History Home | Book Catalog | International Catalog of Sources | Visual Archives | Contact Us

Oral History Transcript — Dr. Riccardo Giacconi

This transcript may not be quoted, reproduced or redistributed in whole or in part by any means except with the written permission of the American Institute of Physics.

This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.

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

Access form   |   Project support   |   How to cite   |   Print this page


See the catalog record for this interview and search for other interviews in our collection


Interview with Dr. Riccardo Giacconi
By Richard Hirsh
Smithsonian Astrophysical Observatory
July 12, 1976

Transcript:

Hirsh:

The phone ring is a telephone interview with Riccardo Giacconi, July 12, 1976. He is now at the Smithsonian Astrophysical Observatory. He used to be at the American Science and Engineering, Incorporated, Cambridge, Massachusetts. Interviewed by Richard F. Hirsh. Very good, and here we go. Well, let me tell you what I am most interested in right now; that is determining what kind of background there was before the first discoverers of nonsolar X-rays in 1962.

Giacconi:

All right.

Hirsch:

Let me ask you this to start off: Why did you get involved with X-ray research?

Giacconi:

The way I got involved was that I joined a company which was called American Science & Engineering for the purpose of setting up a space physics program which they didnít have. The company had mostly been involved in DOD weapons effects activity and much of that had to do with X-ray effects of weapons. Now when I joined I wasnít cleared or anything so I couldnít really get involved with the major activities of the company, and on the other hand they did have in mind that I should start some space physics work, and I started this by talking to a consultant — or two consultants — of the company. One was Bruno Rossi at MIT and one was George Clark. And in the first conversation with Bruno Rossi he mentioned that detection of X-rays [unintelligible phrase] might be interesting. And I had time on my hands while my clearance was coming through, so I started looking up in the literature what was, what had been done. And I stumbled upon a Russian survey written by Monderschtom [spelling?] and Eprimo [spelling?] which was a very good summary of the work in solar X-ray radiation which had been done mainly at NRL. And then I read some of the stuff that NRL had sent out and then I found that there was nothing but upper limits on X-ray fluxes from this guy. And I started thinking about possibly mechanisms of emission and possible instrumentation to detect these fluxes. And well the first thing that we actually came up with was something, a document called ďA Brief Review of Experimental and Theoretical Investigation in X-ray Astronomy.Ē

Hirsch:

Right.

Giacconi:

There we summarized the status of knowledge at the time, the [unintelligible phrase ending with instrumentation?], possible sources of X-rays and so forth. And this took about six months, and then after that I was quite educated and quite interested on my own. But that is how I got started. A little [unintelligible word; less?] by chance.

Hirsch:

Why did Dr. Rossi think that doing work in non-solar X-ray astronomy would be profitable? Do you know?

Giacconi:

Well, there was — The best that I can determine there was some discussion for reasons I saw some — I mean I donít know how much we actually knew about it, but there was some discussion. For instance Leo Goldberg, who was interested in UV and XUV radiation, pointed out that many others, that the interstellar space would become opaque after when you went shorter than 912 A, but then as the wavelength became shorter and shorter then it becomes transparent again and that it might be interesting to look at as another window [through] which one could observe celestial phenomena. And Bruno I think was interested in a general way with new — at least thatís the impression I got — new range of wavelengths and he started looking at things in a range of wavelength which is different by a factor of 100 from that which had been examined previously. He was bound to find something interesting. It was about at that level.

Hirsch:

What theories were there beforehand that led to some expectations or possibly lack of expectations of X-rays in space besides those coming from the Sun?

