Telescopes & Research, Page 2

Harold Larson, on the airborne spectroscopy program

I’d never been in Arizona, so I just got off a plane and here I was. Everything was new, shocking. I didn’t know what was happening because I took this job by mail from France. I like to say I was a mail-order professor. I hadn’t made any visits; I had no idea what I was getting into. I had never met Kuiper; all I had was two letters from him.

So that was the way I arrived, and it took a while to settle in and figure out what my role would be. Kuiper of course was pioneering the use of aircraft. He wanted to use this particular type of spectrometer that Harold Johnson was developing, perhaps more for use on the ground, but Kuiper saw a role for it in an airplane.

So there was an emerging technology, all kinds of changes, all kinds of potential—discovery potential, you might say—and Kuiper had the sense to know that he could be one of the first people using it.

That’s why he hired me through the mail. I was working in France on a post-doc with a team of people who had also been pioneering the use of this kind of instrumentation, not for aircraft, but for ground-based telescopes. I had become familiar with the optics, the technique, the computer programs. My job when I came here was basically to step in and pick up the pieces, and continue developing this program of airborne spectroscopy.

So as soon as I got here I got engrossed in what he was doing on the CV-990; that was the four-engine passenger jet that NASA had acquired. Nothing worked. Nothing even came close to working. But we acquired experience with trying to make things work in what really is a very hostile environment.

Then something very tragic happened. The plane we were using crashed. It crashed out on Moffett field, in the Bay area, and that put an end to what Kuiper was trying to do. But by that time he had demonstrated well enough the potential that NASA replaced that plane with a bigger plane, the C-141, which is a military aircraft, and which eventually had a 36-inch diameter telescope. That isn’t a very big telescope by today’s standards, but it’s a very big telescope because it has to look through a hole in a plane that wasn’t designed for it.

That facility came on-stream after Kuiper died. He saw the plane, but he never flew on it. He walked through it, but he never flew on it. It was eventually dedicated to him. After he died it was dedicated to him because of his pioneering work directing NASA’s attention to doing astronomy this way.

The C-141 became operational in ’74. I was one of the first groups to fly on it, and one of the last. For me it was about a 25-year involvement. It was a plane that had no insulation, so it was noisy, it was cold, it had no windows, and you just sat their for 72 hours being bored because nothing was happening, or when you were observing, you were watching your instrumentation, you were worried about things going wrong every second, and while computers were running everything you were always ready to press buttons and take control if something happened.

Observing isn’t pleasant. It is hard work, it’s tiring, and 80 to 90 percent of what you do is never useful for anything. It’s a very low efficiency operation. But then you get a discovery. And then you forget all the bad moments because suddenly something is important. We had enough discoveries to make the whole effort worthwhile.

George Rieke, on inventing infrared astronomy

Gerard [Kuiper] had a sort of strange attitude for something called the Lunar and Planetary Laboratory, that is, he brought in people that did, I would say, slightly offbeat but very technically advanced kinds of astronomy. [Harold] Johnson left before I joined the lab, but I gather that he used to joke that he was in the stellar division of the Lunar and Planetary Laboratory, which was sort of true.

Because Gerard had this interest in infrared, one of the offbeat areas that flourished was infrared. So he brought Harold in, and Harold had been befriended by a young physicist named Frank Low while he was in Texas. Harold quickly became Frank’s mentor in getting into infrared astronomy. So then you had three major figures in infrared astronomy—not that there was a field of infrared astronomy, but they became major figures as time went on and people realized how much they developed it.

Harold was the premier person in photometry. He knew how to take the data so you could inter-compare stars and study them and actually make field advances in science. He really started with the first photometry measurements in 1961 or 1962, and in 1966 he published a review article with all the infrared photometry results that he had done. That review article is still cited. It’s incredible that in four years he went from a clean sheet of paper to a mature area of astronomy.

Harold had ideas of how to build [photometric] telescopes that would be cheap, they didn’t have very good optics, and they could be moved quickly around the sky, which meant you’d unclamp the telescope and move it manually, just hang on the telescope and move it. The 28-inch was the first one. Harold and Frank then developed and carried out all kinds of pioneering infrared astronomy using the 28-inch. Harold then got a 60-inch telescope built, which followed the same premise of the photometric telescope. It was getting about as big as you could move with my hand, but that’s how it worked. We shifted a lot of these efforts to the 60-inch.

Gerard had his own 61-inch, and interestingly, I found a progress report that Gerard wrote on the 61-inch about a month after it was first being used. In the progress report it said that Frank had discovered the internal energy of Jupiter—which was one of the major discoveries of infrared astronomy—within that month. It tells you something really interesting, which was that infrared astronomy was super-ready to have discoveries come out. There were things that were well within in reach of the detectors and capabilities that people had then, just sitting there, super-saturated with discoveries ready to be made.

For quite a while the 61-inch in the infrared—at least the thermal infrared, which means the wavelengths beyond two microns—was by far the most sensitive telescope in the world. We used to make observations and send them over to Caltech where there was another infrared group, and they would actually not be able to confirm the observations, but they turned out to be right. They had the 200-inch, but the fact that we had optimized the 61-inch so carefully for this application gave us a big advantage.

There were really three centers of ground-based infrared that sprang up. There’s this one, and shortly after Caltech under Gary Neugebauer, and not too long after that Ed Ney at the University of Minnesota. I think the fact that there were three was actually important. You wouldn’t tell the deep secrets of how you did something, but you would show enough that people could benefit from what you’d done. In some ways the rivalry was fiercer than at present, but in other ways it was much more gentlemanly—the way you imagine science should be done, where people pass things around and say, “What do you think?” I think that sense of community was really important to getting the field started.