussions were known to the community. That's another thing that I want to bring up: in connection with the Hirsh book on the story of how Cygnus X-1, the black (hole) candidate, was bound. There's a story behind that; the book says that the Uhuru satellite just found this and it was confirmed by an MIT group. This is not correct. But anyway, to answer your question about other groups, certainly you stayed in touch with all of the people in X-ray astronomy. As far as other astronomies go, infrared astronomy was in its infancy then. Ultraviolet astronomy was just getting started. You didn't really have the angular resolution to pinpoint where these X-ray stars were, so you couldn't tell the other astronomy communities to start searching.
The error box that locates an X-ray source to square minutes of sky is not very nteresting in terms of looking for an optical counterpart because there are hundreds of thousand of stars in that box sometimes. There was some minimal contact with the radio astronomers, so if you talk about just the other astronomies, there wasn't at that time much interaction. You heard them at astronomy meetings, at the American Astronomical Society, you could listen to some of their talk, but there wasn't a strong working relationship between the other astronomies at that point. Now, Frank McDonald, because of his role as the director of the High Energy Astrophysics Laboratory at Goddard, had people in his group working cosmic ray, ultraviolet, gamma ray, and X-ray astrophysics. There were some people in his group who had an overview of all this, but at the working level, I think most people just stuck to their individual specialty. In other words, at that time, you were an optical or an X-ray astronomer, not a full spectrum astronomer like you find today. This is where we're going today, as opposed to where we were in the middle and late sixties.
DeVorkin:Interesting observation. You mean there are people today who work as observationalists in many different regions of the spectrum?
Bleach:There are X-ray astronomers who now go out to Kitt Peak, or go out to the MMT, and do an observation. Josh Grindlay of the Center for Astrophysics, for example, will make observations on an optical telescope to try to find an X-ray counterpart for the source that was found with Einstein.
DeVorkin:He'll do it himself. Now, I know a little bit about the history of the Lupus source, and there it was a cooperation or a contact through the literature between optical, radio, X-ray people and so forth.
Bleach:Yes. It's evolved. It's evolved from the isolated community to the contacts that you're talking about, and to actually a mingling, where the optical community will bring in the people that have done the X-ray observations. They may operate together as a group or as a collaboration. They will make the observation together. As the X-ray astronomers acquire experience, they're welcome back again to do more observations. So what I see happening (and I don't have an all-encompassing view of this, except for the survey study that we just did for the House Appropriations Committee) is that there are more and more people there who don't consider themselves locked in to being just an infrared astronomer.
DeVorkin:Yet there are still many who are purely wavelength range limited.
Bleach:Yes, but the ones who are really at the forefront — I say forefront, that means the ones who are gathering a lot of data, and who are very active — of the three thousand astronomers that are in the American Astronomical Society, there are about a thousand who are very active and may be getting away from calling themselves just single wavelength astronomers. Let me put it this way: The optical astronomers, because of their long history, are more reluctant, I believe, to get involved with the newer astronomies. But the people who are X-ray astronomers or infrared astronomers are much more adaptable to going to a telescope and making optical or infrared or X-ray measurements. I think it's working that way with young astronomers compared to old timers like a Maarten Schmidt, or a Geoffrey Burbidge.
DeVorkin:This brings up a question which is totally out of context, but would lead from this. You're aware, of course, of AXAF and all the new generation space telescopes and that sort of thing. There is a question today as to whether AXAF will have its own institute, whether the Infrared Telescope will have its own institute like the Space Telescope Science Institute. From these different factions, the thousand astronomers who are bridging the entire spectrum as opposed to more classical optical astronomers who are still localized, would you expect them to line up behind one or the other types of concepts of the institutes? A totally combined institute as opposed to separate institutes for each optical wavelength?
Bleach:Well, there are people — very well known names — who want to head toward the idea of an Institute of Astronomy. In the course of the House Appropriations Committee study, again, some of the people who have thought about that (and are not involved with the existing Space Telesope Science Institute), think that it's still much better to have individual institutes. They think that if you have one centralized institute, it becomes a NASA. In effect, they look at that as not accomplishing the most science in the most efficient way.
DeVorkin:But this keeps away this general trend also that you have identified for modern cutting edge astronomers to be able to look over the entire spectrum?
Bleach:No, because as things become more and more automated, and the computer access becomes easier, an astronomer may be able to make an observation on Mauna Kea from somewhere else in the United States. In other words, the X-ray astronomer analyzes data and says, "At this position I see something interesting happening with this source." He calls up Mauna Kea and says, "Can I get time on the IRTF out of Mauna Kea?" and via some kind of communications link, it's made possible. I'm envisioning this in the future. But it may be possible for him to get time on the telescope that he needs, whether it's radio telescope, IR telescope or some optical telescope. That's what I meant by across the board. He really is able in some way, whether it's automated or whether it's by him going there, to do the other observation outside of his initial area.
Tatarewicz:This seem to be a kind of access which would have been unthinkable before automation and the kind of communication that we have now. In other words, if an X-ray astronomer were interested in a very narrow portion of the sky — a couple of sources, not enough to make up a full observing run — previously that astronomer wouldn't have stood much of a chance of going through the whole proposal process, getting the time, for just a lttle bit of observation. He'd have to make do with whatever was available in the record.
Bleach:Well, he would have also contacted a colleague or someone that he could find that was doing those observations, asked them if they would be willing to do it. This is the way it was done in the late sixties. When we found out that Cygnus X-3, an X-ray source, looked like it might be varying — something funny, you know, was happening with it — another graduate student who was a contemporary of mine called up an observatory in Canada that was doing radio observations. They observed Cygnus X-3 for him while he had his balloon flight. That's the way you would have done it before. You would have gotten someone else involved who was a part of the other community, and you would do a cooperative experiment, and you would publish the paper together with all the names on it. Now what I'm saying is, because of automation, you can get away from having really to rely entirely on someone in another community, and have access to the data in some way. You know what I am saying?
Bleach:That's the difference that I'm describing here. That's what automation is doing for you. But not just automation; how data is managed. That's another big concern of the community. As you get more and more of this data from these observatory class instruments, how do you manage all this data? ST will produce mounds of data; AXAF will have a lot more data than another X-ray facility; the Infrared satellites, even IRAS you know is a lot more data. How do you archive it? How do you make it accessible so that people can do the kind of thing I'm saying? What's going to happen — again, my crystal ball is that someone is going to have to figure out a data management system, so that we are able to analyze all this data in a timely manner and get the most science out of it. Because we're getting to that point. Now, I can't tell you that in two years we'll be at that point, or in five or six years we'll be at that point, but you can see already from the type of experiments that are being proposed that someone has to be thinking about it. NASA is just starting, but no one really has a clear idea of how to manage all of this data from the large observatories.
DeVorkin:Okay. Let's get back to the chronological development. Could you describe the types of instruments you were building for rockets at Goddard, in the X-ray group?
These were basically proportional counters. A proportional counter is somewhat like a geiger counter. In the X-ray spectral region, the energy and the frequency of the radiation is so high that you really don't measure it like a wave any more. You measure it like a photon, a bullet, okay? What happens is, an X-ray will go into a geiger counter type of detector. By that I mean a container filled with gas with a thin wire running through it that has voltages of a few thousand volts placed on it. The gas is contained by a sealable window through which the X-rays can penetrate but through which the gas can't escape. So this X-ray, which I'm calling a bullet now, goes into the gas. When it enters the gas, which is usually some kind of noble gas like helium, neon, xenon or argon, it hits an atom inside the gas, gets absorbed and knocks out one of the electrons, the outer electron of that atom.