Giacconi:

Well, one could expect the X-rays from stars actually. If one took the view that all stars were like the Sun, then the conclusion was that the degeneration between visible light and X-ray emission was the same for all stars. Then since for our own Sun the X-ray emission is only one one-millionth of the total aspect [correct word?], then the most star would produce intensities corresponding to something like 103 photons per square centimeter per second [unintelligible word] which were very difficult to detect. On the other hand, one almost sure candidate was the Crab nebula because there we knew that thanks to the work of Shklovsky that interpreted the radio emission as single [unintelligible word] emission from high-energy electrons of the order of 1012 eV — not only in radio, but even in physical light that the emissions were due to [unintelligible word] from high-energy electrons up to 1012 eV even among [unintelligible word(s)] 103, 104 Gauss. Well, one assumes that the spectrum went up to the 1014 eV, which is not too much of an extrapolation [correct 2 words? a speculation?]. Then X-rays would have to be produced. Okay? And then the question was that we didnít know whether the spectrum would go at that high energy, and if it did with what slope and whatever, so it is very difficult, it would have been difficult to predict exactly what number one expected. But certainly at some level the X-ray emission had to occur in more focused quantity than one would have expected simply from Boronow [correct word or name?] emissions. There were some other — For instance in a brief review we made there were some other speculations, for instance in magnetic A stars. It was assumed that due to very high magnetic fields there might be an acceleration of particles, etcetera, and etcetera. So there was some reason a priori to believe that these fluxes would be detected, but the only problem was that all the predictions seemed to indicate very, very low fluxes, and thatís why right away we got interested in developing more sensitive detectors which then had to be used for the Sun. Those detectors were like a point of a pencil type size and really were you know, ďWe are now flying 60 square feet.Ē [Correct phrase?] [Laughs] Okay?

Hirsch:

Yeah. Are you in a hurry to leave?

Giacconi:

No, no.

Hirsch:

Oh, okay. Were you aware of Jim Kupperianís rocket investigation of 1957? He was then at NRL, and he flew and he flew an Aerobee rocket with an X-ray detector. And he did discover or he did get some data. He did find some X-rays colliding with the detector. Now he didnít publish this report, although he told me that he had told other people in the field.

Giacconi:

Well, I met Jim Kupperian; letís see, at the first Conference on X-ray Astronomy, believe it or not, which took place here at the Smithsonian. And this was now 1960, Ď61 approximately, something like that. And Jim did mumble something about that and — the point though was that as far as he knew — I mean there was no certainty to it. The fact that he didnít publish is that probably [correct word?] he was lazy, but that apparently it was difficult within his own measurements to figure out whether he was seeing anything or not — I mean whether it was instrumental or whatever. So as far as Iím concerned I mean, you know — I have heard that many post facto — I mean it is fair to say that I have heard some post facto claims, okay? But I think the principle one, this one of Jim Kupperianís is, I mean you know the fact that somebody mumbled something, thatís not too impressive. But on the other hand he himself and [Herb] Friedman had done another experiment in which they were looking at gamma rays or hard X-rays from the Sun, and later on — and apparently this was presented at the meeting in Moscow, and there was some — although I read actually the paper that was published about it, I mean that they, the contribution that they — There was no mention of extra solar X-rays in the written version. On the other hand Friedman said that had they started speculating whether some of this radiation they were observing couldnít come from other than the Sun. And the problem again here was the detector was pointing at the Sun all the time, and so one could not reach any conclusion. I think that there were a lot of people that were speculating or working on their own in this thing. And I just didnít know about it at the time or I heard some vague rumor like that of Jim Kupperian mumbling something about that probably [unintelligible word] seen something but then not publishing it. The only thing that I can tell you is that when we actually did go up the detector we shot up was 100 times more sensitive than anything that we have flown before.

Hirsch:

Right.

Giacconi:

So there was a reason why we saw something when everybody else who had been talking about upper limits [correct word?].

Hirsch:

So you say that Kupperianís rocket shot had really no effect on your investigations?

Giacconi:

We, in the early Ď60s, February of Ď60 I believe, we published a paper for instance describing a telescope [unintelligible word]. I didnít know at all at that time. I mean it certainly didnít help me get started.

Hirsch:

I see.

Giacconi:

But then it — then I think I think it was at this symposium meeting, and I think he may in fact have said something about it, but not even at the meeting but in inside it [correct 2 words?] or something. It wasnít something that either got me started or published any useful information which one could work on it. I think their work was proceeding [unintelligible] of that.

Hirsch:

I see. How about some interaction with — I think there were two other groups working in X-ray astronomy: the Lockheed Group with Phil Fisher —

Giacconi:

Right.

Hirsch:

— and at the University of Rochester with Malcolm Savidoff [spelling?].

