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B. Thomas Soifer

Tom Soife

B. Thomas Soifer

B. Thomas Soifer

Harold Brown Professor of Physics, Emeritus

By David Zierler, Director of the Caltech Heritage Project

August 11, 19, 20, and 26, 2021

DAVID ZIERLER: OK, this is David Zierler, Director of the Caltech Heritage Project. Today is August 11, 2021. It's my great pleasure to be here with Professor Baruch Thomas Soifer. Tom, it's great to see you. Thank you so much for joining me.

BARUCH THOMAS SOIFER: Well, it's really my pleasure to participate in this.

ZIERLER: To start, first things first, is with your name. Your first name appears to me to be religiously Jewish, and then, of course, you have a secular middle name that you go by. Can you tell me the story there?

SOIFER: If I understood it, I would tell you what the story was. I don't remember what my Hebrew name is. Obviously, my first name is Hebrew. The last name is the immigration officer's transliteration of the word sofer, which is scribe, which was my grandfather's name when he came over. So indeed, I'm of Jewish heritage. All four of my grandparents emigrated from Russia around the turn from the 19th to 20th century, in the decade or so before and a bit after.

ZIERLER: Now, was that your grandfather's profession? Did he write sifrei Torah, Mezuzos?

SOIFER: No, no, no. I don't know what he did in the old country. My father's father was a hat maker. Actually, in Fort Smith, Arkansas.

ZIERLER: The far-flung places that Jews found themselves.

SOIFER: That's right.

ZIERLER: More officially, please tell me your title and institutional affiliation.

SOIFER: Well, right now, I am the Harold Brown Professor of Physics Emeritus at Caltech. I've been at Caltech, first as a senior research fellow, then as a senior research associate, then as a professor, and then as the Harold Brown professor, since the first working day of 1978. And before that, I was an undergraduate at Caltech, entered in the fall of 1964 and graduated in June of 1968, a very turbulent time in the country's history.

ZIERLER: Tom, can you tell me a little bit about the significance of being named in Harold Brown's honor?

SOIFER: Well, I take it as a great personal honor for me. I'm very pleased to have that. Harold Brown, of course, was one of Caltech's presidents. He was the president who replaced Lee DuBridge. There might've been an interim president, but I don't think so. I think it went from Lee DuBridge to Harold Brown. And this is, of course, lore that I heard long ago, the way that he controlled the growth of the upper administration at Caltech was, he said, "You can have as many people as you want, but they all have to fit on the third floor of what was then the Millikan Library." This is after Throop Hall had to be taken down after the Sylmar Earthquake. This is not quite ancient history, it's around 1970. But that's pretty close to ancient history.

ZIERLER: In the four years since you've gone emeritus, to the extent that this has expanded your bandwidth without administrative and committee responsibilities at Caltech, just to pursue the science and the astronomy that's most important to you, what have you been up to in these past four years? What's most important?

SOIFER: Well, I wish I could say that I have abandoned the administration and committees, but I actually have not. What I have been doing is participating in the governance of CARA, the California Association for Research in Astronomy, the governing organization for the Keck Observatory. As Division Chair, I was a member of the CARA board, and when I became emeritus, when the previous provost stepped down, they appointed me to replace him. Basically, I think, because of my long history with CARA, with the Keck Observatory. I certainly have been associated with Keck since its creation, and I have a deep and tremendous affection and commitment to that observatory as a truly magnificent research facility for Caltech.

And I also happen to know an enormous amount of the history. And so, I've been involved with the Keck Observatory as both the vice chair and the chair of the CARA board. And now, I'm back to being vice chair. It rotates between someone from University of California and someone from Caltech on a three-year cycle. And I've been sharing this with George Blumenthal, who is also emeritus. He stepped down as the chancellor for UC Santa Cruz. But we've been working as Chair and vice chair for the last five years or so. I've also been heavily engaged in the board of the TMT International Observatory trying to help make that a reality. It's the next large telescope that I believe Caltech needs to be involved in. It's been a much more difficult road to get there than anybody conceived of.

So I've been doing that, too. And as my sidelight, if you will, for the last five years, longer actually, when I was active faculty, I was working with a very longtime colleague, Keith Matthews, to put together a new instrument for Keck. It's called NIRES, the Near-Infrared Echelle Spectrograph. And we finally got it on the telescope. And so, I've been able to do observations with that instrument, pursuing my interest in spectroscopy of very dusty, very high luminous galaxies in the distant universe. So that's what I've been doing in my retirement [laugh].

ZIERLER: Beyond your immediate areas of interest, more broadly, in observational astronomy. With all of the projects going on right now, what are you most personally excited about? What can be understood now that might not have been possible in earlier areas in your career?

SOIFER: Well, I think the advances in facilities are enabling us now really understand how galaxies formed and have evolved. And that's what I personally, and from my own research interests, am most excited about. I grew up in infrared astronomy. To scratch an infrared astronomer, all you need is to know something about dust. And the fact that all stars start in clouds of gas and dust, and the dust is very efficient at blocking out the optical light of stars and converting it into infrared radiation, sort of leads infrared astronomers to study stars in formation.

And I've been studying, for the last many decades, the large quantities of stars' information in galaxies. And we've found very dusty galaxies. And we have learned with the new space facilities, in particular, with the Spitzer Space Telescope, which I was also a part of, that very dusty galaxies were a major component of the universe as galaxies formed and evolved in the universe. So, from the perspective of what I'm excited about is seeing that's possible now to really understand how galaxies have formed and evolve. That's the long answer to your short question.

ZIERLER: What about the way that advances in astronomy require the successful interplay between observation and theory? Where is the field now in terms of areas where the theorists are leading the observers, and vice versa? And how might that compare to earlier eras in your career?

SOIFER: That's a very challenging question. Earlier in my career, I would've said that one of the exciting things about astronomy is that universe was far cleverer than the theorists. And so, we would make discoveries, and then we'd go to the theorists, and they would think about it for a while, sometimes if it's a hard problem, for a long time, if it wasn't a hard problem, for a short time, and get more sophisticated modeling. But it was always that the theory followed the observations. At this point, it's kind of difficult because I grew up in that era, and so the things that I find most interesting and fun are the things that have not been predicted, and that are new and exciting, where the observations, if you will, have led the theory. And one example of that for me is exoplanets.

We obviously knew that there were planets around our star and expected that there were planets around other stars. But until there was real observational evidence that these things really existed, there was no theory about planet formation – there was a theory of the formation of our solar system, but we've certainly learned that ours is a very unusual, not terribly common stellar system. And so, that's just one example, where, at least to me, the fun part is the kind of thing where the observations lead the theory. An example of sort of the other way around, I would say, is LIGO. That's really more a physics experiment, although because there's the O in LIGO, the observatory, and it really has become an observatory, but there, the theoretical predictions did lead the way. And it was a tremendous experimental triumph to have the detections. And what they're doing is enormously exciting. But it's one of the examples where I think there really is a strong interplay because at least the papers I read show that the modeling is up to explaining the observations very well.

ZIERLER: That gets me to my next question, which is based on nomenclature. There's astronomy, there's astrophysics, and there is cosmology. Over the course of your career, where have you seen these disciplines bump up against each other and even overlap? And how might you represent Caltech more institutionally in its broader approach to dealing with these disciplines?

SOIFER: Well, I think that one of the great strengths of Caltech is that we've, I think, always emphasized the astrophysics, which is, I would say, the understanding of the physics of the astronomical bodies that are observed. One of my colleagues, a physics colleague, not at Caltech, sort of pejoratively referred to some parts of classical astronomy as a sort of botany. In a very pejorative way. But we don't do that. We certainly look for discovery of new phenomena, and then try to understand the phenomena. And that, I think, has been a hallmark of what we do at Caltech. And what is the boundary of cosmology? It used to be that cosmology was finding, in a classical astronomer's sense, two numbers, h-naught and q-naught. The Hubble expansion rate of the universe, and then the deceleration. That was from long ago.

And then, with the detection of the Big Bang and the relic radiation from the Big Bang, the cosmic microwave background, one began to be able to probe the universe back, effectively, to the beginning of time. And Caltech has evolved with the rest of the field and has participated in leadership positions in the cosmology. Cosmology, in that classical sense, is still, I think, more in the realm of physics. The people at Caltech who do that are more professors of physics rather than professors of astronomy. I guess, perhaps, the boundary is, when stars and galaxies form, then it becomes astronomy and astrophysics.

ZIERLER: Now, a generational question. If we can harken back all the way to your undergraduate days at Caltech, would there have been anybody on the faculty who would have defined themselves as a cosmologist the way that, at Princeton, a John Wheeler or a Bob Dicke would have?

SOIFER: I think the answer is, at that time, no. In a slightly earlier epoch than my undergraduate days, H. P. Robertson was at Caltech, and I believe he was what I would describe as a cosmologist. And while not on the Caltech faculty, Allan Sandage, who worked at Mount Wilson and later, Las Campanas Observatory, was indeed effectively a faculty associate because we had a very strong collaboration with the Mount Wilson Observatory, which used to be the Mount Wilson and Palomar Observatories. But he was what, from the astronomy perspective, would be the premier cosmologist. He studied galaxies at great distances, seeking h-naught and q-naught. And there were members of the Caltech faculty who participated in that, not from that direction, but in the early 60s, Martin Schmidt discovered that quasars were at cosmological distances. And so, this turned into, if not the cosmology that Bob Dicke, Jim Peebles, and Wheeler did, the astronomy getting into the cosmology world.

ZIERLER: Much more recently, last year, almost still hot off the press, you were awarded the NASA Distinguished Public Service Medal, which is a huge honor, and one of a number of ways that NASA has recognized your contributions. Tell me what it felt like to receive this medal and what you were being recognized for.

SOIFER: Well, I'll start with the latter. I was being recognized as the Director of the Spitzer Science Center. The Spitzer Space Telescope was the fourth component of NASA's great observatories. NASA had this really magnificent vision of space observatories spanning virtually all of the electromagnetic spectrum, from the gamma rays, which was the Compton Observatory, through Hubble, which is UV and optical. There's the Chandra Observatory, which was x-ray. And then, the infrared observatory, which was the last one to be started and the last to be launched, which was Spitzer. And then, of course, beyond that, the ground is perfectly good. There's no need to get above the atmosphere to do radio astronomy, millimeter and centimeter wavelengths.

But the Spitzer Space Telescope was the fourth component of NASA's great observatory. And it started in the early 1970s as a shuttle-attached payload. And it started as one of the justifications for the space shuttle. And then, after the IRAS survey, which I was also involved with, the Infrared Astronomy Satellite mission, we did an All Sky Survey, which revealed that there was an enormous amount of exciting science to be done in the infrared, within the range of a few microns to hundreds of microns, where you gained this enormous amount of sensitivity by being able to cool a telescope. NASA ultimately decided, in its infinite wisdom, to pursue Spitzer. And JPL was the lead center. And from the beginning when the mission started serious construction, I became the director of the Spitzer Science Center, which was done on the Caltech campus.

And we had a magnificent group of people. Explicitly, this Distinguished Public Service Medal was for my being the director of the Spitzer Science Center. And that term will actually end at the end of this fiscal year, when the Spitzer Science Center and Spitzer project formally ends. The mission actually ended in January of 2020, and we've been finalizing the data for it since then. And we'll hand it off to the archive for curation and use by the astronomical community. So that's what the award was for. I think I was given the award for surviving [laugh]. But it was for being able to let the really smart people who did all the work do their jobs and sort of protect them from the vagaries of politics, make sure they had the money, and get out of their way so they could do their jobs.

ZIERLER: What is your sense of the overall budgetary environment in astronomy these days? Is this a good time to submit grants?

SOIFER: That's a good question. I think for right now, when my understanding is that Congress is very expansive in funding science, I think there's a recognition that science is valuable. It's funny that it's now thought of in economic terms as being an engine of economic development for the country, rather than, at least when I got into it, just for the sake of learning what the universe is all about. But I think it has a tremendous positive effect on the budget of, if you will, the basic sciences, astronomy being one of those, where you can't point to commercial spinoffs. But we always try to justify ourselves to the funding agencies. But at least right now, my sense is that it's a pretty good time. But it remains to be seen.

ZIERLER: Before we go and establish your personal narrative, going all the way back to the beginning, my last current question, of course, is one we're all dealing with. How has the science for you been affected one way or another by the seemingly unending pandemic and the mandates of social isolation and remote work? In what ways has remote communication always been par for the course in astronomy, and you were well-positioned, and in what ways has not having that physical contact with your closest collaborators really hampered the work?

SOIFER: To be honest, for me, because I'm obviously at a very late stage in my career, I think that the impact has been less negative than for others, particularly for people who are participating in experimental instrument development, laboratory work, where people need to go into laboratories, people need to interact much more closely. I certainly see, as I mentioned, my committee work has, dare I say, continued without interruption. Certainly, the personal interaction is far less, and I more appreciate the value of the face-to-face meetings by not being able to have them. Meetings on Zoom are less interactive than would be face-to-face meetings. And that's a real loss, and a loss of efficiency.

But I think that we're able to adjust to that. I think the workings of particularly experimental people, people who are building instruments--and one of my great interests is in instrument-building for observatories--have been much more impacted by the constraints of COVID. One of the things I have seen, a result of COVID, is, far more emphasis, in terms of observational astronomy, of being able to just observe from home. It used to be, when we first opened the Keck Observatory, everybody would go to Hawaii to observe, and we would actually even go to the mountain to observe.

And of course, once microwave links became both high enough in terms of bandwidth and reliable enough, you didn't have to go to the mountain. Because it was unpleasant. Oxygen starvation is not a fun thing to have to deal with. We would go to Hawaii to observe. But then, when the links became reliable to Hawaii, you didn't even need to do that. And now, with COVID, the interfaces have been developed so that you could just observe using your laptop. And that's a loss. Because the people who run the observatory really need to understand how the people who use the observatory use it. And if they're not there, you don't get that kind of interaction. It's nothing I can quantify.

But I am concerned that it's a negative implication for how well these ground-based observatories operate, how well they meet the needs of the user community, particularly for a place like Caltech, where we have a group of users who are very knowledgeable about the facilities, about the instruments, about how to extract the very best out of the observatory. Not having the interaction with the staff in Hawaii that operates the observatory, I think, will have a long-term negative impact on how well the observatory meets our needs. And it will also have a negative impact, in my opinion, on the commitment of the staff at Caltech to the observatory. I've seen that at least in my generation, we have a very strong visceral commitment that the Keck Observatory is part of Caltech.

And then, there are all the other observatories, which we can use. What I don't want to see happen is that the Keck Observatory for Caltech becomes just another facility that the Caltech people can use or not use and go to some other facility. One of our strengths has been having premiere facilities and being able to exploit them. But it requires a two-way commitment, both the people who operate the facility committed to Caltech as an institution, and us, Caltech, committed to the facilities. And understanding that it's essential to our success. And one of my worries about where we are now is losing that tight connection. And I don't know how it's going to play out.

ZIERLER: We'll certainly develop that further as we go into the narrative. But for now, let's take it all the way back to the beginning. Let's start, first, with your parents. Tell me a little bit about them.

SOIFER: Well, they were, as I had mentioned, first generation born in this country. They were children of the Depression. They grew up in the Depression, and so they had that mentality.

ZIERLER: Where are your parents from?

SOIFER: My father was born in Fort Smith, Arkansas. My mother was born in Sioux City, Iowa. These are places where Jewish immigrants were sent when they came to this country. Because they were groups of Jewish immigrants there.

ZIERLER: Now, were the communities large enough that they had a shul to go to?

SOIFER: I believe they did. My mother's family migrated to California I think probably in the early 20s. She was young, probably less than 10 years old when they moved. They became part of the early migration to California. My father moved to Chicago, the big city. And they were both college-educated. And then, they actually met in Washington DC. They were part of the New Deal. They went to work in DC. And so, that was their background.

ZIERLER: What were their fields? What did they do?

SOIFER: My father was an accountant. My mother studied political science. And ultimately, she worked in some administration within the federal government in the 30s. She graduated from Berkeley. And to be honest, I'm not sure what field she was in. But they wound up moving to New York, and my father worked for the Jewish Federation in New York post-World War II. He was diabetic, so he was not able to go into the Army during World War II. And my mother basically became a housewife to raise the kids. And so, I was born in New York, moved to Pittsburgh when I was 2, and the family joined the westward migration to California in the middle-50s. I've been a resident of California, except for the five years of graduate school plus one year of post-doc, since 1957.

ZIERLER: Now, was Pittsburgh just a stopover? Or your family spent some time there?

SOIFER: We were there for about eight years, from when I was 2 to 10.

ZIERLER: What prompted the family to move out to California?

SOIFER: Family. My mother had significant family in California. So that was the reason for that migration.

ZIERLER: Did Sputnik register with you as a kid?

SOIFER: Oh, yeah. I was part of that generation. Sputnik was '5, I think. So the ripple effects of that happened, basically, as I moved from elementary school, to middle school, to high school. The timing, for me, was perfect.

ZIERLER: Where did your family land in California?

SOIFER: On the west side of Los Angeles, actually. My going off to college wasn't too far.

ZIERLER: Now, growing up, were you Jewishly connected? Did your family belong to a shul?

SOIFER: Oh, yeah. I confess, my connection to Jewish life sort of terminated after I got bar mitzvahed. I had checked that box. [laugh]

ZIERLER: [laugh] And you went to public schools growing up?


ZIERLER: Did your high school have a strong curriculum in math and science?

