Remembering Dr. Comet

I really wish Fred Whipple was still alive to see the newspapers this week. There, amidst the Middle East horribleness, he would have read about how the space probe Rosetta is nearing the comet 67P/Churyumov-Gerasimenko. As of this morning, the craft had pulled to within 60 miles of 67P’s surface. Both are traveling about 35,000 miles per hour – that’s 10 miles a second (!) – in a compact duet. And, if all goes to plan, Rosetta will soon jettison a dishwasher-sized box called Philae which will land on the comet and analyze it.1

Screen Shot 2014-08-07 at 1.19.54 PM

Artist’s rendering, courtesy of ESA, of Rosetta and Philae.

This exciting space mission – landing on a comet! C’mon…that’s wild! – makes Whipple’s absence all the more notable. Unfortunately, the American astronomer passed away in 2004, just five months after the European Space Agency launched Rosetta. 

Whipple would have appreciated the Rosetta mission for at least two reasons. It would have spoken to his career as a scientist and also connected with his bold and ambitious plans for large-scale, high-profile scientific programs.

Who was Fred Whipple? He was born in 1906 in Red Oaks, Iowa but his family soon joined the migration of Midwesterners to southern California where he attended the University of California, Los Angeles. His choice of a career in astronomy was serendipitous, almost made by default. The lab work of physics didn’t appeal to him and he was too squeamish to pursue a medical career despite his parents’ wishes. Fortunately, Whipple enrolled in an astronomy course his junior year and he relished it.

Screen Shot 2014-08-07 at 1.07.39 PM

Portrait of the astronomer as a young man.

After graduation, armed with a letter of recommendation from his astronomy teacher, he started classes at Berkeley in 1927. There, Whipple came under the tutelage of Armin O. Leuschner. Leuschner’s research specialty was orbit theory and computing the motions of celestial bodies, especially comets and asteroids.

Whipple finished his degree in 1931 and had to decide what to do next. The Depression was underway, Whipple was newly married with a young son, and few people saw astronomy as the path to riches and stability. Nonetheless, Harlow Shapley, the well-known director of the Harvard College Observatory, offered Whipple the opportunity to come to the Harvard observatory as a staff member. Whipple accepted and soon started a research program studying meteors and comets.

In the late 1940s, the origin and makeup of comets still puzzled astronomers. Most scientists thought comets were basically flying clouds and chunks of particles held together by gravity (i.e. the “gravel-bank” model). Yet this conceptual picture couldn’t account for a good deal of observational evidence or explain their origin. Why did comets seem to be so fragile, with some breaking up after passing by the sun a few times? And why did their movement and speed change over time?

Screen Shot 2014-08-07 at 1.52.04 PM

Astronomer Fred Whipple demonstrates “dirty snowball” model for comets with a five-hundred-pound snowball covered with dirt. Source.

Whipple’s pre-World War Two research on meteor primed him to develop a more accurate model for the structure of comets. Specifically, he tried to account for the jet-like action seen as material vaporized from an incoming meteor. He realized that a new model of a comet’s core could explain such effects. In a series of papers and presentations from 1949 to 1951, Whipple proposed that the cores or nuclei of comets are icy conglomerates or, as the press later called them, dirty snowballs.2

Whipple’s model accounted for a whole host of behavior including the jet-like structure in the region around the comet’s nucleus which can alter the body’s speed and direction. The idea also explained why comets can produce streams of meteors as they near the earth. Later seen as one of the most important contributions to solar system science in the 20th century, Whipple’s articles outlining his comet model became some of the most widely cited papers in the astronomical literature.3  Nicknamed “Dr. Comet,” he parlayed recognition from the science community into more resources for his research programs at Harvard.

Screen Shot 2014-08-07 at 1.23.29 PM

Whipple, later in life. Note “star tie” and picture of him biking with comet tail in background.

In May 1955, Leonard Carmichael, the secretary of the Smithsonian Institution, presented Whipple as the new director of the then-moribund Smithsonian Astrophysical Observatory. Just as important was Carmichael’s news that the observatory would relocate from Washington, DC to Cambridge where it would be affiliated with Harvard University. This placed him at the epicenter of the Cambridge science community, gave him control of the SAO’s research agenda, and enabled him to get an even firmer foothold in Harvard’s astronomy program.

When scientists announced plans for the International Geophysical Year, Whipple saw the opportunity. If the Americans and Soviets were going to launch the world’s first satellites, someone, he reasoned, would have to track and photograph them. While this research might sound mundane today, in 1957 it was basic information essential for any future space exploration by either people or machines. Before orbiting satellites could provide scientists and engineers with this cornucopia of information and applications, they needed know where the satellites were and how they moved.

Screen Shot 2014-08-07 at 1.07.55 PM

Whipple, 1957, explaining satellite orbits to reporters.

Whipple’s bold plan depended on the cooperation and integration of three very different ingredients. First, the SAO would establish a network of a dozen, specially-designed cameras that could photograph satellites while simultaneously viewing relatively large swaths of the sky. These would be located all around the globe – Hawaii, Iran, Australia, and South Africa all had one – and manned by trained technicians.