That electron, which has a negative charge, sees the thin wire that has a positive high voltage. It gets accelerated to the wire. In the process of being accelerated it gains speed and knocks into a lot of other atoms, knocking away other electrons, which are also accelerated toward the wire. This process is called an avalanche. From the initial electron the avalanche contains a million or more electrons. All this happens in about a millionth of a second. That avalanche when it gets collected on the wire provides enough of an electrical pulse that with electronics, you can amplify, shape, and measure that pulse as a count. That's the basis of a proportional counter. Instead of a geiger counter where you get the same signal out for every energy X-ray, with proportional counters you operate at a voltage sufficient that if an X-ray comes in with one energy, a different amount of electrons are collected on the wire than would be collected with an X-ray energy of twice that much.
DeVorkin:So proportional is more sensitive to lower energy photons than a geiger counter would be?
Bleach:No, the difference between the geiger counter and the proportional counter is just the amount of high voltage placed on the central wire called the anode. Let me start with the idea of the central wire and a gas container. If I put a relatively small amount of voltage on the wire, then it's called an ionization chamber. You just collect a few electrons. If I put some higher voltage on the wire — when I say voltage on a thin wire, it means that it's a voltage referent to the container that the gas is in — then it's called a proportional counter. That means that if I have an X-ray going in there with an energy of 1 unit, for example, it will produce a million electrons. If I have an X-ray going in there with an energy of 2, it will produce two million electrons. The number of electrons produced is proportional to the X-ray energy. If I go to an even higher voltage, then every single X-ray will produce the same amount of electrons on the central wire. This is because it's in a saturation mode. That's the difference. The geiger counter is the saturation mode. The proportional counter is the linear mode.
DeVorkin:I'm still confused. The geiger counter has the higher potential wire?
Bleach:Yes. It's a saturated effect. As the voltage increases more of an avalanche forms, eventually no more atoms are available to produce electrons.
DeVorkin:Okay, that makes sense. I didn't think you were counting single electrons.
Bleach:In the ionization chamber mode, you do count single electrons.
DeVorkin:You do but it's because they're saturated?
Bleach:Because you don't have an avalanche. As the voltage increases you first have an ionization counter, then a proportional counter, then a geiger counter. If I drew you a graph of high voltage versus the number of electrons collected for a fixed energy X-ray, you would see a plateau in the ionization chamber region at low voltage; a few electrons. Then as you went up in high voltage, you'd see a linear line with the number of electrons proportional to the voltage. Then at higher voltage the curve becomes a plateau because it's saturated. In fact, for every energy X-ray coming in, you produce the same number of electrons.
DeVorkin:You were using these proportional counters?
Bleach:We were using gas proportional counters.
DeVorkin:Were you experimenting with different gases or different designs?
Bleach:Yes. You have to use a mixture of gases, and the basic mixtures were argon, and methane, or xenon and carbon dioxide; it probably isn't worthwhile going into reasons for all this. But anyway we were going through a testing process, to see which would give the best energy discrimination for the X-rays that you detected. So there was some of that going on, but the graduate students didn't have to do all that. The technicians were helping with that, with the read-out, and with the electronics. Once the signal comes out of the counter it has to go through preamplifiers. This introduces noise. You don't want a lot of electronic noise because then you can't measure low energy X-rays, which produce a small signal because of this proportional effect I was just describing. Other testing that was going on was, when you point a counter in the sky, how do you really know what you are looking at? Now, the only way we had to do this back then was mechanical collimation. We didn't have X-ray telescopes in the late sixties. We had the ideas, but they weren't developed. A mechanical collimator looked like an egg crate or a honeycomb. You put one of these mechanical collimators in front of your detector. By the way, the detector had a thin window on top to allow X-rays of low energy to come in, because the thicker the window, the higher your cutoff in energy.
DeVorkin:You were working with low energies?
Bleach:We were working fron an X-ray energy of about 2 keV, up to about 20 keV. The title of my thesis says, "A study from 2 to 20 keV X-rays from the Cygnus Region." The low energy cutoff was determined by the thickness of the counter window, which was made out of the element beryllium. That was the low 2 keV cutoff. The high energy cutoff was determined by the thickness of the gas cell. When you have a certain thickness of gas in the counter at some energy an X-ray will go right through and won't interact and you won't see a signal. The X-ray energy response curve of a proportional counter starts to rise after the X-rays can penetrate the window, and then it peaks somewhere at a certain energy, maybe at 7 or 8 keV. Then as the gas cell starts to become transparent, the response falls off, so at 20 keV you may have 10 percent efficiency, where you have 90 percent efficiency at 7 keV. That describes how these counters operate. Now, there's one other thing related to developing these counters that's important. It was at Goddard where the work was really started that developed the multi-wire large area proportional counters in the place of the single wire that I just described. These counters were gradually incorporated into other experiments from other X-ray astronomy groups. The ultimate multi-wire large area proportional counter was used in the NRL array of counters, which was fown on HEAO-1 and which wound up being the largest experiment in HEAO-1. It did the most sensitive all sky X-ray survey to date. The initial pioneering work in multi-wire proportional counters for X-ray astronomy was started by graduate student work with rocket experiments up at Goddard.
Tatarewicz:The original work that went into...
Bleach:...developing the multi-wire large area proportional counter. If you had just a single wire and you made a big gas cell, the X-ray hitting way out at the edge of the gas cell would produce an electron that never got to the central wire. If you have a lot of central wires in a lot of cells, you could figure out where the X-ray interacted with the gas. Of course you have got to use a lot of electronics to do this. Then you can build a very large collecting area, very sensitive to weak X-ray sources in the sky, and be able to discriminate real events from internal background.
DeVorkin:I hope to get to HEAO in great detail, but what's the chance that some of those detectors are still around?
Bleach:Which ones, the initial ones?
DeVorkin:The big array, or some of the initial ones?
Bleach:Well, the initial ones were not multi-wire arrays. Those were still single wire ones. Their sizes were maybe six inches long, a few inches wide and a few inches deep. The original multi-arrays may still be up at Goddard with the group that I described to you that I worked with.
DeVorkin:Is Elihu Boldt still there?
Bleach:Yes, three people are still there. Steve Holt is now in the position that Frank McDonald used to occupy. Steve Holt is now the directror of the high energy astrophysics group there.
DeVorkin:These are the people to contact?
Bleach:You should contact Steve or Elihu, yes. Now, the array that we flew on rockets still was about a 650 centimeters squared collecting area. That was considered a large area array in the late sixties. In contrast the NRL group had seven modules, each about a 1700 centimeters squared collecting area. So instead of several hundred square centimeters of collecting area, you had about 11,000 square centimeters of collecting area on this HEAO satellite.
DeVorkin:These were all modulated by slits?
Bleach:These were all mechanically collimated, yes, by slit or honeycomb type arrangements.
DeVorkin:Those are the two basic types. I've seen types that have two rows of wires, and others like the Uhuru that have slits.
Bleach:The wires are called modulation collimators. In other words, there are angles which you can see through the collimator wires. It's not a solid collimator. As the source passes over, the signal that you see is different depending on which angle it's coming from. That's where the term modulated comes from. As the source passes through the field of view, the signal from the source is modulated, so you're able to tell the source's position. The reason that modulation collimators came about is, first of all, it's lighter weight. Second of all, you don't have to make something that's solid. You can string wires finer together sometimes than you can make a very narrow honeycomb.
DeVorkin:Were both of these types of collimators known to you when you were at Goddard?
Bleach:First, mechanical collimators were used, then modulation collimators were used, I believe at first by the MIT group, but it was while I was doing my graduate work that the modulation collimator started to be used.