SOIFER: There were really good teachers. It was not a particularly notable high school. I went to Venice High School. There were some very strong high schools in the neighborhood at the time. University High School, which was right next to UCLA, Palisades High School, which is along the coast were sort of competitors with Venice High School. But there was a strong group of effectively college prep students at Venice High School. So here was a very good curriculum, good teachers that could engage and inspire. My physics teacher was among those. I don't know how well he knew him, but he certainly talked about knowing Dick Feynman. The thing that he gave me as a graduation gift when I was going off to Caltech was Feynman Physics Volume 1, which turned out to be my textbook.

ZIERLER: Growing up in LA while the smog issue was a real problem, did you have clear skies? Could you look up at the night sky? Was that something that was available to you?

SOIFER: Well, it turned out because I grew up in West Los Angeles, the smog wasn't nearly as bad as in Pasadena. And so, I don't recall there being really bad smog days. Certainly, when I moved to Pasadena for college at Caltech, the smog was worse in the mid-60s. But I do remember when I first moved to Los Angeles, there were backyard incinerators to burn garbage. And those were eliminated by 1960 or so. There's no question that the smog was a big issue at that time, but I didn't have problems with it personally.

ZIERLER: When you were thinking about undergraduate programs, was Caltech the be-all and end-all? Or did you apply more widely?

SOIFER: I confess it was not the dream. I wanted to go to MIT. I applied to Caltech, MIT, Harvey Mudd. High schools at the time did not have advanced placement classes. But the smart kids went to UCLA for courses as seniors. And so, I did that. I was actually already admitted to the UC system. And so, if you will, my backup was Berkeley. It just sort of shows the happenstance of life. I wanted to go to MIT because it had the cachet. And I was admitted to MIT, but with no financial aid. And my family couldn't swing that. At Caltech, this was back in the good old days when there were California state scholarships that basically paid what amounted to half the tuition of Caltech at the time, which was an obscenely small number in comparison to today. And that really enabled me to go to Caltech.

ZIERLER: Was it physics from the beginning that you wanted to pursue?

SOIFER: Oh, yeah. Well, the amusing thing, as I think back about it, the flukes of life certainly set your course. Had I gone to UC Berkeley, I think I would've been a history major because I was very interested in history at the time, as well as physics. I'd said long before that, "I want to be a nuclear physicist," because that's what you say when you're a kid, and you don't understand what these things are. So the choice was physics or history. And I'm grateful that I wound up at Caltech. Had I gone to Berkeley, I would've probably landed in the drug culture and the free speech movement. And who knows where I'd be at now? [laugh] But it really was physics. At the time, when I went to Caltech, about half of the undergraduates were physics majors.

ZIERLER: Did you understand physics to be the entree to astronomy? Or were you considering particle physics, solid state? Were you just sort of interested in generally learning physics at that time?

SOIFER: It was really the latter, learning physics, and not really having a very clear picture of what it was. I think what got me into astronomy was two things. I enjoyed the introductory course in astronomy that was given at Caltech. And the other thing that got me into it was, I got a job working for Gerry Neugebauer, the founder of infrared astronomy at Caltech, as an undergraduate. And he was doing this sky survey, which was opening the two-micron sky, seeing the first things that had not been thought of by astronomers or theorists. And this was great fun. I was very much part of that. And it was an amazing time. In the middle-60s, the universe was being revealed through looking at it beyond just the very narrow portion of the electromagnetic spectrum, which is the optical band. And so, this was very exciting. And being able to participate in a truly forefront activity as an undergraduate was an opportunity where I just lucked out and wound up doing something that became my life's profession and is just fun all the way.

ZIERLER: Did you have opportunity at all to interact with people like Gell-Mann and Feynman as an undergraduate?

SOIFER: I confess, no. As a senior, I went to the first class of advanced quantum mechanics that Feynman was giving that year, and it only took me one lecture to figure out this was not what I was cut out for. I would see Feynman lectures from time to time. They were public lectures. But I did not interact with him. And Gell-Mann was not part of my world.

ZIERLER: Did you recognize as an undergraduate Caltech's very special place more broadly in the world of astronomy?

SOIFER: I don't think so. I wish I had been more aware at the time. But the one thing I remember, which was not a Caltech discovery, was pulsars. There was a journal club where somebody, I don't remember who, was talking about this paper in Nature, the discovery of pulsars. Which is one of the profoundly important discoveries of the 1960s in astrophysics. I would go to these things as an undergraduate, and they were great fun. I think it was Jesse Greenstein was sitting in the back, "Little green men." But unfortunately, I wasn't sufficiently attuned to understand what I appreciated later, which was how very special a place it was to be at Caltech at that time.

ZIERLER: And what about Carnegie? Was that on your radar at all as an undergraduate?

SOIFER: It was in the following sense. The telescope that we used for the two-micron sky survey was sited at Mount Wilson, which was run by Carnegie Observatories. And this is one of the great thrills of being able to participate in this enterprise. I got to go up and be the observer. It was run every night. And five nights a week, it was run by a professional observer. And two nights a week, one of the members of the group would go up and operate the telescope.

And so, there were a couple or three times that I got to go up and operate the telescope. And you stayed at the monastery, where all of the observers who used all the telescopes stayed, and you would eat lunch and dinner with all the observers. And so, I certainly was aware very much of Mount Wilson Observatory. And there were, historically, lots of collaborations, but lots of conflicts between the Mount Wilson and Palomar Observatories, Caltech and the staff of Carnegie. And I, of course, didn't know about that. But it was great fun. And then, I actually did get to use some of the telescopes. When I came back to Caltech in '78, I used the 100-inch a few times. I certainly was very much aware of the Mount Wilson Observatory.

ZIERLER: Now, as you already indicated, you would've pursued a much different life had you gone to Berkeley. But particularly toward the end of your undergraduate time, '67, '68, what was campus like? Was there any anti-war sentiment? Was the Civil Rights issue at all on people's minds at Caltech during those years?

SOIFER: It was nowhere near as prevalent as at "real" universities. I guess my description of that is the following. During my time at Caltech, the thing that most riled the undergraduates was the announced cancelation of the original Star Trek. Not anti-war, not Civil Rights. The Caltech Y, which was very socially active, brought in speakers on all of those topics. But I think that particularly the Caltech undergraduates were pretty oblivious to that at the time. But this was pre-co-ed, prior to women becoming part of the Caltech undergraduates. And it was a different world. I think it's a much better world now.

Before school starts nowadays, the freshman go off to a location to meet each other and to hear talks about what life is going to be like. And I was struck one time, maybe 15 years ago, maybe even a bit longer, that when I went to this, it suddenly dawned on me that there were enough women in the freshman class that it was almost parity. I know numerically, it wasn't exactly at parity, but it was such a different and far healthier environment than had been at Caltech before.

ZIERLER: When you were thinking about graduate school, was the advice specifically not to stay at Caltech?


ZIERLER: Where were you looking?

SOIFER: Well, I was looking at Berkeley. It turned out UC Santa Cruz had just opened as a campus, and they had imported, as their faculty, the entire scientific staff of the Lick Observatory. They became the astronomy faculty at Santa Cruz. And so, that was a very interesting one. And then, Cornell. At the time, the major attraction at Cornell to me was Arecibo, the facility that just recently collapsed, which had just been constructed and had been designed and built by faculty at Cornell. And I was somewhat interested in pursuing radio astronomy. And so, that was of an interest to me. At the time, I don't think I had really been aware that there was an infrared program at Cornell. So those are the three places that I had applied to.

ZIERLER: And in making these considerations, was there any faculty member at Caltech you considered to be a mentor or who you could turn to for advice on these kinds of decisions?

SOIFER: To be honest, I don't think so. I had a mentor as an undergraduate, Gerry Neugebauer. But I don't think I went to him for advice about graduate schools. There was, from my personal perspective, a very positive side benefit, which certainly, at the time, I hadn't appreciated, about choosing Cornell and then choosing the infrared astronomy group at Cornell to participate. And this had to do with, as you mentioned, the Vietnam War, which was going on at the time. And their research in infrared astronomy, at the time, was partially funded by the US Air Force.

Because I was working on that project, I was able to maintain a student deferment. So that was a side benefit. Had I gone to either Berkeley or Santa Cruz, I don't believe I would have been able to have that kind of a benefit. But at the time, student deferments were still common. And so, that did not drive my decision. I think the main reasons for choosing Cornell were the radio astronomy and wanting to see a different part of the country.

ZIERLER: Absent a crystal ball, I wonder if you had some inkling that you'd be returning to Caltech as a lifer, and this was one opportunity you had for a sojourn out of Southern California.

SOIFER: Well, no, I didn't think I'd be coming back to Caltech. But I had this foolish vision that I thought it would be nice to live in snow for a while. [laugh] But being educated, I certainly learned that that was a mistake.

ZIERLER: Now, what was the program that you applied for at Cornell? Was it astronomy?

SOIFER: It was astronomy, yes.

ZIERLER: Was most of your cohort coming from a similar trajectory, physics undergraduate, astronomy graduate programs?

SOIFER: Yeah. It was really close to the beginning of the real astronomy program at Cornell. And there were only three of us. But they were all physics majors as undergraduates.

ZIERLER: What observing opportunities did you have right off the bat when you got to Cornell? What was available?

SOIFER: Well, actually, the one thing that I did, one of my officemates had built a Fabry-Pérot instrument to study molecular hydrogen and got time on one of the Kitt Peak telescopes with his instrument (Kitt Peak being the US national observatory), and I went out to help him. But the work that I was doing was building payloads for sounding rockets. You'd spend a year building a payload, and then you'd take it to White Sands Missile Range and launch it. And that was the observing opportunity. I think my first rocket payload was in probably the end of my second year or beginning of my third year as a graduate student. And we had built this payload, tested it, and it all looked great.

And then, we took it out to White Sands, and we were getting our payload ready and mounting it on our sounding rocket, and there was another rocket that was being launched while we were getting ready. And so, I watched this launch. It's great fun to watch these sounding rockets. But my first reaction seeing this rocket launch–because these rockets go off at five Gs. They start coming out of the launch tower with an acceleration of five Gs. So it's nothing like the graceful launch that I would see of the Apollo rockets going from Cape Canaveral. I was both floored and terrified. "My God, my payload can't survive that." [laugh]

ZIERLER: Of course, the 60s continue when you get to Cornell, even into the early 1970s. What was your response to what was going on, on campus, at Ithaca? How was it different at Caltech, and were you any more or less politically engaged as a result?

SOIFER: There was very strong political activity. Lots of anti-war [sentiment]. Around the time of the Kent State protests where several students were killed by the National Guard, which contributed to an enormous amount of protest all over the country, and certainly, Cornell was one of the hotbeds, the student union was taken over by the Black Student Union at Cornell. And there might've been a Newsweek cover of the students marching out of the student union carrying serious weaponry, rifles. And this shut down the campus. And there was a long teach-in that probably lasted a week where, basically, the campus was shut down.

And the central focus of this was this gigantic gymnasium at Cornell, Barton Hall, where the basketball courts were. It was gigantic. Basically, a basketball team would play before a crowd of several thousand. It was a huge indoor facility. That's where it was. And there were teach-ins going on. And so, I would observe the activities. I was never really a significant participant in those activities. But I was an observer. And one thing that I'd learned, I confess, was being very leery and frightened of what I would call mob hysteria. Because I could see this crowd mentality took over everybody. Through this kind of mob mentality, totally irrational things become accepted.

ZIERLER: Who was your graduate advisor, and how did you develop that relationship?

SOIFER: Well, his name was Jim Houck, and he was a wonderful advisor. I continued working with him for the rest of his life. Unfortunately, he died about six years ago. When I first got to Cornell, he was a post-doc in the group that I worked for, which was the infrared astronomy group. And he was sort of the second-in-command. The professor was Martin Harwit, who later became the director of the Air and Space Museum. But Jim was a post-doc, and he was really the hands-on leader of the group. And the second year I was there, Martin went off on sabbatical, and Jim was appointed as a professor. And I basically became his first student.

And so, we worked very closely together. He was a refugee from physics. He had gotten his PhD in solid state physics. And he was interested in astronomy, and he got this post-doc with Martin. But we developed a great rapport. He came at it as an experimental physicist. And this was the wonderful thing about infrared astronomy. Neugebauer, who was the leader at Caltech, came to infrared astronomy from experimental physics, Houck did, all of the people who invented the field were experimental physicists. And that's sort of the way I was taught to think.

ZIERLER: What do you think the significance of that intellectual heritage is?

SOIFER: First of all, an enormous respect for the importance of the technology, of the people who build things, who build the experiments. Always looking for new and better technologies. And a proper appreciation for that contribution. One of the perspectives of the classical astronomer is that the facility is there for the astronomer to use. And when you have to build the facility yourself, you have a much greater appreciation for the contributions of the people who build the facility and how important that is.

So it's that perspective. And we saw that with the Keck Observatory. The people who were able to envision the Keck Observatory, Jerry Nelson – who also, by the way, went through the Neugebauer undergraduate school. He was participant in the two-micron sky survey. I actually took over his job when he graduated and went off to Berkeley for grad school. I took over what he was doing on the two-micron sky survey. But he was the person who envisioned how to build the Keck telescopes or what they should look like and worked through all of the physics. It was a physicist who solved physics problems, solved engineering problems. And he properly got the recognition for his contributions.

ZIERLER: What was the process intellectually, academically, scientifically, for developing your thesis research?

SOIFER: Well, the first thing to remember is that at the time, if you had a new instrument for infrared astronomy, and you pointed it at the sky, you would find something new. All you had to do was build an instrument that would work, and you'd make a discovery. That's the starting point. The focus was building payloads for sounding rockets. And Jim Houck, being a refugee from solid state physics, what he understood was, "What we need is infrared detectors." Because at the time, infrared detectors, the hard problem was detecting the photons. The detectors were lousy.

What one needed to do was build better detectors. And this was a time when it didn't require all of the enormous capital investment to build these very huge devices, megapixel infrared detectors. You'd build single pixels. And so, what I did was build infrared detectors, learn how to dope germanium. We'd buy germanium boules and dope them with copper, which sort of diffused into the germanium, and the copper-doped germanium was a very good detector of infrared photons in the wavelength range from about 5 to 25 microns. And that was the range that we were working in. We wanted to study the sky over that wavelength range. And then, you'd basically fill detectors, put it behind a very small, six-inch diameter telescope that was cooled to four degrees (Kelvin, or degrees above absolute zero) .

And so, of course, you could not open this telescope in the atmosphere because all of the atmospheric gases would just condense on the telescope, and you would get nothing. So that's why you had to use a sounding rocket. You'd put the telescope into a cryostat, a big thermos bottle, and you would launch it above the atmosphere. Then, you'd open the cover, and you'd look out. And so, that was the exercise. The first thing we looked at was just to see how bright the night sky was at those wavelengths. And this was making an absolute measurement, that is to say the total flux of photons onto the detector, which is a very hard measurement to make.

And so, we spent a lot of time making sure that we understood how to do it. But basically, it turned out what we found was that the interplanetary dust in the solar system provides a glow at those wavelengths because it's dust that's heated by our sun and is a real measurable and fairly bright background that is the night sky brightness above the atmosphere. And so, that was that first thing we did. we didn't so much care where we pointed, other than we needed to know where we were, what the coordinates were in solar system coordinates. We used those ecliptic coordinates, so how far above the plane of the planets we were to be able to see how the brightness of the sky changed as you looked out of the plane of the planets or in the plane of the planets.

And then, after that, we knew that the center of our galaxy, from other work, was very bright at those wavelengths. And also, at longer wavelengths, 100 microns. A colleague of mine, another graduate student, Judy Pipher and I, we divided the universe into wavelengths below 25 microns, which were my wavelengths, and above 25 microns, which were her wavelengths. 100 microns or so. But we knew that the center of our galaxy was also a very bright source of infrared radiation. People had measured it from airplanes, from balloons. And so, our next rocket flight, we targeted the center of our galaxy.

And again, we found that it was a very bright source. And these the technologies of making absolute measurements as opposed to measuring the difference in the brightness between one part of the sky and another part of the sky that's very close to it. We found that the brightness of the sky was much greater when you measured the total flux of photons and when you make a differential measurement of the difference between pointing it here and right next to it. Those were the projects that we did as graduate students.

ZIERLER: I'm tickled at the notion that the field was so young at this point that you could look up any time at the sky, essentially, and find something new. With that vast opportunity before you, how was this particular area of research responsive to some of the broader questions in the field at that time?

SOIFER: I think the question of the field at the time was, what is out there at these wavelengths? Because we were among the first people to look. In a way, it's a question that's very simple. You don't have to think deeply. But it's very important because that's the first thing you need to do, be able to describe the environment that you live in or the environment that you find yourself in. And so, at least in my view, it was discovery mode. What is it that's there? What is bright in the infrared sky? That was the question.

ZIERLER: What were some of the central conclusions of your thesis?

SOIFER: I think some of the central conclusions were that there's an enormous amount of dust in these environments that we looked at and that the effects of that dust, in terms of being able to measure the total power output from the celestial objects that we're studying, had been vastly underestimated because you weren't properly accounting for the effects of the dust because you couldn't really see those effects until you could measure the amount of energy that this dust had absorbed and then reradiated. It absorbed the radiation from the power sources, the stars, and then reradiated it. And you weren't really properly taking that into account.

ZIERLER: I'll test your memory. Who was on your thesis committee?

SOIFER: Oh, gosh. Well, Jim Houck, obviously, and Martin Harwit. I hate to say this, I can't remember who else. [laugh]

ZIERLER: Maybe you remember, perhaps, a memorable question or two from the oral defense.

SOIFER: It's so long ago, [laugh] I can't remember, I'm sorry.

ZIERLER: Although, perhaps, an uneventful defense means that it was successful.