Giacconi:

Right.

Hirsch:

Was there any interaction between you and those groups?

Giacconi:

Not with Savidoff but Fisher was at this meeting. I mean I have to tell you. I worked pretty much on my own except for these people that I mentioned to you, that is [Bruno] Rossi and [George] Clark, until I met these other people. And I read of course the work which was published. But there wasnít — for instance Fisher had published nothing up to a point, and neither had Kupperian [unintelligible word(s)].

Hirsch:

Right.

Giacconi:

But I then met them at this meeting. Thatís why I keep coming back, because that was the earliest date in which I met all these other guys. And I did meet Fisher there. Now what he was interested in was he worked [unintelligible word(s)] some work which had been going on. I donít remember now the reference, but there had been work going on from people at the AEC. They were I believe in connection with Vela.

Hirsch:

Right.

Giacconi:

And they were computing possible fluxes from stars in X-rays. And however, all stars for them were at the medium [correct word? median?] degree. And then I think that thatís what Fisher ĎWas going to look for, and that created tremendous confusion because right after we found the Sco [correct word?; SCO?], he was talking about these 1-sigma goals [correct 3 words?] of many, many sources — 1-sigma peak in the sky which he was trying to associate with stars, and of course they were just noise. But he confused the idea very much at that point at the time. And then after that they abandoned whatever it was that they were doing at that time and then got into the mainstream with some of the controlled SES [spelling?] scan rockets and things like that.

Hirsch:

I see. Now this Project Vela, the Defense Department and AEC satellite. You had no involvement with that?

Giacconi:

[laughs] I got involved because the company was trying to do something in the field, you know, do some physics. And [laughs] they gave me the problem of detecting microsecond pulsars from stars, okay? Because I wasnít cleared. I had an interim confidential clearance at that time. And so I came up with a design which had X-ray detectors, [unintelligible word] in a certain way such that you could find position with one satellite. And [laughs] I went to describe this to Dr. Foster, who was the man in charge of, Director of Research for the Air Force, and Al Sharp [correct name?] was these days a scientific advisor at that time. And we had a long discussion and in which I was challenging the concepts that they were following. And they didnít like my attitude too much. But in any case, so they suggested that maybe it was a good idea but we should give it to Los Alamos. They never did implement it because they decided to go proceed with the atomic flight [correct word?] stuff. It was a mistake. I was right, in retrospect [laughs]. We would know the burst sources. We would know where the burst sources come from now if we had followed that approach. But I was unknown and they — it was more of a lark. I mean I never did get with — I went and I got a trip out to Los Alamos in which I explained to them my ideas, but they did not [unintelligible word(s)] at all.

Hirsch:

I see.

Giacconi:

So thatís it. But I mean there is no, nothing else that I — I had nothing to do with those fellows.

Hirsch:

I see. Because you mentioned at the beginning that when you began work with [unintelligible word ] —

Giacconi:

Yeah. This is only [correct word? already?] summarized on my — I do not remember the name of those two authors which worked, that worked out these corona X-rays. It is in the X-ray astronomy book. I think that I quote them in fact.

Hirsch:

Right.

Giacconi:

But I think that in a way I was just surmising that the [unintelligible word(s)] A-Z and I think that their work was to estimate possible background for the Vela enterprise. But I didnít, you know Vela didnít have anything to — had no relationship to anything else, no one thought. I think that, I mean if I look in retrospect it seems to me that you know we were working away there for, oh, since Ď59, and we had the first, we had a launch, it failed, and then we had another launch in Ď62 and then in September Ď62 we announced this. And then in April already NRL was up with a very good instrument.

Hirsch:

Right.

Giacconi:

And I think that this is clear that they were working along a, you know, parallel line. We were up a little bit earlier and we were lucky, but this seemed to be the group that clearly was doing serious work in the area. I donít think Kupperian really was that involved. In fact he never did anything. And I donít think Fisher was on the right track either. But obviously NRL was.

Hirsch:

Right. Well, Kupperian then went to develop more time with ultraviolet astronomy.

Giacconi:

Right, right, right, right.