DeVorkin:Did everyone go to the modulation collimators or did people prefer to stay with slits?
Bleach:Well, HEAO-1 is slits.
DeVorkin:Why is that?
Bleach:One of the reasons was that they had previous experience from rocket flights. They had mechanical engineers who could design and build slat collimators, and there are problems with the modulation collimators. I told you that you can tell where the source is because you modulate the signal. However, you know from an analogy with a radio receiver, as you scan across, that you can have lobes on the source. So you also have false signatures with a modulation collimator. If you're trying to detect a weak source next to a strong source, you do not use a modulation collimator.
DeVorkin:Okay. And since Friedman was producing a sensitive catalogue, he wanted something where he could tell that sort of thing?
Bleach:Yes, because that was the primary mission of HEAO-1; to produce a catalogue of the whole sky with strong and weak sources, even though they're very close. That's why you don't use modulation.
DeVorkin:Let's finish with your education, unless there's something else?
Tatarewicz:On the subject of collimation, I can't remember where I heard or read this but I saw a reference to using a bundle of hypodermic needles as a collimator.
DeVorkin:Is that the honeycomb?
Bleach:That's basically just like a honeycomb. You make a narrow collimator by having a cylinder, like a hypodermic needle, for instance. Say you have something with a small diameter but with a long length. Now, if you have a fixed diameter and you start making the length longer, you have tighter or narrower collimation. If you bundle those things together and can keep them all parallel, you have a narrow field collimator.
Tatarewicz:Did anyone actually use hypodermic needles, to your knowledge?
Bleach:For X-ray astronomy? I know we used them for measurements of laboratory X-ray sources at NRL. I don't really know whether we got the material from a hypodermic needle manufacturer or whether we got it from someone else though. Somehow I have materials in the laboratory right now that look exactly like what you're describing, but I can't tell you if they're hypodermic needles. I don't know the answer to that. I don't know that anyone really did an X-ray astronomy experiment with hypodermic needles.
DeVorkin:What is the advantage or disadvantage of that one as opposed to the others?
Bleach:Well, there are several ways of making these honeycomb collimators. Imagine making something solid and then drilling or etching or whatever. That has problems because there could be imperfections resulting in sides that are not parallel. But if you have hypodermic needles that are all uniformly made, which like I say, have sides that are parallel to start with, then you've already got all the tubes perfectly made. You only have one problem then, how to package them. The advantage of hypodermic needles is that you already have the tubes made. The other way you have to make them. So you have to worry not only about keeping them all parallel but you also have to worry about making them individually.
DeVorkin:Well, in the case of the modulation collimator, where you had the problem with the lobes, are there similar problems with the honeycomb or are there just weight problems or what? That is, beyond building them, would they be more desirable than slats for the modulation?
Bleach:As far as constructing them goes, there are advantages to a modulation collimator since you don't need as much material because you have thin wires. It's easier to build than some of the very tight slit modulations. I think for a given amount of work you can get higher angular resolution, or in other words, tighter collimation, with a modulation collimator than you can with a slit collimator, neglecting the problem that you just mentioned, the side lobe problem.
DeVorkin:And where does the honeycomb collimator fit into this?
Bleach:Well, when I say slit, I'm combining honeycomb and egg crate into one category. One has rectangular openings, while one has cylindrical or hexagonal openings.
DeVorkin:Let's finish with your graduate education. Is there anything else that we should talk about, anything you'd like to discuss in terms of support by NASA for graduate education? Also I'd like to know how many of your own student colleagues went the same route? Was it something that was desired, or was it unusual?
Bleach:I think if someone had a clear idea of what he was going to do for a thesis, that certainly he could have come to Goddard pretty easily. In other words, through the Apollo program, the funds were available for people to get summer jobs at Goddard. There was a lot of work that could be done in support of the experiments that the Frank McDonald group was doing, for instance. Frank McDonald was on the faculty at University of Maryland and he was in a position to be your thesis advisor. You could come to Goddard for a summer job, which could turn into an assistantship that would lead to a thesis. Now, in the first summer I and about three others that I knew came to Goddard. Two of these three students went back after the summer. In the fall about three additional students wound up being fellow graduate students at Goddard, and did their thesis work there. So there was this process. I can't say that it was much easier to get into than some other area of physics, but certainly there didn't seem to be much difficulty if you were willing to get interested in astrophysics as a thesis project. At that time, there was a considerable availability of assistantships, if you wanted to be supported that way.
DeVorkin:Were there graduates of schools other than Maryland?
Tatarewicz:That was my question, was it a unique relationship with University of Maryland?
Bleach:No. Catholic University had a couple of graduate students. It turns out one of the graduate students who was from Catholic University is now the head of the Astrophysics Division at NASA Headquarters, Charlie Pellerin. He's my contemporary also.
DeVorkin:What about schools that were out of town?
Bleach:No, I don't remember when I was at Goddard seeing anyone from a school in Massachusetts or the Midwest or anything like that. As far as I know, that still isn't the case. The way people from other areas come to Goddard is as post-docs.
DeVorkin:Let's talk then about when you began to think about a job after your Ph.D. Nobody could tell you that you needed more education; there were no degrees beyond the Ph.D. Were you looking for a fellowship, a post-doc, or an academic position, teaching? What were your ideas?
Bleach:I wasn't really looking to get into another school where I would have had teaching responsibilities, because I wanted to stay in research; I knew by then that I would like to do research full time. There were several options that were open to me. The option that I explored right away, was staying in X-ray astronomy. It was still the Apollo era; funding may have already peaked, but it certainly looked like there were funds available to continue doing X-ray astronomy. This is 1972. The HEAO satellites were still envisioned as being the size of railroad cars. Now, I could have worked out in California for Lockheed in the private sector. They had and still do have an X-ray astronomy group. I went out there and talked with them.
DeVorkin:Did you talk with Fisher?
Bleach:I talked with a fellow named Richard Catura. It was the same group, though.
Tatarewicz:Did they contact you?
Bleach:Because everyone in the X-ray astronomy community is in touch with one another, he either called Elihu or a letter was sent around saying that we're looking for help. We're building a rocket experiment and if you know of an X-ray astronomer or someone from whom we can get help, we'd like them to be part of our group. There are funds available. That's how it was transmitted. So Elihu said to me one day, why don't you call Dick Catura out at Lockheed? It was getting to the point where in another few months I would be finished with the thesis. What was I going to do next? There was also the suggestion to talk to people down at NRL. Friedman was the director of the Space Science Division, and Talbot Chubb was the head of a branch at that time that incorporated an awful lot of things. There must have been 80 people in that branch. It had gamma ray astronomy, X-ray astronomy, upper air physics, ionospheric physics. It had a whole melange of different things going on. So I was sent to talk with Talbot Chubb, and he told me that Jim Kurfess needed help because Jim was the only one doing gamma ray astronomy at that time. Gamma ray astronomy was done at that time from balloon experiments. Jim Kurfess would be responsible for a large gamma ray experiment on HEAO, as it was envisioned then. There was an X-ray experiment and a gamma ray experiment, that was on the NRL HEAO A package. The gamma ray experiment eventually evolved into what is now GRO. GRO would have really been part of HEAO-I.
DeVorkin:HEAO-III, though, had a gamma ray...
Bleach:HEAO-III had a gamma ray experiment, but that was cosmic ray and gamma ray. That was in part the Goddard experiment. I think there may have been four HEAOs at one point but I'm not sure.
DeVorkin:Four were planned, but three flew.
Bleach:Yes. Both HEAO-I and HEAO-III were planned to have gamma rays. HEAO-III may have been dedicated to cosmic ray and gamma ray; HEAO-I was a complementary thing.
