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?

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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. determined in 1705 for a comet from beyond Neptune. He UBM: Speaking of Frederick Leonard, let’s briefly go concluded from historic records that it had been seen before back to 1933 when Leonard and Harvey H. Nininger founded at intervals of about 76 years, and he predicted its return in the Society for Research on Meteorites (which would switch its 1758. When it appeared, they named it for him, 16 years after name to The Meteoritical Society in 1946). It held its his death. The main point is that, even when they come from organizational meeting in August 1933 at the Field Museum in great distances (including from the Öort cloud possibly half Chicago with 15 charter members in attendance. Leonard had way to the nearest star), comets are gravitationally governed published a call for members in the April issue of Popular by the Sun. Astronomy, and had sent personal appeals to everyone he could UBM: And you were finding it possible to match meteor think of, at home and abroad. That must have included you, but streams with comet orbits? I do not find you listed among the 50 or so charter members FLW: Yes I was, in many cases, and so were other who joined before September 1st. Have you any recollection of astronomers. why you didn’t join the Society at the beginning? UBM: During World War II, you took temporary leave of FLW: No, I haven’t. the observatory and worked with the Harvard Radio Research UBM: You did join a few years later, though. The record Laboratories in Cambridge. Your special contribution was a shows that you served two terms as a Councilor from 1941 to stratagem for confusing German radar. Tell me something 1950 and one as a Vice President from 1950 to 1954. about that. FLW: I suppose you learned all this when you wrote your FLW: I coinvented the chaff-cutter by which 3 ounces of history of the Society a few years ago. aluminum foil could be transformed into several thousand UBM: I did. I also learned that in 1952, the Meteoritical half-wave dipoles. When these were released from B-17 or B- Society met in Albuquerque to dedicate the newly built 24 planes, they produced echoes that looked to the German headquarters of the Institute of Meteoritics, of which LaPaz radar like squadrons of incoming aircraft. It worked very was both the Founder and Director. In his keynote address, effectively. Leonard summarized the responses he had received to the UBM: And I believe it earned you an award from following question which he had sent to leading scientists: President Truman. “What do you consider to be the most important contributions FLW: That was the Presidential Certificate of Merit, of a research nature, that you yourself have made to which he bestowed on me in 1948 for my role in confusing the meteoritics in, say, the last 20 years?” enemy radar. LaPaz named his mathematical approach to meteoritical UBM: In 1945, immediately after the War, you advanced problems, and listed as his most important result the to an Associate Professor in the Department of Astronomy, verification by new, independent, non-visual methods of the and continued your research on meteors and the upper existence of meteorites moving in hyperbolic orbits with atmosphere. But you already were thinking about space flight. respect to the Sun. In 1946, when many people still saw space travel as very You cited the absence of meteorites in hyperbolic orbits much a science fiction sort of thing, you published a paper among those you had recorded during many years of titled: “Possible hazards to a satellite vehicle from observations. You also listed evidence that meteoritic meteorites.” In it, you proposed the Whipple Shield to protect materials are of two types: a) planetoidal, with densities spacecraft from being punctured by high-velocity meteors it consistent with asteroids; and b) cometary, fragile materials might encounter. with densities lower than that of water. FLW: The “Whipple Shield,” which I called the “Meteor FLW: By “planetoidal” I meant asteroidal, but today I Bumper,” also invented for the military, is a thin skin of metal A202 U. B. Marvin that covers the real skin of a spacecraft to protect it from was fully confirmed in 1986 by close-up images of comet penetration by the small bits and pieces of solids it Halley taken by the European Space Agency’s Giotto encounters. The shield could explode a meteor on contact so mission. that only vapor would strike the real skin. Improved versions FLW: I was very excited with those images of Halley. It of it still are in use. had a discrete nucleus, about the size of Manhattan Island, UBM: You soon became involved, didn’t you, in the US with an irregular surface and a dark exterior. Army’s research project on the upper atmosphere being UBM: Also in 1950, you advanced to the Chair of Phillips conducted at White Sands, New Mexico? Professor of Astronomy at Harvard. Yet, despite your teaching FLW: Yes, I did. The Army had modified the German V- load, you seem to have become more active than ever in 2 rocket for use in exploring the upper atmosphere. They national and international groups anticipating space research. adopted my simultaneous camera-telescope technique for FLW: All through the early 1950s, there were symposia photographing the rocket flights. We obtained precise meteor and congresses on topics such as the physics and medicine of velocities and orbits along with measurements of atmospheric the upper atmosphere, and on possible types of space densities at altitudes of 60 to 90 km (the meteor region). vehicles. I attended the meetings and spoke on meteors and UBM: In 1949, the National Academy of Sciences meteorites. The first major effort to interest the public in this honored you with the J. Lawrence Smith Medal in recognition subject came in 1952 when Collier’s magazine ran a series of of your scientific contributions before the War, and in articles that came out as a book, titled Across the space anticipation of your future research. frontier. I wrote a chapter called “The heavens open.” FLW: I was delighted that the Academy was recognizing UBM: I have read it. You began your chapter by saying my pre-War research. And the medal itself is spectacular: a that, in many respects, today’s astronomers might as well be large, heavy piece cast in gold. blindfolded in a deep, dark coal mine because they could not UBM: In 1950, your research on meteor streams and see through the restless atmosphere. You described the comets led to the publication of your paper on the nature of wonders to be revealed by a telescopic observatory in space the comet nuclei: “A comet model I: The acceleration of capable of resolving the far ultra-violet, X-rays, and gamma- comet Encke.” That paper, soon followed by Part II, opened a rays. In your view, that would be as revolutionary as the new era in the understanding of this subject. Please give me a invention of the telescope itself. brief synopsis. FLW: Today, of course, orbiting satellites are detecting FLW: Up through the 1940s many astronomers believed all of these things and many more. Astronomy has had its that comets were interplanetary gravel banks without solid second revolution. nuclei. I was convinced that comets must be discrete bodies. Did you read the chapter by Wernher von Braun, the In my “dirty snowball” model, I said that in the cold and German rocket specialist who was then at Redstone Arsenal darkness of space, masses of ice aggregated to form nuclei a in Alabama? He pictured a wheel-shaped satellite, 250 feet in few kilometers across. They consist mainly of water ice but diameter, circling the Earth every two hours. It would serve as also ices of ammonia, methane, and carbon dioxide (and an a platform for side-trips to the Moon and be a marvel of an abundance of frozen-in dust grains). As the nuclei approach observation post for detailed study of the Earth, but he made the Sun, the solar rays volatilize the ices, nudging the mass no mention of tracking the station from the ground. At that this way and that, depending upon the comet’s rotation axis. time, tracking would have been impossible. In my chapter, I These motions, which are superimposed on the predicted that satellite tracking could be done as soon as we predominantly gravitational forces that govern the comet’s developed more powerful computers. Willy Ley also wrote a orbit, account for the fact that comets sometimes return chapter titled: “A station in space.” Did you read that one? slightly earlier or later than they are anticipated. The