Hirsch:

Can you tell me what happened to that first rocket shot in October Ď61?

Giacconi:

Oh, it blew up in — and it was [unintelligible word] that it blew up. It went up a little and then blew up.

Hirsch:

Was that, did that have the same experiment that you flew in June Ď62?

Giacconi:

No. No, it had some — it had a 1 square centimeter detector, and this was a side window counter, and it did have large field of view and it did have an anticoincidence shield. Okay? That was, there is large field of view I think and an anticoincidence shield were the two most significant changes with respect to the previous flights, you see, because NRL had been flying with 3 degree [unintelligible word] up at every needle. And that was fine if you want to locate something very precise, but if you want to generally scan for something then you want to increase the time on target that you have available. So you increase the field of view as much as you can and then you give up positional accuracy, at the beginning anyway. And then the anticoincidence, that came straight from the fact that most of the people who were involved, including myself, [unintelligible phrase] ray particle, [unintelligible word; elementary?] particle, so we were very familiar with that kind of [unintelligible word]. And that was powerful. I mean that usually [unintelligible word; means?] opening the angle and putting anticoincidence might have increased the [unintelligible word] by a factor, I donít know, 20, something like that. And then in the second — But that, that blew up, and then the second flight we had was the same thing, the same process, but by then we had developed our own counters with mica [correct word?] windows and they were larger; they were 10 square centimeters, so it had another 5 to 10.

Hirsch:

I see. Let me ask you about the chronology of the proposals that you made. Who did you first go to, to try and get funding for your, for shooting the detectors up on Aerobee rockets or any rockets?

Giacconi:

Well, we went to NASA first and we met with Nancy Roman and John Lindsay. And they and we proposed to them two things. We proposed to carry out the remains [correct word?] of development for telescopes, which had applications both for the Sun and stars.

Hirsch:

Right.

Giacconi:

And that they were encouraging about. And then we proposed to them that we go and search for stars, and that they were not encouraging about. Then Bruno Rossi could not — so then in fact that, the telescope for the elements had [correct word? how it?] started actually, but we still didnít have any funds for the rest of it. [Unintelligible word(s)] for looking for stars, for the Aerobee [unintelligible word] — I mean for any rocket. So Bruno suggested that since they had some data on solar waves showing that there was low-energy protons and presumably electrons — although those had not been measured — in interstellar, uh, in the solar, uh, even in the [unintelligible word(s)] — that maybe these electrons giving us their [unintelligible word] would produce enough X-rays to be detectable. And we made several calculations about it, and it turned out that this could be solved as hopeless. In fact if the fluxes which were then [unintelligible word] to exist in the solar wind had been white [correct word? wide?] — which they turned out not to be by 3 orders of magnitude — then the Moon will have been really very bright. So then there was some work that was going on that the company was doing in the classified area, the Defense area, with the Air Force in its research laboratory. And so somebody at the company, I donít remember who, put Bruno and me in touch with somebody there who was interested in starting to move. And so we wrote, at that moment we wrote two proposals. We tried again with NASA. We wrote two proposals: one to the Air Force and one to NASA. And the one to NASA didnít mention the Moon, and the one to the Air Force did mention the Moon — there were actually two different pages in it — and trying to get support wherever we, frankly wherever we could. And they both mentioned detection of stars and Crab nebula and the magnetic A star and on and on and on, and the one of the Air Force also mentioned the Moon because that was the only thing for which they could justify you know having emission, because this was the Moon [unintelligible phrase]. They had as a mission to do something with respect to the Moon. So then he decided to fund us and NASA didnít. In fact NASA didnít fund us until after the third shot. The first was [unintelligible word] and then the second one of the Air Force. There were four shots of the Air Force. The first failed and then the second was June, October, June or July, and so there were four. And then after that the Air Force said that they absolutely didnít want to go on because it had nothing to do with the Moon. And [laughs] so we went to Nancy Roman again, and by this time of course there was our [unintelligible word; world?] work, then there was a contribution from NRL, and so there was — Now, you should know that there is a candidate for a Ph.D. thesis in Dublin —

Hirsch:

Right.

Giacconi:

— who has been working on this.

Hirsch:

Do you mean Edinburgh?