SOIFER: Yeah. Actually, I hate to say this, at Cornell, I think what happened was there was no "thesis defense". What you did is, you got the signatures of the people on the committee on your thesis. And I don't think there was a formal committee where I had to make a presentation. But I would not stake my life on that.

ZIERLER: What opportunities were available to you at that point in post-docs, faculty appointments? What were you looking at?

SOIFER: Well, I was certainly wanting to stay in the field. And there was a post-doc at the Smithsonian Astrophysical Observatory, which, while I was there, became the Center for Astrophysics, a combination of Harvard College Observatory and the Smithsonian Astrophysical Observatory. I actually applied for a post-doc at Caltech, and I think one or two others. I had made a commitment to this person at SAO. Unfortunately, I made that commitment probably too early. And then, by the time I got a letter offering me a job at Caltech, I had already made a commitment, and I didn't feel that I could go back on that commitment. So I went to SAO for a post-doc. But I was not happy, and so I didn't stay there.

ZIERLER: That's a great place to end for today.

[End of recording]

DAVID ZIERLER: OK, this is David Zierler, Director of the Caltech Heritage Project. It is August 19, 2021. I'm delighted to be back with Professor Tom Soifer. Tom, it's good to see you again.

THOMAS SOIFER: Good to see you.

ZIERLER: Tom, to go just a bit back, we were talking before about your decision to join the Smithsonian Observatory, and you intimated that it actually did not turn out to be the best possible experience. Before, obviously, you reached that conclusion, going in, what were you optimistic about in accepting this position? What was something that could've been exciting about this post-doc opportunity?

SOIFER: Well, [laugh] it's a long time ago, so it's a little bit hard for me to remember what I was intrigued by. There were a couple of things. Number one, it was really the first opportunity to get into ground-based astronomy. I had been doing sounding rockets. That was what my thesis was. It was a tough way to make a living. And it was certainly in an era when ground-based astronomy was king, and that was all there was, really. And so, that was the main attraction. There was a study I did for an instrument on what became the Hubble Space Telescope. It was back in the day when it was called the Large Space Telescope. So there was some attraction there. But mostly, it was the opportunities for ground-based astronomy, and I think that's what I found to be the attraction.

ZIERLER: What were your initial impressions when you arrived at SAO?

SOIFER: Well, it was very different from where I'd been. At Cornell I was in a group in a fairly small department, and SAO was a very large organization, and the person I was working with was a young guy trying to make his way and not terribly effectively. It just wasn't really what I had thought it would be. It was an interesting experience. I got to live in the Cambridge area for a year, which was fun. I enjoyed that.

ZIERLER: And what interface did you have with Harvard Astrophysics?

SOIFER: Well, there were two organizations at the time. One was the Smithsonian Astrophysical Observatory, the other was the Harvard College Observatory, and they shared physical buildings. There were joint seminars. And you would go to the seminars. That was really the only interface that I had. This was at the time when the two organizations actually merged into what became, during the year that I was there, the Center for Astrophysics. But I didn't stay long enough to see any real merger in that. But overall, it was just not a terribly productive year for me. And an opportunity came up for me to move after a year. And so, I did.

ZIERLER: The plan was to stay longer though, initially?

SOIFER: Yeah, it was a post-doc, and it would've been a two or three-year appointment. But I was able to find a position at University of California, San Diego. I had moved to Smithsonian in September of 1972, and I left in July of 1973.

ZIERLER: Now, before we leave Cambridge entirely, while you were there as a post-doc, did you see this as an opportunity to expand and refine on your doctoral research? Or did you see, really, new opportunities to move into new areas?

SOIFER: It was new areas. That was what I was predominantly wanting – ground-based astronomy. The doctoral research was what I would call the beginnings of space infrared astronomy. We did it with sounding rockets, there were other groups that were doing balloons, and people were using telescopes in airplanes. And one was finding both the expanded wavelength coverage that you could get from above the atmosphere–the atmosphere is, to a great extent, opaque in the infrared. But there are atmospheric windows, and that's what people had taken advantage of in doing ground-based infrared astronomy. There are other technical advantages that made high altitude/space telescopes very interesting platforms. But I was, at the time, very interested in trying to get into ground-based astronomy.

ZIERLER: And what were some of the big projects? What was exciting in ground-based astronomy at that point?

SOIFER: Well, it was all new. And basically, people were doing everything for the first time.

ZIERLER: And why then? What was it about 1972, 1973, the advances in technology or instrumentation that made this an exploding field at this point?

SOIFER: It was the ability to detect infrared photons that was changing dramatically. In the past, the technology by and large had been driven by the technology that came out of the military. Infrared detectors, or something that the military had been, and continues to be, very, very interested in for their reasons. And the technology that became available from that was continuing to advance and becoming interesting in the context of the sensitivity of being able to measure infrared photons from celestial sources, in the context of ground-based astronomy. There's a very specific problem that infrared astronomy has, which is, to draw the analogy with optical astronomy, it's like doing optical astronomy in the middle of the day. Because the entire environment that you're using is glowing very brightly in the infrared.

You have to develop techniques to cancel this very bright foreground in order to measure the faint background celestial source. And these techniques, basically, require differential measurements. Rather than making an absolute measurement of the brightness of a patch of sky, you measure the difference in brightness between two very close together patches of sky, and those techniques were being developed and really substantially advanced at that time. And so, the two major techniques, those of the infrared detectors and how to make these measurements that canceled the effects of the very large foregrounds were both really exploding and making infrared astronomy, at least to me, a very exciting opportunity to go out, point at something, and make a discovery.

ZIERLER: And what were the research questions for you? What were you most interested in at that point of all the things that you could look at?

SOIFER: Well, that, I would say, came from my thesis. We had learned that regions of star formation in our galaxy were very bright infrared sources. But these were very simple results, trying to gain a better understanding, what the material we were seeing was, how it was related to the environment of a young molecular cloud that is producing stars inside it that you cannot see in the visible but see in the infrared, how that works, how these regions of star formation form and evolve. Just some very basic questions that were really just starting to be tackled. That was, I think, the major question that we started out looking into.

ZIERLER: What were the major funding sources or funding agencies in those early days of ground-based astronomy? Was NASA a player? Or it already recognized that it would not be at that point?

SOIFER: No, actually, NASA was an important player. NASA and NSF. While NASA certainly were cognizant that their role was in space science and space astronomy, they were, at that time, wanting to build up a research capability within this country. And so, they were funding a variety of groups all over the country to develop technologies, develop scientific problems, scientific programs, and they were creating a scientific community. They were an important player in addition to the National Science Foundation, and, indeed, going back to my graduate student days, there was actually even some military funding. The Air Force had funded the program that I was involved in at Cornell. It was not nearly as significant as the other two funding sources, but there was some military funding.

ZIERLER: If you could put yourself back in that mindset, when people talked about the possibilities of ground-based astronomy, how big you can go simply by not having to deal with the launch into space? And what were some of the sizes that people dreamt up in the early 1970s? In other words, if you said 30 meters, was that something that would've been in the realm of science fiction? Or even then, that early on, people could extrapolate and see where the instrumentation and technology were headed?

SOIFER: Well, not specifically in the very early 70s, but in the middle-70s, there were actually people thinking about the possibility of telescopes with 30-meter collecting areas. There was not a straight line from those ideas to where we are now in terms of concepts of big telescopes. But people were talking about it, sort of, I would say, with a lot of assumptions that photon detection technologies would come. Remember, at that time, even in the optical, dare I say it, photographic plates were still the major detection technology for optical astronomy. And there was such a huge gain to be made in improving the quantum efficiency, the detection efficiency of photons, in a photographic plate that it gave you much more bang for your buck to improve the quantum efficiency of the detection than to build a bigger telescope.

But even then, electronic detectors were starting to come into play in ground-based optical infrared. And as the quantum efficiency was getting sufficiently close to unity it then began to make sense to think about really big telescopes. There was a mindset, if you will, that the 200-inch telescope was the model of telescopes. People were having to think about different ways of building telescopes. My recollection is, at the time, they were talking about sort of a set of small telescopes, where you somehow coupled the light together or put instruments on each individual telescope in order to make up the collecting area of the large telescope. But it was very primitive in terms of those concepts. But people were talking, even then. But that was not a major thrust in the field at the time.

ZIERLER: How did the opportunity at UC San Diego come up for you?

SOIFER: It was just a position that was advertised that I applied for. And actually, a person who was there at the time, Fred Gillette, was moving to the national observatory in Tucson, and so the other leader in that group was looking to hire a replacement for him. So I applied for that job, and I got it.

ZIERLER: And it was a post-doc or a tenure track line?

SOIFER: Well, it was peculiar at the time. It started off as a post-doc. But then, it was turned into a tenure track position while I was there. It wasn't really a post-doc in the sense it was a fixed-term, two-, three-year kind of term. It was what was called an assistant research physicist, which could be an open-ended position. There were people who spent their lives in what amounted to a soft money position within the University of California structure.

ZIERLER: And it was all within the Department of Physics?

SOIFER: Yes, it was in physics at UCSD.

ZIERLER: Was there not a separate astronomy program?

SOIFER: No, and there still is not at San Diego. It's still within physics.

ZIERLER: What were some of the major observing opportunities you had from San Diego?

SOIFER: Well, the interesting thing there, they shared the ownership of a 60-inch telescope, a 1.5-meter telescope, with the University of Minnesota. And this telescope was located on Mount Lemon at about 9,200 feet elevation, but just outside of Tucson. And so, it was very attractive to me to go there. It was a small observatory, the groups were very active, both in the maintenance of the telescope and the building of instruments for the use of the telescope. And one of the things that was attractive was that a major observational program at San Diego was starting to do, which I would laugh at now, but what we called infrared spectroscopy. The spectral resolution was sufficiently modest that a real spectroscopist would laugh at it. The wavelength resolution was about a part in 100. That's not real spectroscopy.

But in the infrared, it turned out to be very interesting because the major emitters of light in the infrared turned out to be dust of various kinds, or particulates of various kinds, I should say. And their spectral signatures are sufficiently broad that you can really resolve them with this level of spectral resolution. It was very interesting. And so, that was the great opportunity that I could get in on what amounted to the ground floor of infrared spectroscopy. And we did that from over not only the atmospheric windows, where you could actually look out at two microns, three microns, and ten microns, but we actually got a project going to do this kind of spectroscopy using one of NASA's early airplanes, a 36-inch telescope mounted in a C141 called the Kuiper Airborne Observatory that flew at about 45,000 feet. You were above nearly all of the atmospheric water vapor.

And so, we were able to probe portions of the spectrum that were inaccessible from the ground, and the wavelength range the we worked in was from four to eight microns. We ultimately were able to cover spectroscopically from 2 to 13 microns using this technique of infrared spectroscopy and made some very interesting discoveries.

ZIERLER: What stands out in your mind? What were some of the big discoveries?

SOIFER: Well, the thing that was most exciting was what we called originally unidentified infrared features. Spectroscopic features. The first thing you do when you're in what one would call discovery mode is, you point your new instrument at a target that is interesting for some reason, and the target that we always used was the planetary nebula, NGC 7027. It's bright, we knew it was bright in the infrared, and it had spectral features that, one, nobody had anticipated, and two, we couldn't really identify. My predecessor at San Diego had looked at this object from 8 to 13 microns in the mid-infrared, and then with a new detector that gave us good sensitivity from two to four microns, another ground-based window, we looked at it from that range and found a very strong feature at 3.3 microns.

And then, we did it from the airplane from four to eight [microns], and we found a yet stronger feature. This has become a staple of investigations for many decades, studying these features in various environments. Turns out they've been successfully identified as spectral features of polycyclic aromatic hydrocarbons. And the physical mechanism appears to be a fluorescent mechanism, a higher-energy photon. These particulates really amount to large molecules. And so, a higher-energy photon is absorbed by one of these molecules, and it puts it into an excited energy state. And then, its cascading down produces these very strong infrared features. There are features all over the infrared spectrum from the shortest wavelength features at about three microns, and with Spitzer, we've seen that they go out to about 20 microns.

And these are molecules that have around 20 to 40 carbon atoms and around 40-ish hydrogen atoms associated. An earth-based source is diesel exhaust, so they're very common. We've learned that they're very common in galaxies, too. One of the first things we did besides studying this one particular object, we looked at some nearby galaxies that were bright in the infrared and found that these features are there, too. So already, very early on, we were able to find these features which were rather ubiquitous within many different environments, both in systems within our own galaxy and even in other galaxies.

ZIERLER: What would be a good example of infrared spectroscopy being able to do something that no other observational technique would be capable of doing, and what would be a good example of a place where it served in a complementary way or to verify data or observation with other techniques?

SOIFER: Well, this topic that I've been talking about, the polycyclic aromatic hydrocarbons, and the fact that this is basically ubiquitous within interstellar gas in all sorts of environments. This is something that is truly uniquely infrared because these are fingerprints of these molecules. Another example of this, which is indeed related to this, is fullerenes, buckyballs. Infrared spectral features have been found of buckyballs in various astrophysical environments. And there's no observational technique that I'm aware of, other than infrared spectroscopy, that can be used to find these. That's an example of the former. An example of the latter, in ionized plasmas, which are sort of a standard astrophysical environment, where the gas is ionized from the radiation from a hot star.

The star produces a lot of photons that have energies larger than the ionization potential of hydrogen, for example, and of other elements. They produce an ionized plasma. These plasmas are called HII regions. It's an obscure astronomical nomenclature. I won't go into it, but if you see one of these plasmas–for example, the Orion Nebula is an example of the gaseous region that has an enormous amount of ionized gas. It consists of mostly hydrogen with helium and other heavier elements in the standard cosmic abundance of elements. If you can see that gas with no intervening dust to obscure it, then you can do a very good job of analyzing the physical environment using optical spectroscopy. I think of optical spectroscopy as from about 0.3 microns to 1 micron, where the eye is most sensitive. But a bit beyond that.

Analysis techniques were developed, really, over the early 20th century, to really understand the physical environments of those kinds of regions. If you then study those same regions in the infrared, you'll find other emission lines that can be used to analyze the environment and measure similar parameters of the environment, the abundances of the elements, the densities of the gas, things like that. They're complementary. Those same tools, those same infrared spectral lines, can be used in lieu of the optical lines if you're looking at such a region that's in a heavily dust and shrouded region. And in many (most) of the star-forming environments within our galaxies and in other galaxies, because its interstellar gas, there's a lot of dust associated with these regions. The dust selectively absorbs the shorter wavelength light, the optical light, and so it blocks that light from our view. The infrared light, which isn't as strongly absorbed, more freely escapes. And so, you can use the infrared diagnostics to get at the information that you simply can't see in the optical range. So those are the two examples.

ZIERLER: Was San Diego an exciting place to be in the 70s? Was it in growth mode?

SOIFER: It was an exciting place to be. I very much enjoyed it. I'm not sure how much growth there was. It was a delightful place to be. One of the really enjoyable aspects of it for me was that the leaders of the astrophysics group at that time were Geoff and Margaret Burbidge. Margaret Burbidge, who just recently died at about 100, was one of the true leading astronomers of her time, no question about that.

ZIERLER: Did you get to interact with her at all?

SOIFER: Oh, yes, with her and Geoff. Geoff, her husband, was a theorist. She was an observer, an optical spectroscopist. Geoff Burbidge was a delightful person. He really loved tweaking the establishment.

ZIERLER: What were some of the orthodoxies that he enjoyed to tweak?

SOIFER: Oh, questioning whether the red shift of quasars was cosmological, that was sort of a major one. I think he really did it more out of just wanting to tweak the establishment than anything else. He really enjoyed interacting with the young people in the group. He had theoretical post-docs, but he also enjoyed interacting with young people who did other things. I got to know him very well. It was a very lively place because he was interested in so many different things. Lunch every day would be a lot of fun.

ZIERLER: What was Margaret like as a person, and so long ago, as a woman in the field? Did you see her as a pathbreaker?

SOIFER: She was extremely kind. She was just a wonderful human being. And I guess I was aware that she was a pathbreaker because there were not very many women in the field. But one of my closest colleagues and fellow graduate students at Cornell was a woman, so I sort of grew up with a woman colleague, and I didn't think of it as unusual. I don't recall having thought of this as something that was out of the ordinary. In retrospect, it clearly was. The tales, for example, that Geoff would tell about how when Margaret got observing time at Mount Wilson, he had to get the observing time because they didn't give observing time to women. These were tales that were told more as sort of examples of how old fashioned, how behind the times the observatories were.

But with a sort of a fondness, certainly not any kind of anger or bitterness. How things had evolved. But I remember one of the things that Margaret did that, at some level, was perceived to be shocking at the time while I was at San Diego, she had been given the Annie J. Cannon Prize of the American Astronomical Society, which is a prize for women astronomers. And she declined it at a meeting. I didn't think much of it, but this was great. The symbolism of her declining it was a good thing.

ZIERLER: Yeah. What was NASA doing at this point? What were some of the big things you were paying attention to with regard to NASA in the mid-70s?

SOIFER: Well, NASA was just getting into space astronomy. Space physics was the first field that they had really sponsored in terms of investigations. What they called particles and fields, above the earth's atmosphere. The discovery of the Van Allen Belt and such. And then, the early solar system exploration at JPL and such. And there was a series of early UV and optical telescopes that were launched, the orbiting astronomical observatories. They (NASA) were getting into x-ray astronomy with a series of missions. Riccardo Giacconi was one of the leaders of pushing NASA very hard to do that. But they were also wanting to develop infrared astronomy. Various advisory groups were telling them to get into infrared.

