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Oral History Transcript — Dr. Frank Low

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Interview with Dr. Frank Low
By Patrick McCray
At Tucson, Arizona
May 4, 2000

Transcript

Session I | Session II

Low:

...for the simple reason that I knew what it was like before that. None of these young people coming into astronomy —

McCray:

Have done [inaudible word]?

Low:

— have been educated. They come into the field with that experience. Basically the telescope is growing at 500 watts per square meter approximately, and thereís a lot of square meters, and so this room is like an incinerator as far as the power level that is trapped inside. If you add up the total amount of power that is bouncing around inside this room, itís just huge. Compare that to the amount of power that you have when you turn on all the lights.

McCray:

Sure.

Low:

Which is a few — well, itís not even hundreds of watts, but even though the light bulbs are rated in watts, they are only 5 or 6 percent efficient. So the total amount of power level is just many orders of magnitude different — and thereís no switch.

McCray:

You canít turn it off.

Low:

You canít flick it on and off. And so that carries over in quite a number of ways into how people approach their observations. We tried nationally to design and build a large fair, well actually we ended up trying to build a fair. We had planned only to build one, but thatís another little piece of history. And so the net result of it is, is that Iím afraid I will be completely retired — Iím not completely retired; I still have several research projects going. Iím just not drawing a salary from the university. And so by the time I retire I was hoping that we would have at least one large ground-based telescope, a very good site, if not dedicated solely at least optimized for its infrared performance — to deal with all these issues that occur in the thermal infrared. Now although they wouldnít appreciate my saying it — and I wonít say it publicly, because that just makes their task more difficult — the Gemini Project, which is the U.S. part of Gemini — itís an international project, so there are a number of partners, chiefly the Brits — have attempted, I would say, to do what we had hoped. I say ďweĒ meaning those who understand and really back this project. But unfortunately, for various reasons it looks like they are missing the mark by a pretty wide margin. And there are two of them. They compounded the problem by designing, insisting that they had to build two.

McCray:

One in Hawaii and one in Chile.

Low:

Yeah. So they doubled their problem as it were. And that I consider as one of the big disappointments, because the resources were there, the ideas were there, the knowledge of how to do it was all in place.

McCray:

Where do you think it fell short?

Low:

It all comes back I think to this sociological issue. Relatively few people have been into the infrared astronomy game, because itís different and they prefer to look at it as one of those areas in which you can do certain sort of things but itís all part of the larger picture. And thereís nothing intellectually wrong with that approach, by the way. I understand it and participate in it myself. But I still view it differently, because in the other spectral domains, starting at whichever end you want to start at — low radio frequencies working up to the end [correct word?] frequency — there is this huge band that goes from — Iíll switch to wavelength, because itís easier to remember wavelengths than a whole bunch of frequencies.

McCray:

Sure.

Low:

At a few millimeters, itís sort of a transition from microwave technology to infrared technology, so that somewhat dictates where the transition starts. Then you go then from a few millimeters to a few microns — a factor of a thousand in wavelength, a huge band in terms of bandwidth, spectral bandwidth. And then of course once you get to doing micron by tradition you are sort of CCDs [correct word?] work, I [correct word?] doesnít work, but photographic film does. And so 1 micron is a handy way point that most people go by. If you havenít decided at the outset that whatever the difficulty of doing infrared measurements on the ground really is, itís still worth it. In other words, itís something you would push to the limit of what you knew how to do with your resources that you have. And weíre still not doing that. The MMT, no longer an MMT, itís now a single mirror, and it sure enough has all the problems of large single-mirror telescopes. And so itís no longer going to be as well optimized, in my opinion, as its predecessor was for the thermal infrared.

McCray:

With the six mirrors.

Low:

Yes, with the six-mirror configuration we were able to optimize each one of them, and thatís not whatís happening with the single mirror. And of course itís, I would say, being somewhat dominated by its competition that now exists in optical astronomy, because all the major observatories of the world — the Japanese, the European, the Czech and the rest of us, weíre all competing.

McCray:

Right.

Low:

And these are all multi-spectral compromises, every one of these telescopes, including the Gemini. So here is where it sort of all began. Here at Cal Tech is where ground-based infrared astronomy really proved itself. Many of the early discoveries were achieved. Now Gary Norderbower [spelling?], I donít know if you [inaudible word] Gary.

McCray:

I was at Cal Tech — Actually Iím going to stop this just for a second. [recorder turned off, then back on...]

Low:

That was my other worry, how we were going to get from there to here.

McCray:

Sure.

Low:

So we had better stick to your plan.

McCray:

Okay. You left to go to Green Bank in Ď62.

Low:

Well, the bolometer — yeah, something like that.

McCray:

Yeah.

Low:

Here, Ď64, August of Ď64, I remember it almost to the day, but certainly the week, by ďitĒ I mean my arrival with a car full of our stuff with a wife and three kids — two kids. The third one was born in West Virginia. Coming in from West Virginia into Tucson, that was the summer of Ď64. So we were in — Iím working backwards from that day.

McCray:

Sure.

Low:

Which Iím quite certain of. So summer of Ď64 was our arrival here in Tucson, and we were two and a half years almost exactly in Green Bank. Prior to that was at Texas Instruments in Dallas, which was my first job out of graduate school, there in the Central Research Lab.

McCray:

Okay. Thatís pretty much where we ended [correct word?].

Low:

Thatís where the bolometer was developed and so by the time I gave up that job, which was low-temperature physics. No astronomy. Never had an astronomy course, just physics courses, and astronomy wasnít, back in the fifties, a major part of physics. It was almost like a separate field. But Iím happy to say that that barrier has been demolished over those decades. Iíd say today most places they do real astronomy itís a branch of physics — and should be looked at as that.

McCray:

Well, how did you end up in Tucson or Green Bank? How did you make that transition?

Low:

Well, the motivation was that the bolometer clearly worked. It had proven that in the laboratory. Several — not one, but more than one astronomer when they heard about it became excited about it, because there was this huge void between this gap, which was virtually a void between the optical and the radio astronomy. And the radio astronomy was growing rapidly and making discoveries every day and optical astronomy was in great foment, I would call it. Switching from the eye in the photographic plate electronics of all things.

McCray:

Sure.

Low:

Thatís what was happening. But there wasnít much of anything that had happened or was possible in this infrared band.

McCray:

Was anyone doing infrared work at this time? Who were the astronomers who were working on infrared?

Low:

Yes. Iíll acquaint you with that very shortly, because he played a key role in it. I say ďheĒ because there was really only one at that time. So here I was. Iíll set that picture as clearly as I can for you. I was working away at low-temperature physics, superconductivity, thin-film superconductivity. Had written papers and started projects in that area at Texas Instruments. Purely fundamental research. No application in mind. One of the possible applications, however, was for [correct word?] was a detector — a bolometric, a bolometer, a superconducting bolometer. So I did those experiments. I redid what had already been done in that area and proved to my satisfaction that it was never going to lead to a practical device. And so I then looked around, and because I was working for a semiconductor company. Texas Instruments is where the silicon transistor was started.

McCray:

Yes.

Low:

And so I had all around me, and all the labs that I could walk into, people who were doing one thing or another in silicon and germanium — because germanium was still a big thing at that point. And so the first bolometer that I made was germanium, because it was easier.

McCray:

Okay.

Low:

I considered silicon. Silicon was a tougher way to go.

McCray:

Easier how?

Low:

Because of the contact technology. All the technical aspects. And thatís why the germanium transistor preceded the silicon transistor, but now you can hardly find a germanium transistor. Theyíre all silicon.

McCray:

Sure. Right.

Low:

And thatís an advance in technology and beside the issue here, because subsequently we started making bolometers from silicon and continued with germanium. There are advantages to both. So I wrote, and it took it a year before it came out in the journal, not of applied optics, the journal of the Optical Society of America. The Journal of Applied Optics didnít exist in those days.

McCray:

I have a copy of it back in my files.

Low:

And that paper was, amazingly, read by quite a number of astronomers, three of whom came into play very quickly after the paper was published. One was a fellow by the name of Carl Sagan. I think youíve heard of him.

McCray:

Heard of him, yes.

Low:

And unfortunately his health didnít hold up all that well either. He had been just a year older, maybe a year — no, Iím not sure he was older, actually. He might have been a year younger.

McCray:

He was younger. Yeah.

Low:

Right. Because I was already out, and he was still a graduate student.

McCray:

He was at Cornell I think, wasnít he? Or he ended up in Cornell.

Low:

It was Berkeley. Iím pretty certain of that. And they wanted to do an experiment, those guys did, and they decided that this bolometer that they had read about was the only way to do it, and they showed up at Texas Instruments and we actually — the very first, these metal Dewars that you now see everywhere in infrared labs was founded on that as product line. They were the first. And so while I was still at TI I got permission to go ahead and build them one, and they flew it. Unfortunately it was more a technical success than scientific success. They were looking at Mars, and Mars didnít turn out the way they had hoped it would. They were literally looking for life on Mars, is what they were doing. [laughs]

McCray:

Right. Yeah.

Low:

So they didnít find any. What they did, is they proved that previous results were incorrect. So it was one of those important negative experiments.

McCray:

Sure.

Low:

So it was a technical success, however. People were really impressed by the fact that you could do things with superfluid liquid helium at these wavelengths.

McCray:

How large was this Dewar?

Low:

I have several of those around — not here. [inaudible phrase] about that big.

McCray:

So about a foot tall.

Low:

A liter.

McCray:

A liter. Okay.

Low:

Mm-hm [affirmative]. Inside a liter, and then you put the other stuff in there, so the outer vacuum vessel is about a foot by about seven inches. Thatís still a very popular size today. So there were two inventions there, if you want to call them inventions, but no patents were filed on either one of them. The bolometer is one, thatís the fundamental one, and the all metal research Dewar was the other.

McCray:

Okay.

Low:

Neither existed before that.

McCray:

Iím just curious. Why did —? I mean, you eventually started Infrared Laboratories, and Iím assuming some patents came from that, but those are not [inaudible phrase] patents.

Low:

I am in the process of filing for my first patent right now.

McCray:

Oh. Okay.

Low:

Just in time. But Iím not sure weíre going to get to the modern era if we donít go past this old stuff. This is more fun to try to remember all these seminal details.

McCray:

No, no, itís good.

Low:

Because it humanizes the thing too. Here is this young guy trying to figure out what he wants to do in the research area, and people were coming now to talk to him about the opportunities in astronomy.

McCray:

So who else besides Carl Sagan?

Low:

Another fellow that you may have heard of. His name is Frank Drake [spelling?], of Setty [spelling?] fame now.

McCray:

Mm-hm [affirmative]. Sure.

Low:

Well, Frank was one of the founding radio astronomers at NRAO when it was just getting off the ground and it was located in Green Bank, West Virginia. The only site at that time was there in the hills of West Virginia. Isolation was the theme; they wanted to be as isolated from the east coast population as they could be of the radio interference. And there still is a site there. So Frank showed up. He was much better organized. He knew what he wanted. He wanted me to give up what I was doing and move to Green Bank — which I did. He persuaded me to do that.

McCray:

How did he persuade you?

Low:

Freedom. Carte blanche.

McCray:

Okay. To do what you wanted to do.

Low:

You canít get that ticket anymore. Itís unavailable.

McCray:

Yeah.

Low:

And but there was one other and more important individual, and there I had to seek him out. He, by his character, was not going to seek me out. So we were in the Central Research Lab in North Dallas. Just to the south of us is a college town called Austin, Texas, and he happened to spend a short part of his career there in their fledgling astronomy program at UT. His name is Harold Johnson, H. L. Johnson. His greatest fame was for his origination I would call of the UBVRIJHKL [punctuation?] photometric bands.

McCray:

Designating the —?