DeVorkin:Did you also apply to AS & E or any of the other groups?
Bleach:No. I decided I wanted to stay around the area.
DeVorkin:Why was that?
Bleach:Well, there were a number of groups that I could keep in touch with: the Goddard group, the NRL group. I don't know whether there was a connection with Johns Hopkins. There were some people there who were working at Johns Hopkins and spent time at NRL.
DeVorkin:Dick Henry, Feldon.
Bleach:Yes. Other than that, it was mainly that I was settled here and I didn't want to move to California.
DeVorkin:Okay. Let me ask you one thing from the Goddard era. Your group, or generally people within the high energy group, were doing balloon and rocket work as well as planning solar satellite work and that sort of thing. What was the relative regard of the one for the other? In other words, the balloon people relative to the rocketsonde people relative to the satellite people? Was there a pecking order, a hierarchy, jealousy?
Bleach:No, there were mostly autonomous groups. In other words, there was an X-ray astronomy group. There was a cosmic ray group. There was someone who was interested in gamma rays. Frank McDonald tried to find graduate students to supply all of them. There was enough money at that time for all groups to get enough flights, to be able to do the experiments they were interested in. A lot of them had to do balloon flights because they hadn't evolved the satellites then. I mean, you just didn't know what you should have on a satellite until you got experience with suborbital flights. By the way, there's one thing that you asked before, and that was costs; what were the monies involved in these kinds of things? One thing that should be of interest — at least as a reference point for something later on — is that I remember when we were in rocket flight, the total cost for everything in the rocket, including having it launched and everything, was about $100,000 in, let's say, 1970. And about half of that was probably in the rocket itself.
DeVorkin:That included overhead for the shake tests and all of the flight readiness stuff?
Bleach:Yes, $100,000. To give you an idea, I got a thesis with two rocket flights. If you just take that number you can roughly figure out what it costs to train an X-ray astronomer.
DeVorkin:But these were not rocket flights dedicated to your experiment, or were they?
Bleach:Yes. I can't say that it was my experiment alone, because a problem came up. There was a group of three people, and there may have been a post-doc in the later phases. We all joined in in doing the rocket flight, and we launched the rocket as a group. They wanted to analyze the data and publish it right away. However, the University of Maryoland had a rule that said your thesis has to be original, not published before. We got around that rule. Somehow we found a loophole whereby they could publish the data; my name could be on the paper, and yet it still got into my thesis later on.
DeVorkin:Maybe the rule changed after a while, but at least at some schools in the sixties and seventies, you could submit previously published data in partial fulfillment of the thesis; you still had to write the thesis. But that wasn't the case here, I take it. Did that cause any problems? Did Frank McDonald try to get that changed? Has it changed today?
Bleach:Well, I think the reason that I say it was a problem is because I remember having arguments with Steve Holt. I needed to put this piece of data in my thesis, and meanwhile he was running home to write a letter to the ASTROPHYSICAL JOURNAL right away. So something had to be worked out there. I know they found some way that it could be published but it was published with the intent of putting it into my thesis, something like that.
Tatarewicz:It sounds like Frank McDonald was pretty active in trying to get new people?
Bleach:That's right. I don't know how that's viewed right now, but from my narrow point of view, in seeing what happened to me and what I'm a product of, and looking now at other groups and what they did, I think that was a key thing that he did. He brought up a group of newly trained people into the different areas of astronomy that scientists who worked for him were involved in.
Tatarewicz:He was doing this with many groups within his division.
Bleach:That's right, cosmic rays, gamma rays, and infrared. He got people to populate those groups, through the University of Maryland and other local schools such as Catholic University.
DeVorkin:Were you interested in staying at Goddard?
Bleach:Yes, but I was advised by Frank McDonald that I would be better off if I'd get a different perspective. He's the one who suggested or maybe made the contact with Friedman or Chubb or someone, for me to go talk to people at NRL.
DeVorkin:That's a very academic outlook on things, getting more perspective, rather than having a warm body right there who can solve immediate problems for you. How would you typify the Goddard climate at that time for research? Was it an academic climate or an industrial climate or what?
Bleach:Well, they didn't interact very much with the University of Maryland. I know there was a problem there. In other words, there was a very difficult time, I believe, of getting those people from what I just described before as the astronomy program to come over to Goddard and talk with you or give seminars or collaborate or whatever. The exchange back and forth there was difficult. So it wasn't really academic. On the other hand, it wasn't industrial oriented. It was really a NASA center with its own unique flavor to it. On the other hand, because there were so many Ph.D.'s concentrated in one building, it was a very competitive society. When I left Goddard, all I thought was that the world existed as a laboratory, and they were all Ph.D.'s. I didn't even know I was in such a competitive state; I was always competing with Ph.D.`s from the start of my graduate school. That's the way I sense it.
Tatarewicz:It must have been quite a shock to leave Goddard and go back to campus. I suppose you were doing course work on campus and you had things to do the other part of the week?
Bleach:That was only the initial part. Once I got the research assistantship, I spent 20 hours on campus. Then when I finished my courses after two or three years, something like that, I essentially spent all my time at Goddard. I don't remember whether I was paid on a 40-hour basis or a 20-hour basis, but anyway, half the time I did work that was supposed to be for Goddard, and half the time I could do my thesis. I was paid about the same salary throughout my graduate years.
Tatarewicz:Who was your thesis advisor?
Tatarewicz:Frank McDonald was officially your thesis advisor?
Bleach:He was the professor on the faculty at the University of Maryland at that time. Now I believe it is Elihu Boldt.
DeVorkin:What about Jack Brandt and people in the solar physics division?
Bleach:That was another division.
DeVorkin:You had no contact with the solar people at all?
Bleach:Right. Up to that time.
DeVorkin:Any possibility you know some names of people who went through the solar division the same way you did, at Maryland or other places?
Bleach:I don't know the people. I know the scientists but I don't know graduate students' names that went through the solar division at Maryland. My view is that Frank McDonald was getting most of the people from Maryland.
DeVorkin:I don't know of any solar physicists or solar astronomers, particularly that were at Maryland anyway. Okay. Add anything you wish on the Goddard era and then let's move on to the NRL era. Give us some years, what you decided to do, that sort of thing. You have already told us a little bit about it.
Yes. The Goddard era, in terms of the experiments, was basically experiments on rocket flights. One story I could throw in here which is probably appropriate since it is the Goddard era, is the idea that I told you. You asked what we were looking for. We were looking for new sources as well as trying to understand how these sources worked. No one had really thought too much about compact objects and objects that varied. The process of doing that got started in the late sixties. Uhuru was launched December 12, 1970. My rocket flights experiments began in 1969. I had one in September of 1970, I think, three months before Uhuru, and I have data in my thesis on the Cygnus region of the sky. I looked at all the known sources that were there, with very high time resolution. Uhuru was launched in December of 1970. It had much longer exposure to sources, because it was an orbiting satellite, whereas a rocket flight lasts only three minutes. I collected data for about 10 seconds on Cygnus X-1 with a single rocket flight. Uhuru had many minutes on Cygnus X-1, but because of the requirements of packaging everything on a small satellite, they didn't have the time resolution to look for variability that the rocket flight data did. For instance, Uhuru had time resolutions of about 90 milliseconds.
