Meteoritics & Planetary Science 39, Supplement, A199–A213 (2004) Abstract available online at http://meteoritics.org Report Oral histories in meteoritics and planetary science: XIII: Fred L. Whipple Ursula B. MARVIN Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA E-mail: [email protected] (Received 13 June 2004) Abstract–Born in Red Oak, Iowa, in 1906, Fred Lawrence Whipple earned his Ph.D. in astronomy at the University of California at Berkeley in 1931. He immediately accepted a position at the Harvard College Observatory and remained at Harvard throughout his career. In 1950, he was appointed to the Phillips Professorship in the Department of Astronomy, and in 1955, he began serving concurrently as the Director of the Smithsonian Astrophysical Observatory when it moved from Washington, D.C. to Cambridge, Massachusetts. In the 1930s, Whipple established the Harvard Meteor Project in which two cameras, 26 miles apart, simultaneously photographed the same meteors, for which he invariably derived elliptical orbits indicative of their origin within the solar system. In 1950, Whipple introduced his “dirty snowball” model of comet nuclei, which soon became widely accepted and was fully confirmed in 1986 by close-up images of comet Halley taken by the European Space Agency’s Giotto spacecraft. Keenly anticipating the orbiting of satellites during the International Geophysical Year (July 1, 1957-December 31, 1958), Whipple won contracts to build a worldwide network of telescopic cameras for satellite tracking. At least one of the cameras was ready in time to photograph the Soviet Union’s Sputnik I satellite in October 1957, and all 12 stations were in operation by midsummer of 1958. For his leadership role in this project, President John Kennedy honored Fred L. Whipple in June 1963 with the President’s Award for Distinguished Public Service. In the 1960s, Whipple collaborated with astronomers at the University of Arizona to build a new observatory on Mt. Hopkins, 40 miles south of Tucson. Two of the most innovative instruments installed there for astrophysical research were the world’s largest gamma-ray detector and the Multiple-Mirror Telescope. In 1982, the Mt. Hopkins Observatory was rededicated as the Fred Lawrence Whipple Observatory. Although he retired in 1973, Whipple was present at the dedication and until 2003, he continued to actively participate in research projects. At present, he is anticipating the return of the Stardust mission to comet Wild 2, which will bring back to Earth samples of the comet and of interstellar dust. It is scheduled to arrive in 2006, the year of Fred Whipple’s 100th birthday. Among his many honors, Fred Whipple received the Leonard Medal from the Meteoritical Society in 1970 at its meeting hosted by the Goddard Space Flight Center, in Skyland, Virginia. UBM: Fred, in 1927 you earned your BA degree in most boring thing I could imagine. I wanted to go on in mathematics at UCLA, but then you went on to graduate astronomy, but UCLA had no Department of Astronomy at school in astronomy. How did that come about? Did you, by that time. Leonard had started teaching there in 1922, but it any chance, take an astronomy course with Frederick C. took him ten years to persuade the administration to institute Leonard? a degree-granting Astronomy Department. FLW: Yes, that is exactly what I did. In my junior year, I UBM: So you went to Berkeley. took an astronomy course with Leonard and found it to be FLW: Yes, Leonard advised me to apply and helped me to extremely interesting. When I graduated, I decided that to win a teaching fellowship at Berkeley. I got my Ph.D. in 1931. become a professor of mathematics would be just about the UBM: What was your thesis topic? A199 © Meteoritical Society, 2003. Printed in USA. A200 U. B. Marvin considered galaxies to be his own topic and he didn’t care to have any competition. UBM: When was it that you examined 70,000 sky-survey photographic plates using a hand lens and discovered six new comets that never had been recognized in the sky? FLW: That was in the mid-1930s when I was the curator of the observatory’s astronomical plate stacks. UBM: I believe that effort brought you honors. FLW: Yes, each of my new comets brought me a Donahue Medal from the Astronomical Society of the Pacific. UBM: When did you begin studying meteors and meteor streams? FLW: They always interested me but I got my first real chance to work on them soon after I came to Harvard. I wanted to find out where the meteor streams were coming from. I also was interested in comets and their possible relationship to meteors. We knew that most meteors follow elliptical orbits showing that they originate within the solar system, but some observers, particularly