Giacconi:

Itís Edinburgh? Right.

Hirsch:

Collin Dean [spelling?].

Giacconi:

Right.

Hirsch:

Yes.

Giacconi:

And the reason why I mention this is because he has come to see me and many others, all right? And one of the points that he was not sure about that he was quite insistent that I tell him, you know that I go through and try to find the documents, and I did. [Unintelligible word] was this question of whether we had gone to NASA, specifically to Nancy Roman, asking her support for lunar X-ray research. Because thatís what Nancy Roman had told him.

Hirsch

Right.

Giacconi:

And that actually does conform to the truth. We never did. In fact I was deliberately trying to keep the two things separate, and so that we only proposed to the Air Force that we should look at the Moon because thatís what they you know could support.

Hirsch:

Right.

Giacconi:

But we never did discuss [the] Moon with NASA. And I guess Nancy tried to look good in retrospect I mean, but I donít know what the problem is. But in any case, I pulled out the documents — okay?

Hirsch:

Yes.

Giacconi:

That showed the proposal. And, and you know there is even the double pages and so forth, and so we put copies [unintelligible phrase].

Hirsch:

I see. Because Nancy Roman told me the same thing as she told Collin.

Giacconi:

Right. But that does not correspond to — that is not correct. And that is, to the best of my recollection and on the basis on what I have, you know the documents that I have in my hand that does not jibe.

Hirsch:

May I ask you, do you still have those documents on hand?

Giacconi:

Yes.

Hirsch:

Would it be possible to get a copy of them?

Giacconi:

Mm-hm [affirmative]. Mm-hm [affirmative].

Hirsch:

Because Iím trying to look —

Giacconi:

Yes. It means getting Xeroxes, okay? Because I, you know —

Hirsch:

Pardon me?

Giacconi:

Iíve got one or two. This is like — I donít have copies I can just ship around. I will have to make Xeroxes and send them to you.

Hirsch:

Uh-huh. Well that would be fine, yes.

Giacconi:

Fine.

Hirsch:

Because I have been trying to look through the files here at NASA to find your proposals and her comments, and thatís impossible. I canít find anything.

Giacconi:

Right. In fact itís not in the form of a proposal. If I — what I have is technical notes. I mean it wasnít all that you know formalized, and the technical notes describe more or less what we had in mind. I mean you know the general framework. And then there was a lot of oral [correct word?] communication. There was no — I donít think you would find a formal proposal even for the work for which we did get funded. It didnít work that way at that time, thank God. Good times.

Hirsch:

Yeah.

Giacconi:

Okay. But I must say I, you know, in — Let me just say, I donít understand why she should have that recollection which I believe to be incorrect. On the other hand, it is also true that when, that I do feel great gratitude to Dr. Roman for the following reason, that after the support of the Air Force ceased, well I really was at the mercy of NASA. So I worked very hard. I decided NASA was a very serious agency, and in order to present myself to NASA and have some say and some getting support that I should come there with a real long-range program [unintelligible phrase], okay? And we were just trying to get one lousy rocket, but in any case I described a program X [correct word?] years long that went from this one rocket that I was trying to fly through a sos-A [correct word?] type — and it is called X-ray source [correct word?; spore? score?] in the proposal. OEO [correct word?] partial flight, OEO full flight, a 50-foot X-ray focusing off the telescope and you know, and all of these kinds of things I presented to Dr. Roman. This was September Ď63, where the only sources known were [unintelligible word] lab and so forth. And she not only you know generally [correct word?] supported the rocket, but she encouraged me to make a more [unintelligible word; better?] proposal. It was a 3-page proposal. You know, we went in decreasing order of, in decreasing detail as we went on and on toward the future, but for instance the X-ray source was described in three pages. And she encouraged me at that meeting to actually go on and present a more formal proposal, which I did, and then it got approved or reviewed and approved that spring, the following spring, the spring of Ď64. So I owe her, you know I always felt I owe her a very great debt of gratitude for this, because ultimately you know [unintelligible word] was very successful. But I donít think she was terribly encouraging in the beginning, although for some reason she feels better. I donít know. Anyway, maybe it is just that she remembers it wrong. I donít remember it like that at all.