That was the smallest time gin that they had. We developed and pushed to the limit telemetry rates that were later used on satellites. The Goddard rocket flight experiments had telemetry with about 350 microseconds time resolution or about a third of a millisecond — compared to 90 milliseconds timing resolution with Uhuru. That means we could tell the time of arrival of those X-rays accurate to a third of a millisecond. So we looked at Cygnus and Uhuru looked at it. We also had spectral resolution so we could tell the energy spectra of these photons. In September or October of the fall of 1970, I was analyzing the data from Cygnus X-1, X-2, X-3 for energy spectra to see what shape it had and to see whether it can be fit to a thermal model or non-thermal model. I was doing this analysis, when Uhuru was launched. In January of 1971, a fellow working with the Uhuru group named Oda analyzed the data. At that time people were starting to think about neutron stars. There was a lot of talk about that kind of object. I'm not really the expert, but Oda looked at the Uhuru Cygnus X-1 data, analyzed it, and found about 70 millisecond variability. He thinks he finds periodicity. Now, that's cutting it a little close, because the satellite has only 90 milliseconds timing resolution. He's right on the border there. And this is unbeknownst to us. Giacconi, who's the leader of the X-ray group, comes to talk to us at Goddard.
DeVorkin:Oda is working in Giacconi's group?
Bleach:He's working in Giacconi's group in, I believe at this point, the Center for Astrophysics at the Smithsonian. Giacconi comes down with the data in January and says to Steve Holt, Elihu Boldt, Serlemitsos and myself, "I want to show you something pretty interesting that we found with Uhuru data. We found this temporal variability." The reason he came down is that he knew that we had a rocket flight in September. He said, "Did you see anything like this?" We said, "We haven't looked at the data. We were doing energy spectra." Uhuru had relatively poor energy spectra. We had much better so we concentrated on spectral analysis of the rocket flight data. So we talk a little bit, and Steve Holt runs off that night and does the temporal analysis. He not only finds what Oda found, but he finds lots of other periods, too. So we write up the paper. Now, there's two papers in here within one month of each other that come out in the ASTROPHYSICAL JOURNAL on Cygnus X-1. The first paper that came out is "the X-ray Pulsations from Cygnus X-1 observed by Uhuru".
DeVorkin:That paper is by Oda, plus Gorenstein, Gorsky, Kellog, and it is published in ApJ 166 Letters, page 1 through 7, 1971.
Bleach:Okay. So that's the evidence that there's something pulsating in Cygnus X-1. Now, we write up the Goddard paper, not knowing that they had sent out their paper.
DeVorkin:Did they send this paper in after Giacconi met with you?
Bleach:No, they were clever. They sent it out before Giacconi visited us, I believe. He came down to verify their data, so we thanked him in the Goddard paper for data before they published it. Then we wrote a paper which came out one month later which said, "We corroborate the Smithsonian results plus we found something else. There's something funny about Cygnus X-1 that suggests it's not an ordinary source."
DeVorkin:Amazing. This is Holt, Boldt, Schwartz, Serlemitsos and Bleach, ApJ 166, Letters, page 65 through 68. I notice your receive date is just about ten days after theirs.
Bleach:The interesting thing is, if we hadn't found that, and if we had called Giacconi and said we didn't find it, what would they have done with that paper?
DeVorkin:I don't know.
Bleach:That's the question. So, it's true, Uhuru found something. But they were marginal because they really didn't have the time resolution to do exactly what they were saying in that paper. We not only had the time resolution, but we were able to find other effects, too. So in fact that paper from the Goddard group confirms the discovery that maybe Cygnus X-1 is a black hole.
DeVorkin:You said your data came first.
Bleach:In time, our data were taken first. But, in fact, they analyzed their data before we analyzed ours, so they are the initial discoverers of some kind of an effect. But it is the real validation or confirmation of that effect, plus other effects which suggest that there are multiple periodicities, not just a single pulsar, which makes Cygnus X-1 an unusual source. That's what leads to all the speculation that it could be a black hole candidate. To me, that is the story of how Cygnus X-1 got started, at least from the experimental or observational point. That differs with the Hirsh book where it says that Uhuru found that Cygnus X-1 was a black hole candidate, and MIT validated, with 1 millisecond time response. MIT may have had the capability for 1 millisecond in one of their experiments, but Goddard, a year later, first found 1 millisecond variability in Cygnus X-1, not MIT. So it's really twisted there.
DeVorkin:Why do you think Hirsh got that twisted? He just didn't know?
Bleach:I think it depends on who he talked to.
DeVorkin:So different people would have different versions of this?
Bleach:Giacconi may have a different version, and George Clark at MIT may have a different version. Now, the point then is, it's certainly right to talk to Giacconi or talk to Friedman as eminent scientists but two things should be mentioned. You can ask them for their recollections, but it may be worthwhile asking them, "Tell us all you know about groups other than your group. Don't just tell us about your group, tell us about other groups." The second thing is, when you're trying to collect historical facts like that, it's always worthwhile to ask, if you can, someone else at a different level, you know, at the working level, for example. There is a danger here. You can't sample everything. My reason for bringing this up is this business of Cygnus X-1 being the black hole is that it would be worth sampling information about this object with someone else or at a different working level, namely someone who has a thesis or someone who was also an X-ray astronomer during that time. I visited Steve Holt yesterday to talk with him about some other things, and I went through this whole thing with him, asking for his recollection. And they were similar to what I remember. I said to Steve Holt, "Did Hirsh ever talk to you?" He said, "No."
DeVorkin:I know he didn't spend any time on the Goddard group, and I'm curious as to why.
Bleach:I don't know.
DeVorkin:This brings up another story that is curiously similar in some ways, that is ten years before your move to NRL, about that famous series of rocket flights in '62 and early '63 on the first detection of discrete sources. My understanding from an informal conversation with some people at NRL that included Friedman and Gursky who, of course, worked for Giacconi, was that at one point the AS & E people came down to NRL to find out what they were doing. The story sounded very similar to what you said - Giacconi coming down to check out what other people were doing in the same sort of an area. Any evidence that Giacconi does this sort of thing?
Bleach:Yes. There's nothing strange about that.
DeVorkin:That's his style. But not telling the people that he has a paper in the works?
Bleach:Well, you can take that one example I just mentioned. I can't really confirm other examples but I wouldn't be surprised.
Tatarewicz:He never mentioned that he had a paper submitted at the time?
Bleach:No. That's what I asked Steve Holt yesterday. I said, "Do you remember it the way I remember it? Because I'm going to talk to Dave." He said, "Yeah, I remember it that way."
DeVorkin:That's a fascinating story. Giacconi is obviously a very complex fellow. Was that your first contact with Giacconi?
Bleach:One of the first, yes.
DeVorkin:Let me ask you to review the process of when you decided you were going to go to NRL. You started talking about how your own advisor, Boldt...
Bleach:Either Boldt or McDonald, I don't know.
DeVorkin:...suggested you go and talk to people at NRL, and you did. Who did you talk to? What helped you decide to go to NRL?
Bleach:The initial contact was with Talbot Chubb. Then Talbot directed me toward Jim Kurfess, who was in the gamma ray astronomy area. His background was from Rice University in Houston, Texas, doing gamma ray balloon flights with Bob Haymes, I think it was.
DeVorkin:Right, he's the fellow who wrote a book on space science.
Bleach:Yes. And at that time, Jim didn't have any other scientists or post-docs helping him with the gamma ray work. There was an offer immediately: If you want to do this, it's available. Now, the interesting thing is that at about that time when I started to help Jim design gamma ray detectors, I had just come out of the Goddard group doing proportional counter work to measure lower energy X-rays. At that same time, NRL was designing HEAO-A-1, large area proportional counters. How were they doing it? Not be interfacing with the Goddard group, but by talking to Friedman's old nucleus of X-ray astronomy people, namely Ed Byram and Talbot Chubb — I don't know all the names.
DeVorkin:Those are the two main names.