UBM: Yes, I recently browsed through the whole book. released gases and dust go streaming away from the Sun Ley described the station’s living and working space for about forming the comet tails. I concluded that each comet nucleus 80 men—of course, back in the 1950s, they all were expected not only must become smaller as it loses ice, but it also may to be men. He illustrated his chapter with a double-page acquire a darkened surface layer consisting of cosmic dust cutaway painting of men at work inside under conditions he that is left behind as the ices sublimate. By 1950, we said would be as cramped as those on a submarine. They understood, from short-term variations in the magnetic field, certainly looked it. There also were a few space-suited men that the Sun must be emitting an outward flow of charged working outside. Were these two chapters the first to provide particles, but the first direct measurements of the “solar a detailed description of a space station? wind” were made in the 1960s by experiments on spacecraft. FLW: They probably were the first serious ones written The gases in comet tails are ionized by the solar wind and just as the space age was about to become a reality. The ultimately they disperse, but the released dust remains in concept von Braun described was based on research that orbit and produces meteor showers each time the Earth eventually enabled the launching in 1958 of Explorer I, the passes through a comet’s path. first USA satellite. UBM: Your model was widely accepted early on, and UBM: Meanwhile, back in 1952, the International Oral history: F. L. Whipple A203

Council of Scientific Unions proposed to hold an UBM: I understand that you even showed some International Geophysical Year devoted to research on the willingness to consider the possibility of becoming the Earth. It would be an exceptionally long “year” extending for Director, if the SAO were to move to Cambridge. But 18 months from July 1, 1957 to December 31, 1958. There inasmuch as you then were both a full Professor of would be 14 fields of investigation, including one on rockets Astronomy and the chairman of the Department of and satellites. Astronomy, Menzel first had to clear the idea with the FLW: That’s right, and early in 1955 they set up a study Harvard Dean of Arts and Sciences and with President Pusey. group to investigate the complexities of launching Earth Having got their approval, he proposed it to Carmichael. orbiting satellites. It was called the Long Playing Rocket FLW: Carmichael never hesitated; he began negotiations Committee (as a take-off on the long playing records then in immediately and it was all settled within a few weeks. I began vogue) and I was asked to chair it. We looked into the range of working part-time for the SAO in April 1955, and the official geophysical observations to be made of the Earth, and the transfer from Washington to the grounds of the Harvard technical details, feasibility, budgetary and manpower needs, College Observatory took place on July 1st. SAO had a staff necessary controls, timing, and desired orbit of a satellite. We of five at that time but, within a few years, it would grow to also wanted to be able to track the satellite from the ground. nearly five hundred. My immediate concern was to expand The committee worked out the possibilities of launching a the program of the SAO beyond the research on solar activity 10 pound object, about 20 inches in diameter, painted white or it already conducted to include studies of meteors, meteorites, having some other highly reflective surface, that would and the upper atmosphere. I planned to institute optical appear at twilight as the equivalent of a sixth magnitude star. tracking of satellites, a completely new activity of immense We concluded that a satellite with a payload of up to power for learning about the solar system and the Earth itself. 10 pounds could be launched within two or three years, given UBM: You already had in mind two types of tracking sufficient funds. In March 1955, the US National Committee programs, didn’t you? A highly technical project using passed a resolution favoring the launching of instrumented specially designed telescopic-cameras located at stations in satellites into space. And on July 29th, 1955, President the equatorial regions, and a second project using teams of Eisenhower announced that the United States would launch a amateurs observing the skies from many countries around the small earth-orbiting satellite as part of the International world. I assume it was for the technical project that you won Geophysical Year. for the SAO the first IGY grants for satellite tracking. UBM: By then, another announcement of even greater FLW: It was, and the grants assigned to the SAO the moment to you and your career had been made in May of that responsibility during the IGY for optical (but not for radio) year. tracking of satellites. We weren’t expecting great activity. FLW: I suppose you are referring to the announcement by The USA planned to launch one, and possibly two or more Dr. Leonard Carmichael, the Secretary of the Smithsonian satellites, during the 18 months of the IGY. Institution, that I had been chosen to be the new Director of UBM: But the Russians had announced that they, too, the Smithsonian Astrophysical Observatory and that the SAO planned to launch a satellite during the IGY, and didn’t some itself was to move from Washington to Cambridge, other countries do the same? Massachusetts. FLW: Other countries that expressed an interest in UBM: Yes, that double-barreled announcement must launching satellites included the UK, France, Japan, have caused a great stir in the astronomical-astrophysical Australia, and Canada. No one paid much attention to any of community. their announcements. Here at home, we had two groups FLW: I did receive good wishes from a great many people. competing to build satellites: the Naval Research Laboratory That announcement came after a difficult year for Carmichael. in Washington was at work on Project Vanguard, and Wernher The previous Director of the SAO, Loyal B. Aldrich, retired in von Braun and his group at the Redstone Arsenal were 1954 just as plans had to be developed for the IGY. I learned developing the Jupiter rocket to send a missile around the later that Carmichael had seen Donald Menzel at a meeting and equator. The US Committee for the IGY did not want a told him he wanted to broaden the research program of the SAO German to launch the first American satellite so they gave the to encompass the major fields of astrophysics, but he was assignment to the Navy. having a hard time attracting a leading scientist to Washington. UBM: Tell me something about your plans for your Menzel suggested that he arrange to link the SAO with a nearby Baker-Nunn tracking stations. university, such as Georgetown or American University. A day FLW: I originally planned to track the satellite via the or so later, Menzel was struck with the thought of linking the rapid, large-aperture Schmidt cameras that we had designed SAO with the Harvard Observatory. The more he thought about for the Harvard Meteor Project. In no time, I saw the need for it, the more it seemed to him to offer very real advantages to upgrading the system and asked James G. Baker, a consultant both organizations. He presented his idea to the Harvard to the Perkin-Elmer Corporation, to work out the design. He Observatory Council, and the members responded with created the new super-Schmidt camera-telescope, which enthusiasm. could be geared to follow the apparent motion of a satellite A204 U. B. Marvin and photograph the sky on a continuous roll of film. It had a persuaded Armand Spitz, of Philadelphia, who had designed shutter that would chop star trails into segments synchronized and marketed a popular low-cost planetarium projector, to with a crystal clock timed to an accuracy within one serve as the Director of Moonwatch. millisecond. Basically, it was an excellent system using UBM: I have seen pictures of team members seated at special glass for the lens and special film. In fact, the film lay tables in parallel rows, or L-shaped arrangements, with each inside the lens, which could be opened into hemispheres to member sitting at a table gazing down into a small telescope allow fresh film to be inserted between them. Then, James pitched at an angle of 45 degrees. Nunn, also of Perkin Elmer, designed a mechanism for FLW: That was a comfortable angle for viewing the sky, orienting the camera to photograph a satellite. The final and it worked because each scope actually was looking into a Baker-Nunn