Low:

Mm-hm [affirmative], the various wavelength bands. And ďIĒ stands for infrared. Now that wavelength is about .9 microns, the best one can tell, because we donít really have a good idea of how Harold did it. He was not all that good at explaining it to other people. He was very good at telling people what not to do; he was less shall we say eager to tell them what to do or how to do it. But he and I really struck it off, and that was a big deal. It just so turned out that we had a lot of recent graduates. All of us were young. None of there were out of graduate school for more than a few years in those laboratories. They had been set up instantaneously, created out of youth with the invention of the silicon transistor. The profits were so huge, just huge. Incredible profit margins. Make what Bill Gates did decades later look paltry in comparison. On a much smaller scale, but Iím talking about the percentage. Because they had a monopoly and they could charge whatever they wanted. They could charge fifty dollars for one transistor.

McCray:

And the government wasnít breaking them up?

Low:

And nobody ever bothered to break Ďem up. So anyway, they were plowing some of that money back into basic research. And so as soon as it got noised around the Central Research Lab that there was this very interesting new type of bolometer — and I cannot even remember which of my colleagues pointed it out to me, but they said, ďWell, you know thereís this interesting fellow down at Austin who actually is doing something in this area. You ought to go down there and talk to him and see what he thinks.Ē And I did just that. I got down to Austin with his introduction. I mean, he had taken courses from Harold. And so I visited with him and we struck it off right away. When I explained to him, showed him my paper, showed him what Iíd done and what I could do, he was — we started what for us was — what for him was a lifelong collaboration. And but unfortunately he had a bad heart and died before he ever reached sixty. I canít remember exactly what his age was, but he died in his late fifties. And he was in his early fifties when I first met him, so I think it only lasted about ten years, but it was quite fundamental and productive.

McCray:

What was his character like? What was he like as a person?

Low:

Harold was an enigma, because he was really a very nice person, but he had a way of being extremely hard to get along with and people that didnít agree with him, he would have nothing to do with them. So, in any case, his contribution was he came out of the World War II effort knowing about the fledgling experiments that were being done with infrared detectors.

McCray:

Lead sulfide cells?

Low:

Yeah. Lead sulfide specifically. So he pursued lead sulfide and marched steadily through the 1 micron barrier and was actually attempting to do indium antimonide experiments when I first knew him. Indium antimonide. Lead sulfide cut off at 3Ĺ microns. It was very noisy and unstable. And the indium antimonide, when properly made, covered the same wavelength range but it went out to 5 microns.

McCray:

End speed?

Low:

End speed, as it is now called. You got it. And so Harold was on to end speed, but here was this bolometer, and it didnít stop like the other detectors; it didnít go out to some wavelength and stop. It would just go all the way. And thatís what my paper showed, amongst other things, that I had this detector which when properly tooled you could use at any wavelength — 1 micron, 1,000 microns, it didnít make any difference, any fundamental difference.

McCray:

Very versatile. Okay.

Low:

And so he thought geez, you know, thatís the next thing weíve got to do, and now that itís possible weíve got to do it. And so we joined together, designed an instrument, and even before I left TI, just before I left I made a visit to — Harold was at that time the director of astronomy at UT, and McDonald Observatory was a joint project between the University of Texas who owned it and the University of Chicago. Thatís such a terrible history in those days, that Harold had come from the University of Chicago — he and Kuiper [spelling?; first name?] and the losers in that big battle. That was the ďBattle of the BerbagesĒ [spelling?].

McCray:

Iím not familiar with that.

Low:

It was a celebrated chapter, and it led to the destruction of astronomy at that —

McCray:

Could you say something about that, or will that get us too far off track?

Low:

Thatís too — thatís off the course. Letís just pass by. Harold had put it behind him. I think that shaped Harold. I think that experience, being there in that conflagration — the breakup of the group.

McCray:

I didnít realize that Margaret and — this was Margaret and Jeff [spelling?; last name(s)?].

Low:

It was Margaret and Jeff. Jeff was the power part of it, and he and Kuiper had a, shall we say, terminal relationship and split the department right down the middle, and everybody left. So that — they went their separate ways. They burned their bridges and leveled the city and then resurrected themselves in different places. Gerard —

McCray:

Who was director of [inaudible word] at this time? Was it -Ė? Struppe [spelling?; first name?] had left by then, right?

Low:

Yeah. See, this all happened in the years when I was still a graduate student and had nothing to do with astronomy. And it was such a horrible thing that we never talked about it.

McCray:

Okay.

Low:

We just never talked about it.

McCray:

All right. But Kuiper eventually ended up here, though.

Low:

Gerard [spelling?] [Kuiper?] came here and founded the Lunar and Planetary Laboratory. And Harold didnít want to come to here. He was invited to come here and didnít initially want to come here. He chose to go to Texas. But things must have turned sour for him there, because between the time we did the initial experiment at McDonald which was not successful — but we learned all the things that we had to do to make it better — I donít think we, on that first test we did not detect a single celestial object, but we figured out in hours what we were doing wrong.

McCray:

This is using the 82-inch at McDonald?

Low:

This is using the 82-inch at McDonald. And we didnít spend much time doing it, but it was very illuminating to me, because I really decided that if I worked at it I could conquer the problem.

McCray:

What was the problem?

Low:

Well, that 500 watts per square meter.

McCray:

Thermal emission then of the telescope and —?

Low:

Thermal emission of the sky and the telescope and dome and everything in that dome.

McCray:

How did you figure that that was the problem?

Low:

Oh, well I was a physicist and I expected the problem; I just had to go do the, make the first efforts with a sensitive detector. I had something that nobody else had: I had a detector that was a thousand times more sensitive — ultimately 10,000 times more sensitive than anything that had ever been operated at those wavelengths, which are 10-micron.

McCray:

Okay.

Low:

And the peak of the pond [correct word?] curve is in 10 microns. It never gets brighter than that.

McCray:

Thatís the black-body curve.

Low:

The black-body curve. And so the challenge was to do it — Since Harold was already beginning to do it at 5 microns with indium antimonide and having some moderate success, it was clear that it was going to be [inaudible word] a factor of twenty times harder, but if we figured everything out correctly weíd get somewhere. And on the basis of that, I did two things: I moved, I relocated to Green Bank, because there was money to do what I needed to do and support, and I needed to learn astronomy. I needed to go back — I basically needed to go back to school. I needed to have the opportunity to simply get thoroughly educated in the technology as it stood in those days in the science, because I was going to change it. But I really had to understand at least at some level what had been, you know, what was going on, what worked and what didnít work. So that was a good choice, because Green Bank, thereís not a movie theater within —

McCray:

Yeah.

Low:

Thereís nothing there. Even the television reception is terrible. With a lot of effort — which we all did — we had antennas that would suck it in. [laughs] It was just the right degree of isolation. And these cadre of Harvard people who had collected themselves there were willing to put up with the winters, which is very much like northern Maine.

McCray:

In Green Bank. Yeah.

Low:

In Green Bank.

McCray:

...the transition from Texas to a cold —?

Low:

Not really. Edith had been born and raised in northern Ohio.

McCray:

Okay.

Low:

I had gone to Yale.

McCray:

Yeah, I recall that.

Low:

And had been through four years of New Haven.

McCray:

You had also gone to school in D.C., as I recall, St. Albanís.

Low:

Yes, right, St. Albanís. And so it was great. We just simply loved it. You could go out in your backyard and chop down your own Christmas tree and it was already decorated with snow. When youíre at that age itís just a simple challenge. And so we were there two and half years. During that time Harold and I continued to collaborate.

McCray:

He remained at UT?

Low:

Yes. And so — except I had the National Observatory supporting me now, and I didnít have to worry about the fact that you couldnít sell any of this stuff. TI, by the way was, did take that as, the bolometer, as a serious product, and they tried to market it.

McCray:

Were they successful?

Low:

They were completely unsuccessful. And so that plays back into the story, but they sort of abandoned it of their own accord. And it turns out that thatís exactly what was best for Frank [correct word?]. Because if I had stayed there, they would have owned the patent.

McCray:

Sure.

Low:

So they abandoned it, the patent was never issued. A key point. Had there been a patent, I would have never done what I did subsequently, because there was no economic — you know, I would have just been paying royalties to Texas Instruments. And so that was, it had turned out, fortunate. The things that took place — very briefly — at Green Bank, was that they had a committee that listened to my story. I told them how I needed to build a very large millimeter telescope and put it in a very high, dry site so that the transmission of the atmosphere at 1 millimeter, 1.2 millimeters, would be high enough most of the year to permit observations. And some very good physicists where on that panel in those days, and they simply said, ďDo it.Ē I was given carte blanche to go do it. I had to develop the detector, the bolometer and systems, and I had to design this telescope. It was the first telescope I ever designed.

McCray:

Where was it placed?

Low:

Itís right out there on the top of — near the top of Kid [correct word?] Peak.

McCray:

Okay.

Low:

In those days it was called the 36-foot [correct word?].

McCray:

Thatís the 12-meter?

Low:

Itís now called the 12-meter. It was upgraded from 11 meters to 12 meters through the years. So that all started and was well along when I relocated after two and a half years in Green Bank. The site had been chosen — Iím leaping over a lot of things here — Tucson had been chosen, this place right here, and I wanted to put it right there is where I wanted to put it.

McCray:

Thatís up on top of Mt. Lemon [correct name?].

Low:

Not top, but the adjacent. This is Mt. Lemonís peak over here, and this is [inaudible name].

McCray:

[inaudible word]?

Low:

Yes. I would have put it right there.

McCray:

Okay.

Low:

But the director, Dave Heishen [spelling?], wanted it put at a lower altitude at Kid Peak, so it ended up at Kid Peak — which isnít as good a site, but you know you donít win everything. And Iíve talked him into letting me move out there, however, because the telescope was going to be built here. And the U of A was kind enough with my — Oh, by the way, Harold had lost his — Oh, Iíve left the very important thing.

McCray:

Okay.

Low:

Kuiper was keen — very, very keen — on infrared astronomy. He didnít know how to do it particularly, but he knew that Harold Johnson knew, so he recruited Harold. He talked Harold into leaving, giving up his position at the University of Texas and coming to the U of A. And that influenced me, because we had ended up at Kid Peak. There was no — as I remember that decision, I looked everywhere. I looked at the highest parts of the Rockies, I looked up in, there are some interesting mountains up in Nevada and Wyoming area which are high enough at least very cold — because you need it to be cold and dry and high.

McCray:

Low humidity and high.

Low:

But when I studied the whole thing thoroughly, I realized that this area, southern Arizona, was very good from a — Because the — I donít want to get into it, but it was a good decision on my part in hindsight, to locate here. And —

McCray:

What types of science projects were Kuiper and Johnson interested in?

Low:

It was very clear. Johnsonís fixation was entirely stars, nearby stars, and he had his own ideas about interstellar matter. Stars and interstellar matter were his thing. Kuiper was planets, planets, planets. Okay?

McCray:

Right.

Low:

Planetary sciences. And I didnít have any such biases. I thought galaxies might be interesting, if we could detect them. At that point that was way beyond what was thought to be possible. But we did do the key experiment and it did succeed. In the summer of Ď64 I had — I hope Iíve got this right. Yes. I had come here in April, and Kuiper had built a little 21-inch telescope up here at this site. This location weíre looking at here is right up there.

McCray:

Okay. Up on Mt. Bigelow [correct word?].

Low:

Yes. And he had built the first telescope up there, 21 inches. Terrible little telescope. Just terrible. Because people keep getting hurt by it. It was one of these German — I think itís called the German mount, that has the telescope on one side and the balance weight on the other.

McCray:

Yeah. Yeah.

Low:

And you know, youíre working in the dark and this big weight hits you in the head. It didnít happen to me, but I — It was a very bad telescope. But I was given the use of it to prove — Harold wanted me to prove that the changes that we had made worked. So I came out here on my own in April of Ď64, went up the mountain, lived down here — because there were no facilities of any kind up there.

McCray:

Sure.

Low:

Nothing but bears running around in those days. I mean real bears. And I didnít know how dangerous they were in those days. I wouldnít fool with those things at all, knowing what they do to people — and usually at night. They are much more dangerous at night than they are in daytime.