Bleach:Anyway, they decided that Ed Byram was going to develop and construct the counters. The thing I see there, in hindsight, is that instead of using this cross-fertilization and taking advantage of the technology that was developed at Goddard, they put me in a gamma ray group to do something else. I never interfaced with the people designing large area multi-wire proportional counters at NRL.
DeVorkin:Even though you had done it earlier?
Bleach:Even though I had the experience at it.
DeVorkin:Why is that? Is there something peculiar about NRL, the way they run their business?
Bleach:It may be that the old-timers thought that they would just do it their own way. They not only didn't ask me, they didn't go and talk to people at Goddard like Boldt or Serlemitsos who spent years developing these counters. Serlemitsos was the most active scientist developing these things. I don't know if it's because of the relationship between Friedman and McDonald. There could be that element of it in there, too, or just the interaction per se between NRL and Goddard.
DeVorkin:You say there was friction there?
DeVorkin:Were you directly aware of the friction at the time?
DeVorkin:So it wasn't that overt.
Bleach:No. So, anyway, the reason that I'm bringing this up is that when the HEAO experiment finally did fly, there were many problems with it. Eventually, they produced a catalogue showing the position and the brightness of the sources, but they were also supposed to get a lot of spectral information, namely the energy spectrum of all these X-ray sources. But the proportional counters didn't work the way they should have worked. In my opinion, they could have taken advantage of technology that we had already developed up at Goddard. They had problems getting the high voltage wires not to arc, and to get good pulse height signals out of the counter. That part of HEAO-I was a failure, and they got into trouble with NASA Headquarters over that. That's the regret. I probably could have contributed to HEAO-I, if I had been asked, rather than go just into another area like gamma ray astronomy.
DeVorkin:So you were put into the gamma ray project?
Bleach:Because there was no one else there. That's where I was needed the most.
DeVorkin:Did you feel the atmosphere was not conducive to your going over and talking to Chubb or Byram and trying to get them to try the new technology?
DeVorkin:It was not conducive to that?
Bleach:Not conducive. There were two people at NRL, Gil Fritz and Seth Shulman, who were also developing multi-wire proportional counters or proportional counters for rocket flights. Even they didn't get in, as far as I know, to work with Byram developing the HEAO counters. Byram did it himself.
DeVorkin:Isn't this the old legacy from a high security institution where nobody talks to anybody else? Or doesn't it have anything to do with that?
Bleach:No, I think it's just the personalities and how they were used to working. I mean, when they started in X-ray astronomy, no one else was doing it. They thought they had all the experience they needed to do this — that's what I believe.
Tatarewicz:Are you aware of this same kind of lack of communication within NRL in similar groups in areas other than X-ray? Was this something that was throughout the organization?
Bleach:NRL even today exists with a lot of branches that are very independent, empire-like, autonomous groups. Basically, they do what they want to do. Talbot Chubb had a large amount of people in his branch. On the average, branches at NRL have a third or a quarter of that many people. It was luck if you talked to him at the right time because you needed some money or you needed to get permission to do an experiment. This is how things were resolved. It seemed like it was hit or miss. Now it's different. Things have been broken down into smaller groups. Kurfess has a gamma ray group; Gil Fritz has an X-ray astronomy group. There's a radio astronomy group, and a solar physics group.
DeVorkin:That's right. Did Gursky change this recently, or is this something that was broken down before Friedman left?
Bleach:Before Friedman left.
DeVorkin:So Friedman did it?
DeVorkin:Okay. Well, you worked on gamma rays with Kurfess. What were your responsibilities there and what were the problems?
Bleach:Okay, the idea was to build gamma ray detectors, called scintillation counters. A scintillation counter is something that glows when the gamma ray hits it; it emits visible light. You have a photo tube that collects the light; you can tell by the amount of light what the energy of the gamma ray is. The hard part is, you also need some type of collimation to determine the direction that the gamma ray comes in. There was a balloon program. We put these detectors on balloon flights. I have all kinds of interesting stories about flying balloon experiments such as sitting on the mountain tops in Huntsville, Alabama, tracking these things. The next day in the local paper they said it's a flying saucer that they finally identified. That is an example.
In back of Marshall Space Flight Center. We launched balloons from Palestine, Texas. They would float east or west depending on the time of the year and so they would track in Palestine until the balloon was over the horizon. On this particular flight, I went to Huntsville on top of a mountain to track the balloon further east to get more data. The first flight I had, I was piggy backing on someone's experiment flown out of Palestine, Texas. The balloon burst at 60,000 feet and fell into a forest there. So we went on a truck riding around until we finally found it spread out — it looked like Christmas, all this mylar over hundreds and hundreds of trees — and the experiment was up in a tree. We spent half a day cutting trees trying to get the experiment down, the parachute and everything. We got it loaded on a truck four hours later. Then just as we were packing up to leave, two guys came out of the woods. We thought these were the owners of the land, and you've got to watch out — they might have shotguns — who knows what's going to happen? These two guys came out of nowhere and they said, "We saw the balloon burst, and we've been looking for it all this time." "Yeah, what do you want?" We were all set. The ground recovery crew were well versed in giving owners of the land money, to compensate them for cutting down trees.
We were all set to do that when these guys said, "Well, the reason that we spent all this time looking is that we are painters, and we would like to have this material for drop cloths?" So we said, "Feel free!" and left them there to gather up mylar for drop clothes. Those kinds of stories are amusing after you have time to think about them. The balloon people are used to going into someone's land. Most of the places around there are cornfields or forests. It doesn't hit houses. Maybe it hit a house once or somethng. Most of the time it lands in somebody's corn field. Usually a spotter plane operated by the recovery crew comes around, tells the guy in the truck where to go. He drives around in the truck, goes in there, cuts away everything, puts the experiment package or what's left of it on the truck and gets out of there as fast as he can. And if he can't do it without being seen, then he offers the owner of the property some money.
Tatarewicz:He carries some extra cash. This is just a nice little-known aspect of balloon work!
DeVorkin:And you did this yourself?
Bleach:Yes, I did this for a couple of years, ending up after balloon flights in some part of Texas, who knows where — Calapoosa, Georgia — collecting balloon experiments for data. We analyzed the data and we looked at the same sources basically that emitted X-rays because these things are already high energy sources of radiation.
DeVorkin:What sort of collimators did you use?
Bleach:Again, mechanical. There were some experiments which were very cumbersome using detectors called spark chambers where they could tell by tracks where the gamma rays were coming from but we didn't do that. We just used scintillation materials like sodium iodide, caesium iodide, and mechanical collimation. Now, that was the basis for what composed one out of four experiments, to be flown on the satellite, GRO. One of those experiments was the evolution of the kinds of detectors that I developed with Kurfess back in the early seventies.
DeVorkin:Were these balloon experiments seen as evolutionary steps to satellite work?
DeVorkin:Would you say this was the common thing for both rocketsonde and balloon work at the time?
DeVorkin:Was there anybody working on balloon and rocketsonde experiments that had no intention of going into satellite work? Or was this really just accepted?
Bleach:If they did accept rocket or balloon experiments by themselves, they had such a small program that they realized that they might never have a bigger group, never have the capability, never be able to get the funding to do that. They would just do a few experiments. The people that wanted to stay in the business knew they had to evolve to satellites.
DeVorkin:Did this create — because this is on the topic even though it's timeless — a hierarchy between balloon, satellite and rocketsonde people? I asked you that before because we've detected that in the infrared groups. I don't know about X-ray.