Hirsch:

I see. You say that NASA was — you realized after a while that NASA was a serious organization. Did you not think that it was very serious in its early days?

Giacconi:

Oh no. I mean I was saying that I was scared of NASA. I mean all of this — First of all as soon as we approached these people they said no, while the Air Force seemed to be you know more responsive. And in fact I think that this is [unintelligible word] it wasnít generally true that when there were different sources of funding I think you know he looked at antigravity machines [unintelligible word]. Well, so the first approach was kind of discouraging.

Hirsch:

Right.

Giacconi:

Although Lindsay was the one that encouraged us to proceed. I mean we did start developing the X-ray telescopes which ultimately got into the ACM mirrors [correct word?] and then EOB now.

Hirsch:

Right.

Giacconi:

So that was fine. And Nancy was kind of, you know, not — didnít inspire us a great deal [correct 2 words?], didnít warm you up any, but it — so I was trying to have all my ducks straightened out before I went in again, not to be rejected. Because obviously there was no other way, once the Air Force lost interest because they realized there was nothing to do with the Moon.

Hirsch:

Right.

Giacconi:

Then there was no other way to go on except through NASA. So it was very important. And well, I mean there were a lot of good ideas in this proposal and they took us seriously. Itís not that I thought that they were not serious before; I thought they were even too serious and too tough. I mean they wouldnít give you a chance.

Hirsch:

I see.

Giacconi:

There was a problem — all right? — that I was working from a private corporation.

Hirsch:

Right.

Giacconi:

And I felt that, notwithstanding the fact that Bruno was a consultant that really the burden of proof was on us. At least that was the impression I got.

Hirsch:

Let me see.

Giacconi:

I didnít get the impression that they were anxious to support us. Let me put it that way. At all.

Hirsch:

They were not?

Giacconi:

No.

Hirsch:

I see.

Giacconi:

As a matter of fact it was rather discouraging.

Hirsch:

Yes. I can imagine, after the first time. Yeah. Tell me, what predictions were there predictions were there? You mentioned some, but do you have any more specific references to the predictions of —?

Giacconi:

Yeah. Those are contained in those documents which I can send you. There is, you know, something like, ďI believe weíll find numbers like 103 counts [correct word?] per square centimeter per second from Sirius [correct word?] say. Then you will find some vaguer number from Crab.Ē Then some speculation about magnetic A stars.

Hirsch:

Right.

Giacconi:

I mean remember; there were no pulsars now, okay?

Hirsch:

Right.

Giacconi:

So it was pretty tricky. Mechanism we understood already. I mean [unintelligible phrase], magnetic [unintelligible word] and central emission. This mechanism, you know the mechanisms havenít changed. I mean the basic physics hasnít changed. In fact there would be no objects in which these conditions would occur.

Hirsch:

I see. But the predictions from the Moon for getting the X-ray fluorescence off the Moon.

Giacconi:

Yeah.

Hirsch:

Which predictions were those that you mentioned?

Giacconi:

Those gave you more, gave you about a count [unintelligible word(s)) per second. Thatís why it made it so attractive, because it seemed like a — I mean the point of view was that we had to develop these instruments quite a bit before we starting seeing stars, and it would have been convenient — Well, the Sun of course you could see but that was too bright.

Hirsch:

Right.

Giacconi:

It would have been convenient to see something underneath the median [correct word? media?] level so that you would have a chance to keep working and develop better instrumentation.

Hirsch:

Right.

Giacconi:

By the way, just at that time the [unintelligible phrase ending with T-60?] we applied for a patent on this X-ray telescope. Or, you know, it doesnít mean anything because ultimately it was assigned to NASA and so forth. The reason why I mention it is because in the patent, in the specification what we would do with it, there was the study of the Crab nebula, the study of the interstellar medium, and on and on and on, all right? I mean, so I am stressing this because from time to time people have liked to think that you know we were just moving along without knowing what we were doing and then all of a sudden you find a few things and —

Hirsch:

Right.