the Estonian astronomer, Ernst J. Öpik, who was a visiting scientist at the Harvard Observatory from 1930 to 1934, were reporting hyperbolic meteors. I wanted to find out if there really were any. UBM: Hyperbolic meteors would come in from interstellar space and simply continue on out of the solar system after one swing past the Sun. FLW: That’s right. And meteors in hyperbolic orbits should have higher velocities than those in elliptical orbits. UBM: How did you go about studying meteors? Fig. 1. Fred L. Whipple about 1968. (Courtesy of the photographer, FLW: In 1936, I established a system of using telescopic Babette Whipple.) cameras to take simultaneous photographs of the same areas of the sky from two sites: the Harvard College Observatory in FLW: I worked on variable stars with Donald Menzel, Cambridge and the Oak Ridge Observatory, 26 miles to the who held an appointment as an astrophysicist at the Lick west in the town of Harvard, Massachusetts. I fitted rotating Observatory. shutters with synchronous motors onto the two telescopes to UBM: Did you come to Harvard as soon as you got your determine meteor velocities and rates of deceleration due to doctorate? atmospheric drag. FLW: Yes, I did. In 1931, I accepted an offer from UBM: Is this what became known as the Harvard Meteor Harlow Shapely, the Director of the Harvard College Project? Observatory, to serve as head of the observing program. The FLW: Yes, and it continued on for more than 20 years. observatory was, and still is, Harvard’s only separately From the beginning, every instance in which both cameras endowed unit that is independent of the university deans. The photographed the same meteor trail simultaneously, I found following year, 1932, I was appointed an Instructor in the that the exposure limits included an elliptical solution. Department of Astronomy, which is located under the same UBM: But Öpik remained unimpressed? roof as the observatory. Both were small organizations back FLW: Yes, he did. Öpik had designed a very clever device then. Six years later, in 1938, I advanced to the status of a he called a “rocking camera” which convinced him he was Lecturer on Astronomy. seeing some meteors with hyperbolic velocities. He could be UBM: When did Menzel come east to Harvard? very sarcastic about my insistence on elliptical orbits. In FLW: Menzel came to the observatory in 1932, as the 1932, Harlow Shapley sponsored an expedition for observing resident astrophysicist. He was appointed as Harvard’s first meteors in the clear, dark skies of New Mexico. Öpik went on Professor of Astrophysics in 1938, and he succeeded Harlow it and reported measuring hyperbolic meteors. Although Öpik Shapley as Director of Harvard College Observatory in 1954. was one of the most brilliant astrophysicists in the world, he UBM: Did you continue your research on variable stars stuck to his hyperbolic meteors until 1959 when he concluded at Harvard? he was mistaken about them. I am not sure just what it was FLW: Yes, Shapley encouraged me to work on them. I that changed his mind, but he wrote a nice letter to me also wrote a paper on galaxies, but I soon learned that Shapley apologizing for his years of stubborn opposition. Oral history: F. L. Whipple A201 UBM: From the late 1930s onward, Lincoln LaPaz also would have to add meteorites from the Moon and Mars as reported observing hyperbolic meteors. I believe that during planetoidal types. and after the War, he was using radar as well as optical LaPaz and I continued to disagree about hyperbolic techniques. meteors for another five years or so until he stopped coming FLW: He was. And LaPaz was very positive of his to meetings and publishing papers. That was a loss to us results. I don’t remember that he ever changed his mind. For because, on the whole, he had been a strong, mostly positive years, LaPaz accused me of withholding crucial evidence of influence in meteoritics. hyperbolic meteors when I did not loan him certain UBM: Did your consistent measurements of elliptical photographic plates that were archived at the Harvard orbits imply an asteroidal origin for most meteors? Observatory. I explained that those plate exposures were one FLW: No, because the velocities I was measuring hour long and the instants of the images had no measure of the suggested that many of the grains were of loose, fragile time on them, so you could use them to calculate a range of material, more likely to come from comets than from orbits with no assurance of being correct. He did not accept asteroids. All established comet orbits are elliptical; this explanation and neither did Frederick Leonard, who had beginning with the long-period one that Edmond Halley become a great friend of LaPaz.