And so, they were starting to tiptoe into infrared astronomy. There was some prejudice associated with an experiment that the Air Force had done, some sounding rockets that were trying to do a sky survey from sounding rockets, that had a bad reputation as being very unreliable. And this ultimately turned into a reasonably good catalogue called the Air Force Cambridge Catalogue. And it was sort of in the spirit of, no good deed goes unpunished. The people at Air Force Cambridge were using sounding rockets to detect celestial sources. You get above the atmosphere and you see these sources. And then, they were trying to get some ground-based validation of the data. They gave out very early attempts at reducing the data, and people found that there were a lot of false sources.

There was a very bad reputation of work from space as a result of this. This led to a tremendous amount of skepticism associated with doing infrared astronomy from space. The idea was that particulates come off of vehicles that then mimic astronomical sources. This is the kind of thing that people were thinking about could be producing spurious signals –and the environment would be very hard to do astronomy from space. And so, there was skepticism. But at the same time, they were getting a lot of advice that this was a frontier to get into. And luckily, I got involved in this, and thinking about it, it just sort of illustrates how random life is. NASA had put out what they called an announcement of opportunity. They were soliciting proposals for upcoming satellites. And I think this actually came out in 1974. And various groups were building teams to respond to this. And there was a group of fairly eminent infrared astronomers that was putting together a team to do this. The leaders of that team were Gerry Neugebauer, who was the founder of infrared astronomy at Caltech, Frank Low, who was the leader of infrared astronomy at Arizona, and another person who was involved in building the team, although he did not participate in the actual effort, was Ed Ney. He was the leader of the infrared astronomy group at the University of Minnesota.

Ed was just somebody that Neugebauer and Low talked to. So they were putting together a team, and I was going from San Diego to Tucson one time to go observing at Mount Lemon, and I got off the airplane in Tucson, and I happened to run into Neugebauer, who was getting on a plane going back to Los Angeles. He had been in Tucson talking to Frank Low about this team. As I told you, I had worked for Neugebauer as an undergraduate. And so, I happened to see him, he saw me, and he, I guess, was reminded of me, and so my name bubbled up to his consciousness. I told you that San Diego and Minnesota were the collaborators in this telescope at Mount Lemon. Ed Ney had known who I was. I think somehow, my name came up as a potential person to participate in this proposal. And so, Neugebauer invited me to participate in this project. And this proposal ultimately became the Infrared Astronomy Satellite, which was something that I then got deeply involved in.

ZIERLER: What was compelling? Why did you want to get involved in this?

SOIFER: Certainly, from my experience with the sounding rockets at Cornell, I felt really comfortable with space astronomy. I saw there were substantial gains going into space. I mentioned this Air Force Cambridge work with their sounding rocket survey. There were interesting things coming out of that if you had the patience to sort through and find the real sources. There were good things that were coming out of it. So, I just saw that there was a lot of opportunity to get into space astronomy. That excited me about it. And so, as I said, I was invited to participate in this team, writing a proposal for this announcement of opportunity to NASA. We submitted a proposal, I think in about '74, and our team was selected to study an infrared astronomy satellite.

NASA merged our group with an international group from the Netherlands and the United Kingdom. They were also interested in building a satellite to do infrared astronomy. And NASA, at the high levels, saw this as a way to do something for less money by making it an international collaboration. And so, these two groups were not merged at the time of the study, but they were basically doing parallel studies with the knowledge that we would merge. And so, we looked carefully at the technology and how to do something that would be exciting and within the reach of the existing technology at the time. And out of that came the IRAS satellite.

ZIERLER: What were some of the big research questions that prompted this work?

SOIFER: The work done in infrared from the ground and from balloons and from airplanes showed that many galaxies produced the vast majority of their light at wavelengths beyond 20 microns, at around 100 microns, which was effectively a totally opaque environment from the earth's surface. You could do a little bit of it if you got on a balloon or an airplane. But it really needed the power of going into space, to be above the atmosphere entirely.

One of the big scientific questions was, what are these galaxies, the very infrared-bright galaxies? So that, at least to me, was the big question that was driving this. I think the other big question at the time, people were learning that regions of star formation in our galaxy were enormous emitters of infrared light. So finding all of the regions of star formation in our galaxy, understanding how the process of star formation worked was one of the big drivers of astronomy, not the classical astronomy, of optical astronomy because the light didn't come out in the optical. But there was a new field, molecular line of astronomy, which was just beginning to start. And they were finding that there were these molecular clouds. And infrared astronomers were finding that these were copious sources of infrared light. And so, sort of appreciating that that's where the action was, and if you wanted to see how stars formed, you needed to study them in molecular lines, which is in the millimeter wavelength range, and in infrared light. You can do some of it from the ground-based windows, but mostly, you've got to get sensitivity and be above the atmosphere.

ZIERLER: Who were some of your key collaborators in this work?

SOIFER: Well, as I mentioned, Neugebauer. Ultimately, I wound up moving back to Caltech. Neugebauer, Jim Houck, who was my thesis advisor at Cornell. These were the senior people I worked with. I would say those are the two main collaborators in that work. In terms of getting into IRAS, there were a lot of people involved who came later. But in the early stages of it, they were the two people.

ZIERLER: Now, in the hybrid position that you had at San Diego, did you have sort of the standard professorial duties? Were you teaching? Did you take on graduate students?

SOIFER: I did that. I became a professor in San Diego I think in '76. And in '75, I became part of the IRAS science working group. But I was teaching, I had graduate students, who were doing work at Mount Lemon. That was work that was appropriate for the graduate students because they needed to have something they had control over in order to get theses done. And I was also involved in IRAS.

ZIERLER: What were the circumstances that brought you back to Caltech?

SOIFER: Well, that was a complicated set of circumstances.

ZIERLER: But you were happy at San Diego?

SOIFER: Oh, yes, I was very happy at San Diego. The first thing pushing my return to Caltech was my connection with IRAS. And this was at the time before the internet, before Zoom, and I was convinced that I really wanted to be a significant part of IRAS. And the role that I had in IRAS had to do with, from the science perspective, overseeing the development of the data processing. And the way we structured this, the work would be done by software engineers at JPL. And the way you worked with them was, you worked at JPL, and you went to meetings. I had to spend a lot of time in meetings with software engineers from JPL. I was in San Diego, and I needed to spend several days a week in Pasadena at JPL. And so, from where I lived, I would have to drive to the San Diego airport, fly to Burbank, drive to JPL, spend the day there, then reverse that, or simply drive to JPL from where I lived. But the amount of time in transport basically amounted to a two-and-a-half-hour one-way commute. And I was doing that twice a week. I didn't feel that I was doing the right thing by my commitment at San Diego, and I was exhausting myself. I was a lot younger, but it was painful.

ZIERLER: That's a lot.

SOIFER: That was one thing. The second thing, a job came up at Caltech working with Neugebauer. It was a soft money position. The person who had been in that position had moved to the University of Hawaii to oversee the building of the infrared telescope facility on Mauna Kea. And so, that position came open. But that also meant that there would be an opportunity to use the 200-inch telescope for infrared observations. And at the time, that was the biggest useful telescope in the world, and it was very attractive. Those two effects, the commitment to participate in space astronomy and trying to make that work more reasonably–and obviously, this was impacting my family. I had a wife and a little girl. So I wasn't able to do what I wanted to do there. I just felt if I could move to Caltech, I would be better able to pursue the scientific career that I wanted to pursue, and I would be better able to be a participating father and husband.

ZIERLER: Not being on the road for ten hours a week helps.

SOIFER: That's right.

ZIERLER: Did you see it potentially risky at all, leaving a tenure track position for a soft money position?

SOIFER: I was young and stupid. At this point, I scratch my head and say, "That was a pretty stupid thing to do." Or gutsy. At the time, I didn't feel that it was risky. I felt that professionally, it was the right thing to do, which turned out to be true. The scientific opportunities, I thought, were better. The combination of really being able to deeply involve myself in IRAS plus have the opportunity to pursue research with the 200-inch telescope…

ZIERLER: And who were the funding sources initially?

SOIFER: NASA and NSF for the ground-based work. And obviously, NASA for IRAS. I was young and innocent. And certainly, from my current perspective, if someone were to come to me with, "What should I do with this?" I would at least explain the perils as well as the opportunities. But yeah, it was risky. But it worked out.

ZIERLER: Did returning to Caltech feel like a homecoming at all? Or were you at a sufficiently advanced stage in your career where it really felt like a new experience?

SOIFER: It was a new experience. It was a totally new experience. I had sort of reconnected with Neugebauer through the IRAS project, so I'd worked with him. But coming back, it was in a completely different position. It was new.

ZIERLER: Besides the obvious benefits of being close by, how was the research enhanced simply by being at Caltech, having that access to JPL?

SOIFER: Well, first of all, it was the access to the 200-inch, being able to pursue research projects that I had grown into wanting to pursue. 60-inch telescopes are not 200-inch telescopes. You just can't do certain things. And the infrared astronomy group, which was led by Neugebauer, had a lot of different things going on. It focused on ground-based astronomy, not the kinds of things that I had been doing in San Diego, but other very exciting things. And being able to engage more with JPL and get to know other aspects of JPL, the technology development that was there. When I was commuting, I would just go in to talk to the people I needed to talk to. But when I became a local, I could explore a bit more and understand that they were doing really important technological development that had long term implications for being able to advance the technologies, both for space investigations, which is what their mission was, but then there are the spinoffs of being able to apply those things for ground-based uses.

ZIERLER: Coming back to Caltech, obviously with a very different frame of reference, at this stage in your career, what was striking to you, at Caltech, at JPL, in terms of the administrative and intellectual interplay between astronomy, physics, and astrophysics? How did all of these things work from where you sat?

SOIFER: Well, we were in physics. The division between astronomy and physics was, in terms of astrophysics--we were all in the division of physics, math, and astronomy – the new astronomies, the things that had developed more from the technological side were in physics. Infrared astronomy, millimeter astronomy (at least the development of the millimeter telescope), x-ray astronomy. These were disciplines that were in physics or were housed in the physics option. Astronomy had optical and radio astronomy. The founder of astronomy at Caltech, Jesse Greenstein, had had the wisdom to see that radio astronomy was an important new field. And so, he sponsored radio astronomy, building, effectively, the Owens Valley radio astronomy group within the astronomy option. But there was an enormous amount of interchange. We would have weekly sack lunches. Just enormous intellectual stimulation.

This was a time when there were lots and lots of discoveries being made everywhere in all these different disciplines. And there was a lot of informality as well as some formality. The young people with some of the faculty would be very interested and participatory in the sack lunches. They were the more informal rather than the classical seminars and colloquia. But I would say there was a lot more interplay between the newer aspects of the astronomical arena, the newer wavelengths, the infrared astronomy, the radio astronomy, the x-ray astronomy than there was interaction with the "classical optical astronomers". But there was certainly interaction with some of the optical astronomers. People were interested in both ways. The optical astronomers were interested in what we were doing, and we were interested in what they were doing. We were looking for things to jointly collaborate on. And some of those collaborations developed.

ZIERLER: And as you said before, when there's that amazing opportunity to point up at the sky and can see new things, when you arrived at Caltech in those early years, what were you looking for? What was most compelling?

SOIFER: I got very interested in quasars, and it certainly had some connection with my background with the Burbidges, Geoff Burbidge in particular. This was still a new, interesting, exciting field, and studying them with infrared techniques was really new. I was interested in pursuing that, trying to do some infrared spectroscopy of quasars, looking at emission lines in quasars. It didn't turn out to be as important as I thought it was at the time, but certainly at the time, I thought it was an opportunity to see something that was certainly unconventional, a different approach. I came to Caltech thinking that would be one of the things I would be pursuing actively. And I did that for a while. But I then lost interest in that. Ultimately, I wound up focusing my research at Caltech on the study and follow-up of the work that I did with IRAS.

ZIERLER: Where was IRAS developing? What was its trajectory at this point?

SOIFER: IRAS was a challenging project. It certainly was a hard project technically.

ZIERLER: What was technically challenging about it?

SOIFER: Well, IRAS was a 24-inch telescope stuck into a cryostat, which is just a fancy word for a thermos bottle. And so, the whole telescope was cooled to about two degrees because the fluid that kept it cold was superfluid helium. Superfluid helium becomes superfluid at about 1.2 degrees above absolute zero. The goal of IRAS was to do an All Sky survey at four wavelengths: 12, 25, 60, and 100 microns. The challenges were everywhere. Building the detectors. This was back in the days when you hand-built every single pixel. And we had 62 pixels in our focal plane.

ZIERLER: What does it mean to hand-build a pixel?

SOIFER: Well, you take a piece of a semiconductor, either doped silicon or doped germanium semiconductors, you mount them on a structure, you wire up a J-FET preamplifier, field effect transistor, but you have to figure out how to thermally isolate it from the cooling bath, which is at 1.2, at which point the transistor does not work. You have to elevate it so it can self-heat to about 70 degrees so that it works, but not let any of the radiation that it's producing leak out to illuminate the detector. You have to get the wires out, you have to make sure that the cryostat works, there are no thermal leaks, no thermal shorts that would reduce the lifetime. Even building the optics of the telescope.

The telescope was built of beryllium because it was lightweight, and it has properties that make it more amenable to being able to figure it at room temperature. You have to test it when it's cold, you have to figure it when it's warm. People had done this kind of work on smaller optics for military purposes. As I mentioned, this sounding rocket program that the Air Force Cambridge had been working on. And all of these things, of course, were done predominantly by industrial contractors. And working with those contractors, getting them to be open and frank about where they were, all of this was challenging at best.

ZIERLER: But it was worth sticking with it.

SOIFER: It was worth sticking with it. IRAS was a spectacular success.

ZIERLER: What's the timescale of IRAS? What's the feedback where you start to appreciate just how successful it's going to be?

SOIFER: Well, one horror story that I will replay had to do with the final thermal vacuum test of the satellite before launch. The satellite was launched in January of 1983. I think in about September or October of that year, the whole satellite was assembled and put into a thermal vacuum test at JPL. And they tested it. That's the standard process that NASA follows. They found that there was a failure of a capacitor, a simple part in this thermal bath test. The failure analysis showed that the whole batch of capacitors had a problem with it so that the conservative thing to have done would have been to take apart all of the electronics, replace all the capacitors, put it all back together, and then redo all the testing. And we were in a sufficiently shaky position that project management--I was nowhere near project management at that time--said, "No, that's too risky. We're just going to take this, we'll fix the capacitor that failed, and we'll just launch it."

There was a real fear that this would be launched and it would fail. So, it only became clear that this was going to work after it was launched. Of course, because it's a cold telescope, it's completely enclosed for launch. You then have to eject the protective cover, and first, you have to let the whole satellite out-gas as much as you can before you eject the cover. But basically, it only became clear that it was going to work after the cover was ejected and we could actually see signals. And the signals were amazing. But they were just raw signals from individual pixels. And then, there was a whole process of using those individual detectors and going through the data processing to produce the first round of results, of actually the reduced data, from which we then did analysis. And so, I would say, in terms of when it became clear that it was all going to work and work well, it probably took me a couple of months before I was really confident that this was worth it, that my bet had paid off.

ZIERLER: What was so satisfying from a scientific perspective?

SOIFER: Well, the most satisfying thing to me from a scientific perspective was finding that there was what astronomers call a class of galaxies that were producing 99% of their energy in the far infrared.

ZIERLER: Which tells you what?

SOIFER: Which tells you that you're missing a huge amount of what's going on in these galaxies, that you're just not seeing the activity going on in these kinds of systems.

ZIERLER: Would this have any ramifications for dark matter or dark energy research?

SOIFER: Not really, but it has huge implications for how galaxies form and evolve. Basically, it was the first evidence that galaxies are building themselves up in a way that is hidden from the view of optical light. The optical light simply doesn't get out. We saw these galaxies where all of the action is going on in the infrared and where you have to study them in infrared. That's the only real tool that you have to explore them, to study them, to understand what the physics involves. Are these things star-forming systems? Are they dust-enshrouded quasars? You need to look at them where you can apply your diagnostics, and the diagnostics that you can apply are in the infrared. And so, that was the most satisfying thing to me.

ZIERLER: To go back to one of my earliest questions in our previous conversation more broadly about the interplay between observation and theory, specifically in this line of research, galaxy formation, at this time, what guidance, if at all, was theoretical astrophysics or cosmology playing in these questions? Or was the observation so way out in front it was not that much of an interplay?

SOIFER: This is, at least to me, one of the fun things about astronomy in general. The universe is so much richer than our imagination. And astronomy's one of the real highlights of that, where even the smartest people can spend all their time figuring out what they know about, so they're not really thinking about things they haven't yet imagined. And so, we find things, we observe things that then the theorists get interested in and start to think about and understand. And then, they start making predictions. But I think, in answer to your question, there was really no theoretical structure to understand the galaxy formation and evolution that we just were starting to scratch the surface to see. We were doing the work to convince our smarter colleagues that this was really an interesting area to study.

ZIERLER: Tell me about winning the NASA Exceptional Scientific Achievement Medal in 1984. What were you being recognized for, and what did it feel like?

SOIFER: Well, it was for this work on these very luminous systems, the infrared bright galaxies. My shorthand for this is the ultra-luminous infrared galaxies. The whole IRAS science team were all given this Exceptional Scientific Achievement Award. And we each got one for what we were doing. To be frank, NASA was very much in the doldrums at the time. This was the time when the shuttle was supposed to be doing things, it was way behind. There was not much going on at NASA in terms of new science. And so, we got these awards, to be blunt, for being there. [laugh]

ZIERLER: Well, you didn't have to be there, and if you weren't there, that's not to presume that there would've been achievable either.

SOIFER: Yeah. It was a fun thing. Certainly, the science that we did was exciting, I think. But I was young and innocent enough that I didn't think much about it. [laugh]

ZIERLER: One specific question that you've highlighted yourself, the remarkable infrared galaxy Arp 220, what was remarkable about it?