telescope-camera stood about eight feet high and mirror, clamped to the bottom end of the tube and tilted at a was larger, heavier, and more expensive than we had ever complimentary angle of 45 degrees. A pole was set up in the anticipated. In spite of their cost and tonnage, these line of sight of all the scopes, to mark the meridian, and each instruments eventually were mounted in 12 field stations observer was given a star-finding chart. When an observer encircling the globe. Each station was a self-contained spotted a satellite, he or she signaled the timekeeper and then photographic laboratory, office, machine shop, and obtained a fix of the satellite’s location against the communications center with a trained technical advisor from background of stars. The readings were phoned into the SAO. the SAO and mostly local staff. Later, they were telexed or sent by Navy teletype. As time UBM: Where did you plan to locate the first few went on, we developed better timing techniques and the stations? National Geographic Society supplied us with excellent star- FLW: We planned for three stations in the USA, at Las finding kits. Many team members became highly skilled and Cruces, New Mexico; Jupiter, Florida; and Maui, Hawaii. At reported accurate sightings of objects down to 7th or 8th an IGY meeting in Barcelona in September 1956, we got magnitude, or even fainter. agreements from astronomers for stations in Peru, Argentina, UBM: As I understand it, the members not only the Netherlands, West Indies (Curaçao), Spain, South Africa, volunteered their time but also furnished their own Iran, India, Japan, and Australia. To gain permission to build equipment. and equip these stations, we had to approach each country FLW: They did. After testing about 30 optical through the State Department, but our sponsorship by the IGY instruments, we chose a simple design that came to be called helped greatly with cutting red tape and getting the job done. the “Moonwatch Monoscope.” It was very much a do-it- UBM: Were you still working on your original IGY yourself instrument. It had a tube 8.5 inches long with an grant? eyepiece at the top and an objective lens at the bottom. The FLW: No. The original one ended on June 30, 1956. After mirror was mounted just below the objective lens. The optics that we obtained a number of new grants totaling about three could be purchased for about $20.00 and a tube for a few million dollars. Our new specifications included tracking all dollars. Many of the team members were amateur telescope USSR satellites. It actually was well-known in the upper makers so they made their own. Those who preferred to buy circles that the Russians wanted to beat the USA in sending one could purchase a so called Edscope for about $50.00. All up the first satellite. But practically no one believed they the team members seemed pleased to own their scopes. could do it. UBM: But you had some ‘official’ ones too, didn’t you? UBM: Lets talk for a few minutes about your plans to I’ve heard a story about your presenting a Moonwatch assemble teams of amateur sky-watchers who would locate Monoscope to a Russian visitor. newly-launched satellites and provide SAO with the FLW: Oh, yes, the Soviet Union had teams similar to ours coordinates needed to calculate their orbits. to whom they provided telescopes costing $200–$300. When FLW: These were the Moonwatch teams. I planned Dr. Alla Masevich, the Director of the Russian teams, visited Moonwatch because I knew from experience how dedicated Washington, she presented one of their telescopes to the IGY amateur astronomers and science buffs can be and how Committee. So when she came to Cambridge, we presented pleased they would be to take part in the new adventure of her with one of our Monoscopes. Later on, I began to hear satellite tracking. Our military planners didn’t believe rumors that we had given away government property amateurs would be capable of making systematic illegally, and might be prosecuted. It is true that the one we observations of such vital importance, so I had something to gave her was government property, so, to avoid possible prove. We put out our first appeal in the late summer of 1956 prosecution, I put up $5.00 and so did Menzel and three others and people volunteered from all around the globe. The to buy a new one for Uncle Sam. Japanese were especially anxious to take part because of their UBM: How many Moonwatch teams did you have in all? love of science, particularly astronomy. Eventually they FLW: I can’t give you a precise figure, but there were fielded more than 75 Moonwatch teams, some of them about 230 of them operating in 1958. We had about 120 teams consisting mainly of college or high school students. I in the continental United States, 77 in Japan, 13 in South and Oral history: F. L. Whipple A205

Central America, and a few in Africa, Australia, continental us to advise Moonwatch teams when and on what part of the Asia, and islands in the Pacific Ocean. sky to focus their attention. On October 8th, good sightings of UBM: What was your schedule, in 1956, for getting the Sputnik I, itself, were reported by Moonwatch teams in both tracking systems fully operational? Sydney and Woomera, Australia, and on October 10th, a FLW: We planned to get some of the Baker-Nunn stations sighting came in from New Haven, Connecticut. From these and all of the Moonwatch teams in operation by March of reports our team calculated Sputnik’s orbit and predicted its 1958. But, I was particularly anxious to get at least one path. camera working in time for the IGY meeting in Washington in UBM: So amateur teams proved their worth and the SAO early October of 1957. We had had some serious delays in fulfilled its immediate obligation to the IGY and to the public. operating the camera stations, and I began to hear gossip that FLW: Yes, for a time the SAO actually became the the US Vanguard satellite program was being held up by our information center for the world. Of course, from the night of inability to track it. I had to prove that wasn’t true, so we got October 4th onward, SAO was besieged by the press, radio, the Baker-Nunn camera that was built at Pasadena, California, and television, plus numerous calls from the public. We had to assembled and set up temporarily on October 2nd. It set up a public relations office to handle it all. photographed several thousand feet of film of the night sky UBM: I have read that on the night of October 4th so just in time for me to show the film around the meeting in many lights were blazing in the observatory and its grounds Washington on October 3rd. That same day, the camera had to that a woman down the street called the Fire Department. be torn down for minor machining, but the reputation of the FLW: That’s true, she did. At least the place was not on SAO was saved. fire, but it was in such an uproar that I didn’t leave the The next day was October 4th, 1957. observatory until 4:00 o’clock the next morning. UBM: The unforgettable day the Soviet Union launched UBM: Didn’t the Russians give out any information on Sputnik I, which astonished the world as it went beep-beeping the orbit of Sputnik I? overhead. FLW: No, nothing except the times when it passed over FLW: The Russians at the IGY meeting had said nothing certain cities. In fact, they appear to have painted Sputnik I at all about the satellite. The rest of us left for home looking black, making it more difficult to see. All IGY satellites were forward to the launching of the US Vanguard the following expected to broadcast on a frequency of 108 megacycles, but spring. the Russians had announced in their own journal, Radio, that UBM: When did you first hear about Sputnik I? they would broadcast on 20 and 40 megacycles to permit FLW: After the meeting in Washington, I flew to Boston certain of their experiments. They had told everyone who and took a taxi to my home in Belmont. My wife, Babette, would listen that they intended to launch the first satellite, but met me at the door and told me the news so I turned around practically no one in any official US organization paid heed to and went to the observatory. Some scientists were there them. As a result, no radio tracking station in the United because the observatory’s Philharmonic Orchestra was States was prepared to track Sputnik I. One critic said the holding a rehearsal. J. Allen Hyneck, the Associate Director country was “caught with its antennas down.” in overall charge of the tracking program, was still in his UBM: At least it was not caught with its Monoscopes office. Hynek learned about it when a Boston newspaper down. When did you obtain the first film of Sputnik I? reporter called and asked if he had any comments about the FLW: On October 17th. The Baker-Nunn camera in Russian satellite. Stifling an urge to laugh, he asked for the South Pasadena, California, had been set up again and was full dispatch. When the reporter read it to him, Hynek realized aimed at the sky by reference to Moonwatch data. It took the that a satellite was in the sky and that it had to be tracked by first photograph of Sputnik I, which came in at such a low whatever means were available. altitude it looked very large and bright. A few days later, that UBM: So, as of that day, there was something new under camera was shipped to its permanent station at Las Cruces, the Sun. New Mexico. FLW: There was, indeed, and the SAO had the UBM: I gather that you were not as surprised by responsibility of finding its orbit. None of our cameras were Sputnik I, itself, as you were by its timing. in operation that night, but some Moonwatch teams were, and FLW: That’s right. I had talked with a number of the one in Springfield, Virginia, was set up for a practice run. Russians who attended a symposium at the SAO in July of Now, instead of a practice this was the real thing. 