Giacconi:

Particularly NASA has never understood all of the greater work that had gone on behind it and Bruno [Rossi] and George Clark and myself and actually letís see, there was this, plasma physicist at MIT, Sven Olber [spelling? Stan Albright?], did an awful lot of work in trying to understand what would come out. And it was questions of you know what — I mean you couldnít tell the order magnitude. It was clear that you know something which is a factor of 10 below your prediction, itís nothing from the point of view of nature, but on the other hand it requires an instrument 10 times more sensitive and itís not so easy. So we thought it would take quite a while. We didnít think we would be — we were amazed when we saw SCO. I mean at that level we never suspected there would a source that bright. And in fact you know binary X-ray stars had not been predicted by anybody, and in general the fact that there would be stars which would emit X-rays, for which X-rays would be the prevalent energy loss mechanism, which had been — that nobody had predicted, okay? So that you know the prediction where maybe you can pick up something that would make it brighter than the Sun, the Sun is about 10 27 rhos [correct word?].

Hirsch:

Right.

Giacconi:

And so you could come up you know and say maybe 10 [unintelligible phrase] and you know [unintelligible word] turns out to be more logarithms [correct word?] to speculate about. On the other hand these things are 10 36 rhos. So thatís why they were so bright. I mean and thatís why [they] were unexpectedly bright, because nobody had anticipated there would be things that are 6 orders of magnitude brighter. That made it easier, I mean that, instead of waiting for years and perfecting the instrument and seeing a little thing and then better and better, all of a sudden you were [unintelligible phrase]. Then it becomes just a question of improving instrumentation, but you were doing good work as you went along, which was much — We would have settled for a much longer development time than what it actually turned out to be, and nature surprised us.

Hirsch:

Right.

Giacconi:

That was nice.

Hirsch:

So that was one of the big things.

Giacconi:

Itís not so much the fact that there should be actually emission, but the fact that there should be at this luminosity. I mean you know 10 36 rhos, this is about the brightest stars in the galaxy.

Hirsch:

Right.

Giacconi:

So this was not at all suspected. And of course we didnít understand anything about the mechanism. There was no particular prediction that — but this was before we started seeing it, but there was no prediction about binary — The first binary I thought [correct word?] it was in 1964 or something like that, but certainly not before we started that.

Hirsch:

Oh I see. So this was the great excitement, finding such a super —

Giacconi:

The real excitement was finding something that was so luminous and without any apparent explanation — I mean not connected with supernova and no understanding of the energy source, no understanding of the mechanisms of production. I mean it was a big step forward with the world [correct word?] really has been that in one fell swoop by seeing the binary nature, but in fact indirectly being [unintelligible phrase] you could determine the fact that you were talking about a binary system by observing the fact that the processions [correct word?] speed up rather than slow down. You know that the energy source is not pulsar emission because pulsars would be emitting radiation at the expense of [unintelligible phrase; ends with gravity of rotation?]. And [unintelligible word] instead you are acquiring energy, so there is something wrong. Thatís not the source energy source. And then finally [unintelligible word emission?] which has now become, you know, become the explanation of — every source that we find is [unintelligible phrase] has become the main, the main explanation for what is going on. So itís not really so much the fact that X-rays were emitted. At some level thatís true, certainly [unintelligible word(s)] become true, but actually the fact that there were extraordinary objects. And right now, itís only now that we are beginning to see the stellar corona, normal stellar corona, [unintelligible phrase] things like that. But thatís 4 orders of magnitude below scope [correct word?; SCO?]. And actually [correct word?; afterwards?] we would have had to go and [unintelligible phrase] 4 orders of magnitude until we started seeing anything, which would have been very painful.

Hirsch:

Right.

Giacconi:

Okay. I will send you, if you, you know, what do you say, end this conversation, if you will give me your address, your name and address, I can send you this stuff [unintelligible phrase].

Hirsch:

Okay. Would you like that now?

Giacconi:

Yes, please.

Hirsch:

Okay. My name is again Richard Hirsh, H-i-r-s-h.

Giacconi:

H-i-r-s-h.

Hirsch:

Right. And Iím at NASA Headquarters History Office

Giacconi:

Yeah.

Hirsch:

Code ADA-3.

Giacconi:

E-A?