McCray:

When they come snooping around for food?

Low:

Theyíre kind of shy in the daytime. But yeah, theyíre after food, and they have this incredible sense of smell, and they can just virtually see in the dark, so they are really dangerous animals. You can hear them banging around out there. I didnít know enough about it to be scared, but I was rather novel actually. But so the tests were successful. I detected with the 21-inch telescope the first — I believe the first — detection of stars other than the Sun. And didnít publish it, but I did follow up, because Harold was still the director at that point. He was in transition and he still had — he allocated a couple of weeks, which is a big block of time, on the 82-inch. Of course he did it in July, which is known to be the worst time of the year.

McCray:

Hot and humid at the time.

Low:

Yeah. And I didnít know enough about it to know that I was being assigned two weeks to go watch the clouds, the lightning beat down on the top of the mountain. But as it turned out there were, out of the two weeks, one and a half nights that were amazingly good, and on those two — The first — The bad night was the first night, and we got everything working. So if you really want to say when it occurred, it was the first night that we got it all working, and it was just astounding.

McCray:

When you say ďgot it all working,Ē whatís all?

Low:

Okay. Bolometer and a way of modulating the star such that the star can be detected and measured against this huge amount of infrared background. You have to detect something to part in 100,000.

McCray:

So were you subtracting the sky background?

Low:

Yes. I had figured out a way to do that.

McCray:

And how was that? Were you re-wobbling the secondary by that time?

Low:

No, that came later. The first — you have to crawl before you run, and so the first success was with a mirror that jumped. It used a mechanical cam like what opens the valves in an engine to move this mirror about a millimeter. The travel you need is about a millimeter, and you need to do it at five or ten times a second. So it has to be a very small mirror. And so hereís the Dewar, and you look out the side of the Dewar. The telescope is up here looking at the zenith, and you put this little mirror, and the beam goes straight up to the telescope and out to the universe. And if you just shift it back and forth, the bolometer is looking at a mirror whose distance is moving slightly.

McCray:

Okay.

Low:

Itís the best, cleanest geometry you can use. It doesnít work very well.

McCray:

Why?

Low:

Reasons are hard to understand in detail, but thatís called a focal plane chopper. There are several ways of doing it. That one was the method that worked the best. We tried them all, actually.

McCray:

Five or ten times a second, was it noisy?

Low:

If you tried to go slower, then the low frequency meanderings would just kill you. So youíve got to modulate faster than the low frequency changes are occurring due to Ė I think the biggest source of noise is invisible clouds that are changing the opacity of the path through the atmosphere. And you donít see them directly, but they produce these undulations at low frequencies. And the more turbulence in the atmosphere — it can be very clear and very cold but still quite turbulent. You know that from flying along at 30,000 feet and you start, the plane starts jumping up and down. You look around, thereís no clouds anywhere; just clear air turbulence. And on those nights it really gets active, the sky. And so dealing with what was called sky noise became one of my tasks. You minimize all the extra. You design the instrument so that you just use good engineering techniques to minimize the amount of photons. You donít want any more photons than are necessary from the atmosphere and then the two mirrors.

McCray:

Okay.

Low:

And then you start working on the telescope to minimize the telescope contribution. So you come closer and closer to the sky — which you can do nothing about, other than go to the very best site, and Mt. Akaya [correct name?; spelling?] certainly is one of the very best sites. But so will Mt. Graham [spelling?] be. Mt. Graham will be an excellent site. This one, the mountain down here with the — Mt. Hawkins [spelling?], where the NNT [spelling?] resides, is also an extraordinary site. We had sites. We werenít lacking for sites. And weíve used them pretty well I think.

McCray:

The idea for the MM2 [spelling?] came about roughly about this point too, didnít it?

Low:

Well, that was later. Iíve got to run through a couple of things. Harold had designed and built a better telescope — 28 inches, however — and then he built a bunch of very poor telescopes at 60 inches. There are a lot of — several of those built.

McCray:

When you say ďpoor,Ē why? Just poor for infrared work or —?

Low:

Yeah, just poor. They were all designed for infrared. I mean, once we had done this very successful run at McDonald — and thereís a paper in which we had measured a dozen stars and measured them quite accurately. Now unbeknownst to us at the very same time, a group of — not, Gary wasnít in that group, but he was closely related to it. He was I guess still a postdoc somewhere. Iím not quite sure what Gary was doing, but these other guys at Cal Tech got a hold of a different sort of 10-micron detector. Not a bolometer, but a competing device, and it worked at 10 microns and they had the 200-inch. And so we got, Harold and I got the 28-inch going at the site up here in the Catalinas [spelling?], and we were competing with those guys with the 200-inch, and that was amazing. Because — I had better choose my words carefully — let me just say we were extraordinarily competitive. And the way we went about it was sufficiently different from the way they had gone about it out on the 200-inch. Whereas they got rather — they were much more affected by the local environment than we were.

McCray:

You said a competing device.

Low:

I guess Iíve got to get into that, because you can build photoconductors in silicon and in germanium that go all the way out to 100 microns. We knew that even back then, but the work that was being done was classified, and itís no longer classified. But the bolometer beats that all out in some ways, so that if you really are going to work over wide spectral ranges a bolometer still is the only — the helium — cooled bolometers are still the only way to do it satisfactorily. On the other hand, if you have a collection of different photo detectors, each optimized for a piece of the spectrum, then you can push that further. A good example is the COBE satellite.

McCray:

Sure.

Low:

Which was a mixture of both types of detectors. There was a beautifully designed experiment in which they used both bolometers and photoconductors, photovoltaic and photoconductors, to cover the entire band that we are speaking about from say 1 micro to 1,000 is what COBE did. And not looking at objects, but looking at the sky in its general sense. The cosmic background experiment. And so thatís —

McCray:

Who were the competitors at the 200-inch?

Low:

Well, Westfall. They never — they didnít — they are best known today as Westfall, and he is I think retired. But, oh gosh, he became director of JPL. What the heck is his name?

McCray:

Ed Stone?

Low:

No, but prior to Stone.

McCray:

Okay.

Low:

Talk about memory lapses.

McCray:

Okay. I can track that part down.

Low:

You know [inaudible phrase]. There were three of them. One was just a young guy I never heard of again, but there were two prominent individuals, and they both went quite diverse ways after that. But they succeeded. They just didnít manage to measure anything. And work continued on with the 200-inch, but it was very slow. And we went zooming ahead, because I developed the next innovation, which was the modulating secondary. And Iím leaving out a lot of details. I think weíve got to speed up. Iím giving highlights — not a systematic, thorough thread.

McCray:

Well, you can be as thorough as you want. Thatís fine.

Low:

The key thing was, is that we continued to struggle on the ground with the scheme I told you about, the focal plane modulation, and I wanted to go beyond what could be done on the ground. And I was a participant in the early balloon flights, because I supplied the bolometers and helium stratospheric balloons didnít seem to me to be as attractive as an airplane. [inaudible phrase] Once you start flying around in jet airplanes, you get up to 30,000-35,000 or maybe 40,000 feet and you look around and you donít see any clouds; they are all below you. And so the clouds are gone. And if you study the atmosphere a little bit, you can see that you can go a little bit higher with airplanes and get above whatís called a tropopause, and then the water just drops like gangbusters. So since itís water the major — CO2 was important as well, but itís the water vapor in the atmosphere that provides the opacity and the background. And it fluctuates, the water does. Itís never the same. And so if you can get above the water, it really makes a remarkable improvement in the transparency and the thermal background of the atmosphere. And it was easy to figure all that out, so we started playing around with airplanes. Well, Kuiper was also interested in airplanes, and he liked big airplanes. I like little airplanes. And that was the major difference.

McCray:

Did you have a pilotís license?

Low:

No, Iíve never legally flown. Iíve flown a Leer jet, but not legally.

McCray:

Okay.

Low:

And itís — I had very good friends who were very good pilots, the worldís best. And so this all took place out at AIMS [spelling?]. The AIMS Research Center was where a lot of the fundamental stuff in wind tunnels and high performance aircraft were done, so it was an appropriate spot for NASA to be doing this kind of thing. I left out the first succeed I had. It was not with NASA, but using a Naval airplane. But unfortunately those guys crashed it without — well, a year was in it when they crashed, and it was fatal. Those two pilots and the aircraft. But it was very successful. The very first thing we did — I wanted to do something fundamental and reasonably difficult, and I picked the Sun, because nothing was known about how bright the Sun was at these wavelengths.

McCray:

Okay.

Low:

It was very, very bright at longer wavelengths and surprisingly cool at shorter wavelengths that had been done from the ground. Itís infinitely bright, but so I did need a big instrument. And we put it in the sextant hole in a Navy aircraft and it flew to about 45,000 feet. Now this is published. We did write this up. And we calibrated this little gadget and made absolute measurements of the brightness of the Sun at 1 millimeter. And it stands today, I am told by my solar colleagues [inaudible phrase]. Well, not the only anymore, but I think one of the best measurements of the brightness of the Sun. Itís the textbook experiment.

McCray:

How large of an instrument were you having at this —?

Low:

Same little Dewar, about so big. I shortened it a little bit because I wanted to fit it up into the window which was 45 degrees. Being Navy pilots, they needed their sextant. They were flying a ship. And so they needed to know where they were.

McCray:

Thatís funny. Yeah.

Low:

So in every Navy airplane of that era they had a sextant port where they could stick the — once they got up to altitude they could stick their sextant in there and take citings [correct word?].

McCray:

Okay.

Low:

They got lost at sea. Thatís what they were trying to do. Get themselves back to the carrier. And so — it was already there. I didnít have to make this hole. I just had to design my bolometer so that it could look out that hole. And part of that survived the crash, and I still have that piece in my, what was my office. An interesting gadget.

McCray:

Iíd like to see that at some point.

Low:

Okay. Weíll do that.

McCray:

Iím curious. Was the military funding a lot of infrared stuff?

Low:

Yeah. No, no, no. They knew — At a place like China Lake they knew that infrared was important. They didnít exactly know why it was important, but it had military applications, because they were all classified. [laughs] Everything was classified that was infrared. And so here comes this infrared guy who all he wanted to do was measure how bright the Sun was. The Navy really thought that was worthwhile. They didnít ask any questions. They just provided me pilots, a place to set up my experiment, and free flights with the captain or commanderís personal airplane.

McCray:

Nice. How did you get connected to them in the first place?

Low:

Just connections. I donít remember. Just connections. And so I went out there, visited with those guys, talked to them for a few minutes, and after that I was given carte blanche. I think we altogether made three trips to China Lake.

McCray:

Where is China Lake located?

Low:

Near Edwards Air Force Base, in that part of the Mojave Desert, and easy to drive out there from here.

McCray:

Okay.

Low:

So we carried all of our gear and a station wagon or something, we had two of us, and set these experiments up, calibrated this thing, flew it, did it several times, made sure that everything repeated, and I published it. And that proved that you could sit there in an airplane and point this thing by hand and make astronomical measurements. And that was probably the first open port experiment, in that there was no window, no airplane window. It had to be the usual vacuum window, because the bolometer wouldnít operate without one. But there was no fixed window through which you were looking out. Part of the instrument that was exposed to the sky was outside the airplane — not inside the airplane looking out a window. Kuiperís stuff was a little telescope looking out through a window just like you and I look when we are sitting in a seat.

McCray:

Just putting it right up against the glass?

Low:

Yeah.

McCray:

Okay.

Low:

Yeah, yeah. He was looking out windows. And so ďopen portĒ means that the telescope itself has direct access to the sky. And so it proved all that. The airplane crashed, making a cross-country flight. It had a problem and they couldnít get it on the ground properly, so that terminated that. So we then went up to Aimes, where Kuiper had already made contact and talked to them and here was this beautiful little Leer Jet, just gorgeous. And I asked how high that could go, and he said, ďOh, well, we can take it up to 50,000 feet.Ē I said, ďOh, really.Ē Because the tropopause is around 45,000 feet. So thatís 5,000 feet above the tropopause. That really makes a difference. Thatís the stratosphere. Itís the lower stratosphere. And so we — I wrote a proposal to NASA Headquarters to the Astronomy Branch, and it was rejected.