1957. They wanted to hear all about Moonwatch and even UBM: Did they spot the satellite? broached the subject of possible direct communications FLW: No. They had no idea of just where to look for it or between Cambridge and Moscow. They clearly intended to what to look for. No one ever had seen a satellite in the sky. send up satellites: perhaps after, but preferably before, we did. Early the next morning, though, reports from the Geophysical As soon as they left, I wrote to the Chairman of the US Institute in Alaska led to sightings by several Moonwatch National Committee for the IGY saying that we should teams, not of the satellite but of its rocket carrier. This helped consider setting up additional Moonwatch teams at higher A206 U. B. Marvin latitudes, both north and south, to prepare for the tracking of formidable that they might have to begin with projectiles no Russian satellites. We also should plan to add a number of larger than a softball. As we read this, Sputnik I was beeping new Baker-Nunn stations at these latitudes. its way around the globe for the third week. I think that UBM: Did the committee believe you then? information must have come from a source like the one that FLW: Not really; they thought the Soviet Union was far would be telling us a couple of years later that the Cubans from ready to send up a satellite and that their would rise up in celebration of our landing their émigrés at the pronouncements on this subject were just talk, aimed a Bay of Pigs. drawing attention away from our own impending launches. FLW: Perhaps. I know nothing about the ultimate When they learned that Armand Spitz was mentioning sources, but if you look into the clippings of articles from Russian satellites in his popular lectures, an IGY Committee magazines and newspapers archived at the SAO, you will find representative called and ordered me to “Shut that man up!” that the majority of them are written accurately and UBM: Did you do it? thoroughly by very responsible reporters. Later on, Nelson FLW: I didn’t even try. On October 9th, with Sputnik I Hayes, our chief editor at SAO, wrote up the first ten years of overhead, the Committee issued a memorandum stating that the tracking story in a book. all visual and optical data should be sent to the SAO in UBM: A very readable book. Nelson was a fine science Cambridge, and all radio data should go to the Vanguard writer and a great help as an editor. Control Center in Washington. Did Baker-Nunn cameras photograph Sputnik II when it UBM: I understand that you resisted a bid by IGY took off on Novermber 3, 1957, carrying the dog, Laika? Headquarters in Washington to have all your news releases FLW: Yes, but two of the Harvard super-Schmidt meteor and public statements channeled through their office. cameras photographed it first from Organ Pass and FLW: I certainly did. I felt that the people were entitled to Sacramento Peak, New Mexico. Then the Baker-Nunn station know everything about the satellite programs, so we issued photographed it from Las Cruces. our own releases and answered questions as best we could. UBM: On December 6, 1957, the first US attempt to For the first several months, we gave press conferences at launch a Vanguard satellite failed, spectacularly. SAO every day at 9:00 a.m. and 3:00 p.m. The big problem FLW: It did, The rocket lifted a few feet off the ground was to avoid making remarks that could mislead or alarm and then collapsed. But the next one, Explorer I, from the people. The reporters quickly became quite expert at asking Redstone Arsenal, was launched on a Jupiter C vehicle on good questions and writing good articles. Of course, our January 31st, 1958, and performed brilliantly. It discovered switchboard was jammed much of the time by calls from the the Van Allen radiation belts around the Earth, adding public. Some callers simply did not believe the Russians something completely new to our scientific knowledge of could have launched a satellite. Others believed they had and space. Then, on March 17, 1958, the Navy’s Vanguard I, the were terrified for their lives and/or furious at the government first solar-powered satellite, was launched and began yielding for failing to do it first. Some said we were wicked to be information on the size and shape of the Earth, the density and meddling in cosmic affairs. But the largest proportions of temperature of the upper atmosphere, and micrometeorite them were intensely curious. They wanted to know all we impacts. Vanguard I still is up there holding, by far, the could tell them about the science of Sputnik I—its payload, its longest record for staying in orbit. When the International orbit, its signals, and so on. This actually led to a serious Geophysical Year ended on December 31st, 1958, the United effort to improve the teaching of science in American public States had eight satellites in orbit and the Soviet Union had schools. three. For tracking them, we had more than 200 Moonwatch UBM: I vividly remember my own response. Tom and I teams and twelve Baker-Nunn stations in operation. were living in Rio de Janeiro at that time evaluating ore UBM: Was SAO tracking every satellite? deposits on trips into the interior. When we heard the news, FLW: It had been for awhile, but on July 29th, 1958, Tom took it in stride, but I was greatly alarmed at the Congress passed a bill creating NASA, and that agency discovery that United States technical expertise was inferior. quickly took responsibility for most US space activities. I had no way of knowing that the US expertise was just fine, NASA assigned SAO to track specific satellites. We also took but US scientists and engineers were not in any hurry. They on a special assignment from the Army Ballistic Missile didn’t know they were running a race. A short while later, we Agency to track Explorers IV and V. received our October issue of Scientific American in the mail UBM: I understand that you always had in mind applying and read in the “Science and the Citizen” section that the the orbital data from the Baker-Nunn network to link the satellite projects were not going well. It said that scientists of stations with the center of the geoid and develop precise the USSR had not yet made laboratory models of their knowledge of density distributions and crustal volumes satellites or decided on their size or weight, and that in the within the Earth. United States workers on Project Vanguard had built FLW: That was part of the plan. It resulted in the 10 pound models, but the propulsion problem was so formulation of the “SAO Standard Earth,” which we adopted Oral history: F. L. Whipple A207 in 1966 on the basis of tens of thousands of precisely reduced which Ed Fireman had contoured the distribution of helium-3. Baker-Nunn observations. In the 1950s, points on continents Suddenly, I came upon a greenish glob of glass containing were uncertain by 100 meters or more but, by 1966, we had crystallites of cristobalite, of all things—a low-pressure silica located our tracking stations to an accuracy of plus-or-minus mineral in the middle of an iron meteorite with Widmastätten ten meters. Our next step was to supplement and/or replace figures showing that iron to be a large single crystal. the cameras with lasers for tracking purposes. That would FLW: That was back when some leading meteoriticists increase the accuracy to plus-or-minus one meter, and believed the Widmanstätten figures formed