Hirsch:

No, ADA, Albert David Albert.

Giacconi:

Right.

Hirsch:

3. Washington D.C. 20546.

Giacconi:

20546.

Hirsch:

Right.

Giacconi:

Okay. Well, is there anything else? I have another five minutes and then I have got to [unintelligible word].

Hirsch:

Okay. Well let me ask quickly, yes. I notice just by looking at the people who were involved in X-ray astronomy that the scientists were not traditional astronomers who got involved in X-ray astronomy or actually any other space science.

Giacconi:

Yep.

Hirsch:

Do you have any explanation for why this is so?

Giacconi:

Yeah. But that is all aposti aurori [correct 2 words?], okay?

Hirsch:

Okay.

Giacconi:

I mean, I have come, particularly by getting to know all the astronomers I have come to the view that there has been a whole generation of astronomers which has been brought up in which the bright people were observers using existing facilities, and the name of the game was to do great science with the existing facilities. And I think that there is a lot of optical astronomers who are very different [correct word?; diffident?] about building instrumentation or trying you know some of these experiments like we are doing in space science. On the other hand physicists by tradition have been trained — I mean at least I had — I was an experimental physicist, I started off in cosmic rays, starting building up my own cloud chamber, you know, to observe. So they have been traditionally much more inclined to look at a problem, find out if this tradition existed or not, and then build instrumentation if required and then carrying out the experiments. So I think that at-least at the beginning of — well, itís interesting that for instance radio astronomy didnít get started by astronomers, that gamma-ray astronomy didnít get started by astronomers, and X-ray stars didnít either. So there is a little departure from you know traditional or conventional techniques, and not very great expertise even in the astronomy community itself.

Hirsch:

Right.

Giacconi:

And also there is a certain failure of understanding I think. I think, for instance I feel that NASA was very slow and [unintelligible word]. If you are thinking of recording that, just take it out. NASA, I feel —

Hirsch:

Donít worry. Whatever you say about NASA is fine. Really I donít care.

Giacconi:

Okay. Well, I think that when the space program had to be outlined or the very beginning or something, when one talks about astronomy, well the only thing one could think of was optical or an extension to that regional wavelength that could not be done from the ground, and most of the people, to most of the people that was UV. Well, then substantial commitments were made for UV astronomy through the OEO program. And for some reason or other NASA was very slow in making room for new regions of the wavelength. For instance I have still not understood why X-ray telescopes — okay? — could not be flown on OEO except as little things on the bridges that, you know, that they [unintelligible phrase] which is, itís a toy.

Hirsch:

Right.

Giacconi:

And in fact it is due to this reason that X-ray telescopes were developed for solar physics — simply because Nancy Roman didnít care for them for stellar work. And on the other hand John Lindsay was quite in favor of using them to get pictures of the Sun. So in order to develop telescopes at all that was the way one could do it. And [laughs] thatís the way they got developed. And, but I think itís not really the people so much as a certain inertia in the — a programmatic inertia. You are all set; you have made commitments for a long time and Vietnam [correct word?] [Unintelligible word(s)] scientists or physicists telling you that you should do something else, and itís not clear if they are right or not. But it is clear it takes some time to come around and make a commitment in proceeding. In fact itís amazing that the X-ray SCO [correct word?] got approved in Ď64. And itís too bad that then it took three years to figure out the management scheme.

Hirsch:

Yeah.

Giacconi:

But otherwise we could have had the world [correct word?] in I donít know, Ď66, Ď67 maybe. We would have pushed even faster maybe. Thatís not so good. Maybe it gave us time to digest. Okay, but I mean there is that little bit of — I think there has been certain slowness, and I think for instance this is happening in gamma-ray work that is going on.

Hirsch:

Right now?

Giacconi:

Yeah. Itís taking a little time. I mean you know after all in Ď69, then [unintelligible word(s)] got into the open literature, and a mission is being started now about, of graduate courses [correct 2 words?]. Six years? Thatís a long time. So there is certain inertia to the system, a certain — Maybe shuttle will change that.

Hirsch:

I see. Hmm. Okay. Well. I see you are due at a meeting.

Giacconi:

Yeah.