Features

Dr. Dale P. Cruikshank, Astronomer and Planetary Scientist, NASA Ames Research Center, Moffett Field, CA

NTB: Dale, I was hoping to look a bit into your biography here, too.  You have an asteroid named after you, is that right? In 1988, Asteroid 3531 was named Cruickshank by the International Astronomical Union. Is that a good one?

Dr. Cruikshank: It’s a nice honor; it’s certainly not a unique honor. The people who discover the asteroids -- and there are some specialists, some of whom have found hundreds and hundreds of them -- according to the International Astronomical Union, have the privilege of recommending a formal name rather than just a number for an asteroid. So a lot of these folks, some of whom I work with, honor their friends and sometimes their pets, and their favorite rock group with names that originally, when only a few asteroids were known, were named after Greek Gods and other notables and mythological characters. And here we are now, with one named after me, and several other people I work with, in the company of Greek Gods. It’s an ego boost. It’s not by any means a unique honor, as I said, and by the way, there are at least a quarter of a million more asteroids unnamed, so there’s potential for naming a good fraction of a population, an asteroid for each.

NTB: You spent time in the USSR as a National Academy of Sciences scientist. What kinds of work did you do there?

Dr. Cruikshank: That was a long time ago. In the end, on three different visits, I spent a total of about two years there. When I finished my PhD work at the University of Arizona, in the late ‘60s, it was clear that there was a Russian scientist that was working on the same types of problems that I was, and so I applied for this program that the National Academy had as an exchange arrangement with the Soviet Academy of Sciences, and was able to spend a year there in 1968-69, working with the guy who was doing very similar kind of work to mine. At that time, he and my boss back in the US were the only people in the world doing this kind of work because it was pushing the technology of the time to make infrared, spectroscopic measurements, so it was an opportunity to see first-hand what he and his people were doing, to learn from him, to work with him, and establish what turned out to be a life-long friendship and collaboration. So we had many years of collaborating and discussing and mutual visits, and that turned out to be a very positive thing in the development of my career.

NTB: As an astronomer at the Institute for Astronomy, you helped with the development of Mauna Kea, an important observatory site. What role did you play in that development?

Dr. Cruikshank: When I went to the University of Hawaii in the summer of 1970, the decision had already been made to build a telescope on that site, which is at an altitude of about 14,000 feet. It’s a difficult environment to work in, because of the low oxygen and the limited access by a bad road and all that, but nonetheless, the University of Hawaii and NASA had already put a medium-sized telescope up there, and it was just coming into operation in the summer of ’70. So I was one of the first users of that telescope. The conditions to use it were a bit adverse, but I was young and eager, and it was an opportunity unmatched anywhere else. Together, with colleagues who had the similar inclination, we made very good use of that telescope and demonstrated the utility of that particular site, as a world class, maybe the best in the world, site for infrared astronomy from the ground. That’s before we had infrared telescopes in space.

So, on the basis of the work that we did, and the results we got, which were quite unique, other organizations decided to put infrared telescopes up there, too. For example, the United Kingdom put an infrared telescope up that went into operation in ’79. The Canadians and the French teamed up to put a large telescope there that also went into operation in ‘79. And NASA decided to put a dedicated infrared telescope up there as well. It was the third of those three that came into operation in ’79. Since that time, the importance and efficacy of that site have been so well demonstrated and reinforced that the Japanese have a telescope there, the Keck Observatory, with the two largest telescopes in the world, have been established there, and there’s yet another giant telescope and more to come.

So it was the early work that my colleagues and I did at that newly opened site, which was, I repeat, difficult to work at, and still is, because of the altitude, that made it clear that infrared astronomy could best be done there, that infrared astronomy is critical to the understanding of the universe, planets, stars, galaxies, the whole thing, and that that’s a great place to build a telescope. Many countries and many organizations have done so and it remains to this day the premier infrared observatory site in the world.

NTB: Looking at your years of spectroscopy and radiometry experience, what has been the most exciting discovery for you?

Dr. Cruikshank: I think the most exciting discoveries have been the detection of these ices on the objects in the outermost part of the solar system: in particular, Neptune’s largest satellite, Triton, which is an object roughly the size of our moon, but is a long, long way away. We found frozen nitrogen there for the first time. I already mentioned the discovery of frozen methane on Pluto, which was a few years earlier, and eventually nitrogen on Pluto as well.