McCray:

Why?

Low:

Well, it wasnít optical. It wasnít optical astronomy, and thatís the only thing they did was optical astronomy. And it wasnít really clearly space because it was going to be done in an airplane, even though it was going to be done on a NASA airplane. And so it was just rejected out of hand. Well, I said, ďTo hell with this.Ē So I had met some interesting senior colleagues by that time. I mean I was, you know — published a few papers and was known. I had been invited to give talks all kinds of places — Princeton, Harvard, [inaudible word] — and met these prominent astronomers. And one of them, who is Leo Goldberg, who happened to be highly placed in his advisory capacity to NASA, and I just simply explained to him that this proposal had been summarily rejected — without review, I think. You could get away with that in those days. And he said, ďOh, I think I can do something about that.Ē And pretty soon I was awarded I believe $50,000 was the grant. It would be hard to look that one up, very hard to get the historical fact. It was an amazingly small amount of money, but on that amount of money I was able to design and build a telescope that fit in the emergency exit. We took the emergency escape hatch out of the airplane, [inaudible word] a panel about this big so that a small person could force themselves through — maybe that wide. And so the telescope was built into a replica of that hatch, and it was 12 inches in diameter. Unhappily, you cannot go see it anymore. Until about two years ago it was, I thought, permanently ensconced in the Aaron [spelling?] Space Museum. For twenty years or more it sat there as an exhibit.

McCray:

I know people there. I can ask at least. Itís probably in their collections in —

Low:

Yes. Itís in their collection somewhere.

McCray:

Yeah. Iíd like to see that.

Low:

I would like to know what theyíve done to it, and I do have the name from Martin Harwit [spelling?], who gave me the name of the person — Iíve got it written down someplace — who he said would tell me. When Martin was there, our [correct word?] new director, it was still there. It was done before his time, but it was — they completely — itís now a gift shop, that whole part. They completely changed that whole area and that exhibit is entirely gone and swept away and replaced with a large gift shop.

McCray:

Iíll ask about that when Iím back in town. Iíd like to see that.

Low:

So we had a half scale model of RS [correct word?] —

McCray:

Excuse me.

Low:

What we had in the museum — and this is not in order — we had the real Leer Jet telescope. It ended up two of them were built. A copy was built, and I think it was the copy, because it looked nicer. When we made all of our flights, which were over a hundred, the telescope, the Dewar, the entire thing Ė in NASA you somehow came up with a little section of a Leer Jet. How they got that Iím not quite sure. A scrapped airplane, no doubt. So they actually had a cross-section of the Leer Jet.

McCray:

Okay.

Low:

With the telescope in it. It was a really nice exhibit, I thought.

McCray:

When were these, the Leer Jet things, first done? I mean it sounds like you did the hundred flights and they certainly werenít done [inaudible phrase].

Low:

They were done over about a four-year period.

McCray:

Okay.

Low:

And every couple of months we would go out there for a one- or two-week period. Sometimes we were there for two weeks at a time due to weather.

McCray:

When did you start the —?

Low:

Okay. Letís see. Sixty-nine? Sixty-eight?

McCray:

Okay.

Low:

Somewhere in there. The papers tell the story.

McCray:

Okay. So the late sixties. Leo Goldberg then is at Harvard at this point.

Low:

He was still at Harvard.

McCray:

Before he —

Low:

Before he came here. You know, I never took the opportunity to thank him for all of that in later years, when I could have. He died of cancer.

McCray:

Yeah, he passed away I think in Ď87 or Ď88.

Low:

Passed away rather quickly. I mean he just got away too quickly. I never ever sat down with him and told him this story from my perspective. Because he had probably forgotten it. You know, he was quick at the job though. He turned them around at headquarters just like that. After that I had no problem. But of course as soon as I started making — It worked right of the, you know, it worked very quickly once it was airborne, and so the internal energy of Jupiter and Saturn, that was the first thing I chose to do with it, and that was a biggie. If you want to have the pearls, that was one of them. And there the bolometer was used in its fullest, because what I did is I knew how bright certain bright stars were.

McCray:

Okay.

Low:

Okay? Because we had been measuring them from the ground and had them tied down to within say 10 percent accuracy or better. And so by virtue of the fact that the bolometer could work equally efficiently — and you had to prove that, but I tested that in the lab at the short wavelengths looking at a star and at the longer wavelengths looking at where Jupiter peaks, which is about 30 or 40 microns, which is opaque from the ground, you canít do that from the ground — or even a high mountain you cannot do it in an absolute sense. So it had to be done above enough of the Earthís atmosphere that the sky was basically transparent. And so I broke the spectrum up into two pieces and used the, flew at a time when the proper stars were near Jupiter in the sky. Because even though you are in an airplane and you can point in any direction, itís narrow in the Leer Jet what directions you can point at. So you can pick the right time of year to fly, which we did, and did that a couple of times, and threw Saturn in for good — extra. The thing was more sensitive. And the thing that made that possible was the modulating secondary.

McCray:

Okay.

Low:

Because the first initial experiments that I flew used a focal point chopper.

McCray:

The one that you were describing earlier?

Low:

Yes. The temperature gradients in the telescope are huge, because the whole telescope is sitting in a cavity with this big opening in the side of the airplane. So here you are in the stratosphere at 50,000 feet and the temperature is minus fifty or something, and youíve got temperature gradients basically. And thatís what causes really big problems. I mean you have to move the telescope around to point it. The airplane is up there flying as stable as they can get it, and it is very stable, amazingly stable, but it isnít stable enough for pointing a telescope at Jupiter. And so youíve got to be able to articulate the telescope to track the thing youíre pointing at.

McCray:

Sure.

Low:

That causes big changes in the amount of radiation coming in from the side and scattering its way in to the field. And so thatís what we were looking at with the focal pointing chopper. We were modulating that fluctuating background. And one thing about that was [inaudible word; locking? lugging?] everything else. So it was down here on the ground and it was actually right outside the Lunar and Planetary Laboratory where I set the telescope up at night to look at stars. There was really no need to take it up the mountain. We werenít going to measure anything; we were just trying to see. We wanted the sky noise. We wanted the sky to be bad. So we did it right here, downtown Tucson, on campus, at 10 oíclock at night, and if you point it up at the North Star, in that vicinity, the sky isnít — you donít, you know, the sky isnít zipping by.

McCray:

Sure.

Low:

[inaudible phrase] stationary, so that we did it on the north side of the building, and it was very clear that when we ran our conventional chopper that we had at the time — it was the miniature version of the thing I already described — that we were seeing huge amounts of up and down fluctuation, so that we werenít able to see stars. We werenít able to see bright planets from the ground. We should have been able to see them. And I guess the moment of inspiration — Desperation is a better term for it, because if I couldnít make it work on the ground I was not going to make it work in the airplane. That I knew very well. It had to work on the ground first to a certain level, and I had a pretty good idea of what that level needed to be and I wasnít getting there, so I couldnít see anything else to change. The telescope was a [inaudible word] telescope, 12 inches in diameter about this long with a secondary that was 2Ĺ inches perhaps, and it was mounted firmly to spiders [correct word?]. The spiders were held in place, the spider rings held in place, by screws. So I loosened the screws in such a way that I could wiggle the ring up and down by — if I figured out what the angle needed to be. And so I limited the range of motion like so, and I had my assistant looking at the output of the bolometer. And as I moved the secondary to a small angle and it was the right size, nothing changed.

McCray:

Hmm. How did you get the idea?

Low:

Well, desperation. Just pure desperation.

McCray:

Hmm.

Low:

And I was able to move it more than what I needed. See, the amount that you have to move it is enough to move the thing youíre looking at out of the field of view so that you can look just at the sky or right next to the object. Because you then do that very quickly, and you are taking data all the time so you subtract the sky from the sky plus Jupiter.

McCray:

Sure.

Low:

And the sky then disappears if the subtraction works. So youíve just got to make sure that you donít change anything in that process. And if you can do that, youíre in business.

McCray:

Who was your assistant?

Low:

It was probably Carl Gillespie [spelling?]. Heís the guy that most of this stuff was done with. I had two or three by that time. If it was a bolometer thing it was Arnold Davidson [spelling?] and if it was an airplane thing it was Carl Gillespie. And those names are on those papers. Those guys that were doing the work with Frank got their names on all the good papers. They werenít astronomers, but they appreciated having their names added.

McCray:

Were these students of yours?

Low:

No, they were — Carl is older than I am. And so is Arnold.

McCray:

Okay. Did you have students, though, who were beginning to get interested in infrared work at this time?

Low:

Yes and no. In the Leer Jet program students played a big role.

McCray:

Okay. What would they do?

Low:

They werenít U of A students; they were Rice students. That was another interlude of mine. I decided I could be two places at once. I was professor at Rice and at the U of A at the same time.

McCray:

Did you travel back and forth a lot?

Low:

I could fly from — I could go on out and get on the airplane at nine oíclock leaving Tucson, and we would stop at El Paso and Austin or San Antonio, and finally end up at Houston about six oíclock in the morning.

McCray:

Okay.

Low:

And I could sleep on the airplane enough to, you know, do whatever I had to do the next day. I did that for two and a half years or so, and it got tiresome.

McCray:

Iíll bet.

Low:

We would go over there in the summertime, because the summer was bad here and there, so that was the time to do other things other than observe, and but I could still observe here the other nine months of the year. I thought it would work. It didnít work very well. It really didnít. You have to be at a place to really do the job right. However, I got very good students out of that.

McCray:

George Reike [spelling?]. I know you did a — Thatís jumping ahead a bit, but was he from here or —?

Low:

He was a postdoc.

McCray:

Here or at Rice?

Low:

No. The connection with George was that he did his degree at Harvard, the Smithsonian, that group. Giovanni Fazio [spelling?] was his mentor there. And he worked on the gamma ray telescope up in Mount Hopkins. And so he just strolled into my office one day in LPL [spelling?] looking for a job, because he had heard about this infrared stuff and thought it might be interesting. He was just finishing up his thesis and heíd been down here at Mt. Hawkins.

McCray:

Klineman [spelling?].

Low:

Susan or Doug? Because thereís two of them.

McCray:

Iím not sure, but one time I interviewed you — a while ago in your office you showed me a picture I think of the Klineman-Low Nebula.

Low:

Thatís Doug.

McCray:

Okay. I didnít realize they were —? Theyíre husband and wife?

Low:

They are currently married, after many years.

McCray:

Okay.

Low:

So thatís — Unfortunately neither one of them is doing astronomy anymore.

McCray:

Okay.

Low:

Susan is the one that basically should be doing astronomy, but she is or was — Iím not quite sure of her status, but —That shouldnít be on the record, I mean. And so Doug and I made the Orion discovery up at the 28-inch in the Catalinas, one of many. The first galaxies were detected there. I think it would take a little — I would have to be better organized to really give you what I think are the principle discoveries in their chronological context, but once we learned that we could actually, that galaxies are actually bright in the infrared, I went after them in the Leer Jet. And Bill Hoffman [spelling?] played a very important role with his balloon. He — we built Billís bolometers for him, and he was doing balloons at the same time I was doing the Leer Jet stuff.

McCray:

Okay.

Low:

And so some of the things got done in the Leer Jet at the longer wavelengths and some of the things got done with — The big, important thing was the mapping of the galactic center. The galactic center, as you well know, is completely obscured from human eye, and only — well, the radio astronomers had pretty well figured out where it was but didnít have it tied down. And the two guys that deserve the credit — I tried first and failed. I tried on those very first nights at the 82-inch.

McCray:

To look at the galactic center.