in irons under eventually, we hoped, to a few centimeters. We began with high pressures. Your cristobalite added to the other lines of lasers in 1965 and had “Standard Earth II” calculated by 1969 evidence that we needed to take another look at that problem. and III by 1973. Mike Gaposchkin directed the geoastronomy UBM: What finally put an end to the arguments for high research. pressure meteorite parent bodies was the shock-wave UBM: In addition to building the first global optical synthesis of diamonds from graphite by Paul De Carli at tracking system, you broke a precedent for an astrophysical Stanford Research Institute (now SRI International). In 1961, observatory by hiring an experimental physicist, Edward L. De Carli produced aggregates of minute diamond crystals that Fireman, to establish a laboratory at 60 Garden Street to study yielded X-ray patterns similar to those of the fine-grained the effects of cosmic radiation on meteorites. aggregates in the Canyon Diablo iron. His evidence finally FLW: I did. Ed arrived in 1956, directly from the persuaded Harold Urey that meteoritic diamonds need not be Brookhaven National Laboratory, and he soon was drawing formed in the cores of Moon-sized objects. In 1967, Urey contour maps of cosmogenic isotopes on sections through stated in public that De Carli had changed his mind for him. iron meteorites and counting short-lived isotopes on new FLW: That solved several big problems about meteorites falls. all at once. UBM: In 1959 you invited the Meteoritical Society to UBM: Meanwhile, on September 5th, 1962, Sputnik IV meet at the SAO. came streaking out of the sky and landed in Manitowoc, FLW: Yes, after some hesitation. I had wondered if it Wisconsin. would be worthwhile to host a meeting and try to save the FLW: That was very exciting. We knew Sputnik IV was small, feud-riven Meteoritical Society. But my friend John in a decaying orbit and expected it to re-enter the atmosphere Russell, at the University of Southern California, who was within a day or two of that date. It would pass southeastward then the president of the Society, assured me that it would be from Canada over Milwaukee and on toward the eastern tip of worthwhile, so I issued the invitation. Ed Fireman arranged a Brazil to South Africa. We alerted the Moonwatch teams in its symposium on cosmogenic isotopes and the constancy of the path to watch for it. By that time, there were so many satellites solar flux. A number of leading scientists gave papers, and spent rockets up there it was important to keep track of including Ray Davis, Oliver Schaeffer, and R. Stoenner from which ones might soon be re-entering. Brookhaven, and Parma Goel from Carnegie Mellon. They UBM: I have checked the details. It landed just before continued their discussions right through cocktails and dinner. 5:00 a.m. in the middle of 8th Street at the corner with Park UBM: That meeting gained a reputation as a turning Street. The parson’s wife, in a house at the corner, woke up at point in the quality of the Society’s annual meetings. After a sudden sound but saw nothing unusual outside. At 5:30 a.m. recruiting Ed, you began bringing in additional scientists to two policemen in a patrol car drove by and dismissed it as a do laboratory research. In 1961, you hired me to work on the piece of cardboard. At 7:00, the same policemen saw that it mineralogy of meteorites. might be a hazard to traffic so they stopped and carried it to FLW: I learned from Cliff Frondel that you were working the side of the street. They were surprised to find it was warm, on meteorites in his lab, but he hadn’t got the grant he applied heavy, metallic, and embedded into the pavement, but they for. We were planning some joint research with Cliff, so we left it in the gutter. On the previous night, the Milwaukee took you onto Fireman’s grant; later on this developed into a Moonwatch team saw nothing during the predicted pass, so permanent civil service position. they set their alarms for 4:00 a.m. At 4:49 a.m. on September UBM: I was very pleased with that. It soon became clear 5th they saw an incredible display: a bright reddish-orange to me that you were hiring and promoting women scientists fireball coming from the northwest split into several pieces on an equal basis with men. In retrospect, I realize that this low in the sky. One member got a compass fix on the was more than a decade before the advent of movements trajectory just before the glowing pieces vanished. toward equal opportunities and affirmative action. FLW: Farmers, milkmen, policemen, and other early- FLW: I always hired talent whenever I saw it. risers witnessed the show, but nobody saw an object fall. UBM: Even after I joined the SAO, I retained my office Later in the day, after the news was spread by radio, TV, and and lab space in the Geological Museum for several years. newspapers, the two policemen remembered the warm, heavy That’s where the meteorites were, and the best equipment for object they had found that morning. They retrieved it from the studying them. One of the first things I did was to begin gutter and sent it to the Milwaukee Journal. digging into a troilite nodule in the Carbo iron meteorite on UBM: The journal called the Moonwatch leader, the A208 U. B. Marvin

Moonwatch leader called SAO, and the next afternoon the oxide (Fe1–xO) that occurs in industrial products but is piece arrived at the observatory. exceedingly rare in nature. It had not been reported in FLW: It was taken directly to Chuck Lundquist, our meteorite fusion crusts, so finding it along with magnetite Assistant Director of Science, and we all crowded around his on Sputnik IV made me wish to look for it on a freshly fallen desk to look at it. iron. But how many years would pass, I wondered, before I UBM: Chuck told me, later on, that he was very could examine a newly fallen iron? As it turned out, I didn’t pessimistic about it at first sight. He had seen all sorts of have to wait very long: an iron had fallen at Bogou in Upper satellite bits and pieces at Redstone Arsenal but none of them Volta three weeks before Sputnik IV fell in Wisconsin, and looked anything like that. in the midst of our work on the Sputnik fragment Ed FLW: But Sputnik IV was a special satellite. The Russians Fireman got a small piece of Bogou from his friends at announced that it contained a full life-support system and a Brookhaven. The Brookhaven group had done their best to dummy man. They launched it in May 1960, and after a few abraid off the crust of Bogou but, I found a trace of it left on weeks they fired a retrorocket to bring it back to Earth. But the Ed’s specimen, and there it was—wüstite! A new meteoritic rocket misfired and sent the satellite farther into space, where it mineral! I assumed the wüstite would quickly revert to orbited for more than two years. Now it had returned on its magnetite but I checked the crusts of several older falls in own. The piece we got did look rather odd. It had a thin the Harvard Museum and found wüstite in all of them, cylindrical “cap” with a smooth rounded surface that had including Braunau, which fell in Czechoslovakia in 1847. impressed itself into the pavement. The cap was welded to a FLW: So it was common in fusion crusts but nobody had circular plate covered on its backside by a mass of loosely looked for it? attached spherules that clearly had been melted and quenched. UBM: That’s right. Not much attention had been paid to The piece certainly had been subjected to high temperatures. fusion crusts. Looking more closely at the black oxides on We took pictures of it from all angles and then measured it. Sputnik IV, I found small patches of a dark reddish bloom that UBM: The SAO Special Report says it weighed about gave the X-ray pattern of a strictly artificial iron 20 pounds and was about 9 inches across and from 2 to oxyhydroxide: βFeO(OH). I thought this might be its first 3.5 inches thick. natural occurrence (except that Sputnik IV was not a natural FLW: We sent it to the machine shop and had a pie- object). Then Cliff Frondel showed me a recent notice from shaped wedge sliced out of it. The cut exposed a bolt with a England that this mineral had been identified in limonite from metric thread! the Akagané Mine in Japan and named “akaganéite”. I don’t UBM: A thing passing strange to be embedded in a know how long the Japanese material lasted, but my Wisconsin street! Sputnik IV akaganéite altered to hematite during its first six FLW: Strange indeed. The bolt left us with no doubt that weeks of sitting in my lab. this was part of Sputnik IV, so Lundquist called NASA’s Finally, I X-rayed and