SOIFER: Well, this was the prototype of this ultra-luminous infrared galaxy. It was a galaxy that was known. Chip Arp was a really creative astronomer. He took pictures of a bunch of interacting galaxies. This is one of his interacting galaxies. And it looked like the remnants of a galaxy collision. And the very earliest stages of modeling, of what two galaxies would look like when they collided, were done with a few hundred particle simulations. And those simulations basically just dealt with the stars in the galaxies. And so, they predicted things like tails of stars strung out. And what we found with Arp 220 was that there was, in the core of it, completely unseen, a source of energy that was as luminous as a quasar. Quasars are, basically, 100 times more luminous than our own galaxy. And they are objects where that energy is coming out of something about the size of a solar system.

Now, we had no handle on what the size of this was. But were this thing to be seen in visible light, it would be the closest quasar. But it was completely invisible in optical light because it was entirely enshrouded in dust. And so, this is one where, as I said, 99% of the energy's coming out in infrared light, far infrared. And this is what, at least to me, made it remarkable. One could remark upon that. [laugh] But it was, in particular, one of my most enjoyable experiences as an astronomer, to have found this. Leafing through one of the computer printouts that we were going through to validate the data from the IRAS satellite. And finding this thing, this object, and scratching my head and saying, "What is this?" And then, finding out. So that was a particularly exciting experience.

ZIERLER: Last question for today, a bit of a somber question on the social side. Where were you on the day of the Challenger disaster? What was the impact of that more broadly on the field?

SOIFER: Well, I believe I was actually at the IRAS data processing facility. It was actually not on the physical Caltech campus – it was a few blocks away. And it was just a complete shock. And quite frankly, a disaster for NASA and for all of us who worked on NASA things. Besides the human tragedy that it was, I guess we had sort of forgotten about the loss of life in the early Apollo program. And this was just a reminder that NASA is fallible. And I think we were all in a state of shock for quite a while. One doesn't like to admit this kind of thing, but it turned out, I think, to be helpful for IRAS research.

ZIERLER: In what way?

SOIFER: The IRAS mission where we were collecting data was ten months. And that was in 1983. And then, we had sort of a period of several years of data analysis that NASA was committed to. But what happened with Challenger was that it basically stopped new programs from going forward for several years. And we had our data in hand, and we were producing exciting results. And so, it was never explicitly stated, but I believe the funding for IRAS was able to continue beyond where NASA had committed to it for several years because there was really no other science coming out of the space astronomy enterprise at the time. They were waiting for the Hubble launch. And that was delayed by many years because of Challenger.

ZIERLER: Well, Tom, we'll pick up tomorrow as you get closer to joining the faculty full-time at Caltech.

[End of recording]

ZIERLER: OK, this is David Zierler, Director of the Caltech Heritage Project. It is August 20, 2021. I'm happy to be back with Professor Tom Soifer. Tom, thanks again for joining me.

SOIFER: Once again, a pleasure.

ZIERLER: All right, Tom, today, I'd like to transition to when you joined the faculty proper at Caltech. The question there is, were you looking for this throughout your time up to that point at Caltech? Were you looking for an opportunity? Did you want the opportunity to interact with students more, to teach classes? How did all of that come together?

SOIFER: Well, it's sort of an interesting story. Certainly, when I came to Caltech, I was very happy just being on the research track. I had no other obligations, I interacted with graduate students and post-docs. Most predominantly, with my faculty mentor, Gerry Neugebauer and with other faculty because I was a reasonably senior research track person. But as we age and more responsibilities come to you – and in particular, the impetus really was external. Gerry Neugebauer, since, I think, 1980, had been the director of the Palomar Observatory. I'd come back to Caltech in 1978, and in, I think, 1988, Gerry became the division chair of physics, math, and astronomy. There was a professorial position available, basically effectively taking over his role in more senior leadership in the infrared astronomy effort at Caltech because he was very much between division chair and other responsibilities.

He, of course, worked 80 hours a week. That's just how he was. That was the emergence of the position. About that same time, I was feeling more, if you will, the maturity of middle age and sort of looking for more long-term security. I was beginning to think about possible more permanent positions rather than the soft money, writing proposals all of the time to ensure that one has salary. Which is, in fact, what the kind of soft money positions really are. So the position at Caltech opened up, and I was the successful candidate.

ZIERLER: And you were a full professor right from the beginning. You essentially leapfrogged the whole tenure process.

SOIFER: That's right. And in retrospect, I have to say [laugh] it was a better way to go. Because I ultimately became the division chair, so I saw the whole process from the very beginning and saw the pressures that the junior faculty are under. And so, I was able to avoid that just because by the time I was appointed, I was sufficiently senior. It certainly was sensible for Caltech to make it a senior appointment.

ZIERLER: What considerations were there in terms of what your home department should be? Of course, you're a professor of physics. Were there any other options given your research areas?

SOIFER: No. This was where infrared astronomy lived at Caltech. And by that time, I was very well-integrated into the physics component of astrophysics within Caltech. I think the importance was to be as interactive as possible with all of the people doing astrophysics at Caltech. And I think I've done that.

ZIERLER: A budget question. As we get into the early 1990s, between the cancelation of the SSC and the end of the Cold War, from your vantage point, to what extent was astronomy and funding in your research areas affected one way or another?

SOIFER: That's an interesting question. I think that the funding in astronomy–let me break it into two parts, space astronomy and ground-based astronomy. In space astronomy overall, I think funding, while not luxurious, was OK. The important missions that the astronomical community said needed to be done, NASA found a way to do. One of the great rubrics of the NASA astronomy enterprise was their great observatories. Observatories that would span the electromagnetic spectrum, from gamma rays to infrared. And it was, at times, a struggle. At times, substantial descopes were required to meet funding constraints. But NASA found a way to get those projects done, to the great expansion of our understanding of the universe. The success of Hubble, of Compton, of Chandra, and most personally, of the Spitzer project that I became heavily involved in.

ZIERLER: Was planning for Spitzer the next major project for you in the early 90s?

SOIFER: Well, I need to rewind a little bit because the Keck Observatory came along. And that came along in the mid-80s. And I was heavily involved in that to the extent of being the principal investigator of the very first instrument that was put on the first Keck telescope. I had a great involvement in that. And that started in the mid-80s. But to go back to your question, there's always a, "With a little bit more, you could do so much more." But in retrospect, I think if you just look at the size of our professional society, the American Astronomical Society, it's grown enormously over the last number of decades. And that's a statement both about the excitement of the field, but also about the resources that have gone into the field. And overall, I attribute most of that to NASA because the NASA resources have been quite plentiful in building the world-class enterprise in this field.

ZIERLER: Let's develop the narrative a little more deeply of Keck. Are you involved even from the earliest discussions of what would become Keck? Or did you join that effort a little later on?

SOIFER: Well, I joined it as soon as Caltech joined it, which was around 1984. I was part of the Caltech enterprise with Keck. What became the Keck telescope was the 10-meter telescope project at the University of California. Caltech alum, Jerry Nelson, who had worked for Gerry Neugebauer as an undergraduate, was developing the concepts, the architecture, demonstrating the technologies necessary to build it, and they got stuck in finding the funds to execute it. And in the early-mid-80s, '83-ish, they approached Caltech with an offer for Caltech to join the effort at effectively a minor partner share. And while I was fairly low on the totem pole at that point and not party to these activities, I believe I know at least roughly what happened. And effectively, Caltech succeed through the generosity of the W. M. Keck Foundation in, basically, providing the stunning offer of paying for the whole thing, the construction of the Keck Observatory.

The commitment of the Keck Foundation was 80% of the construction of the telescope, and then Caltech and the board of trustees took on the responsibility of finding the final 20%. The Caltech share was 100% of the construction. And the negotiation between the university of California and Caltech was how to do this. And to cut to the chase, the final agreement was that Caltech would build the observatory, and University of California would fund the operation of the observatory, until such time as the financial contributions from both parties were the same. And after that, we would then equally share in the cost of operation of the observatory. So that happened in the mid-80s. It was announced publicly probably in '84 or '85. Neugebauer was the director of the Caltech observatory, the Palomar Observatory, at that time, and so he was heavily involved in the negotiations and the upper-level planning of this. And I was heavily involved in the development of what the instruments would be that would populate this magnificent new telescope.

And so, as sort of the senior working person in the infrared astronomy area at Caltech, I was deeply involved in defining what the infrared instruments would be for this telescope. By this time, the technology of infrared detectors had advanced to having aerial detectors being able to make two-dimensional pictures or do real spectra. And so, we were trying to plan to be, I would say, relatively conservative, knowing that we could build what we had committed to. And then, seeing that what we planned was built and put on the telescope at the time the telescope was ready.

ZIERLER: What was so exciting about the Keck Telescope? In its planning stages, what was the promise? What could it do that was not possible before?

SOIFER: Well, when you're promoting a new project, you always write down the things that you think you can do when you take what you know, and you change the sensitivity. We knew that we had four times the collecting area of the 200-inch telescope, and we knew that the site for the Keck Observatory, Mauna Kea, was a superior site to Palomar, that the image quality would be better. We wrote down that we could go deeper and study in more detail. But the real excitement, at least to me, was knowing that we would find things that we hadn't known about. So it was the discovery potential that, for me, was the excitement.

That's, if you will, the theme of my scientific path, the discovery potential of new facilities. But that was what at least drove me as far as the Keck Telescope. And by this time, I was deeply involved in both the IRAS data and using the Palomar Telescope, the 200-inch, to study in more detail the objects we had discovered with IRAS. And so, I saw it as a clear opportunity for me scientifically to pursue the continued, more detailed investigation of the objects like Arp 220 that we talked about last time using the more powerful analysis tools available with this new largest telescope in the world.

ZIERLER: Thinking about the TMT weighs heavily on this question. The politics of developing the Keck. Was there any consideration, or partnership, or sense of importance that the Native peoples of Hawaii should be brought in on this process?

SOIFER: Unfortunately, the answer is no. I have become very much better educated about both the historical and the current situation in society in Hawaii and have learned a lot about the history of it. And at the time we were making the agreements with the University of Hawaii, the managing entity for the astronomy precinct on the mountain. There was a lot of unhappiness from the Native Hawaiian community, and to be frank, they (UH) ran roughshod over any kind of objections or expressions of concern. There were some, as I have come to learn, modest objections to building up the astronomy precinct on Mauna Kea from some elements of the Native Hawaiian community. And those were ignored. It's interesting we're sort of digressing into Hawaiian history and such.

The idea for an observatory on Mauna Kea seemed to have emerged out of two things. One, I believe it was Gerard Kuiper who had identified Mauna Kea as a potentially fabulous site for doing astronomy, both because it was high and in the middle of the ocean, so the air above the mountain was more stable than it would be over a continental landmass. But it was also identified because I think it was in '60 or '61, there was a tidal wave that did an enormous amount of damage to the biggest city on the island of Hawaii, Hilo. And so, they were looking for sort of mechanisms to provide some economic help to an island that was, at the time, heavily agricultural.

The confluence of these two needs, economic and the identification of the site, led to pushing, within the power structure, the governor at the time and others, to want to develop Mauna Kea. And they saw it as an opportunity for the university to develop a world-class astronomy effort, which it has become. But it came as a lot of things happened in Hawaii, at the expense of ignoring the concerns of the Native population that considered Mauna Kea to be both a sacred mountain culturally and also part of the land that they perceived, with some justification, to have been illegally seized with the overthrow of the Hawaiian monarchy and the takeover by the US. So there's a lot of complexity associated.

ZIERLER: We won't treat the Native peoples as speaking in a monolithic voice, but overall, is your sense that they would have been supportive of the project, had they been included in the planning? That the tensions that arose were not, at the end of the day, about existential questions, would it or wouldn't it be built? Was it more about the process?

SOIFER: I believe they would have been supportive. In fact, there was very little voice, and I knew nothing about any objections at the time. And there was little objection to any of the developed telescopes in the 80s on the mountain. I think had they been part of the process, had they been consulted, yes, I believe that they would have been strongly supportive. I believe that even now, what we're trying to do with TMT is to change our thinking about this and try and engage this community.

ZIERLER: What do you think that says about the culture of astronomy in the 80s and 90s that it had this run roughshod, cavalier attitude and a lack of sensitivity to what the Native Peoples were saying? I'll ask you to put on your sociologist hat.

SOIFER: Well, I think it, indeed, says that historically, astronomy, as many other sciences, has taken the attitude that, "What we are doing is self-evidently virtuous. Our intentions are pure and of the highest achievement of mankind, the search for knowledge of how we came to be. And so, we can't be questioned as to how we go about this." And as I have been learning, there are other perspective, and there are other considerations that you just can't ignore. And we, the astronomical and scientific communities, the communities who want to build big facilities on site that might have substantial importance to other peoples, to the residents of those areas, the Indigenous peoples of those areas, have to recognize that and work with those people to find a way to be collaborative.

ZIERLER: More of an atmospheric question, if that's correct: why Keck? Why Hawaii? Why is this an ideal spot from an observational perspective?

SOIFER: Well, number one, it's high. It's at about 4,200 meters. It's 13,700 feet above sea level. That puts it above a goodly amount of the atmosphere. The opacity of the atmosphere is less. The atmospheric windows that we use are more transparent because you're above more of the molecules that cause opacity. It's also drier and colder because it's high, and water vapor is one of the major opacity sources of the atmosphere. And so, the more water you're above, the more transparent the atmosphere is. And colder is better for infrared because the infrared radiation that you're bathed in by being at a temperature above absolute zero is reduced in brightness and moves to longer wavelengths. That's a modest effect, but it's a real effect. And the main advantage of it is, you lower the temperature so the shorter wavelength infrared windows become much more sensitive. For that reason, it would be even better to build a telescope at the South Pole. And people have done that. But Hawaii is accessible, much more accessible than the South Pole.

ZIERLER: It's also on American soil, which helps from a funding perspective.

SOIFER: That's right. And the other reason is the stability of the atmosphere. What you have is an island, which is a small perturbation sticking up in the middle of a very stable thermal environment, which is the sea. And so, there's a much smoother (Laminar) flow of air over the mountains and above you than when you go to a site on a continent, where much more turbulence can ensue. And it turned out that adaptive optics (technology to correct the image distortions of the atmosphere) was being developed as a military funded effort. Some people associated with the project knew but I wasn't aware of it. Mauna Kea is a superior site for doing adaptive optics because of the better stability of the atmosphere. All of these reasons combine to make Mauna Kea, I think, probably the best site in the world, excluding extreme sites like the South Pole.

ZIERLER: What were some of the technical challenges in getting Keck up and running?

SOIFER: Well, it was a completely revolutionary telescope. The concept of a segmented mirror telescope had many ramifications. How do you figure the segments? How do you mount them precisely? How do you control all of that? Those were the key technical challenges to making sure that the concept would work. And those were the areas where Jerry Nelson and his collaborators really did a magnificent job of demonstrating the techniques and then executing the construction. Then, just building a big telescope is a nontrivial exercise. It requires really solid high-quality engineering. And one of the big contributions that Caltech made, the concept and architecture was a Jerry Nelson-led effort, but Caltech with its connection to JPL brought in really high-powered project management to turn this concept into reality. As I have worked on various projects, I've recognized how important good project management is to the successful execution of a project. You can really tell the difference between a good project manager and a mediocre project manager. And it ultimately shows in the outcome of the project that you're trying to execute.

ZIERLER: On the question of project management, at the personal level and at the institutional level, who were your key partners in getting it up and running? What stands out in your memory in terms of the individuals and the institutions?

SOIFER: On the Caltech side, I mentioned Gerry Neugebauer was one of the key people. Because he was the director of the Palomar Observatory, he was the leader of the Caltech astronomy community in the project. Ed Stone, who was the division chair at the time and stayed on as the chair and vice chair of the board of the organization that operated the observatory. Robbie Vogt was the provost at the time that the project started, and he negotiated with the University of California to nail down the agreement. And that was very important.

On the UC side, Jerry Nelson, of course, was the architect of this enterprise. Bob Kraft was the director of the UC observatory at the time, and so he was very important in getting the UC astronomy community supportive. There were a lot of skeptics, not so much, I think, at Caltech, but within UC and in the broader astronomical community, that this kind of telescope would work. Because it was revolutionary, a segmented mirror telescope. Bill Fraser, who was the UC provost, was really very important in creating the partnership. Turns out, he was the department chair when I was a junior professor at UC San Diego, and then he got appointed to be the UC provost.

After I left San Diego, he left San Diego to become the provost of UC. On the engineering side, Jerry Smith doesn't get nearly the credit that he deserves. He was the project manager. He was a JPL engineer/manager. They just create these amazing managers who have a strong technical background and know how to get the job done. He came out of the JPL culture. He had been in Hawaii building the infrared telescope facility, the IRTF, a three-meter telescope, on Mauna Kea in the late 70s, early 80s, came back to JPL. He worked on IRAS and became the IRAS project manager, so I knew him very well. And then, he was the manager of the Keck project. There are three parameters that projects have. They have cost, schedule, and performance. And the job of the project manager is to find the right optimization between those three parameters.

Nelson, as the project scientist, as the architect, was insistent that performance should take primacy. And Smith, as the project manager, had to balance that against the amount of money he had and knowing that schedule drives cost. There was a tension between the two of them in terms of getting the job done. And the outcome has been magnificent. And I think that Jerry Nelson gets as much credit as he deserves because he was a revolutionary telescope designer, but Smith doesn't get the credit that he deserves as the person who actually got it built very close to the schedule and budget that he had been given.

ZIERLER: What were some of the considerations in terms of observation time on the telescope? What were the percentages that worked out? Who got what?