Low:

Way back in Ď64. But we just didnít know. We had all the sensitivity we needed. It was just a matter of not knowing where it was. Iíll never know how close I came, but it was ten years later that that was detected by Bill Hoffmanís successful balloon flight, and then almost at the same time as I recall detected by Becklen [spelling?; first name?] and Nordebauer [spelling?; first name?].

McCray:

Who were the other groups [with which] you were doing work? I mean, I know the Cal Tech people were involved, and Minnesota was [inaudible phrase] people.

Low:

Minnesota people, yes.

McCray:

Were those the [inaudible word] principal —?

Low:

Yes. Ed Nye [spelling?] and his students, and one of his students was Fred Gillette [spelling?], and then Fred moved down here and he and I worked together a lot.

McCray:

Nick Wolfe [spelling?] was another one.

Low:

Nick Wolfe. You got it. Nick is here too.

McCray:

Were those the three main centers, would you say — Minnesota, Arizona and Cal Tech?

Low:

Yeah, because the guys up at Smithsonian never got their act together.

McCray:

Okay.

Low:

I mean they had all the opportunities, but — but you know if theyíd hung on to Doug instead of letting him wander away, they could have been far more successful, I think. Thatís my view of it. But if Doug didnít want to do it, then there is nothing you can do.

McCray:

Sure. Right.

Low:

So Fazio has proceeded onward the best he can. He switched from X-ray astronomy to infrared astronomy — a big switch for him. And, again, we all collaborated, so I shouldnít — The problem with their effort was, is that although they did a lot of things that had a lot of support, they just didnít seem to produce any big results.

McCray:

Okay.

Low:

And one of the important things about this field is you need — Since space opportunities are so rare, I mean theyíre just extremely rare, you have either got to do it with balloons, with airplanes or on the ground. Thatís basically your options. Rockets never played, sounding rockets never played a significant role. The Air Force kept trying, and a few astronomers have tried, but they just donít last long enough. I mean, they go up and you know a minute is the total length of time.

McCray:

Sure.

Low:

And itís not going to work productively.

McCray:

Cal Tech was also doing the — this is around the time they began to do the 2-micron [inaudible word].

Low:

Thatís what Gary [last name?] — I mean, Garyís contribution, he was not involved in the 10-micron stuff. He got involved with Layton [spelling?; first name?] doing the 2-micron survey, and it was certainly essential. Because what was happening was that Harold was still around in those days.

McCray:

When did he pass away?

Low:

I canít remember those dates. Iíd have to look them up.

McCray:

Okay. All right.

Low:

Gerard [spelling?; last name?] outlived him even though I think Gerard was a year or two older, but they both died within a few years of one another. Heart attacks in both cases, premature heart attacks. Both still in the saddle doing their thing, which is a good way to go actually — if there is a good way.

McCray:

One of the better ways I can think of.

Low:

I think so, yeah. The — where were we? I got confused about this one issue.

McCray:

The 2-micron survey.

Low:

Two-micron survey. Harold and his followers were trying to figure out what was there by measuring everything from the ground, and I played the role that I outlined, namely starting it at 5 microns and going to longer wavelengths. And but when you do it that way, you have to select which stars to look at and what problems to work on. And Harold was quite focused in that regard. He had sort of a simplistic view of it. You figure out what the normal stars are doing and then you look for differences — stars that donít do that.

McCray:

Okay.

Low:

And thatís how you make discoveries. Well, he attributed the infrared — what we call generically as infrared excesses — to the interstellar medium, because that was his preconceived notion. And therein he made a huge mistake, Harold did, a huge conceptual. What Gary and Bob Layton did with their uniform survey — and they still only looked at very bright stars; in fact, they werenít able to go as deep as Harold and I had gone because they were doing an all-sky survey, but there is, as Gary likes to call it, they were unbiased. They didnít select what was there; they just observed what was there. And when you do that and you look into what they found, there are all these infrared stars and thereís no way that they have anything whatever to do with the interstellar medium. The interstellar medium simply isnít constructed that way, and you already know that from visible stars. And so it became very, very clear, as soon as they started publishing, as soon as they published those 3,000 stars — Because Harold had singlehandedly done more than 3,000 stars. You see the point?

McCray:

He had picked specific ones.

Low:

He had picked stars that he thought were important for one reason or another.

McCray:

Right.

Low:

And so letís say he had done 5,600. I donít know the actual number, but I suspect it was 6,000. And so there were about 3,000 as I recall in the — I hope my numbers are right.

McCray:

But he had a biased sample in a sense.

Low:

Yeah. One was a very biased sample, and the other one was basically selected to prove his ideas, if you see what I mean.

McCray:

I do.

Low:

Whereas the survey didnít have any preconceived notion other than to find out what the brightest 3,000 stars are.

McCray:

Okay.

Low:

And then working amongst those 3,000 were letís say a dozen or two dozen stars with huge infrared excesses. It simply couldnít be explained.

McCray:

By the interstellar medium.

Low:

By the interstellar medium.

McCray:

Okay.

Low:

So it didnít take Frank and others very long to catch on to what that meant. And so no sooner had we, coming back to the Klineman and Low Nebula discovery, no sooner had we been given the inkling that there was something not centered on the Trapezium, where from the optical point of view you think the center of activity is, itís not. Very misleading. The Orion Nebula is very misleading. It has its signpost pointed in the wrong direction — but not far away. It is the Beckler Norgebower [spelling?; correct two words?] object, and itís embedded in the Klineman-Low Nebula. Itís actually one of a dozen very bright, luminous infrared stars that have recently formed out of that nebulosity, that particular dark cloud. And it is not situated in a three-dimensional sense; it is by accident fairly close to the Trapezium, but now from many detailed studies of that whole system itís clear that there are several centers nearby of fairly recent active star formation out of these dark clouds, molecular clouds. They are quite a dynamic place, particular for luminous stars. And so the whole subject of star formation got a tremendous boost from that, and it goes ongoing.

McCray:

Right.

Low:

But at the same time that we were detecting things at 10 and 20 microns of this magnitude, we were able to do galaxies and we were able to show that galaxies have this — some galaxies — have this huge peak in inner [correct word?] luminosity beyond 20 microns. And thatís where the Leer Jet came in. The Leer Jet led to the C-141 [punctuation?], the Kuiper Observatory, and then [inaudible word] Sophia [spelling?], but it also led to IRAS [spelling?] in a very direct way, because well, letís see, I did one other thing. I gave up — since this is more a personal account than anything else — I reason in the following fashion. I had gotten almost everything that I wanted to do with the Leer Jet. And it continued to be flown by students or ex-students of mine and others who had been there at Aimes for several years, but other than filling in details I think I was right: it didnít make any more big discoveries.

McCray:

So the cream had been skimmed.

Low:

Yeah. We pretty well skimmed the cream from what would be done there. The C-141 never appealed to me, because it was just a big airplane that didnít fly as high and it didnít — It had some wonderful discoveries. Iím not trying to knock it. It just didnít appeal to me personally. It wasnít a tool that I was interested in. So I decided, rightly or wrongly, that we hadnít had a full return on balloons. And with a small balloon that was very carefully designed to minimize the extraneous results that you tend to get in these wavelengths that there were still some interesting things to be done. And so built such a system, and made a dozen or two dozen, I forget how many balloon flights. Because I was into making lots of balloon flights. Iíd make two to three balloon flights in one trip.

McCray:

Where would those be done from?

Low:

Well, Palestine, Texas.

McCray:

Palestine, Texas. Okay.

Low:

And one of the best results we got of that was a map, the first map of the galactic plane. And it convinced me — and I think convinced a lot of others — that not only was the galactic center bright, and of course it is the brightest part, but that the whole plane is bright. Anything thatís anywhere near within 5 degrees of the plane, and you know where the plane has a circle —

McCray:

Yeah.

Low:

Not circle, but a loop around the sky as we see it from where we are inside the galaxy. And so it all is there, at infrared wavelengths. And many, many bright molecular clouds and so forth. So we made, Mishimora [spelling?; first name?] and I made a very nice map going from like, letís see, how far south did we get? We got probably below the galactic center maybe 20 degrees. And say from 20 degrees to the south of the galactic center and going up by 60 or 70 degrees north we were able to do that in a small series of balloon flights, and that was just an amazing, it is an amazing picture of the sky. It was, I believe, crucial in our success with IRAS.

McCray:

Why?

Low:

Because it told us enough about what we were going to get into that we were able to design it to work. Thatís another one of my, shall we say, achievements that I have considerable personal satisfaction from. Because if we had went up there blind, as we were trying to do, we would not have done — In fact, it was a royal battle was fought in the design of IRAS over just what it should focus on and what it should be capable of. And to go up there and get clobbered by the kind of galaxy itself seemed to me an enormous mistake. If I hadnít done that balloon stuff I couldnít have proved it.

McCray:

Okay.

Low:

I could never have proven it. So I had to win that argument in order to make the changes in the way we proceeded. So the entire design of IRAS was based on something that we knew when we launched it should work. And it did.

McCray:

So the idea then was to have IRAS not looking at that area.

Low:

Oh, no. It mapped the — Geez, I donít have — One of the most — The spectacular thing about the IRAS map of the sky is the galactic plane.

McCray:

Okay.

Low:

I mean thatís the wondrous thing about the IRAS mission is that here the galactic plane, revealed in all of its glory, all of it is there and —

McCray:

Do you have a picture here?

Low:

I used to have all these things hanging on the wall. I just threw them away when I, shall we say vacated that office that weíve been in. Itís easy to dig them up.

McCray:

Sure. Yeah. I remember from your —

Low:

Where is —? Letís see. Where is that — I mean, it was on the cover of Science. This is Ď83 now.

McCray:

I can track that down.

Low:

Youíve got to go back to Ď83.

McCray:

And I know Scientific American had an article about IRAS.

Low:

Yes, right.

McCray:

Nature.

Low:

Every single magazine of any sort has had one or more, and I donít have that particular one in the hallway. I have the inner part of it. Yes. Thatís hanging — thatís, I know where that is, Stuart [correct name?].

McCray:

Okay. Itís in that hallway going —?

Low:

Yeah. Going to Peterís office.

McCray:

Okay.

Low:

Thatís a nice chunk out of it. Thatís the core of it. Itís a beautiful picture. But the ones that show the entire ring of emission and other — no, thereís a slide. Iíve got — Iíve have not gotten into my slides. My slides are all intact.

McCray:

Okay.

Low:

If we make a list, then I think — I should have extra copies of those. Iíll give you — Iíll give you — Can you handle 35 mm slides? I mean you can —?

McCray:

Oh yeah.

Low:

If they havenít faded. I havenít looked at them recently. I can go through my collection and give you a set —

McCray:

I can have copies made and return them.

Low:

No, no, I donít think that — If I give you extras, I donít care about it.

McCray:

Okay.

Low:

I need to thin it out some anyway.

Low:

...because we have done is get to it with this balloon, and if you want an account of IRAS from my perspective, that I can certainly do in a few minutes.

McCray:

Sure.

Low:

And I think weíve got an account of most of the highlights of everything else, although theyíre not very well put together systematically. IRAS was a project which came into being after SERTIF [spelling?], because it was realized — and I think we realized it collectively, I donít know who was the leader of this thought, but it was realized sort of shall we say communally that we were foolish to build appointed observatory to go in space where things would be a thousand times deeper than we were able to do from airplanes and from the ground without first having some kind of all sky survey.

McCray:

Okay.

Low:

So having made that intellectual leap, we then got behind the idea, the community did — at least, shall we say the leadership of the community seemed to pull together around the concept of an all sky survey. It turned out that the Dutch were ambitiously trying to put together an infrared space mission of their own, found it was over their heads, sought an ally, and they heard about our plans. And so we were forcefully put together by NASA management into an international collaboration. When they started running out of money and the project was vastly overrun in terms of its budget — those were the overrun days, and that was sort of the accepted method of doing space science — they brought in the Brits and it was decided to make the Brits an equal partner. Did you push the —? Do you want to order? Weíve got to order.