The question is whether there was a hierarchy of competition among these different types or modes of launching experiments. Certainly the people who were further ahead were those who had their experiments on a satellite, like the Uhuru satellite. There was the hope by people at Goddard or other places that their rocket program would evolve and they would be able to propose for a satellite next. So in that sense, there was competition. But everyone realized that you had to go through some kind of a learning curve. You went and started with rocket flights and other people started with balloon flights. But sometimes they did either balloon or rocket experiments for different scientific reasons, too. There still was the hope that you would be able to get to satellites. And some groups got there faster.
Then there was a feeling that the other group had to catch up in order to be competitive and write papers, you know, on the same level with the other group. But balloon flights were really used in a different mode compared to rocket flights because balloon flights naturally don't get up as high in altitude as rockets. Balloon-borne experiments don't get up high enough to see the lowest energy X-rays because there's still enough of an atmosphere above them to absorb those X-rays. From balloon flights you can only do gamma ray astronomy or high energy X-ray astronomy. So there really was no competition between balloons and rockets, because usually the one group was looking at the sky in a different wave length range from the group who was looking at the sky from balloons.
Tatarewicz:So the people who were working primarily in hard X-ray or lower energy gamma rays were the people who stayed with balloons?
Bleach:No, the groups who really remained viable had to go to satellites. Once one group got on satellites, there was so much more exposure time available from the orbiting satellite - looking at a source again and again — that you just couldn't do the same kind of science. You just couldn't get the same kind of science out of the rocket flight or the balloon flight that you could with a satellite once the satellite is launched. You could do auxiliary experiments from rockets or balloons concentrated on getting more precise measurements than from a satellite experiment, but what I'm saying is, you couldn't stay in touch with the newest, forefront discoveries.
Tatarewicz:So balloons then occupied a kind of a stepping stone?
Bleach:A good way to look at the role of balloons and rockets is as a stepping stone, as well as in terms of training graduate students. The way NASA headquarters looks at that now is that balloons and rockets, namely the suborbital program, will evolve to small things launched on, or piggy-backed on, the Shuttle.
Tatarewicz:SPARTAN kinds of things?
Bleach:Yes. So a person now going into graduate work in X-ray astronomy or in gamma ray astronomy can't even do some of the interesting science with balloons and rockets. That person will have to find an experiment with a longer exposure time that's available using the Space Shuttle, in order to do his thesis. So there's an evolution there in the way graduate students might do their thesis experiments.
Tatarewicz:Were there high energy groups in other NASA centers besides Goddard that you were aware of, or interacted with?
Bleach:Yes, there were about a dozen X-ray astronomy groups in the United States at that time only some of which were at NASA centers.
Tatarewicz:Virtually each NASA center, then, had a high energy group?
Bleach:No, there were university groups, private industry groups. At that time most of them probably were university groups.
Tatarewicz:Do you recall any other NASA centers where there were groups? Was there a group at Ames, for instance? Or at JPL?
Bleach:At the time I was there, there was, I believe, a group at Marshall Space Flight Center. I don't think it was an X-ray group, but there may have been groups at other NASA centers that I can't recall. I don't know if the gamma ray group was at Marshall then or not. They may have been involved with cosmic rays. To my recollection, there were just a lot of university groups and a few companies like Lockheed.
Tatarewicz:Can you recall companies besides Lockheed?
Bleach:AS & E.
Tatarewicz:Okay. Let's see, why don't we continue more or less chronologically? You left off as we were talking about your work with the gamma ray group at NRL.
Bleach:Okay. About two years or maybe a year after I started doing that gamma ray work, the funding for the Apollo program began to decline. As a result, the HEAO program, which was funding a lot of this work, was cut to maybe a quarter or a fifth of the level that had been envisioned originally. What that did was take the railroad-sized HEAO and now make it the size of a car or something a little larger. The gamma ray experiment was removed from the NRL part of HEAO. So now, there was no longer a satellite gamma ray experiment, there was just balloon work. At that time, I began to look at NRL in different areas, areas that maybe were doing laboratory work related to X-rays. In 1974, I made a transition to do laboratory atomic and plasma physics work instead of astrophysics or astronomy work.
Tatarewicz:How did your group get the news about HEAO? Do you remember when you found out about it?
Bleach:No. I think this is the kind of thing that filtered down. As soon as NASA makes a decision, or as soon as NASA gets a budget where it says that it's going to be cut back in HEAO, then that information filters down. You have to remember, I was the lowest guy on the totem pole right then. So it filtered down from NASA to Friedman to Chubb to Kurfess and on. I do not recall how I learned about it. I wasn't really on top of administrative things at that time. I know approximate times, but I don't know how decisions were made. I don't know the history of that HEAO cutback. But you can find that out from either people at NASA Headquarters who were around in 1972, '73, or people at these different X-ray labs, in particular, people at NRL. Chubb isn't there anymore but Gursky may know the history of that. Gil Fritz was head of X-ray astronomy. He may know the history of that.
Tatarewicz:I was interested in the reaction within your group. Here you've been working on this project and experiments for HEAO and all of a sudden, you've got nothing to put it on. Presumably, you've gotten to the end of that phase?
Well, it had only been developed as balloon work at that time. In other words, there was a carrot dangling out. We thought we were going to get a satellite experiment, but meanwhile, all we really had was a carrot sticking out there. We hand't really gotten into cutting hardware or anything. We were planning satellite experiments but I was still just flying balloons. The only crushing blow was that there were no more expectations of increased financial support there and there was no other funding source on the horizon. What did that tell me? That I didn't want to do balloons forever, for as far as I could see ahead. So I looked for other work at NRL, namely the laboratory work, and I wound up doing X-ray diagnostics of laser fusion plasmas. That evolved into X-ray diagnostics of other kinds of plasmas in the laboratory, of magnetic fusions plasmas and Tokamaks. Tokamak is a Russian acronym meaning doughnut shaped. It refers to the shape of the magnetic confinement machine that contains the hot plasma. So what I'm saying is, I knew I had to make a connecting point with my previous experience to get an interesting job.
The connecting point was that I was using instruments which measured X-rays — which I had experience in — except now I was applying these instruments to measuring laboratory plasmas. I had to find out who at NRL was using any of these instruments and how they were using them in order to join another group at NRL. Well, a group called the X-ray Optics Branch was using them for several different things at NRL. They used X-ray detectors like proportional counters to do spectro-chemical analysis. They had contracts with the EPA. Those contracts were looking for ways of determining trace amounts of impurity materials in water and air, for pollution effects. How do you determine a trace amount of that? You can take a sample. You can shoot X-rays through this sample. Each material will essentially emit characteristic X-rays as a signature by the type of material it is. You can determine not only what the material is, but how much of it is there, by the energy spectrum and intensity of the X-ray signature. This is something that goes even back to the beginnings of X-ray astronomy. There really is a tie-point there, because what AS & E was doing — and I am not sure if it's in connection with a DOD contract or some other contract — is they were going to try to look for fluorescents, characteristic X-rays from the moon, when they first shot off that rocket in 1962. So they were also looking for ways of identifying materials on the moon. They were going to take these proportional counters and look at fluorescent X-rays from materials on the moon and try to determine what kinds of elements are there — for mining purposes or whatever.
DeVorkin:We've heard that that wasn't a serious proposal, that they really wanted to do celestial studies but didn't think they'd get funded. How do you feel about that? That's what Richard Hirsh says, of course.
Bleach:That's probably true but I don't think they knew that there might be celestial things and they couldn't have had a clear idea that they would find anything.
DeVorkin:Didn't someone talk about this in '59 or '60?
Bleach:Around 1950, Friedman had already measured X-rays from the sun. But if you take the brightness of the sun in X-ray and put it out to the distance of the nearest star, again, you'll never measure it with the detectors that they had at that time. So besides a dream, what possible guarantee could AS & E expect by pointing the same kind of detectors out in space?