SOIFER: Well, the University of Hawaii got 10% of the time on Keck 1. And actually, they got 15% of the time on Keck 2. And then, the rest of the time was expected to be split equally between the University of California and Caltech. One of the corrections to that distribution came about because remember, I told you that Caltech was obligated to come up with the final 20% of the cost of construction of Keck 1. And a similar arrangement was made for the second Keck telescope, Keck 2. Caltech had the obligation to find the 20% of the construction cost of both facilities. And the arrangement that came to pass, arranged, I think, predominantly by Ed Stone, was to bring NASA into the partnership as a 1/6 partner. 1/6 of the cost of construction, 1/6 the cost of operations, and 1/6 of the observer time. So the first thing, you take off the top the Hawaii time, which effectively was the rent for the use of the mountain. And then, the rest of the time, 1/6 of it went to NASA for the NASA scientific community. And the rest of the time was split equally between Caltech and UC.

ZIERLER: Once everything came together, you could point it at the sky, what did you want to look at? What could it do that was most compelling to look at first?

SOIFER: Well, there were lots of things. Because this was the biggest and the best, we did several things. There were some very interesting objects that came out of the IRAS sky survey that I was particularly interested in. One in particular was a very luminous infrared galaxy, or we thought it was a galaxy at the time, and it was an astonishing red shift. It was at a red shift of two, which meant it was a look-back time of something like 10 billion light years. It was even 100 times more luminous than these ultra-luminous infrared galaxies that we had discovered early on in the IRAS data analysis. And it turned out it was a gravitationally lensed object, so its apparently luminosity was much higher because there was this lensing due to an intervening galaxy that effectively magnified its brightness by about a factor of 50.

But these are the kinds of things we were able to do. The image quality of our imaging was such that we were able to discern that it looked funny. We missed that it was a lens. We should've figured out that it was actually lensed, but we missed that. But somebody else came along and effectively did that. We were able to do spectroscopy with a very crude spectrometer with our initial imager to see some very strong emissions features that we were able to understand the excitation of the plasma that was in this object. That was one of the things that we did. We did very deep observations. One of the things that astronomers have become enthralled with is, you take a blank patch of sky, and you just put your most sensitive imagers at that blank patch of sky, and you see what's there, and you just count the objects.

And this sort of lets you start to get a handle on the very most-distant objects in the universe, how many there are at that particular time. And so, that's the thing that you always do with the next big telescope. So we did that. And I did a lot of follow-up studies of the galaxies that we had been finding to be particularly interesting with IRAS. Those are the kinds of things that we were doing early on.

ZIERLER: With all of this new observational data, what planning was there in terms of computation, in terms of analysis and storage of all of the data?

SOIFER: One of the good things about the timing is that the new telescope, the new detectors, the new capabilities were coming along at exactly the same time as the explosion in computing triggered by integrated circuits, companies like Intel building better and better computing chips. And so, I think at least at the time that we were doing the initial round of Keck instrumentation, the computing that was necessary to do the analysis of all of the instruments, not just the infrared instruments, was easily within the capabilities of the available computers at the time. But it was never an issue. Now, things have gotten even more ambitious today. So there are, without a doubt, data challenges in keeping up with the data from newer facilities. But at the time, that was not an issue.

ZIERLER: Let's move to Spitzer. How did that get started?

SOIFER: [laugh] That was an interesting tale. Spitzer started as a NASA project in the early 70s. It was called the Space Infrared Telescope Facility. Actually, it was originally called the Shuttle Infrared Telescope Facility for the reason that it was envisioned as a facility that would be what we called the shuttle-attached payload. It would sit in the shuttle bay. NASA had this concept for a reusable capability of flying to space, and it would go up, observe for a couple weeks, come back down, change the instruments, then go up and do it again, as sort of a very cartoonish description. This is the early 70s. And it got more and more complex and challenging as the space shuttle became more real. Finally, in around 1980, it became an important, interesting project.

This was pre-IRAS. And it was being led out of NASA's Ames Research Center, which is up in Mountain View, California. And it was really sort of not going very far, not going very well until the concept of the great observatories was put together by some very clever people at NASA headquarters and from within the science community. And then, it became, if you will, NASA's marketing skills to explain why you needed all these observatories. "Why isn't one telescope enough?" It became a really significant project that NASA bought into. And of course, the discoveries from IRAS really energized the infrared astronomy community, but it even excited the rest of the astronomy community, so that there was an enormous amount of support for it scientifically. The astronomical community does a prioritization of what it thinks are the important things every decade. It's called the Decadal Review of Astronomy and Astrophysics.

These things are slow. In 1990, SIRTF came out at the top of the US astronomical community's prioritization for space astronomy. Leading up to that, during the 80s, there was a lot of work invested in building the concept of SIRTF, again, called the Shuttle Infrared Telescope Facility. And then, there was a push in the mid-80s to take it off the shuttle. By that time, the shuttle had started to fly, we had the Challenger disaster, and we knew that the complexities of putting the telescope on the shuttle, which had men, would make it very compromised. And so, there was a big push to take it off the shuttle and make it a free-flyer. But we preserved the acronym. Instead of the Shuttle Infrared Telescope Facility, it became the Space Infrared Telescope Facility.

And NASA then decided that there needed to be a competition among their NASA centers, for which center would actually execute this mission. And by that time, I had become a professor at Caltech. So Neugebauer and I pushed very hard for JPL to propose to lead this project. And it was successful. JPL submitted a proposal. We were active contributors to it. And the proposal was successful. NASA chose JPL to lead the project. I should rewind a little bit to mention that, as part of the follow-up to IRAS, I had been part of a proposal to build one of the instruments for SIRTF. And I was part of an instrument team to build the infrared spectrograph. And the leader of the team was my old thesis advisor, Jim Houck, from Cornell. I had maintained my connection with him.

And when NASA moved the project from NASA Ames to JPL, I became more involved in it. The person who was the project scientist for SIRTF, Mike Werner, moved from Ames to JPL to stay project scientist. And I began helping him. I took on the role of deputy project scientist as well as being a member of the infrared spectrometer instrument team. And so, I got involved in that. It got this very high ranking out of the 1990 decadal review, and we were really on course for a start right then and there. And then, they launched Hubble, and spherical aberration happened. And that was a disaster at the time for NASA. They've since corrected that with their rescue mission. But it was also a disaster for Spitzer, for SIRTF because it was a facility that, at the time, was large and incredibly expensive. At the time, in the early 90s, the JPL folks thought this was around a $3-billion mission.

Now, that was a lot of money. And so, basically, it got put on a track to either reduce or go away. And so, there were some years of agonizing, reappraisal. "How do you extract the most important capabilities for Spitzer/SIRTF and preserve the quality science?" This was really a science-driven exercise recognizing that if one didn't do it–and it was hard because everybody thought that all of the capabilities that had been put into the mission were important. It had spanned the range from two microns, about four times the wavelength of visible light that your eye's sensitive to, all the way to 1,000 microns, a millimeter. How do you change it into something that's doable for a finite amount of money and has a reasonable chance of being funded?

There was a three- or four-year period of that sort of agonizing reappraisal. I like to, in non-public conversation, describe it as the difference between a dinosaur and a mammal. The pre-Hubble-launch Spitzer was huge. It had about an 85-centimeter diameter telescope, and it had a huge cryostat. Fundamentally, it was the same design as the IRAS telescope, where you cooled the entire system in a huge cryostat, and it required the largest launch vehicle that the US had at that time, the Titan IV. Afterwards, by using radiation cooling, so you didn't have to cool everything all the time from before launch, we got it down from around 2,000 or 3,000 liters of superfluid helium to 300 liters of superfluid helium using radiation cooling. Physically, the satellite went from a large Greyhound Bus down to–you're old enough to remember - a VW Bus. It was that size.

It was able to be launched on a much smaller rocket, a Delta rocket. And the price went down from about $2.5 billion to about $500 million for the satellite. This happened by about 1995. The core science was preserved. And the most important thing in terms of the science and why this was worth pursuing was, the technology of infrared detectors had continued to advance enormously from the 70s. The technique of infrared detectors for IRAS–remember, I told you about building individual pixels? We were already, by the mid-90s, building arrays of detectors with pixel counts around 50,000. And so, the capability, and the sensitivity, being able to point at a target for a longer period of time than IRAS, for as many hours, rather than a few seconds and with a sensitivity that was really limited only by the number of photons that fell upon the detector from the very faint glow of the interplanetary dust meant that the sensitivity gain was enormous, 1,000-fold over even what IRAS could do.

Plus, instead of just imaging – and IRAS had sort of done crude imaging – to both imaging and spectroscopy, which really meant that the scientific opportunities remained vast. We were able to preserve the scientific potential of the observatory while reducing the cost by this enormous factor. And so, in the mid-90s, around '96, NASA finally started it. And once it got started, because I had been a part of pushing JPL to do this, the director of the instruments area at JPL, Charles Elachi – he wasn't yet the lab director – came to me and asked me to be the director of the SIRTF Science Center.

The Science Center was the organization that effectively took the science observations from the average astronomer, turned them into the sets of commands that you had to issue to the satellite, sent that up to JPL for commanding and collected the data, processed the data into a form that was really usable, and an astronomer could then do science with those data and deliver those data to the astronomer who had requested the observation. So that's what the job at the Science Center was. It's really the interface for the science community, user community, to the operation of the observatory. And he asked me to become the director of that. And I took on the job.

ZIERLER: What were some of the considerations in terms of how long Spitzer would be viable?

SOIFER: The biggest consideration was, at the beginning, we had three instruments, and they all needed superfluid helium. We envisioned a project that would only work as long as the helium lasted. The biggest consideration as to how long it would be viable was, you wanted to be able to have thinking time. You wanted to make a set of observations, make a discovery, and then see what that meant and respond with further observations. The important thing that was always in our mind was that we had so much sensitivity that there was no telescope on the ground, no mechanism to follow up a Spitzer discovery other than Spitzer if you had to use the same wavelengths.

The most important consideration was the consideration of getting enough thinking time to be able to have a second pass and possibly even a third pass at that same piece of sky so that you could extract as much insight into the phenomena that you were finding that you possibly could. And that led to a goal of five years for the lifetime of the observatory. Goals and requirements are different things in the world of NASA. A requirement means you have to spend the money to ensure that that will be done. A goal, you don't have to. You say, "We'll try our best." And so, while we said we hoped for five years – and the system was designed to last for five years – the requirement was two and a half years. The way this works is, the scientists create these top-level requirements, the engineers go off, and they design something, and then they analyze it and calculate how well it's going to do compared to your requirement. And they come back to the scientists and say, "Is this good enough?" The requirement was two and a half years, which gave us a little bit of thinking time.

Because of the way SIRTF looked at the sky, you needed an entire year to be sure that you could look at the whole sky. When you take into account the on-orbit commissioning of the observatory and such, it gave us two full looks at the sky, which is sort of barely the thinking time that I'd been talking about. But the goal was five. And in fact, the engineers designed a system that would work for five years at cryogenic temperatures. The safety factor from the requirement to the goal was a factor of two in lifetime. That was the biggest consideration in terms of what would ultimately turn into the amount of science that we could do. Ultimately, we wound up having a system that operated cold for five years and eight months, which is fantastic. And we were just delighted with that.

ZIERLER: Obviously, it's not a good comparison, but in light of the Hubble and the fact that, amazingly, it continues to give us these incredible images, all technological limitations aside, does five years strike you in retrospect as too short? Or is it possible that it could've gone longer?

SOIFER: Well, it did go longer. When all was said and done, there were 11 separate channels of detectors of imagers or spectrographs that worked on Spitzer. Once we knew it worked, you got to change the name, and it was named for Lyman Spitzer, who was, if you will, the father of space astronomy in the US, who was a major proponent of putting telescopes in space. There were 11 separate measurement modes when Spitzer was cold. When the helium ran out--remember, I talked about radiation cooling--the telescope and the detectors operated at about 27 degrees Kelvin, 27 degrees above absolute zero. That meant that there were two of the channels that continued to operate, the two shortest wavelength channels. They operated at about three and a half and four and a half microns. And they continued to operate at the full sensitivity that they had had during the cold mission. And so, it ended in January of '20, and we had launched in August of '03. That sounds like about 16 and a half years, five and a half of which was cryogenic. So another 11 years in what we called the "warm" mission.

ZIERLER: So this really did exceed all expectations.

SOIFER: Oh, yes.

ZIERLER: Last question for today, purely on the scientific side, the observational side. What was so satisfying about what Spitzer was able to do?

SOIFER: Again, I come back to my motivator, discovery. We didn't discover that there were planets orbiting other stars, but we made major contributions. We found the thermal emission from planets orbiting other stars. We were able to find the systems that had multiple planets. The discovery of galaxies barely after they had formed. These are observations that were done in combination with Hubble. But at least to me, absolutely astonishing things that we had no idea when we defined what Spitzer should do. We never thought that we'd find anything like that. That was the most satisfying thing for me.

ZIERLER: OK. We'll leave it there for next time.


[End of recording]

DAVID ZIERLER: OK, this is David Zierler, Director of the Caltech Heritage Project. It is August 26, 2021. It's my great pleasure to be here with Professor Soifer. Tom, thanks again for joining me today.

SOIFER: This is great fun.

ZIERLER: Today, I'd like to start by talking about the recent afterlife of Spitzer, given the fact that it retired in January of 2020, and we're a year and a half out. So my first question is, what do you see as the long and short term afterlife of Spitzer in terms of the science, in terms of the administration, in terms of follow-on space telescope projects? And interwoven with that question is the obvious, all of this has been happening amid the pandemic and the effects that that has taken on these issues.

SOIFER: Let me start with the short-term afterlife. As all the data have been processed, they've been placed into a publicly accessible archive. This is standard NASA policy for space missions. And we have a large user base of people, both the observers who requested observations plus people who milk the archive. We turned off the satellite in January of 2020, and the timing was good because we didn't have to deal with COVID. And work has been done since then and through the end of September of this year--there are still a couple of people working--to finish off the final documentation, to make sure that we leave an archive that is well-documented that people can use, and to hand over all of the information to a group at the Infrared Processing and Analysis Center on the Caltech campus, which will basically provide the archival support to anybody who wants to use the data.

And I envision the usage of the data will be very important, particularly, I would say, over at least the next ten years because hopefully, in about October, or more like November or December, the James Webb Telescope is going to be launched. This is really the follow-on to a combination of both Hubble and Spitzer. The James Webb Telescope is a 6.5-meter telescope. It works from the near infrared at about two microns out to about 25 microns. Very natural follow-on to Spitzer. It has much higher spatial resolution, much higher sensitivity because it's about a 40 times larger collecting area and six and a half times the diameter. But for people to effectively use the Webb Telescope, they need to understand what the sky looks like where they want to point.

I think one of the afterlives of Spitzer after the scientific usages of the data are completed will be effectively for observation planning for James Webb, and that will last for at least a decade. I think historically, when you look at old space missions, people continually mine the data for decades after the data collection has ceased. And I expect that that will continue for Spitzer. I think two particular areas Spitzer will live on. We had a very important program at the end of our life combined with Hubble to try and find the most distant, the youngest galaxies, the earliest forming galaxies. And we got to galaxies that are about a red shift of something greater than ten, so we're seeing them somewhere between 600 and 800 million years after the Big Bang.

And certainly, continuing to search those data for more candidates will be very important, both scientifically on its own but also as I said, in preparation for then attacking these same targets with the power of spectroscopy that James Webb affords. That's one big area where I think Spitzer will continue to live quite long. The other, I think, will be the study of exoplanets, where we really made major contributions, both in the cryogenic mission and then in the afterlife of the warm mission, where we used just the two shortest wavelength channels. I think as people gain a greater understanding of the wide variety of planets that we're finding that are orbiting other stars, people will be going back to the Spitzer data to apply and refine processing to better understand those planetary systems. Because what we've seen, I think, will turn into what are effectively the best and the brightest of these exoplanets. As increasing capability lets people look at things with more sensitivity, they'll need to go back and really understand the best of their ability what we already have.

ZIERLER: Is this to say that all of the data that Spitzer has given us has already been analyzed? Or how long would the tail be for that?

SOIFER: I think the significant tail for the analysis will be at least another decade. I'm just judging from the way history's gone in the past and how people used the IRAS data. When people make discoveries of new or interesting objects, they'll see if they were seen by Spitzer, and if so, what are the Spitzer data on them? And astronomers from all walks of astronomy, regardless of whether they're doing space or ground-based astronomy–this is one of the wonderful things about NASA, they have structured their space astronomy programs so that the data are absolutely accessible to the entire world. Anybody can ask those same questions. And that's why it's so important to have a good archive and knowledgeable people supporting that archive. And that's what we're handing off.

ZIERLER: It's exciting because Spitzer could yet yield surprises that we don't yet know.

SOIFER: That's right.

ZIERLER: And there is also, as you alluded, a complementary nature to this data that subsequent missions might enhance something that was initially seen by Spitzer.

SOIFER: That's right. We don't know what it is, but I think there's a reasonable confidence that those things will emerge.

ZIERLER: Before we transition back a little chronologically, I'd like to ask you about, in 2015, the circumstances by which you were honored with the Kent and Joyce Kresa Leadership Chair. The first question there is, what is your connection, if at all, to the Kresas, and what were the circumstances of this award coming to you?

SOIFER: First of all, in 2010, I became the chair of the Division of Physics, Math, and Astronomy. And later, basically, this leadership chair was one of the chairs that the institute was using as a fundraising mechanism to build endowment. Kent and Joyce Kresa made a donation to set up this leadership chair, which all subsequent division chairs of physics, math, and astronomy hold. Anybody who is the division chair becomes the Kent and Joyce Kresa Leadership Chair for physics, math, and astronomy. But I got a chance to meet Kent Kresa. Unfortunately, his wife passed away very shortly after their donation was made, so I don't think I ever had an opportunity to meet her.