McCray:

We can order. [recorder turned off, then back on...]

Low:

Iím just going to stay with water since I donít really like sugar. Almost everything you drink has sugar in it except water.

McCray:

Yes.

Low:

Or something very close to it, which is called alcohol, which I definitely donít need for lunch. Letís get back to it. So do you want to push your button?

McCray:

Ready to go.

Low:

Oh, weíre going already. I didnít see you. Youíre very stealthy. Okay. SERTIF was put on hold whilst we got together with our foreign allies and worked for at least a decade — I donít have the chronology laid out for you, but the time span between when we started and when we finally launched in Ď83, January of Ď83, the mission only lasted ten months. But we did actually cover the sky almost twice. So only due to a flight bungle did we miss a few percent, and we never made that up. So we didnít quite get 100 percent, but itís like 97 percent.

McCray:

Okay.

Low:

And it was done in four bands, as you may know, that were well chosen and well-spaced, extending from roughly 10 microns — which you could do quite nicely on the ground by then — on out to 120 microns, which you could only do from airplanes and balloons. And we achieved our goals in terms of sensitivity. It was a 60 centimeter telescope, so it didnít have a lot of spatial resolution, but the scientific achievements of it were first of all what is the sky actually like as opposed to our glimpses of it that we had previously, and therein the great role of the zodiacal cloud, the discovery of the zodiacal dust bands as a permanent feature of the solar system, the galactic plan itself with all of its star formation activity which dominates the picture at 60 and 100 microns and is still very prominent even at the shortest wavelengths at which we observed. The myriad number, whereas we had ferreted [correct word?] out, discovered and measured dozens of galaxies in the infrared, both from the ground and from airborne and balloon experiments. We went from two or three or four handfuls of extragalactic objects to 50,000, something like that.

McCray:

Okay.

Low:

In the stellar domain, the pure star domain, it doesnít strike me that we made great advances there, with one exception, and itís quite notable, and that was that some of our favorite stars — in particular Vega, Alpha Lyrae turned out to have a huge [inaudible word] infrared [correct word?] excess. Huge, and totally surprising. No thought of it at all, such a thing. And it turns out that some large number of the very young stars, the ones that are just most recently formed, say with lifetimes of 10 to 100 million years — and the Sun is 4 billion years, to give you a scale — these stars have such cool dust envelopes. And itís quite clear that they are somehow related to the formation of planets around those stars and the residual. One of the residuals of the formation of planets.

McCray:

Okay.

Low:

Thereby laying the groundwork for what I hope will be one of the most productive scientific investigations to be carried with SERTIF where you have, in the legacy of IRAS, to tell us where to start the search in the study and we should be able with our 100 times improvement of sensitivity in SERTIF relative to IRAS we should go quite far with that.

McCray:

Okay.

Low:

Now there were, in addition to the all sky survey there were pointed observations. They were for the most part quite limited in their success simply because there wasnít enough time in a ten-month mission to figure it all out and figure out where to point. So we were just really getting started with the pointing of IRAS when the helium ran out in November. So we launched in towards in towards the end of January, ran out ten months almost to the day — I believe on my birthday, the 23rd of November.

McCray:

Okay.

Low:

In 1983.

McCray:

I remember that picture — you had it in your office — of a rocket lifting off from Vanderburgh, and I believe that was the IRAS.

Low:

That was the launch of IRAS. You know, it was a technical success in that once we finally got it up there, and it was very difficult, the focal plane performed as I have already indicated as well or better than we had projected. The sky was beautifully complex, but it — as I also pointed out on an earlier tape — we knew enough about the basic structure of what we were going to see, the dynamic range. We even had the gain [correct word?] set right. So very little saturated, and we were able to push it to its ultimate limit by being only slightly efficient at operating the mission. So we pushed on the faintest, weakest sources and we captured the brightest only at the very center of the galactic plane where resolution isnít, spatial resolution isnít adequate, did we actually get into saturation problems. And we were able to, because we had a dc coupled system we were able to see the entire thing; not just the ripples, but the total emission was there. So we got the temperature of the zodiacal cloud and the other major distributed sources across the sky, very well defined. The galaxies, what we have basically learned, fall into three groups I suppose: those like our own galaxy which are not particularly strong in the infrared, where the infrared emission comes primarily from star formation and rather well-behaved molecular cloud systems, the same mechanism by which we think the solar system and its neighbors formed 4 billion years ago. We opened up a field of study of star formation in a way that is profound, and the follow-up work that has been done both in explaining the results theoretically and extending them from the ground has kept that one of the most active areas of research in astronomy. Again, thatís a great prelude to missions such as SERTIF where we will be able to select from the thousands or tens of thousands of opportunities and study in detail both the spectroscopy and imaging.

McCray:

Imaging. Yeah.

Low:

And very deep imaging. [inaudible phrase] noise in all of the various cameras, of which there are quite a number. I wonít enumerate them all for you.

McCray:

Okay.

Low:

When the mission is launched it will become well publicized if all the systems work as advertised. And with a five-year mission, that gives you plenty of time to make discoveries and follow them up with the satellite and any of the other tools that weíd have operating subsequently.

McCray:

What about before IRAS? The Air Force did a survey. Iím not sure what wavelength, but it was done from the Cambridge —

McCray:

It was basically 10 microns. It was the — CRL was —

McCray:

Cambridge Research Lab.

Low:

Cambridge Research Lab.

McCray:

Yeah. You participated in that, didnít you?

Low:

Well, I played a curious role. I managed to get my hands on a map of the sky that somehow leaked out of security. And those were in the days when I practically had the sky memorized. You know, we were doing all these things from airplanes and telescopes and there werenít that many prominent sources, and I could almost recognize what was there but not quite, in this map. And so we sat down to see if we could solve the puzzle, and we did. Even though there were no identifications of any kind or even good positions, we figured out where these objects, what these objects really were — at least quite a large number of them. And so we corrected — we formed a little catalog of our own. George Fricke [spelling?] and I did this together, and I forget how many sources there were, but it was the order of a few hundred.

McCray:

Okay.

Low:

And as I say, some of them were clearly recognizable to us; others were not. And so we were about to publish this, had it all written up. It was a neat little paper explaining how they had made a certain positional error which had caused them to be unable to identify their sources. And we had it all sorted out for them, and we were going to tell the world what they had done and what it meant. And Nancy Boggess, who was in charge of the infrared program for NASA, called up almost in tears because she had promised me that if we did this that she would get it declassified — because although we had not used classified data, we had basically created data that was better than what they had and hence highly classified. And so she felt that although she had every reason to believe that the Pentagon would understand that this was actually benefitting them and that they should allow us to proceed and publish these results, she called. And we had it already done up, ready to go to submit it for refereeing, and said, ďBurn it. Destroy it.Ē

McCray:

What was she worried about?

Low:

Well, she wasnít worried at all, other than going to prison. Sheíd had her meeting at the Pentagon, and they had turned it down.

McCray:

How did they get wind of what you were working on?

Low:

Well, she told them. She decided that it was not wise to proceed without their permission — or somebody at NASA Headquarters decided. I donít think I ever asked Nancy that exact question whether she did that on her own or whether she did it from on high, but there are liaisons between the different branches of government, as there should be, and so Iím sure there were official channels running back and forth, and all these people got together and had a meeting one day and we lost.

McCray:

Hmm. What was your reaction?

Low:

I was very unhappy. But I simply went on. Now, what role did it play? It still played a huge role, because what they had done is fly oh I think a half a dozen or more sounding rockets, and they had covered little pieces of the sky, and then they had somehow patched this together. If I ever knew the details which I wasnít supposed to know, I have conveniently forgotten them. I truly have forgotten them, so I canít tell you. But between their sounding rockets and their other efforts, some of which may have been orbital efforts, they put together this map. And one of the companies — I guess it was Hughes — had leaked. Had figured no one could figure out what it was. They couldnít figure it out, so it wasnít going to do any harm to put it out as a simple advertisement. So we literally did all this by getting our hands on a 8Ĺ x 11 sheet of paper which was all black except for little white dots —

McCray:

Indicating infrared sources.

Low:

Indicating what they had — The highlights of what they had detected.

McCray:

Yeah.

Low:

They probably had detected more than that. But so, the fact that those guys had managed to do this with sounding rockets actually did impress some of us, and we — Oh yes, that will do very nicely, thank you. Wait person: You care for something to drink, or you stay with water?

Low:

So there you are. It did influence — Gosh, can I finish this sentence?

McCray:

No, no, please.

Low:

It did influence positively, along with the stuff we had done from the balloon, the determination to go ahead with this pioneering IRAS mission. Because we were taking a great leap beyond what the U.S. Air Force had been able to do. There is a neat little side comment that goes with my other story, which is that right up until the launch of IRAS there were those from the military who laughed at it, who scoffed at it.

McCray:

Why?

Low:

Because they didnít do it themselves, and it was clear that we were trying to do something far beyond what they had done. And it was — even went so far as to threaten the launch of IRAS, because they were, they had some of the NASA people — I wonít mention names — who thought that they were right and that we were wrong and what we were about to do would just be an embarrassment to the Space Agency.

McCray:

The link between the military and the other side of the fence is interesting to me. Did you have a foot on both sides, or did you remain firmly on the civilian side?

Low:

I had a few random glimpses of what was going on, simply because I was asked to — I had Top Secret clearance at one point, and the reason for that was I had been asked to consult on specific issues where it was thought that my expertise would be useful to them. I donít know if it ever was or not, because you never have any follow-up from that sort of activity, but I did participate, and so I got little random glimpses and was generally aware of what was going on. Then when we started IRAS we managed to squeeze as much as we could out of our contractors, who actually failed to deliver a functioning focal plane.

McCray:

Who was the contractor?

Low:

Well, Rockwell. One of our big hurdles was to fix the damn thing. When we finally got it delivered it was such a colossal failure, right out of a package, that it was going to terminate the mission. An interesting side commentary is that the Dutch partners were key in preventing that from happening. If we had not been an international project, I am quite certain that we would have been terminated right at that point. But there was a great amount of disagreement over whether or not there was anything that could be done to fix this ailing focal point.

McCray:

Okay.

Low:

No one had a — no one was in — there was no total, no general agreement on that point.

McCray:

Based on what you saw, how would you rank the sophistication of the military work in IR versus what people such as yourself were doing? Were you envious of what they had?

Low:

No, no. Never envious. What went on from my perspective was that first of all I had this classification. The contractors used that to their own advantage. It allowed them to keep the military management if not in the dark at least badly misled. There is no independent test of anything. Despite that, they made, by [inaudible word] of the magnitude of their effort — which was huge — they made technical progress. There some good, many good people working behind the scenes on the various aspects of the technology. And since they could afford to fail, they did — regularly.

McCray:

If I wanted to speak to people or companies who were vendors or contractors, who would be some price places to go to or to speak with?

Low:

Well, in focal plane technology there were two survivors. The corporate identification is shifted around a little bit. Rockwell International still provides material to DOD. They have sold their DOD business to Boeing, but so the basic materials for the military system still originate inside Rockwell. The other one, their chief competitor and survivor, used to be called Santa Barbara Research, a part of Hughes. Well, Hughes no longer exists as a corporate entity, so itís part of Rathion [spelling?] today.

McCray:

Lugabauer [spelling?; first name?] mentioned that. He said, you know, if I wanted to go back in time to go back to Santa Barbara Research and talk to them, you know, however I could find them.

Low:

Well, since we ended up selecting Rockwell instead of Santa Barbara Ė there was a big shootout between them for IRAS — Santa Barbara undoubtedly played a much larger role in the classified projects than they did in IRAS and as far as SERTIF is concerned, some of — There are three suppliers of the focal planes. We had three instruments, and each instrument had its own supplier. What used to be Rockwell, now Boeing, is one; the other is what used to be Santa Barbara, which is now —

McCray:

Raytheon.