analyzed a white powdery material Office of International Programs to discuss the implications that occurred in streaks across the surface of the spherule of the recovery. mass. I identified it as periclase (MgO), a mineral that UBM: You had a plaster model made, and I still have that commonly occurs in contact metamorphosed limestones but model in my office. I exhibited it at the observatory’s 40th was dusted like talcum powder across Sputnik IV. So, the anniversary celebration of Sputnik IV on October 4th, 1997. spherule mass recorded the melting of steel to droplets, and FLW: About one week after we received it, Lundquist got their incrustation by iron oxides followed by a final episode of instructions to deliver the specimen to the US Mission to the the sublimation and deposition of magnesium oxide during United Nations. Debates about issues of liability for damages flight in the atmosphere. done by returning satellites already were in progress in the UN FLW: All this time, the US offer to give back the Committee on Peaceful Uses of Outer Space. Two days later, specimen to the Soviets remained in effect. Early in January the US delegate produced the piece of Sputnik IV and offered 1963, they decided to accept it. So, one day, with no warning, it to the Russians. The chief Soviet delegate refused the offer Chuck Lundquist received official word that our Sputnik IV and he and his delegation promptly walked out of the meeting. specimen must be handed over, forthwith. Within half-an- UBM: That left us with a fascinating object for study. hour, Chuck collected the main mass from Ed Fireman and Metallurgists at MIT identified it as ordinary steel, and Ed gave it to a messenger for delivery to representatives of the Fireman detected 37Ar and 54Mn in it—clear evidence that it Soviet Embassy in Washington. had been bombarded by cosmic rays in space. I focused my UBM: He didn’t get the piece I was studying, though. It attention on the mass of what looked like ablation droplets. was in my lab at the Museum and I was out. I believe it still is They consisted of steel encrusted with black iron oxides. in the Harvard Museum. FLW: You found some interesting minerals on the Now that we have progressed to 1963, I hasten to declare spherules, but I have forgotten what they were. that in June of that year John F. Kennedy presented you with UBM: My first X-ray films gave a strong pattern of the Presiden’'s Award for Distinguished Public Service for wüstite. Wüstite is a non-stochiometric, metastable iron your leadership in creating the worldwide network of satellite Oral history: F. L. Whipple A209 tracking stations. That must be one of the most gratifying of Each exposure lasted from one to three or four hours the many honors you have received. depending on sky conditions, but shutter breaks of known FLW: That’s right. I still am very proud of that award. frequency provided accurate timing. UBM: By that time, you already were heavily involved in UBM: Didn’t anybody have to check up on things? setting up the Prairie Network. Tell me something about that. FLW: We arranged for a local person to check the FLW: The fireball of only one fallen meteorite ever had cameras at each station every few days and to change the film been photographed simultaneously by more than one camera. rolls twice a month. They sent them to Lincoln, where the film That was the fireball of the P¯íbram meteorite which was was processed, scanned, and shipped to the SAO. recorded by 11 cameras when it fell in Czechoslovakia in the UBM: And whenever a bright meteor appeared on the late 1950s. film, a team member or two from Lincoln would search for UBM: I recently checked the date: P¯íbram fell at 7: the meteorite? 30 p.m. on April 7th, 1959. It was an ordinary chondrite. FLW: Yes. And we assumed that as they approached the FLW: Several fragments of the meteorite were collected site of fall, the local people most likely would have heard the weighing a total of over five kilograms, but the brilliance of explosions and might have found specimens or could point the fireball suggested that at least three to four times as much out where to look. material may have fallen. Calculations showed that its orbit UBM: When were the first stations built? extended to the far reaches of the asteroid belt. That was our FLW: The first ones went up in 1962 and all 16 stations first actual proof that at least one meteorite had come from the were operating by midsummer of 1963. We had a total of 64 asteroid belt. cameras viewing more than a million square kilometers of the UBM: So, the idea of the Prairie Net was to take sky. Dick McCrosky, at the SAO, was the project director, and systematic photographs of the night sky in hopes of obtaining Chuck Tougas, one of our most experienced Baker-Nunn more fireball orbits and finding more meteorites. Station operators, was running Headquarters along with FLW: Yes, and in getting a better understanding of the Walter Munn, a Moonwatch field representative. The Prairie nature of the upper atmosphere and its effects on meteors. I Net was planned and funded for ten years. considered all sorts of ways to go about it and finally UBM: Knowing the outcome, I hesitate to ask how many proposed to build a network of automatic camera stations in a new meteorites were predicted. geodetically-measured network somewhere in the rural FLW: We hoped for one meteorite per month, but would Middle West, where the land is relatively flat and free of not have been surprised at one per year. stones, the horizons are wide, and the skies have a minimum UMB: NASA made an optimistic estimate, and the of light pollution from big cities. I knew that NASA was prospect prompted them to prepare a request to Congress to much concerned with meteorites, both as fragments of amend the Space Act so as to nationalize meteorites. planetary bodies and as missiles orbiting through space, so I FLW: I remember something about that but, I never took drew up a proposal and got funding from NASA. it seriously and have lost track of what happened. UBM: How large a network did you plan for? UBM: I remember fairly well what happened. In the mid- FLW: At first, I planned for 12 stations but they grew to 1960s, Dick McCrosky asked me to join him in representing 16, located at the apices of adjacent equilateral triangles. The the SAO in the committee meetings to be held in Washington. Net extended from South Dakota south through Nebraska and We went down there and found a big table surrounded by Kansas to northern Oklahoma and east to parts of Iowa, scientists, an administrator or two, and a legal advisor from Missouri, and Illinois. At least two stations, and very likely NASA Headquarters, plus mostly scientists from NASA’s more, would photograph any one bright fireball. We located Goddard Space Flight Center and the Smithsonian’s National the Headquarters at Lincoln, Nebraska, almost in the middle Museum of Natural History, where the national meteorite of the Net. collection is curated. The committee Chair, Maurice Dubin, of UBM: I remember your remark that the Prairie Net NASA Headquarters, started out with the attitude that covered much of the Louisiana Purchase except for meteorites must be and would be nationalized. It was Louisiana, itself. How automated would the stations be? unthinkable to him that, after NASA provided funding for the FLW: Each station was a 6 × 6 foot concrete block with Prairie Net, a local farmer could withhold a meteorite from us four plate glass windows looking directly north, south, east, if he chose. Dubin likened the situation to that of a wild duck and west. A camera at each window was aimed at an altitude landing on a farmer’s pond. The farmer could not shoot it and of 60 km in the sky. A sensor opened the cameras soon after eat it. The duck is not his; it is federally protected and the sunset and closed them at dawn. To avoid taking pictures of same should be true of meteorites. cloudy skies, the sensor closed the cameras whenever it failed FLW: Even though, in this country, meteorites always for 20 minutes or so to detect the North Star. The film came in have been recognized as belonging to the landowner? rolls 390 feet long and 9 inches wide and was automatically UBM: Yes, Dubin thought a policy change was in order fed into the cameras and held against the back by a vacuum. for the space age. The committee also was charged with A210 U. B. Marvin deciding, in principle, what should be the proper procedures density, fragile cometary objects! Furthermore, the fireball for collection and curation of meteorites and the distribution photos from both Nets recorded the infall of