But Kent is a very fascinating person. He was the chair of the Caltech board of trustees for a while. I believe he was also the head of one of the big aerospace corporations in Southern California. But I had a great opportunity to participate in a tour of one of the LIGO facilities with him and some others that we had organized. He's a fascinating person. One thing that I thought was quite amazing, he started off as an engineer on Kwajalein Island, which is where all of the anti-missile work was being done and had some fascinating tales about life on Kwajalein, which, of course, is way in the middle of nowhere in the South Pacific. But he's a great person, and I was very pleased and honored to be the Kent Kresa Chair.

ZIERLER: Besides just the fundraising aspect, what ways did this honor really free up what you were able to do in your position?

SOIFER: One of the important things that division chairs do, perhaps the most important thing, is when our division identifies a potential new faculty member, we are usually invariably in competition with other very powerful institutions who want to recruit the same person. The division chair is always trying to find the resources to help make an offer to the candidate that we're trying to recruit to give them the resources to start their research program in a way that they're not limited by financial resources, but they have the beginning financial resources to get their science program going in the way they envision. The resources that became available through the leadership chair are used for what the division chair is always trying to do, which is to recruit the very best faculty. And that does require the kinds of resources to allow us to attract the very best people. And I have to say, I think one of my most satisfying achievements as division chair was being reasonably successful in attracting the faculty members that our division had identified as candidates. The faculty's job is to identify the candidates, and then the division chair's job is to close the deal, if you will, recruit them, get them to come.

ZIERLER: Just one question from your vantage point as division chair that merges the administrative side and the scientific side. Between the unique arrangement at Caltech, where physics, math, and astronomy are together, and the unique position that the division chair holds, where it's much more than a department chair at other universities, what was the value of that for you from a research perspective, having these things administratively housed together and being in a position where the division chair really yields significant influence in the institute?

SOIFER: I think the real value to my own research was just having a better picture of all of what was going on in astronomy because there's such a large component of physics at Caltech that is astrophysics. When I say astronomy, I'm talking all of astronomy plus a significant portion of the physics area within the division, which is astrophysics. Just having that broadest possible picture of what is happening, how all of that is going on, that certainly helped me personally. But that's the only way it was of help to me. Obviously, as a division chair, your responsibility is to promote your division. So that was that role. But the knowledge of what people were doing. I confess, what little knowledge I had gotten of mathematics didn't help my astronomical research. [laugh]

ZIERLER: Well, if you were in string theory, maybe it'd be a different story. [laugh] As an entree to our discussion on the TMT, I'd like to ask sort of a broad, sweeping question from your perspective on the interrelated value of space-based observation and land-based observation, given the fact that chronologically, TMT was sort of right smack in the middle of Spitzer.

SOIFER: I think the difference sets of platforms, space platforms and ground-based platforms, have grown extremely complementary. You can do things in space that you can't do from the ground, which is what I've done, using the wavelength coverage and the cold telescopes to achieve things that would be virtually impossible from the ground. But then, the ground-based telescopes, because you're not nearly as limited in the kinds of instrumentation you can put on a telescope, you can probe and study in detail that you just don't have those tools in space. The tools that you use in space are more limited just because of the intense pressure to have only the most crucial measurements, or if you will, the discovery measurements, the things that will identify new targets, new phenomenon.

But then, the detailed exploration of those is usually left to ground-based platforms to pursue the things that have been discovered in space. And we did this very much in Spitzer, finding the targets that we were most interested in, using the Spitzer instrumentation, and then I actually wound up doing a lot of optical spectroscopy using the Keck telescopes to, first of all, get the redshifts because the first thing you need to know about a target is how far away it is. That tells you an awful lot. And that's just one very limited example of the interplay between the space and ground-based facilities. JWST is going to be launched sometime before the end of this year. Our plan was that the TMT would be up and running by now, and we would have that same kind of interplay.

You really need, because of the vast gain in sensitivity of space telescopes, a much bigger aperture ground-based telescope to study in detail the kinds of targets that are being found in space missions. And so, we really do need a 30-meter telescope to study, for example, the youngest galaxies in the universe. When the James Webb Telescope finds them, identifies them by redshift, the kind of probing that we need to do from the ground would really require the significant gain in collecting aperture that the 30-meter telescope provides. But we're not there.

ZIERLER: What were the earliest discussions that you were aware of or involved in that eventually coalesced around the 30-meter telescope idea? How far back does that go?

SOIFER: A lot of discussions really started taking place around the beginning of the 21st century, which was actually, to me, rather astonishing because the first Keck telescope had only been commissioned in 1993. And by the year 2000, people were already talking seriously about what the next generation of telescope was. Other 8-meter-class telescopes were coming online, and people were already thinking about the next generation of telescopes. And at the time, I was not involved in those discussions because I was totally focused on Spitzer. I was, and still am, the director of the Spitzer Science Center, at least until the end of next month.

And so, I was not party to those discussions. But they got going and Caltech was one of the places where these ideas were being advanced very vigorously, always, to be honest, in collaboration with University of California, which is our partner in the Keck Observatory. Using what I would describe as the brilliance of Jerry Nelson, the architect of the Keck Observatory's segmented mirror, to develop the ideas of pushing that effectively as far as seemed credible at the time.

ZIERLER: Now, because so many of these decisions are made by committee, I'm curious, we say all the time now, TMT, 30 meters. Why 30 meters? Did some people say 20 and some say 40, and you landed on 30? Or is there something specific to 30 that makes sense for this telescope?

SOIFER: That is a very interesting question. It's not a question that I actually participated in addressing, but my recollection is that there was a science committee, which had a significant number of people from Caltech, most notably, to my recollection, Chuck Steidel, who is a professor of astronomy, was a very active participant. And they analyzed what could be done, what the potential was. And I don't know what the specific problems that drove them to 30 meters were, but they concluded that 30 meters was feasible, that you could reasonably extrapolate the cost, and you could reasonably extrapolate what the performance would be. And it all seemed like the right size telescope to go for next. I have a t-shirt that you can acquire at the Palomar Observatory gift shop. It's a quotation from George Ellery Hale, the person who built the largest telescope in the world three or four times, the last one being the 200-inch. He envisioned it. And that quotation on that t-shirt is, "Make no mean plans, dream no mean dreams." And I think that, really, the idea for a 30-meter telescope is certainly consistent with that spirit of if you're going to dream, dream big.

ZIERLER: Yeah. Although I wonder where we are today with the TMT.

SOIFER: Well, I'm great at hindsight.

ZIERLER: What was the process from your informal involvement in these early discussions to becoming formally involved with TMT? How did that process go?

SOIFER: I got formally involved in 2009, when we were into the Spitzer warm mission, and life had really calmed down. And I was able to think about other things. I was asked by the incoming division chair, Andrew Lange, to serve as his deputy division chair. And given my background in astrophysics and astronomy, my focus was on the astrophysics part of the division. By then, TMT was a big deal, and we were very actively involved in it. So I got involved in TMT when I became the deputy division chair.

ZIERLER: What were the earliest signs as you saw them that there were these political and cultural problems with Hawaii's Indigenous population?

SOIFER: The earliest signs happened in the 1990s. Because at that time, part of our partnership with NASA on the Keck Observatory, the reason they wanted to get involved with Keck, one of the major scientific objectives was to identify planets orbiting other stars. And their concept was to build small telescopes around the two Keck telescopes and combine the light from all of these telescopes--I think there were planned to be four outriggers and the two Keck telescopes--to do interferometry. And one would detect the wobble of the influence of a Jupiter on a star. And you would see that and be able to infer that there was a planet orbiting that star. That was the plan. It was a very nice plan. But it got delayed, and delayed, and delayed through protests. At the time, it was environmental groups that had started to protest. They were concerned about the Wēkiu bug on Mauna Kea.

ZIERLER: What were they concerned about?

SOIFER: They were concerned that we would be disturbing the habitat of the Wēkiu bug, which, if I understand it, has blown up from lower elevations and has evolved into something that can survive at 14,000 feet.

ZIERLER: How much habitat would have to be destroyed, disrupted in order for the TMT to be built? What are we talking about here, exactly?

SOIFER: My recollection is that the footprint of the TMT is five acres. And it's been carefully chosen to be away from any sites of evidence where cultural practices have been found. Let me go back. The Keck experience started with environmental groups, but then the cultural issues got intertwined. Not so much with Keck. Keck was killed by delay. There were suits, and by the time the suits were resolved–and the license was approved to build the outriggers - by then NASA had run out of money. So that never happened. But that was the first real serious objection to telescopes on Mauna Kea. Around 2007, predating my involvement, the Moore Foundation, which has been an incredibly generous donor to Caltech and has wanted to support building the 30-meter telescope from the very beginning, commissioned a study, and that study identified the issues with the culture and society in Hawaii that we would have to confront and overcome in order to be successful in building the TMT. That study was done, as I said, in 2007. They identified, basically, every issue that we're dealing with.

ZIERLER: They understood, even as early as 2007, the things that have played out through today?

SOIFER: That's right. And I hate to say this, but we – and I use the word we since I'm part of TMT – didn't take this analysis seriously enough. We really followed the model of how the previous telescopes had been built. The voice of the Natives has become stronger and stronger. It's a voice of dispossessed people, it's a voice of the people who believe, with some real justification, that their land has been taken from them unjustly via the history of the US taking over the Hawaiian Islands, and it's a voice of a group that is very cynical about the commitment of government writ large to address their needs.

ZIERLER: This is such an interesting picture you're painting, because to go back to the mindset of between 2007 and 2009, as you say, there's already a strong awareness of the Native people's concerns, and yet at the same time, there's optimism and expectation that the TMT is going to be built. So, if you can square that circle, what's the plan there? Is the idea that you're operating on a playbook that harkens back to Keck? That these concerns will fall by the wayside, that these people can be strong-armed, and that's acceptable? That there is some negotiation that will lead to an agreement? What's the pathway from 2009 looking forward that explains both an appreciation of the concerns and an expectation that this will come to fruition?

SOIFER: The pathway from the perspective of 2009 is the perspective I want to talk about. It was that we would do something different. We would create what we call a community benefit. We would provide resources that would hopefully enhance the local community and carefully follow the law, meticulously follow all of the procedures that are required. Take no shortcuts. And we felt that the community benefit and the economic benefit would be sufficient. The fact that we would be doing this huge construction project, there would be additional work for the island. And we thought that these would be sufficient. And we didn't think that we would have to strong-arm anybody. I think that there was a real lack of appreciation of how deep the feelings, the resentments were within the Native community. The establishment, the business community, even the labor unions, and the government were all very supportive of TMT.

They saw this as a great thing. And of course, so did the people we talked to. And one of the huge mistakes--and my hindsight is great--was not talking to the opponents, not understanding what the real issues were. We could have addressed them. As an example, and this is all stuff that we've learned, a big part of our community benefit was enhanced STEM education. As a scientific enterprise, that makes sense for us to support that. And here, we felt we were going to provide a significant amount of money annually for scholarships, for young people to be able to delve into STEM fields. The difficulty is that a lot of the opponents don't see that this is part of their future. They feel that it's only the elites whose kids get to the Kamehameha School, who then go off to college.

And one of the fundamental issues is that, in the STEM fields, there really are very few opportunities on the Hawaii island. The only real opportunities on Hawaii Island are the observatories. And much of the employment in the observatories, particularly at the higher level, is based on national recruitment, not on recruitment on the big island, because there's very little base, and the kids who go into those fields move away. Here we thought we were doing good, creating a STEM scholarship program, but it certainly was not perceived by the community that we were trying to reach as having any relevance to them. We did it based on advice from the people we talked to. [laugh] We didn't talk to the right people.

ZIERLER: Just to be very direct about it, this all suggests that had a different path been taken, this project would've gotten the support that it needed from the Native peoples, as opposed to the possibility that there were no circumstances, no inducements, no agreements at that stage in time, based on what had happened historically, that would've made this a done deal.

SOIFER: Oh, I absolutely believe that. There are other things that we have to keep in mind. If you will, the fabric of our society writ large is unraveling. And I'm referring to the tribalization that we're going through now all over the country. People are, in my mind, thinking more and more of just their own tribe. And my tribe is the highly educated, intellectual tribe. I'm a member of a tribe. So there's that. There's the disillusionment with both government and big things. And I think I see this as reflected in Hawaii's society, as it is in every other part of this country. But this has been building.

And on top of that, there's the social justice movement, the Indigenous peoples' movements, and there's social media. All of these things have been growing, mostly in the period from 2010 to the present. And so, the issues have been amplified, and the people who have been leading the opposition to building TMT have been able to conflate TMT with all of the ills of Hawaii's society as viewed, quite frankly, from the bottom, from the people who have suffered the most, who have the least opportunity. And there are real profound social issues in Hawaii. And what we have done has been, effectively, to follow this model. The model was, we follow the law. As long as we follow the law, do everything right, get our permits, we'll be able to build. And we thought that we would build community support through the various programs that we had planned to implement and have implemented. And things have moved far faster than I had any imagination to see. And I think the rest of the project, the rest of the partners haven't seen it.

ZIERLER: A question that will make us all look smart only in hindsight. This idea that you weren't talking to the right people, that you were being advised that it would be a good prospect of doing scholarship programs and increasing educational opportunities. Why did nobody say at the time, "Maybe we should just talk directly to the people who were voicing these concerns"?

SOIFER: That's a tough question. It's a question that is hard for me to get my arms around. Because we had this report that said, "These are the issues." And somehow, I think we sort of forgot about it. We, without saying so, convinced ourselves, "If we do this thing, we create this community benefit and follow the law, that will get it done."

ZIERLER: Given that this attitude reinforces the sense that the Native peoples were disenfranchised from the process, do you think that in some way legitimizes their concerns?

SOIFER: Their concern that they have not been party to the discussions is correct. In that sense, it's legitimized. They have not been. We have been very much following a playbook that is, at best, 20 years out of date in a rapidly changing environment. Trying to think about what the playbook should be five years from now, or even in a time in the last two years, since we've last attempted to take construction equipment up to the mountain, things are changing substantially. And it is very hard, at least for me, to try and figure out how if there's a constructive path forward. Some things lead me to believe that there is a constructive path forward starting with talking to the people we've never talked to. But that's challenging because, as we've learned, there's such pent-up frustration--I think animosity is a fair word--that even having conversations, talking to people is a hard thing to accomplish. People will not talk to us because they think we will not listen to them.

ZIERLER: To bridge this divide between the 2009 era, whereas you indicate there was this lack of awareness and the importance of directly talking to the people who were voicing these concerns, to where you are today, where obviously, there is that awareness now, how do we connect these two points? What is the process for you, for the TMT community, of recognizing, even in retrospect, that a different tack should've been used in this regard?

SOIFER: Well, we are talking to people. We are talking to people who we are comfortable with talking to, who have very good connections, and who can tell us frankly how we're viewed and what the issues are. We try out ideas on them. "How do you think this would work if we did this?" And these are people, as I said, who have a good sense of what the community's reactions will be. At this point, the current project manager for TMT has actually moved to Hilo. And he's volunteered to do that. And he's talking to people very low key. He says he's here to listen and learn. And I'm going to be going over to Hawaii for a couple weeks very soon to basically participate in this.

The Hawaii culture is far more, I think, Asian-oriented than hard-charging US business-oriented. I know pretty well the NASA culture. It's not that. And you can't go into a meeting and say, "OK, these are the things we're going to accomplish. Let's go through this agenda." Doesn't work that way. The two words I have become very aware of are respect and trust. You have to start by showing respect. And showing respect means you don't come in expecting them to follow your culture. You have to accept that we're visitors. And we have to build trust.

ZIERLER: On the administrative side, on the budgetary side, when there was this optimism, this expectation 10, 11 years ago that the TMT would be built, where was the support coming from? Was the NSF already on board, at least conceptually? Was there confidence that they would come through with the resources that TMT needed?

SOIFER: Let me go back more like 13, 14 years ago as the project was being well-defined. The cost at the time looked like it might be of order of a billion dollars. And at that time, we thought that Caltech and UC each could come up with a quarter of that. The Canadians had become a partner, and we thought that was a quarter. And we thought the NSF would be a quarter. And we were sort of building this collaboration in that model. And the National Optical Astronomy Observatory was participating under the assumption of that model. That got derailed around that time because the group that put together the Giant Magellan Telescope basically insisted that the NSF consider their project as well.

And so, the NSF had to step back and stop participating in our project so that it would not show favoritism to either. There was an idea the NSF would be a quarter partner. And then, in 2008, 2009, when the previous decadal survey was being undertaken, we were in head-to-head competition with this other project, the Giant Magellan Telescope. And while the decadal survey said that the large ground-based telescope was scientifically the highest priority, they said that resolution of the competition between these two projects would take too much time. And so, they chose a different project, a project that was called the Large Synoptic Survey Telescope, the LSST. They placed that as the highest priority for NSF funding participation for 2010. And with that, basically, we needed to identify other partners.

It turned into a very international project. The Japanese were very interested in participating. Because they have a big telescope on Mauna Kea, they were very interested in building TMT on Mauna Kea. Back in the early days, we were comparing sites between Mauna Kea and Chile. And it was a combination of our Japanese partners insisting that Mauna Kea was where they were willing to go–we, of course, thought that Mauna Kea was a wonderful site because we have the Keck Telescope there. And there was pressure from the Moore Foundation as well to have the telescope there.

ZIERLER: What can be gleaned from the interplay between private and public support? The Moore Foundation is a player, the NSF is a player. How did these things work together in terms of the overall planning to get this thing built?