Low:

Part of Raytheon. And the third of is the good old U of A. And since there was no one else to do it, if we wanted a mission that could work beyond 30 microns, we had to do it ourselves. I think I probably minimized a little bit for you the, some of the technical contributions we made here at the U of A to the technical success of IRAS. There were several, going back to IRAS, those days. Even though we were relying on Rockwell people to build the detectors, they hadnít really figured out how to do it.

McCray:

Okay.

Low:

And so when we rebuilt the focal plane it was a major overhaul.

McCray:

And that was done at the U of A primarily?

Low:

It was done using a technology that I had worked out for a small mission which was unfortunately not very successful. It was done in collaboration with Fazio at the Smithsonian and was done on Spacelab in shuttle bay, and it didnít work very well, but the technology worked and that was carried on independently by me because I knew that it was going to be needed. And so when the IRAS focal plane finally self-destructed, as delivered to NASA, the choice was either to fix it or to terminate the mission. The main reason that the decision was taken —There were two main reasons that the decision was taken by NASA to go ahead and fix it was that the Dutch had spent all of their money, they were all ready to launch, and we couldnít deliver the focal plane, so they were so unhappy about that that NASA had to think twice before pulling the plug. And they did think twice, so they looked into this alternative which I had developed. And by Iím sure what was a very narrow margin they chose to take a shot at it. So we moved the project from Aimes to JPL — because the people at Aimes were against it. I guess thatís a blunt but true fact. They were simply against it, and so we were going to go ahead. We werenít going to go ahead at Aimes, so we picked it all up, picked all the pieces up and transplanted them down the coastline to JPL, formed a tiger team, and set about rebuilding the focal plane. And the readout devices, the jayfets [correct word?] were done here in my little company at a very low cost, I might say. There was no profit. But it was a very profitable thing because it saved the entire focal plane. The other thing was that, although the military knew that we were going to encounter a hostile environment in our orbit, it was very slow and difficult to get that knowledge out. It was classified.

McCray:

That must have been frustrating.

Low:

It was nearly fatal. We tracked [correct word?; trapped?] to the Van Allen belts in our orbit that was essentially fatal to the kind of focal plane we were flying, We would have never completed more than one or two orbits without being shut down.

McCray:

By the radiation?

Low:

Mm-hm [affirmative]. The South Atlantic anomaly is quite destructive. Well, the focal plane already existed in its defective state when we found out about this. So Eric Young [spelling?] and I leaped into the fray and went over to the medical school at the U of A and talked, conned the radiologist there into letting us have some material, and they requested that we read the safety guides on what to do, and I think Eric and I assured them that we were physicists and we knew all the things that — [laughs] And so we set up there in a blind alley of the building a little radiation laboratory where we set about irradiating detector samples from the flight material.

McCray:

Using this material from the medical school.

Low:

Using the — I forget which gamma ray. It was a gamma ray source that was used in, you know, for radiation therapy. And since Eric was much younger than I, I volunteered to handle the hot stuff. So, so far it hasnít done anything to me that I know about. And so we moved as quickly as possible, and we discovered right away that yes indeed the South Atlantic anomaly was going to put us out of business.

McCray:

[inaudible name] had to contend with the same difficulty.

McCray:

So you had to redo the focal plane as a result?

Low:

Mm-hm [affirmative]. We had to make modifications in the focal plane. We had to make modifications in the electronics and in the data analysis; the whole blooming thing had to be overhauled just to allow us to survive and take data in this hostile environment.

McCray:

And the military was aware of this from their other —?

Low:

Mm-hm [affirmative]. They had shot stuff up there and it didnít work, so they knew about it. Wait person: How is your salad, sir?

Low:

Mmm.

McCray:

Of all these projects — and Iím think of SERTIF, IRAS, the MMT — did you have a favorite?

Low:

Itís really analogous to having a bunch of children. I mean, you know, they all have their highlights, so I wouldnít want to do away with any of them.

McCray:

Okay.

Low:

Some were more successful than others, but they all had their rewards I think. Iíve been extraordinarily lucky I think in terms of selecting stuff to work on.

McCray:

Projects that turned out to be winners?

Low:

Mm-hm [affirmative].

McCray:

Was the MMT fun to work on?

Low:

Yes and no. I got bogged down, and I basically quit working on it. I mean it was either going to be the MMT was going to be my consuming project or IRAS, and I elected IRAS instead. They were in competition.

McCray:

Okay.

Low:

Once I figured out that you could build a telescope this way and that it ought to work very well in the infrared if you did everything right — and you could — it really did get bogged down. It wasnít adequate funding to proceed. And as more astronomers became involved, the requirements kept changing. It wasnít sufficient just to build an infrared telescope; it had to be an optical telescope as well.

McCray:

It was originally designed as a spectroscopic telescope, wasnít it?

Low:

That was one of the justifications used. Now it was originally — it depends on what you mean by originally.

McCray:

Okay.

Low:

And in my version of it, it wasnít going to be a spectroscopic telescope at all but it was going to be an infrared telescope, pure and simple.

McCray:

To do photometric work.

Low:

Yes. To get improved sensitivity on the ground.

McCray:

Okay.

Low:

And but in order to get enough money together, enough people pulled together, it was necessary to broaden that. It was pointed out that you could make a very efficient spectrometer in the visible, and that was done, and a good part of its scientific work was in that mode. It took many years to complete.

McCray:

I have never —

Low:

I got actively involved in it again when things werenít working in the early stages of commissioning the telescope.

McCray:

So around 1980?

Low:

I forget exactly the dates of that, but it was in the years before — Well, how did it fit in? IRAS was launched in Ď83, so when was the MMT dedicated?

McCray:

Seventy-nine.

Low:

Yeah. So it was a year or two when the MMT was in existence but it wasnít really, certain aspects of it were not working very well at all. Secondaries were one of them. We needed to get involved in that. And the other, there were so many doubters on the optical side that we wouldnít be able to combine the images. They insisted on putting lasers all over the place. The thing was an experiment in lasers.

McCray:

To align the mirrors?

Low:

Yeah. Each telescope had laser beams going through it, and we could show on paper that the system that they had wasnít going to work, though it may actually oddly enough have served a curious purpose: it may have kept the money being made available each year to keep building the thing because the lasers were there. But then when we got it all built with the lasers, the lasers simply made the images worse. It became quite obvious that not only did it not work, it made the images worse. So the only way you could get a decent image was if you turned the lasers off. [inaudible word] was instrumental in helping make the decision to take the lasers completely off and put the telescope back into its original configurations.

McCray:

Okay.

Low:

It was a big disappointment to a few people who had insisted that the lasers were fundamental.

McCray:

Who liked the lasers?

Low:

I donít remember exactly who they were.

McCray:

The lasers attracted moths, I remember reading somewhere.

Low:

Mmmm. They were just a complete disaster. The closest thing to the MMT now is going to be the very large binocular telescope, which is another one of my proposals, and I hope it works as an interferometer. Thatís fundamentally what it is, is a pair of 3.4 meter mirrors — telescopes really, complete telescopes — operated as a Michelson interferometer.

McCray:

I have spoken with a number of different astronomers about the MMT, and I havenít yet [met] anyone who didnít have an opinion about it. Everyone either said it was great and it worked well or it was horrible and did a — What do you think?

Low:

Thatís a very deep question. I think that as an optical spectrograph I happened to end up using with John Hookra [spelling?]. The two of us did a fairly extensive piece of spectroscopic work. Unfortunately it has never really been completely published. Several papers came out of it, but the big paper is never going to get written, so neither John nor I or our younger co-workers are ever going to find the time to publish all the data. Itís sad, but thatís what happens sometimes in science. It was a very competent telescope for things that it was asked to do, and it did deliver the worldís most sensitive 10-micron photometry.

McCray:

Okay.

Low:

It delivered on that. Thereís no doubt about it. What happened though was IRAS came along and you could just look up on your computer the answer. It was right there in the catalog. Now the MMT was instrumental in the area of spatial interferometry, and we will have to wait and see since the MMT is gone how that pans out. The LBT, large binocular telescope, is a much more powerful concept, using all the same principles. And if it is made to work, it will be so much more powerful than all of the other large telescopes put together. However they choose to put them together, they cannot put them together the way the MMT — I mean the way the LBT is done. So one has to simply hope that that instrument will be completely in due course successfully and will be made to work in the same sense that we made the MMT work. Now itís a harder task, because itís much larger.

McCray:

Right.

Low:

And that just automatically makes it much harder. But if it is successful, it will establish — whatís the ballyhoo? Twenty-five times higher spatial resolution than Hubble. Something like that.

McCray:

Okay.

Low:

And there is a quiet battle going on. The two Kek [correct word?] telescopes are being made into a type of interferometer.

McCray:

Iíve seen the pictures with the outrigger telescopes.

Low:

And so the LBT will be in competition with that, and if I were still young and in the competition, which I am glad Iím not, I would bet on the LBT.

McCray:

Okay.

Low:

Because in fundamental principles itís the way to go. Now the implementation is so important that the answer is often in the details. And so the LBT as a project is another one of these international clubs, not particularly well funded nor even well directed. Since there is no strong guiding —

McCray:

Personality?

Low:

Personnel, person or team. Itís a bunch of committees. And so who knows what the outcome will be. We will just have to, again, tune in. But I havenít answered your question about the MMT.

McCray:

No. And maybe there isnít an answer. Maybe itís just too simplistic of a question.

Low:

Depends on — It is a simplistic question, but there ought to be an answer to it. If there was a major scientific discovery that I or somebody else had managed to make with the MMT, I would be a whole lot more enthusiastic.

McCray:

Okay.

Low:

A lot of good work was done at a reasonably economical cost when you compare it to other big telescopes.

McCray:

Sure.

Low:

Itís amazing how much like the MMT all of the other big telescopes look. It represented a tremendous departure from the past and many of the concepts which may not be obvious to the eye that were successfully — innovations which panned out in the MMT have now been made just a standard part of this newer generation, the main difference being the pointing system, is the main one.

McCray:

Okay.

Low:

But the use of active computers to control the systems. The MMT wouldnít have worked at all without a half a — I once spent a cloudy night, walked around that building and did a survey of all the computers, and I even included the little one in the microwave oven, but I got the number up to about twelve. And all twelve were essential. So thatís the way all of these large telescopes have to work. And the alignment system, though simple, is a forerunner of the check [correct word?] in a very real sense.

McCray:

Okay. It only had six elements versus thirty-six.

Low:

Yeah. But —

McCray:

Weíve talked about —

Low:

The light weight. The other aspect of it is really not just the pointing system; itís the computerization, the alignment, the basic altazimuth, computer-controlled altazimuth mounting, and reducing the mass.

McCray:

Of the optics?

Low:

Of everything.

McCray:

Everything?

Low:

Not only — When you reduce the mass of the — It starts with the optics, because if that is very massive then it has to have a very massive cell. Thatís the thing thatís wrong with the Gemini. They point to one thing thatís fundamentally unsound. Itís this vast amount of steel thatís required in its design to support this thin lightweight mirror. There is no point in having a lightweight mirror if everything else is so incredibly massive — and it is. And it doesnít even have enough strength to support, enough active strength — Thereís passive mass and then thereís an active component —

McCray:

As itís moving.

Low:

— that is supposed to keep it in shape. The thing has no stability of its own. Itís stability is entirely due to the stability of the steel which sits underneath it and the hundreds of active elements that bend the glass. Unfortunately, they calculated something wrong and they cannot bend the glass into the proper shape. So they donít have a telescope. What theyíve got is a two-mirror telescope that doesnít make an image. And so they then have to add an active optic system to that which is supposed to correct the problem. Weíll wait and see how well it actually works.

McCray:

Yeah.

Low:

The compromises that had thereby been introduced are fatal to the original concept of that telescope.

McCray:

The infrared optimization of it?

Low:

Yes.

McCray:

Because this is a personal interview, we havenít talked about your personal life hardly at all. Is there any —? I mean, we talked a bit about your kids with the recorder off. Are there elements that you would like to bring out about your life?