many low density of samples for research. objects (average: 0.4 g/cm3), which were several orders of FLW: That was a big order. magnitude larger than anything we predicted from our UBM: It certainly was. We had a succession of meetings, extrapolations from the distributions of small particles of which revealed some interesting differences of opinion cometary origin. The ablation of these immense objects was around the table. NASA claimed a special interest in both essentially catastrophic and their terminal masses were meteorites and in pieces of their space junk that might come negligible, so nothing was left of them for us to collect. We coursing down the sky, but so, as someone pointed out, would came to realize that the mass influx of fine material in the the Department of Defense. It has a great interest in fiery atmosphere is much larger (and that of meteorites is much projectiles exploding and rumbling through American skies. smaller) than all our previous estimates. At the time, we had no How could the competing claims of NASA and DOD be adequate understanding of the physical processes active upon a resolved? My own thought was that Americans never would high-speed, ablating body. The Prairie Net taught us a lot about stand for losing their property rights to meteorites that fall on the densities and winds of the upper atmosphere and the their lands—and once they learned of the effort to nationalize development of forward scatter communication techniques. them they would demand “Nay” votes from their But it showed us that we had a lot to learn about meteors and congressmen. Several other members agreed; someone added fireballs. that nationalization would tend to dry up sources. Nobody UBM: In 1971, the Canadians erected a 12-station would admit to finding a meteorite knowing it would be Meteorite Observation and Recovery Project in their prairies claimed by the government. In the end, nationalization was and maintained it until 1985. I recently asked Ian Halliday, in killed by differences between NASA and the Smithsonian. Ottawa, about their results. They recovered one meteorite in The draft favored by NASA would award to NASA the first their 14 years of operation. That was Innisfree, an ordinary say in disposition of meteorites collected by the Prairie Net chondrite that fell on February 5th, 1977. It gave us our third (and possibly elsewhere in the USA), so Roy Clarke, one of orbit originating in the asteroid belt. So, the three camera our curators, said SI would oppose it. That effectively brought networks (in Europe, the USA, and Canada) operated for a these negotiations to a close. total of about 20 years and recovered one meteorite each! FLW: Congratulations to Roy. As things turned out, we FLW: I’m glad we each got one instead of one of us didn’t need new legislation. We recovered only one meteorite getting all three. from the Prairie Net in its ten years of operation. UBM: I agree, but this does make meteorites seem more UBM: That was the Lost City, Oklahoma, chondrite. It rare than we supposed they were. The Canadians observed fell on January 3rd, 1970 and yielded the second orbit that cometary objects often attain greater brightness than originating in the asteroid belt. asteroidal ones of similar mass, possibly because of their FLW: The fireball was recorded by four cameras and the higher velocities and/or because they fragment more severely. sonic booms were heard for about 1,000 square kilometers. FLW: Even so, I believe that by compiling an immense Six to eight inches of snow fell before our team from Lincoln amount of data on velocities and brightness of meteors and found the first stone on a dirt road close to the predicted fireballs, and keeping track of the amount of clear sky impact point. observed at each station, they eventually learned to UBM: It had been discovered previously by a dog, hadn’t distinguish between asteroidal and cometary materials. That it, as shown by footprints and yellow snow? was one of their important results. FLW: Yes, it was hardly pristine for purposes of UBM: Let’s go back for a moment to 1965, when you astrobiology. Later on, three more pieces were found in the were beginning to install lasers at the Baker-Nunn stations. fields, making a total of 17 kg. We made mutually agreeable Given the increased accuracy of station locations, you arrangements with the landowners. expected not only to refine the model of the geoid but also to UBM: Even without more meteorites, I believe the measure crustal motions, if any. So a series of seminars was Prairie Net was truly worthwhile. planned for the summer of 1966 to discuss new research FLW: It was. When McCrosky and Zdenek Ceplecha results to be expected from laser tracking. Chuck Lundquist compared the Prairie Network results with those of the All-Sky asked me to give a session on what was known about motions Network in Czechoslovakia and Germany, we learned that we across the East African Rift system (that was before Paul shared problems that were new to us. We had supposed that Mohr joined us). However, in mid-June, when I received the meteorites produced fireballs of greater brilliance than did program for the seminars, I discovered I was expected to fragile, cometary materials. But both networks photographed speak on the status of the continental drift controversy! many very bright meteors that did not produce meteorites. In FLW: And Chuck hadn’t told you are asked you about that? fact, the fireball of P¯íbram, itself, which has a density of 3.6 g/ UBM: No, he certainly hadn’t. But I didn’t complain cm3, displayed all the characteristics we expected of low- because continental drift is a much more interesting topic than Oral history: F. L. Whipple A211 the East African rifts. I had learned in graduate school at Permit and immediately began to build a road up the mountain. Harvard that continental drift was a preposterous notion, but UBM: That was a very steep incline requiring many by 1966 new ideas were stirring. I read every new publication switchbacks. If I remember correctly, the road is about five about it I could find and talked with Pat Hurley, the miles long. geochronology professor at MIT. He persuaded me there was FLW: It is. And to put up our instruments and living solid evidence for the horizontal motion of continents. In July, quarters, we had to level off some of the high ridges as well as I tried to give an even-handed account in my seminar but by the highest peak. The first major instrument to be installed, the time the manuscript was due in December, I was an avid early in 1968, was the Large Optical Reflector, or “light convert. Pole reversals had become gospel, magnetic stripes bucket,” for research in gamma-ray astronomy. It is a 10- on midocean ridges had been dated, and Hurley had matched meter concave mosaic of 252 hexagonal mirrors of curved rock provinces between Ghana and Brazil. The ocean floors glass with a photomultiplier tube at the focus. were seen as moving from ridges to trenches carrying along UBM: Gamma-ray detection was very new to astronomy continental fragments. I wrote several articles on this and a at that time, wasn’t it? book, at the request of Smithsonian Press. FLW: It surely was. We had assumed for years that gamma FLW: Your book was full of fresh information and ideas radiation must exist, but it was not actually detected until the I wasn’t fully up-to-date on. I forget just when it came out. early 1960s when balloons and satellites lifted the detectors UBM: It was published in 1973. By then, the plate above the atmosphere. The atmosphere absorbs gamma-ray tectonics model had taken hold far and wide. In the three photons but, at Mt. Hopkins, we used the atmosphere as an aid decades since then, the actual motion of plates has been to detection, not of the photons themselves but, of the Cerenkov measured by global networks of our stations and of very long radiation produced when air is bombarded by gamma-rays. Our baseline interferometers, and by the slowly shifting positions dish has measured gamma radiation from numerous sources of laser ranging observatories on Earth as they beam to the within and beyond our galaxy. retroreflectors placed on the Moon by Apollo 11 and some of UBM: That gamma-ray detector is an exotic instrument the later missions. The results are close to those predicted by that looks like a futuristic piece of art with its hexagonal the theory. amber-tinted mirrors looming high above a visitor. Along You served on at least one of the committees that was with the gamma-ray dish you installed a laser for satellite preparing for Apollo 11, didn’t you? tracking and broke