SOIFER: In principle, it should be very productive. It should be a very productive interplay. The Moore Foundation effectively has the flexibility to take on new and very risky ventures. And TMT was risky. And they can do it on a short time scale. The NSF is a mature federal agency. It cannot do things quickly. And it cannot take risks. My description of that is, in this era, the NSF could not fund LIGO. It just would be perceived as too risky. It should be a good match. A private foundation, the Moore Foundation, gets it going, gets it to the point where you really understand what it is you're going to do, works on some of the hardest technical problems, and then it moves smoothly into the NSF process. That's the model.

And in fact, this previous project, the Large Synoptic Survey Telescope, really followed that model. They didn't get nearly the amount of funding that the Moore Foundation gave for TMT, but they got a reasonable amount of early private funding to get going. And then, the NSF just came in and took it over. But because we've gotten to be a very big project, the NSF has a real problem that they don't understand how to work with nongovernmental agencies. They can work in collaboration with other governmental agencies just fine. They know how to do that. But when you're dealing with private universities that have real resources in the game or foundations, it's not clear to me that they really know how to do it. And so, it's a learning experience for them. And because it's a mature government agency, it's ponderous. And it takes time. And the people who are there are not terribly imaginative. They're as worried about something bad happening as they are about making something good happen.

And so, it takes much more time to bring it together. We're in that process now. We're hoping for a strong decadal review, where we've joined forces with GMT. We've discovered that the competition was killing us both. And so, now, we've joined forces. We're trying to convince the decadal review committee that two big telescopes, one in the north and one in the south, is important for the US to maintain its leadership in world astronomy. We're hopeful that the astronomical community through the decadal review will agree with that. We're now at the point where we really do need the NSF funding to be able to complete the project. They have their own process, and it's, at best, cumbersome, and it is slow.

ZIERLER: Was TMT originally conceptualized to be an international collaboration?

SOIFER: I would say the answer is yes because Canada became a very early partner. And so, from the outset, it was recognized it had to be a partnership. It got started as a UC-Caltech effort, and we had this model of the Keck Observatory, which, while somewhat painful at the time, has become this nirvana of how to do a project. You get the amount of money that you need at the outset, and you go at a technically paced schedule. The only thing that is driving the schedule is how long it takes you to do the technical things that you have to do. That's what I mean by technically paced schedule. And that was the mindset that we had. That's certainly not been how it's played out, where we have the site issue, we have the funding issue, we have all of the perspectives of international partners who have very different perceptions, and at the highest level, we all want to see this fantastic facility built. But once you step down from that, we each have different goals in terms of wanting to make sure that our communities get the very most out of this facility.

ZIERLER: Was a primary motivation for the establishment of TIO to serve as a clearinghouse for these different perspectives and motivations within the collaboration?

SOIFER: There is still actually a TMT Corporation, which is a California nonprofit. That's the way TMT got started, through TMT Corp. But when we brought in international partners, with Canada and Japan, and then later, India and China, it was not a structure that could be changed to have other partners have an equal weight. And so, we had to create a different organization, which became TIO, TMT International Observatory, LLC, where all of the partners have effectively the weight according to their financial share.

ZIERLER: The decadal survey is going to drop any day now, it feels like. What are you hoping that it says? Best case scenario.

SOIFER: Best case scenario? The US ELT program should go forward as rapidly as possible. The Northern Hemisphere Telescope is the higher priority because the European Large Telescope is being built in the south. And so, scientifically, the northern telescope should proceed. And that's really as far as the decadal should go. The execution of the objectives is the responsibility of the agencies. This decadal group is not at all charged with telling the agencies how to do their jobs. That's what I'm hoping for.

ZIERLER: To what extent do you think the decadal survey will consider the political aspects to this issue? In other words, best case scenario, they say, "This is exactly where astronomy should be heading. This is exactly the right telescope to be built." Will it consider the scientific value in a vacuum? Or do the social and political contexts have to be part of the calculation?

SOIFER: The social and political contexts will be part of the calculation. They're not detached from reality. They understand how Washington works. They understand how the Astronomical Society works. One of the things I'm expecting they will say is that US astronomy is going to have to face issues of siting facilities on lands that are sacred or important to Indigenous peoples. And we, the astronomical community, are going to have to learn how to deal with this in a constructive and productive way.

ZIERLER: As you say, now, we are speaking to the people who are voicing these concerns. To what extent has the astronomy community evolved within this larger push in STEM for greater sensitivity, greater inclusivity, an emphasis on diversity that Caltech is experiencing itself and is in many ways taking a leading role? To what extent does TMT have the opportunity to convey to the Native Peoples its sincerity on the basis that these are cultural transformations that are happening at the same time, which would allow, hopefully, to allay these concerns that, "You're just telling us what we want to hear, and it's going to be business as usual"? To what extent are there those opportunities to convey this story?

SOIFER: I actually think there are good opportunities to do that. As I said, we're listening. We're seeing actions that we think can be taken. One of the bigger obstacles right now is that I am finding it hard to convince my colleagues within the TMT organization that we have to change, that we cannot proceed with the playbook that I've described to you, that we really have to change. Because there's a level of conservatism. I think the people who are not as totally immersed in the issues as I have become haven't yet seen that this is a necessity. If we want to make this telescope happen on Mauna Kea, we have to change. And that's basically one of the things I'm doing now, trying to understand as best I possibly can the perspective of how to change, how to communicate with the people who currently are opposing us.

But also, I'm finding that I have to be more eloquent than I have been in convincing my colleagues within the project, and when I say within the project, I mean the other partners, that this is necessary, that business as usual is doomed to failure. And it's broader than TMT. Because there's a master lease for the astronomy precinct on Mauna Kea, and it expires in 2033. And if astronomy doesn't change its way of doing business, we're going to find ourselves without authorization to continue the astronomy enterprise on Mauna Kea.

ZIERLER: A really blunt question, maybe one that'll seem obvious, but I'd like your take on it. Because TMT has done all of the right things legally, gotten the permits, gone through all of the applications, why is it unacceptable to simply clear the protestors from the road? Because just to be clear, so I understand correctly, TMT could have gotten started absent these protestors on the road.

SOIFER: That's right.

ZIERLER: So it does beg the question, even if it seems obvious why not…why not just do that?

SOIFER: Let me answer that by trying to explain the evolution in my thinking. I used to be of that view. "Let's clear the protestors. We'll do it politely. But we have the legal authority, and we should be exercising that." I've come to appreciate a couple of things. Number one, we cannot build this facility, if you will, as an occupying army.

ZIERLER: It's neocolonialism, essentially.

SOIFER: Right. It's unsustainable.

ZIERLER: Yeah. From the beginning of your answer, it's morally indefensible, and it's scientifically indefensible.

SOIFER: Right.

ZIERLER: You mentioned the major investment that would be required for security in that unfortunate situation where TMT was built under duress and protest. What about the enormous amount of money that's been spent just on the basic science, the instrumentation, the mirrors, the lasers? What are the plan B's so that, heaven forbid, this does not happen in the best possible way, all of this work is not for naught?

SOIFER: Well, one plan B is to build TMT in La Palma on a site that's not as good. It's at 8,000 feet in the middle of the Atlantic Ocean. It has the advantage in terms of image quality that Mauna Kea has, and our analysis shows that that's a good option. It would be a good site. The amount of science that we would be able to achieve at La Palma is between 90 and 95% of that which we could do at Mauna Kea. It's not as high, so it's not as dry, and it's not as cold. It impacts the infrared more than anything else, but that's tolerable. The biggest obstacle to that right now is funding. The National Science Foundation bureaucrats have convinced themselves that Congress would not appropriate the money to build this size of a facility not on US soil. So the obstacle is to convince both the NSF and Congress that this is a reasonable investment.

ZIERLER: What are the stakes in that opportunity that dramatic congressional testimony? If you had the opportunity to tell legislators, the people who will make this decision, what are the stakes if we lose this? Are they existential in terms of US leadership in the astronomy in the 21st century?

SOIFER: I think yes. Dennis Overbye, the science writer for the New York Times, has basically written that statement. To date, the US has led world astronomy, basically, by always having the biggest glass, being able to deal with the most challenging problems. And if we don't have this next generation largest telescope, the people working on these most challenging problems will be going to the European Southern Observatory exclusively.

ZIERLER: I wonder if you've ever reflected on if that happens, the would-be historical parallel between the collapse of the SSC and CERN and what might happen here in astronomy.

SOIFER: Yes. It's very plausible. The one place where at least right now the US stands unmatched is in space astronomy. I don't think it would be as marked, but it would be real. And one of the things that I worry about for Caltech is that at its very base, foundational to the astrophysics enterprise at Caltech, has been access to the biggest glass. And not just because of the science that emerges from that, but because that's an attractor to people who don't even participate in that or only dabble in that but do other things. A current example is Fiona Harrison, who is currently the division chair of Physics, Math, and Astronomy [at Caltech].

But she's also a PI on NuSTAR, which is a satellite that does x-ray astronomy. But she does follow-up with Keck. We have other examples on our faculty. We have people who are doing really first-rate, state of the art radio astronomy. But the attraction to them of Caltech, at least I've convinced myself, has to do with the fact that we have this preferred access to the biggest glass to allow us to tackle the most challenging problems. And if that goes away, I think it will have a negative effect on the future of astrophysics at Caltech.

ZIERLER: Because we're in such this dramatic moment right now where things can be turned around, everything theoretically can be salvaged so that everybody is satisfied, TMT gets built in Hawaii with the support of the Native Peoples, how does that happen circa August 2021?

SOIFER: I think it happens by learning from our past mistakes, by listening, by demonstrating both respect for the Hawaii community and trust that we will do things that not only enhance or enable TMT, but that will enhance the community in Hawaii. And not just the establishment, but we will promote the advancement of all of society, that we'll look for ways to provide opportunities for people who grew up in Hawaii, who live in Hawaii to thrive and partake of what we're doing.

ZIERLER: All of this, of course, requires an active and positive partner in Hawaii. How do we achieve that? How do we get the Native peoples to receive this message, and accept it, and not just accept but welcome the TMT?

SOIFER: Basically, as I have learned, we do that almost one person at a time. We have to have a ground game, which is interacting with the Hawaii community almost on an individual basis to dispel the misinformation that's out there, to talk about what we want to do to improve the society there. We don't have authority. That's absolutely true. We don't have, within the project, a lot of resources that we can apply. But I think we have a big voice because we're so visible. So we can be leading in ways that promote our interests, but also the interests of the local society. And I think we're getting there in terms of understanding both what the issues are, but also what the needs are. And one of the real problems we face is, we're in a time crunch. If we had 100 years, or even a decade, to get to this, we could do it. But we have very limited time. We have a few years at best. And if we don't get going within a few years, all of the partners will simply just walk away.

ZIERLER: Highly cautious optimism sounds like the label I would affix to your approach right now.

SOIFER: Yes. I think that's about right.

ZIERLER: Well, we began our talk discussing your current interests. And so, I think as we come to the conclusion of this amazing discussion that we've had over these several sessions, I'd like to ask a few broadly retrospective questions about your career, and then we'll end looking to the future, which obviously will be very much wrapped up in the big question mark that is the TMT. So let's bring it back to the science. What have been some of your most satisfying moments in understanding the evolution of galaxies?

SOIFER: I would say first, understanding that there really are significant numbers of very dusty galaxies even very nearby. When I say nearby, I call it the local universe within a few hundred mega parsecs. So that's three times the number of million light years. But it's the local universe, the here and now of the universe, these galaxies where all of the things that are going on are completely hidden by dust. They're plentiful. And then, following that to see how much more important those galaxies were in the past, so that by the time you get to sort of the teenage years of the universe, looking back to about ten billion light years ago, when the universe was most active, most of that action was hidden by dust.

That's one of the things that I was able to do with Spitzer data because we had the sensitivity to find those things and draw the lines from the here and now to back then. For me personally, that had been an extremely satisfying path, and it's basically consumed much of my scientific career with IRAS, with the 200 inch telescope on Palomar, with SIRTF / Spitzer, and with Keck. So from the personal perspective, I think that's been what I would point to as what I've done that's useful.

ZIERLER: In a life saturated in infrared instrumentation, what have been some of the biggest surprises in terms of the technological leaps and bounds that you've seen and have been a part of over the course of your career?

SOIFER: I think the most fundamental change has been going from hand-building every single pixel and detector. And so, you had a handful of detectors at best to do the science that you wanted to do. And now, technology is such that even in infrared sensors, we're talking about 16-megapixel devices, 16 million pixels at a time. And so, just the concepts of things you can do, the problems that you can tackle are just astonishingly different. But this is the path from a field that's being invented to a field that's pretty mature. It's not a different path than other areas of astronomy or other areas of the physical sciences, which is where I have some level of appreciation of how things go. But to have lived through that, I think, has been a hell of a lot of fun. I never would've thought that we could detect planets orbiting other stars. That, at least to me, is the most astonishing discovery of my scientific lifetime.

ZIERLER: And therein, if we ever see it, will be the root of discovering life beyond Earth.

SOIFER: That's right. And even a decade ago, we said, "From the ground, you can't discover life on other planets." But now, there are really bright people like Dimitri Mawet, a member of our faculty. They're inventing the ways to do that. It's exciting.

ZIERLER: Of all of the collaborations that you've been a part of, both scientifically and administratively, what do you see as some of the major connecting threads in all of your adventures in your career?

SOIFER: The desire to discover. I see that as driving the space projects, the Keck, even my job as a division administrator, hiring the exciting young people who are inventing new fields of physics to discover new phenomena, to discover how the world works in a better way. I think that's, I guess, how I would tie it all together.

ZIERLER: Because Caltech is such a special place, because your career is so special, I wonder if you can reflect on the things that you've been able to accomplish because Caltech has been your home.

SOIFER: I think that the main thing is the spirit of, "Why not do this?" No sense of limitation associated with people issues, of a bureaucracy. Even though at Caltech the bureaucracy has gotten bigger, it's still a place where the science is paramount. People – I like to think of myself when I was a division chair – would try and find a way. If somebody would come to me and say, "I really need to be able to do this," I'd try and find a way to help them make it happen. I think that's what permeates this place.

ZIERLER: Looking to the future, to the extent that you play an advisory or mentor role to students or graduate students, using your powers of extrapolation, because there are so many exciting things happening in observational astronomy, if a student comes to you and says, "What should I focus on? I'm interested in so many things. Help me narrow my interests down," what would you say to them for somebody who's looking at the next five or ten years in their research career?

SOIFER: Exoplanets. [laugh] That's what I would say. I think that's an astonishing field. It's just opened, and there's so much opportunity. And it's not just opportunity to use existing telescopes. It's opportunity to be creative in inventing new ways to make measurements that I think can have a huge impact.

ZIERLER: So much of our discussion over these sessions has been about what has already been discovered by you, by your colleagues, as part of your career. What today, when you look up to the sky, is as big of a mystery as it was way back when you were an undergraduate, and you first started thinking deeply about these things?

SOIFER: I would pick out two things. Is there life on other planets that we can detect? I'm reasonably confident that the answer is yes.

ZIERLER: That would be two yeses, one, that there is life, and two, that we can detect it.

SOIFER: Right. The part about detecting it is the part that is highly uncertain. But that, I think, would have such a profound impact on the worldview of, I would hope, most of humanity.

ZIERLER: It would reframe even the revolution from a geocentric to a heliocentric view of the world.

SOIFER: I would hope so. We didn't even think about that question when I was a student. But that's an area that is huge. And in fact, when I was a grad student, I took a planetary astronomy class from Carl Sagan. He had just moved to Cornell, and I had just moved to Cornell. He wasn't yet a superstar, but he was tremendously excited about his goal, to find life elsewhere in the solar system. And he certainly would've been very, very happy to see that there are many solar systems. That's one question that has been bubbling around and is still there. Another question is finding the first stars. Even from when I was a graduate student, people were writing papers and talking about what the first galaxies looked like, when that happened in the history of the universe. And that one, I think, is one that the James Webb Telescope or possibly the telescope beyond James Webb will really be able to see, the first stars, as in the first galaxies, in the universe.

ZIERLER: What might that tell us about cosmic inflation?

SOIFER: I'm not sure that will tell us anything about cosmic inflation because we're already, with the studies of the cosmic microwave background, reaching well beyond when the stars formed. Recently, I was reading obituaries of Steve Weinberg, one of the Nobel Laureates in physics, who wrote a book, The First Three Minutes, talking about the Big Bang and what happened in the early universe. And he was quoted as saying, "After the first three minutes, nothing really interesting happened in the universe." And, if you will, cosmic inflation is part of the first three minutes. What I'm talking about is part of the nothing really interesting happened. But it's interesting to me. How did the galaxies that we inhabit really form? When did they form? There's a lot that we certainly don't understand about that. And as I said, it's been a question that, even as a graduate student, I would read papers about. Theoretical calculations. But that one, we're within reach of being able to get there.

ZIERLER: Last question, looking to the future. What else do you want to accomplish, and how much is the uncertain future of the TMT wrapped up inevitably in that question?

SOIFER: What I hope to accomplish is to get to a site for TMT and to see the construction equipment get to that site. I hope I'm alive for the dedication to the telescope. And if I am, I'm going to demand an invitation. But that's going to be a while. It's unclear to me whether I'll make it. But if I can get to a site selection for TMT, I think I will have done my share.

ZIERLER: Tom, this has been a fantastically fun, important, and engaging discussion. I'd like to thank you for spending all of this time with me. And as you know, when I first got to Caltech, I was so hungry to know, "Who are the people that I should speak to right away?" And I'm so glad that I was pointed to you. I'm so appreciative that we were able to do this. Thank you so much.

SOIFER: It's been my pleasure, too.