DeVorkin:The radio people had been finding synchrotron radiation, so conceivably they expected stronger and stronger magnetic fields. Or maybe it wasn't conceivable?
Bleach:These are theories. The neutron stars were postulated in the 1930s. Why didn't anyone in 1940 or so say, "A neutron star is going to emit X-rays."? The connection just wasn't there. Now with hindsight maybe someone will tell you differently, but personally I don't have any reason to believe that AS & E really wasn't going to try to do that experiment and look for X-rays from the moon. It's just because they found what they did, that X-ray astronomy got started then.
DeVorkin:Right. But determining surface compositions by X-ray, the radiation...
Bleach:Well, the way this works is that the cosmic rays from the sun hit the moon. They excite the atoms on the moon to fluoresce, and you measure the X-rays generated by this process.
Tatarewicz:At the same time, Air Force Cambridge Research Laboratories was funding a lot of research in infrared identification of lunar surface composition.
Bleach:I think there was an interest at that time by DOD in finding how to measure materials on the moon. And I think that that's how AS & E got its money to do these rocket flights.
DeVorkin:They certainly got it from the Air Force.
Tatarewicz:Okay. This is the Air Force Project Horizon Study in 1960. It may still be classified. It was a several hundred man lunar base using Saturn V's, ABMA and Maderas, as a last ditch attempt to keep the von Braun team. But there was a lot of interest within the Air Force in lunar surface assays, and in finding construction materials on the moon and the whole thing of building a lunar base. So it's not implausible.
Bleach:Yes. You know, you really have to probe the AS & E people like Gursky and Giacconi to see their true motivations. In the back of their minds, they may have hoped that they would find something in the sky. But certainly they weren't funded for that.
DeVorkin:Was there ever any interest in pointed X-ray experiments from rocketsondes or from balloons? Or were these simply things that just floated or spun?
Bleach:No, when I did my thesis it was pointed.
DeVorkin:You did have pointed X-ray experiments?
Bleach:The attitude control systems and startrackers, I believe, were developed in the early sixties. At that time, we could only point to an accuracy measured in fractions of a degree.
DeVorkin:Is this the Spark [Strap?] system on Aerobees you're talking about?
I think that system was later than when I started. But originally my job at Goddard — this is how I got paid, you know, I told you, 20 hours a week — in the X-ray group there was to take cameras and align them with the experiment. I would use film to take pictures of stars in the sky; to do aspect solution of where the detectors were pointed. That's how we knew what portion of the sky we were looking at. That was the most accurate way of determining aspect. I was the first person who used cameras to do this; certainly for the Goddard group. I think I remember talking to other groups, and telling them how I did it. It's like this story I told you about Steve Holt having a balloon flight. The experiment they did was used to test a camera system that eventually could be used for our rocket flights later on. I remember Steve was going to go down to Arizona the next day for his balloon flight, and I didn't quite have my camera package set up and checked out to work automatically.
It was battery operated and had electronics in it, as well as insulation to protect it from the cold temperatures at say 100,000 feet altitude. So Elihu Boldt and I stayed up all night long trying to get this thing ready for 7 o'clock the next morning when Steve Holt was going to pick it up and go down to Arizona. At 5 o'clock in the morning, after Elihu and I took turns all night sleeping for a half hour on the desk there then working for a half hour, we soldered one thing wrong and the whole thing didn't work after that. So Elihu looked at me and he said, "How would you like to take a trip to Arizona?" Two days later I got the thing working properly again. That was my first trip. I brought it to Arizona, put the thing on the balloon experiment package, and then I went back before the balloon was launched. The balloon took off in Arizona, floated across the country, and landed in a cornfield in Illinois. When I got my experiment back, the camera didn't look too good. The lens is a little bit crazed and had marks on it. I got the film out. I went into the dark room and developed it. I looked at the film and it was all blank except for the last three frames. The last three frames had funny lines in them.
So I took the film and showed it to Elihu. He didn't know what to make of it. About two days went by and I was still thinking, what could possibly have happened? Later Steve Holt said, "You know, that balloon went up in Arizona and it landed in a corn field in Illinois." This was the first clue as to what happened. After the balloon went up, the batteries, which were supposed to energize the heating coils to keep the camera warm, never worked. The thing froze and the lens crazed. It came down, landed in a cornfield, heated up. It was a warm day out there and the batteries started working again. I took pictures of corn stalks! That was my first experiment. That's how I earned my living then.
DeVorkin:We're in the middle of your NRL years. We've pretty much finished the gamma rays?
Bleach:Yes. I was telling Joe how the money for HEAO got cut back, and at that point, I looked towards the laboratory work and made a transition from the group that I was in with Kurfess to another group at NRL which I'm still in today, doing laboratory diagnostics. I came back later on to help out with HEAO data analysis. I helped to create the HEAO A-1 All-Sky X-ray Catalogue.
DeVorkin:I'd like to bring this to a close now — this is long enough for one session — and talk in outline fashion for no more than a minute or two about what topics we should discuss next time. We would like to go for another session. Is that all right with you?
Bleach:I think so, because one thing that we didn't get into at all is the House Appropriations Committee Astronomy Study and the implications it has for the whole astronomy program in the United States. It's very timely right now, particularly because the hearings were just held. There was some information that we wrote up relating to questions which were asked at the hearings about the impact of overruns on Space Telescope, which also has gotten a lot of attention. What are the implications of these things, not just in terms of Space Telescope, but of all space and ground-based astronomy? We tried to get an idea of what is going to happen or what may happen in astronomy and astrophysics for the rest of this decade and into the early nineties. We were interested in terms of the United States program but also in terms of our interfacing and our competition with the Europeans and the foreign community in general. We looked into that and talked to some people on that subject.
DeVorkin:You were mentioning SKYLAB but I don't know the context. Did you have any contact with Tousey's group during the SKYLAB years?
DeVorkin:By the time you got to NRL, those groups were already well along?
Bleach:Yes, Chubb was responsible for one part, and Tousey was responsible for the other part of space science research at NRL, at least in terms of the astronomy areas. They really were two autonomous groups. I was in Chubb's group. I really didn't interface very much at all with Tousey's group.
DeVorkin:But I'd like to know a little more about NRL generally, what it was like at that time. Maybe we can talk about that next time?
DeVorkin:Then I think we should talk more about how you got into this general study. You're doing other studies now for the Pentagon?
DeVorkin:Yes. You can't talk about them...
Bleach:I can a little bit.
DeVorkin:What I'm personally interested in with you is that here you were trained in physics, doing stuff aligned with astronomy. But now you're really existing in a very interesting, unusual position with scientific Washington, if you want to coin a term, and I'd like to talk about that, too. What is your impression of being in this kind of a role?
Bleach:Yes, I have been meandering around a little bit with my career. It started with getting out of the astronomy research area. Once I got into other areas of NRL — such as X-ray diagnostics of laboratory plasmas — it happened that every couple of years, I really found myself changing from one kind of experiment to another. Instead of measuring the laser plasma, two years later I was measuring some X-ray simulator plasma. Next, I was measuring X-rays from a Tokamak plasma, and then the next thing I was measuring was a high energy laser plasma again. It wasn't the case that I devoted all my efforts to one specialty anymore. Getting involved with the Congressional studies was a serendipitous type of thing. I learned to be adaptable, I guess. Or I learned to accept that. Being involved in different projects is interesting to me. Somehow I liked the idea, and I took advantage of the opportunities that were there.
Well, we'll finish for now. Thank you very much for this session.