Low:

How important the other aspects other than astronomy are?

McCray:

Yeah. I mean, what else —?

Low:

Well, the family is the number one, and I have had two careers. I have had the career as a scientist and Iíve had a career as a business person. I donít even consider myself a business person, but I have put together a very sound little company which — Infrared Laboratories — and I actually take much more pride in that now in my last years of ownership and leadership than I ever did. Itís almost like a second family to me.

McCray:

How many employees are there?

Low:

Thirty-two.

McCray:

Okay.

Low:

And their well-being and future is a large part of what itís all about as far as Iím concerned.

McCray:

Okay.

Low:

And I also value the community, because people keep telling me how important it is to the community, the research community that we serve. The people in the other community that I serve, namely the semiconductor industry, arenít so nice about nice about telling me what they think, but I still think that there is at least some appreciation or recognition or whatever you want to call it in that area. So having been given the talents or abilities, whatever they are, to do all these different things, I certainly have had a lot of rewards that are not just purely financial from the combination of things. Thereís a large number of different things involved that [inaudible word] donít often think about, but they are all interacting. But if I didnít have the family, I might have just gone off and, as soon as I had a million dollars, bought a $800,000 sailboat and sailed away into the islands.

McCray:

Do you like sailing?

Low:

I like sailing, I like snorkeling, I like the water, period. And so —

McCray:

Itís interesting you live in a desert.

Low:

That was because of the water vapor.

McCray:

Yeah.

Low:

I mean, chose this place to settle down because it had the right combination. Itís not the best in any category, but if you look at all the categories I could never live happily on Hawaii. I donít even particularly like visiting there, much less living there. I mean, I treat islands like people — there are people I like to be with and there are islands I like to be on. Although I like to be on almost every island that Iíve ever seen, there are some that I would prefer, if I got stuck living on an island — which I donít think I could survive on for very long, but if I had to do it, I would pick different islands than the Hawaiian island[s?], mostly because of all the people that are there I guess, but itís sort of — you know, you are torn many different ways, and you canít go in all the different directions. The other thing that I havenít even mentioned personally was music, and I gave up on music at an early age when I went to graduate school is when I finally decided. But all the time I was in Yale, I was a four-year member of the Glee Club.

McCray:

We talked about that before.

Low:

I one time thought I could have — I considered — let me put it this way — I never went so far as to be certain of it, but I thought I had a chance at operatic vocal, a dramatic tenor.

McCray:

Do you have favorite composers?

Low:

Oh I mean, you know, the standard ones. I mean, Mozart is my favorite. Parts of Johann Sebastian are right at the top, but other parts are not. I didnít like everything. And Doherty [spelling?], Puccini, the whole run of Italian opera is really wonderful stuff. But as far as my participation in it, I had to make a choice.

McCray:

Do you regret the choice that you made?

Low:

Sometimes I have. Yeah. I think I have. I have reason to regret it. I could have done a little more and kept it alive. Iíve just let it go completely down the tubes, and in fact if I had it to do over again Iíd like to have found a way to keep it going at the right level. Because itís really rewarding when you perform. I have also done drama as a young person in addition to singing, and just acting is also really keen stuff if youíre good at it. And I donít know whether I could have been good at it or not — I didnít pursue it that far — but another set of talents entirely that arenít used very much in science, although giving talks is something that, where a little bit of that comes into play.

McCray:

When you were observing, did you have favorite pieces of music that you would like to listen to?

Low:

Didnít listen to music. Concentrated on the observing.

McCray:

Okay.

Low:

I have noticed that a lot of people like to have some kind of background noise, I call it.

McCray:

You donít.

Low:

And I canít stand it. I have to concentrate on what Iím doing, and it really bothers me. And so itís not — it just doesnít work [inaudible word]. I can listen to music and become involved in the music very easily, but if I am working then itís not — I have music on my computer, and I always end up turning it off after I get into it. I just, you know let it — Fortunately the CDís only last about forty minutes, so one CDís worth and -Ė Iím not sitting there plugged in with earphones and working [inaudible word].

McCray:

You mentioned family. How about religion? Has that been a big part of your life, or a part at all?

Low:

It was a huge part early and doesnít exist now.

McCray:

Okay.

Low:

In any formal sense. I came from a — Well, you know, I didnít have normal parenting, but I had nevertheless a close Southern family, and I was baptized as a child and I was going to become a minister.

McCray:

Episcopalian?

Low:

No, no. No, no. These were fundamentalists. More fundamental than Baptists. The real honest baptism. The one that you can only barely survive.

McCray:

Immersion in water? Okay.

Low:

And I was, I am told by my aunts and uncles that when I was six or seven I was sought after as this little kid that could spout forth the scriptures. So I had a good part. I wasnít really reading them, but I heard them and I must have been memorizing it. So when, you know, when the truth spouts from the mouths of babes itís particularly wonderful, and so I was really cut out, selected, preselected for a role in the ministry. But science — when I started figuring out how things actually worked as opposed to the mythical aspect of religion — and all religions have some mythology in them — it didnít seem to mix very well with physics. You know, I have some good friends who are good physicists, and they have worked that all out. And so I know that if you need to do that, itís possible to do that. But we stopped taking our kids to Sunday School at a fairly early age. And itís interesting. The three kids were not indoctrinated as I had been and as also my wife at a young age, so we just stopped doing that. Decided that they should find their own way, which is what we had done, and it was harder doing it the way we had done it. And so where we are today as a family is that the three kids are all three more religious than either parent in the formal sense. And I donít think — look, I donít think that being trained the way we were hurt us in any sense of the word. It was actually great. Our youngest son almost became a Catholic priest, and neither one of us are Catholic. He and his wife are devout Catholics, and Emily will be raised that way, because thatís the way itís done in such families. Our oldest daughter is a little, shall we say non-standard but much more religious than, as I say, than we are. And the two grandchildren in Norway are being raised as good Norwegian Lutherans, [inaudible phrase] what they are. And so we didnít break the link evidently, but we didnít try to, you know, bind it.

McCray:

Yeah. How about politics?

Low:

I tend to be on the conservative side. I voted for Deacon Sini [correct two words?].

McCray:

Okay.

Low:

As the best man. So Iím at least that liberal. And when given a choice —

Low:

Is it running?

McCray:

Yes.

Low:

I do listen to that side of the argument.

McCray:

The far right.

Low:

The far right. Because a lot of it I sympathize with. But I canít buy the whole package, and most of it. So I donít think I can be easily labeled as a member of the far right. And find that politics is not — itís a necessary evil, because society has to be run in some way, and thatís how we run our world, is through the type of politics that we have. But it doesnít mean you have to admire the politicians. And as Iíve gotten older Iíve admired the politicians less and less. How many great Presidents have we had in my lifetime? I think that Franklin Roosevelt was a great President all right, because he definitely changed things and made them better. On the other hand, he left behind him — He started or rejuvenated or in some peopleís minds instigated a part of the Democratic Party that I am rather suspicious of. In other words let the government solve all problems of humanity. It can be traced pretty much to his philosophy.

McCray:

Sure.

Low:

And so Iím ambivalent about that. I mean, itís a lot of pluses and minuses. Eisenhower was a strong leader evidently, but he didnít seem to do much. Truman was a pleasant surprise, but again Iím not — I donít know what he would have done in more difficult, in other circumstances. Kennedy — dangerous, basically, John Kennedy and his brother. They almost got us all blown up, meddling. And so Iím not too happy with them. Actually Carter has become one of my favorites now that heís completely powerless and almost without influence in the Democratic Party also. Because they donít really listen to him very much, it seems to me. But as a person, I canít help but think highly of him. And on down the list. I mean, and Nixon was such a problem, depending on how you look at him. And thereís probably two or three Nixons there to look at.

McCray:

At least.

Low:

There was certainly a lot of bad in that man, and he didnít set a good example.

McCray:

Did politics enter into any of the work that you did in any way?

Low:

No.

McCray:

Okay.

Low:

No. I am sort of apolitical. I mean, I detest politicians in principle because of what they do and how they have to do it. And I understand that itís a selection process and if youíre going to be successful you have to do those things to be successful, so you can always get — successful politicians are always going to carry that baggage. But — Ronald Reagan. He certainly did some things. Whether he was a brilliant thinker or not, I tend to err on the side of caution there [laughs], and sometimes people were just lucky.

McCray:

Yeah.

Low:

Things happened right for them. In the Evil Empire, and he did identify it as such, and it was, and still is in the sense that it isnít completely gone, not in that part of the world. I mean, you know, it fell apart not so much because of what we did but because of what they couldnít do.

McCray:

Now that you mention the Russians, was there any fertilization —?

Low:

I had some interesting interactions between, with individual Russians, but outside of the fact that they provided the competition we needed to convince the U.S. government to spend billions and billions and billions of dollars on space as well as space research and on — in a sort of technological race, now what the heck are we going to do now that we donít have to worry about being militarily superior? Where is going to be the impetus? People are going to get tired of high tech computers. Weíre going to have to have something else to take its place. What is going to be the future motivator? Solving the energy problem is what we ought to be working on. If I had any political influence, I would put it in two areas: one is better, more effective science education.

McCray:

Okay.

Low:

I donít worry too much about Shakespeare. I mean that ought to be an option of course, but the sciences are so important, and weíre not doing — we just havenít figured that one out as a society. And we had better figure that one out if we want to continue to prosper. And the other part of it is, is the energy problem. I donít think itís an environment problem; I think itís an energy problem. If we had the energy problem solved we could fix all the environmental problems pretty well — and sustain a population probably larger than what weíve got, although it cannot continue to grow. So thatís number three on my list. Education is number one — science education, so Iím biased. I mean, [there is] nothing wrong with being — I mean, Iím widely educated. I know a lot about a lot of different subjects and it all fits together, and so you should have a general education if you possibly can, but the part that you canít do without in the society is the science and the math and the — [inaudible phrase] all that stuff.

McCray:

The three areas that you identified wouldnít generally put you in the social, into a conservative box, if you will. Education, energy, these issues. Itís interesting —

Low:

The political part is, how do you get people motivated to behave themselves on the one hand and produce whatís best for them. Iím perfectly happy with the idea that you look at it from a personal point of view instead of a collective point of view. Because if everybody really was doing what is best for them, the world would be a very good place. As long as they also realize that they canít — you know, you have behavior — If you are an evil person, your tendency is going to be to get ahead by using your evil tendencies. And I havenít dealt well or successfully with how you, how society ought to do that, take care of that. But I think that in my experience competition — clean competition and freedom, individual freedom. Thatís how I got along. Thatís why I was successful. And Iím sure it could be that way with other people. And so if you put a lot of barriers, and if you start removing personal accountability — with is the liberal thesis as I understand it; I have a hard time thinking in positive terms about the liberal philosophy — but certainly at the core of it is, is that what is good for the community is what is best for the individual.

McCray:

Okay.

Low:

And we see that in Norway, and it is lovely, but itís going to lose it for them. I mean, you know, itís not going anywhere. The Euro is sinking. And we are going to have to have another plan to rescue Europe, for Pete sakes.

McCray:

Another martial plan?

Low:

I guess. I mean those poor helpless souls over there just canít seem to get the picture. And itís so thoroughly socialized now. I mean you talk to people that come over here and then have to go back and live in Germany, itís horrible there. It really is. They donít have much to look forward to. And that does tend to be the basis of wars.

McCray:

Yeah.

Low:

I was too young. Born in Ď33, so I certainly didnít have any direct knowledge of the First World War, although it hadnít been over very long when I was born. The Second World War I remember very well. I was a kid. And then we had this succession of skirmishes, shall we can them, bloody skirmishes with the Communist world. Itís hard to see where thatís headed with the freewheeling attitude that we have today. We want to do commercial enterprises that are to our benefit throughout the world. And we seem to be good at it. I donít know. [inaudible phrase] philosophical.

McCray:

Well, itís important to —

Session I | Session II