Screen Shot 2014-08-07 at 1.08.06 PM

Fred Whipple stands in front of a Baker super-Schmidt meteor camera, ca. 1952. (Credit: AIP Emilio Segrè Visual Archives).

Second, these camera stations would send their information and photographs to the SAO in Cambridge where experts would crunch the numbers and predict the satellites’ orbits. But all of this depended, however, on having a rough idea of where to look in the first place. The third element of Whipple’s plan was Operation Moonwatch, a global network of amateur satellite spotters. Whipple’s satellite tracking network was far-flung and complex with many moving parts. Yet, during the first years of the Space Age, it functioned very well as tens of thousands of observations from professionals and amateurs alike poured into Cambridge to be processed into orbital calculations. It also helped make Whipple and his colleagues Space Age celebrities.

Screen Shot 2014-08-07 at 1.23.49 PM

Whipple and SAO colleagues, posing in satellite-tracking mode.

NASA and military contracts for satellite tracking, worth millions of dollars annually, became the SAO’s largest source of revenue in the early 1960s. They enabled Whipple to oversee a rapid expansion of the SAO into promising new areas of research such as space studies, planetary science, and astrophysics while strengthening its expertise in meteoritic and cometary studies. These endeavors were linked to Whipple’s own interests in the upper atmosphere and meteorites and greatly expanded his observatory’s research networks. The end result – by the 1960s, Whipple  had transformed the SAO into the world’s largest astronomical research center. 4

Despite the long list of honors he received including election to the National Academy of Sciences, recognition for his research from Presidents Truman and Kennedy, and dozens of awards from scientific societies around the world, Whipple hesitated to describe himself as a scientist. “I’m fundamentally,” he told an interviewer, “an engineer at heart.” Comets, meteors, planetary astronomy, variable stars, supernovae, radio astronomy, telescope design – Whipple worked in all these areas. Yet his view of himself as an engineer, someone with an intuitive understanding of how things work and what can be done with them, explains a great deal about Whipple’s career.

ESA’s accomplishment will be a fitting tribute to Whipple who possessed a lifelong fascination for scientific research while also imagining the possibilities that futuristic and ambitious endeavors like landing on a comet held. So – on November 11, when Rosetta sends Philae down to stick a landing on 67P, I’ll be raising a toast to Dr. Comet.



  1. Named after an island in the Nile where an obelisk was found that was used in conjunction with the Rosetta Stone to decode Egyptian hieroglyphics. []
  2. Fred L. Whipple. “A comet model. I. The acceleration of Comet Encke.” The Astrophysical Journal 111,  (1950): 375-394. []
  3. 1950 and 1951 were especially fruitful times for comet research and Whipple’s work meshed well with Jan Oort’s 1950 idea of comet clouds about the sun and Ludwig Biermann’s 1951 interpretation that electrically charged particles from the sun could interact dramatically with a comet’s tail. Whipple’s 1950 article about Comet Encke was named in 1999 as one of the most important papers to appear in The Astrophysical Journal. []
  4. Consider the institution’s personnel — when Whipple was hired, the SAO had three scientists on staff. By 1963, the SAO employed some 330 people and had grants and contracts worth several million dollars. []

Did the Hippies Give Us Drones?

Should we blame the hippies for today’s generation of drone aircraft?1 Hmm. An interesting but odd proposition. Here’s another question for you, one which might lead to an answer. What do the two aircraft below have in common?

Screen Shot 2014-08-01 at 9.43.19 AM

Answer #1: Both are connected closely to the career of inventor Paul B. MacCready (shown below in a 1999 photo). To be sure, in this picture and every other that I’ve seen, MacCready looks nothing like a hippie).2

Screen Shot 2014-08-01 at 10.06.02 AM

The object on the left is the Gossamer Condor. Designed by MacCready, a Caltech-educated scientist (1925-2007) with advanced degrees in physics and aeronautical engineering. In August 1977, the Condor became the first aircraft capable of sustained human-powered flight when pilot Bryan Allen pedaled it around a figure-8 course. Only one was ever built and it’s currently hanging in National Air and Space Museum.

The craft on the right is a Puma, an “unmanned aircraft system” – i.e. a drone. A four and a half foot-long craft with a propeller in the nose and a swiveling camera on its underside, it was originally built for military applications. Recently the Puma was also approved for environmental monitoring and resource surveys. Since it first flew in 2007, more than 1,000 Pumas have been built – each costs $250,000 – and they are deployed all around the globe.

Answer #2:  Both aircraft originated from the machine shops and design boards of AeroVironment, the California-based company that MacCready started in 1971.

Drones, of course, are a hot news topic now. What is more of interest to me, however, is the indirect path that led from MacCready’s fascination with gliding to his desire to make a person-powered aircraft to today’s AeroVironment which supplies some 85% of the U.S. military’s drones.