ground, early in 1968, for both a Baker- FLW: Yes, I was a member of a scientific advisory Nunn camera station and a 60-inch reflector telescope. That committee so I watched the Apollo 11 landing from the was quite an assemblage of things. When was the Mt. Mission Control Center at Houston. I thought I was paying Hopkins Observatory dedicated? close attention but I missed seeing the astronaut collect the FLW: It was dedicated in 1968 At last, the SAO had contingency sample. earned the “O” in its title. The 60 inch (152 cm) reflector UBM: Perhaps you didn’t recognize it for what it was. telescope was dedicated in 1970 and named for the SAO’s The astronaut held a pole with a scoop and a bag at the far end administrative director, Carl Tillinghast, who had died quite and swung it through the surface soils several times. suddenly at an early age after putting a great deal of effort into FLW: I must have seen it, but had no idea what he was developing Mt. Hopkins. doing. UBM: I remember Carl with much affection. He saw to UBM: I would like to turn now to your plan to build the my all administrative needs very graciously and often wanted SAO its own astronomical-astrophysical observatory— to talk with me about South America. It was his favorite place something it had lacked from the time it was founded in 1890. to travel. FLW: My idea was to build an observatory on an easily Long before 1970, you had ideas of erecting an entirely accessible mountain peak somewhere in the Southwest where new type of telescope on the mountain peak, didn’t you? skies are relatively dark and clear. I always was on the lookout FLW: Yes, I had. I always have been fascinated by the for good observing sites and, with guidance from Gerard multiple lens system of a fly’s eye, and wondered if a Kuiper, at the University of Arizona, I decided on Mt. Hopkins, telescope could be designed with an analogous structure. To 40 miles south of Tucson. The peak is just over 8,500 feet high make a rather long story short, that is what we did. In the late and located in the Coronado National Forest, which protects it 1960s, we received word that the US Air Force would give us from private development. I personally think this was the best seven light weight, 1.8-meter, fused quartz mirror blanks. observing site remaining in North America. Both the Kitt Peak Such a saving of costs enabled us to persuade Dr. S. Dillon National Observatory, west of Tucson, and the University of Ripley, the Secretary of the Smithsonian, to approve the Arizona’s Lunar-Solar Observatory north of Tucson, are in the building of a multiple-mirror telescope, and it enabled him to general vicinity. I should emphasize that the Mt. Hopkins persuade congress to support it. We designed a telescope Observatory was a joint venture of SAO and the University of consisting of six identical, 183 cm reflecting telescopes, Arizona. In February, 1966, we received a Forest Service mounted in a hexagonal array and beaming their images to a A212 U. B. Marvin single focus. In the center was a 76 cm reflector as a guide without a mishap. The telescope has the largest effective telescope. This arrangement gave us the light-gathering aperture of any in North America. It is a worthy successor to equivalent of a 447 cm mirror, in a much lighter weight and the MMT. lower cost (although more complicated) instrument. During UBM: Of the many honors you have received, Fred, I construction, the floor on which the MMT rests was made to would like to ask you about two of them. The American rotate, and this added versatility. In addition, the MMT could Geophysical Union presents a Fred L. Whipple Award to “see” in the infrared. scientists who have made outstanding contributions to the UBM: Some say that the MMT should be called the MTT geophysical aspects of planetary science. You were the first (multiple telescope telescope) because it actually consists of recipient. six separate telescopes. FLW: Yes, that was in 1990. I played no role in establishing GLW: Well, but, that name never caught on. the Award. That was done entirely within the AGU. The UBM: The MMT was dedicated on May 9, 1979. You geophysicists said it was for my contributions to geodesy, were the opening speaker at the ceremonies, Fred, but you had derived from satellite tracking, and to our knowledge of the retired in 1973, six years earlier. upper atmosphere gained through meteor studies. FLW: Yes, I saw lots of my projects develop successfully UBM: And in 2000, the Library of Congress declared after my retirement. you to be a Living Legend. UBM: I believe you played a role in the linking of the FLW: I don’t feel very legendary, but I am pleased to be Smithsonian Astrophysical Observatory with the Harvard still living. College Observatory to form the Harvard-Smithsonian Center UBM: And all these years, until very recently, you have for Astrophysics, although, the change took effect in 1973 continued to raise grants for research on comets and small under your successor, George B. Field. George and his bodies of the solar system. In fact, you were a member of the successor, Irwin I. Shapiro, have each served as Directors of science team of NASA’s Comet Nucleus Tour mission which both observatories, while each one has maintained its own blasted off in 2002, the year of your 95th birthday. business office, human resources office, support staff, and so FLW: I had a grant for taking part in that project, but that on. mission came to a sad end. FLW: Yes, but I think it appears to be more complicated UBM: The Stardust mission, of which Don Brownlee, at than it is. Many of our scientists share appointments from the University of Washington in Seattle, is the Principal both observatories and all of the major projects include Investigator, is still performing beautifully, though. It is the first scientists from both. US mission dedicated to sampling a comet (comet Wild 2) and UBM: Some of my colleagues from the Smithsonian in returning the material to Earth. It lifted off on February 7th, Washington thought I was getting snobbish when I added 1999, collected interstellar dust in 2001 and 2002, and Harvard to my Smithsonian address, but that is exactly what encountered comet Wild 2 last January 2nd. You were the guest we were instructed to do on all our publications, letters, and of honor at the blast-off in Florida, and Stardust is scheduled to name tags. return to Earth in 2006, the year of your 100th birthday! It is FLW: I’m sure your friends must have gotten used to it by imperative for you to be on hand to celebrate its return. now. It happened more than 30 years ago. FLW: I certainly would like to—I’ll do my best. UBM: Another long ago event we should remember was UBM: Thank you, Fred, for discussing your career with the rededication in 1982 of the Mount Hopkins Observatory me. Your lists of accomplishments and honors go on and on, as the Fred Lawrence Whipple Observatory. So your way beyond what we have included here, but I believe we accomplishments are memorialized by a very active array of have touched on most of the highlights. Incidentally, I innovative research projects on the mountain top and an attribute your continuing health and vigor to the fact that for attractive visitor’s center down below. The staff members of nearly five decades you rode your bicycle two and a half the Center carry on strong educational outreach programs. miles from your home to the observatory and back with a FLW: I am pleased with that and with the leading roles steep hill at each end of your route. Young people should find being played by the scientists who come and go to the great inspiration in your example. Thank you, again. observatory to use the equipment for their research. UBM: The MMT served very well for 19 years and then Acknowledgments–I wish to thank the Council of the it was replaced in 1998. Meteoritical Society for support of this effort. This interview FLW: It was replaced by a single 6.5-meter mirror that has been edited in consultation with Professor Whipple. could not have been made in the 1970s. It was the creation of Roger Angel at the University of Arizona. He cast tons of SELECTED REFERENCES borosilicate glass in a rotating furnace that produced a lightweight, honeycombed structure with a parabolic De Carli P. S. and Jamieson J. C. 1961. Formation of diamond by surface—an amazing accomplishment. We all held our breath explosive shock. Science 133:1821–1822. (not quite literally) while the mirror cooled, but it did so Field G. B. and Cameron A. G. W., editors. 1973. The dusty universe. Oral history: F. L. Whipple A213

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