As the title of the post suggests – a twisted trail leads from countercultural ideals of “soft technologies” to displays of hard power and omnipresent surveillance via drones in today’s war zones. Can we blame the hippies for drones? Well, not quite. But there are some interesting connections.3

The story of MacCready and AeroVironment is one of contingency and chance, not causality. That is to say, MacCready’s environmental interests and explorations of alternative approaches to flying do not directly lead to Predator drone strikes in Pakistan.4 But I think the story of AeroVironment (and MacCready’s career) says something about how childhood passions can be turned in unexpected directions.

Screen Shot 2014-08-01 at 11.41.28 AM

MacCready, age 15, posing with gas-powered model plane. Photo from Paul B. MacCready papers, Caltech Archives.

Born in 1925, as a boy, MacCready was fascinated with model airplanes. He was part of that generation influenced by what historian Joseph Corn called “the winged gospel” – the idea that flight could serve as a means to transform society in positive ways. He soon became a champion glider pilot. This required having supreme mastery of a piloted craft, an irony given the turns his life’s work would ultimately take.

Screen Shot 2014-08-01 at 11.42.48 AM

MacCready, 1948, competing in soaring contest over Torrey Pines, CA.

After graduating with his PhD from Caltech in 1952, MacCready founded a company called Meteorology Research Inc.. Its primary activity was weather modification via cloud seeding.

In a 2003 interview, MacCready noted that, by the early 1970s, he was increasingly interested in environmental issues. In the summer of 1971, with two colleagues from Caltech, he started AeroVironment. Some of their first work involved building instruments to study meteorological disturbances like thunderstorms. But what brought media attention and profitability to MacCready and his fledgling company was the Condor and its pedal-powered successor, the Gossamer Albatross.

MacCready, as he often related it, was motivated to build the Condor because of a business debt he owed. He learned of the Kremer Prize, set up in 1959 by a British industrialist, which offered £50,000 to the first group that could demonstrate sustained human-powered flight. The Condor flew in 1977 and the Albatross crossed the English Channel two years later. The prize money for both feats paid off MacCready’s debts and then some. 

Screen Shot 2014-08-01 at 11.01.44 AM

AeroVironment’s Solar Challenger

Interests in alternative energy and energy efficient vehicles followed along with documentary films, books, and magazine articles about MacCready’s designs. In November 1980, another craft built by AeroVironment flew – the Solar Challenger – powered by an electric motor charged by photovoltaic cells.

Besides also crossing the English Channel, the Solar Challenger also set an altitude record of over 14,000 feet. MacCready saw feats like this as a way of bolstering support for the solar power industry. As he recalled, “we felt that flying an airplane on solar power would be a bit of a help to the field, because it would bring a lot of publicity.” The strategy succeeded. Bolstered with a higher profile, one of the projects he pursued was the Sunraycer, a solar powered race car, that AeroVironment developed in the 1980s with General Motors and Hughes Aircraft.

Screen Shot 2014-08-01 at 11.10.14 AM

Altogether, MacCready’s work brought him personal accolades and attention. In 1982, for example, he received the Lindbergh Award for his “significant contribution toward creating a better balance between technology and the environment.” But government support for solar power, and alternative energy projects in general, diminished starting during the Reagan years as costs of fossil fuels fell and MacCready looked to other patrons.

The Department of Defense, flush with money from Reagan’s Strategic Defense Initiative, funded AeroVironment to explore unpiloted high-altitude solar-powered craft.  One of these projects, Helios, first flew in 1999. Later, the project was taken over by NASA. In August 2001, Helios flew to over 100,000 feet, the highest any aircraft had ever flown. A month later, 9/11 happened and armed drones – not made by AeroVironment, just to be clear – were deployed in the Afghanistan region.

Given this history, AeroVironment’s gradual drift into unmanned drone aircraft seems more understandable. But what is intriguing to me – regardless of how one feels about issues drones raise about safety, privacy, proliferation, and foreign policy – is that one part of their technological history goes back 1970s-era ecological thinking. We might think of AeroVironment’s history as one of good intentions, a “what if” story…and that’s where the contingency and circumstance come into play.

Over time, AeroVironment had transitioned from a company with 70s-era environmental aspirations to a military contractor.5 Near the end of his life, MacCready expressed great pessimism about the future, humans’ technological control of nature, and the state of the world.  As he told an interviewer, “We are no longer living in a big world that we’re just a part of and a lot of other things are a part of, too. We are now in charge…I’m probably the most pessimistic [of our board members]. The businesses we get into are good businesses for the company, but they tend to be businesses that fit with the realities of the world.”

Today, the company MacCready started more than forty years ago still maintains an Efficient Energy Systems division…so maybe there’s still some hope that the animating aspirations that got AeroVironment started can still take flight.


  1. Those in the history of science community may rightly see this post’s title as an homage to my colleague Dave Kaiser’s splendid book How the Hippies Saved Physics. []
  2. MacCready’s professional papers have been donated to the Caltech Archives; a finding aid for them is available here []
  3. Obviously, there is a much longer history of drones and unpiloted aircraft, one that goes all the way back to World War One and the “air torpedoes” that inventor Elmore Sperry developed for the Navy. []
  4. The Predator and other such models are not made by AeroVironment; according to its website, the company only makes one weaponized model []
  5. According to its 2013 financial report, 43% of AeroVironment sales are to the U.S. Army []